Heat-receiving member and exhaust pipe heat-releasing system

Description

TECHNICAL FIELD

[0001] The present invention relates to a heat-receiving member and an exhaust pipe heat-releasing system.

BACKGROUND ART

[0002] An exhaust pipe connected to a vehicle engine becomes significantly hot in driving operation because combustion gases (exhaust gases) flow therethrough. In a high-load and high-revolution area of the engine, fuel is increased so as to avoid a rise in temperature of exhaust gases. In such a case, however, a problem arises that the fuel efficiency is lowered and the concentration of exhaust gases is raised, so that the discharge amount of contaminants is increased.
Further, when the temperature of the exhaust pipe is raised by a flow of exhaust gases, it causes heat degradation of the exhaust pipe.

[0003] Inside an exhaust pipe, a catalyst is provided for converting exhaust gases discharged from a vehicle engine. For example, a three-way catalyst can convert contaminants such as hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) which are contained in exhaust gases.
In order to convert these contaminants by a three-way catalyst more efficiently, it is necessary to maintain the three-way catalyst at a predetermined activation temperature.

[0004] However, in a high-speed operation of a vehicle engine, exhaust gases become very hot and there may be a case where the temperature of a three-way catalyst becomes out of the effective range for conversion of exhaust gases and the three-way catalyst fails to convert contaminants properly. Moreover, there may be a case where the three-way catalyst is thermally deteriorated due to high-temperature exhaust gases.

[0005] Accordingly, it is desirable that, in the high-speed operation of the vehicle engine, the temperature of the exhaust pipe connected to a vehicle engine not rise too high and the exhaust pipe be appropriately cooled.
Patent Document 1 discloses a heat insulator that can appropriately cool an exhaust pipe connected to a vehicle engine.

[0006] Patent Document 1: JP-A 6-336923
DE 42 06 247 discloses an exhaust pipe for an internal combustion engine. It is described that a housing for a water-cooling is provided with an anodized oxide layer as a corrosion protection.
JP 58-19654 describes the formation of a selective absorber film for solar energy wherein pores are formed by anodic oxidation of aluminum and that metal is precipitated in the pores fully and uniformly by electrolytic coloring treatment.

DISCLOSURE OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] Fig. 1 is an exploded perspective view which illustrates a vehicle engine and a vicinity of an exhaust pipe connected to the vehicle engine.
In Fig. 1, "110" indicates an engine and a cylinder head 117 is mounted on a top of a cylinder block 116 of the vehicle engine 110. Further, an exhaust manifold 111, which contains cast iron with high heat resistance, is attached on one side face of the cylinder head 117.

[0008] The exhaust manifold 111 has a function of gathering exhaust gases from respective cylinders and transferring the exhaust gases to a not-shown catalyst converter and the like. That is, the exhaust manifold 111 functions as an exhaust pipe through which exhaust gases from the engine flow.
Part of the outer peripheral face of the exhaust manifold 111 is covered with a heat insulator 118. The heat insulator 118 is arranged over the outer peripheral face of the exhaust manifold 111 with a predetermined space therebetween.

[0009] Patent Document 1 sets the emissivity of the heat insulator to be more than the emissivity of the exhaust manifold. Patent Document 1 describes that setting the relationships of the emissivities as such increases the amount of radiation heat transferred between the exhaust manifold and the heat insulator, and thus improves the cooling ability of the exhaust manifold.

[0010] Patent Document 1 also describes that a black, heat-resistant coating is applied to the heat insulator that is made of cast iron so as to improve the emissivity of the heat insulator.

[0011] Recently, aluminum or an aluminum alloy (hereinafter referred also to simply as aluminum) has often been used as a material for a heat insulator in order to reduce the vehicle body weight, and the like.
However, when a heat insulator made of aluminum is arranged so as to cover the peripheries of an exhaust manifold, the amount of heat for the heat insulator to receive from an exhaust pipe by radiation heat transfer is not so large because aluminum is a material with low emissivity.
Hence, there has been a problem in which the temperature of the exhaust pipe, when aluminum is used as a material for a heat insulator, cannot be decreased by radiation heat transfer and therefore the temperature of the exhaust pipe rises too high.

[0012] In view of such a problem, the inventors of the present invention studied a method of applying to aluminum a black, heat-resistant coating which is similar to the coating disclosed in Patent Document 1 so as to increase the emissivity of aluminum. However, sufficient adhesion was not obtained between aluminum and the heat-resistant coating, and the heat-resistant coating peeled off from aluminum. Thus, the inventors were not able to increase the emissivity of aluminum by this method.

[0013] The present invention was made in view of the above problem, and an object thereof is to provide a heat-receiving member which demonstrates excellent performance in receiving,
by radiation heat transfer, heat energy that is released from a heat source such as an exhaust pipe; and an exhaust pipe heat-releasing system that can prevent the temperature of the exhaust pipe from rising too high.

MEANS FOR SOLVING THE PROBLEMS

[0014] That is, a heat-receiving member according to claim 1 receives heat energy released from an internal combustion engine, and comprises: a base that contains aluminum or an aluminum alloy; and a surface layer that is formed by anodizing a surface of the base, and a plurality of crocks formed in the surface layer.

[0015] The heat-receiving member according to claim 1 has the surface layer formed by anodizing the surface of the base that contains aluminum or an aluminum alloy.
The emissivity of the surface layer formed by anodizing the surface of aluminum is higher than the emissivity of aluminum. High emissivity of the surface of the surface layer allows the surface layer to receive by radiation heat transfer a large amount of heat released from the heat source, when the heat-receiving member of the present invention is arranged with the surface layer thereof facing the heat source such as an exhaust pipe. That is, the heat-receiving member of the present invention is excellent at receiving, by radiation heat transfer, heat released from a heat source. Further, use of such a heat-receiving member makes it possible to promote heat release from the heat source.
The interface between aluminum and a surface layer formed by anodization is chemically stable and the adhesion between aluminum and the surface layer is strong. Therefore, the surface layer does not peel off from aluminum.

[0016] In the heat-receiving member according to claim 2, the heat-receiving member has a first region and a second region, the first region is located farther from a high-temperature part of the heat source than the second region, and the first region has emissivity higher than emissivity of the second region.
The first region herein also means a region far from the high-temperature part of the heat source. The second region herein means another region or a region close to the high-temperature part of the heat source.
Now, the variation of temperature distribution inside the heat-receiving member adjacent to the heat source is considered. With regard to the temperatures of respective regions in the heat-receiving member, much heat is transferred to the region close to the high-temperature part of the heat source, and thus the temperature of the region tends to rise. On the other hand, not much heat is transferred to the region far from the high-temperature part of the heat source, and thus the temperature of the region tends not to rise. As a result, a high-temperature region and a low-temperature region generate inside the heat-receiving member. This temperature difference inside the heat-receiving member leads to generation of thermal stress in the heat-receiving member, which might distort the heat-receiving member.

[0017] The region having higher emissivity than the another region in the heat-receiving member according to claim 2 receives a large amount of heat per unit area because the region easily receives heat by radiation heat transfer. The region having higher emissivity than the another region is thus a region in which the temperature tends to rise due to heat reception. Accordingly, placing the region having higher emissivity than the another region at a location far from the high-temperature part of the adjacent heat source makes it more likely for the temperature of the heat-receiving member to rise even if the region is located far from the high-temperature part of the heat source; hence, generation of a low-temperature region inside the heat-receiving member can be prevented.
That is, generation of a temperature difference inside the heat-receiving member can be prevented. Further, generation of thermal stress and distortion in the heat-receiving member can be prevented.

[0018] In the heat-receiving member according to claim 3, a micropore is formed in the surface layer in the first region, and a metal is deposited in the micropore.
Deposition of a metal in the micropore in the surface layer makes it possible to increase the emissivity of the region. That is, placing the region with a metal deposited in the micropore formed in the surface layer thereof at a location far from the high-temperature part of the heat source makes it possible to more effectively prevent generation of a low-temperature region inside the heat-receiving member.

[0019] In the heat-receiving member according to claim 4, the second region includes a region in which the surface of the base is unanodized and exposed.
In this case, the emissivity of the region with the surface of the base exposed thereon is low. Placing the region with the surface of the base exposed thereon at a location close to the high-temperature part of the heat source makes it possible to prevent the temperature of the heat-receiving member from rising too high even if the region is located close to the high-temperature part of the heat source; hence, generation of a high-temperature region inside the heat-receiving member can be prevented. That is, generation of a temperature difference inside the heat-receiving member can be prevented.

[0020] In the heat-receiving member according to claim 1, a plurality of cracks are formed in the surface layer.
Here, a coefficient of thermal expansion of the surface layer formed by anodization is different from a coefficient of thermal expansion of aluminum or an aluminum alloy used as the base. Thus, a rise in the temperature of the heat-receiving member leads to application of thermal stress between the base and the surface layer. When the thermal stress applied between the base and the surface layer is large or the thickness of the base is small, a fissure might be generated in the base (the base might split).

[0021] Since the plurality of cracks are formed in the surface layer of the heat-receiving member according to claim 1, part of the thermal stress applied between the base and the surface layer is absorbed at the cracked parts, whereby an increase in the thermal stress applied between the base and the surface layer is prevented. As a result, generation of a fissure in the base due to the thermal stress can be prevented.

[0022] In the heat-receiving member according to claim 5, the cracks are separated from each other.
The cracks separated from each other absorb the thermal stress and grow upon application of the thermal stress to the surface layer. As a result, generation of a fissure in the base is effectively prevented. Further, the continuous surface layer increases the rigidity and thus makes it easier for the heat-receiving member to maintain the shape.

[0023] In the heat-receiving member according to claim 1, at least one of the cracks has a zigzag shape.
When the cracks each have a zigzag shape, resistance to the force applied in a direction parallel to the cracks is generated. Hence, generation of a fissure in the base can be more effectively prevented.

[0024] In the heat-receiving member according to claim 6, a surface layer is also formed on a surface on the reverse side of the surface of the base.
In this case, surface layers are formed by anodizing both respective surfaces of the heat-receiving member, and therefore the emissivity of the both surfaces of the heat-receiving member becomes high. Then, the heat-receiving member can receive much heat on one surface and release much heat from the other surface. Accordingly, the temperature of the heat-receiving member tends not to rise, whereby the thermal stress to be generated in the heat-receiving member can be reduced.
The lower the temperature of the heat-receiving member, the larger the amount of heat that the heat-receiving member can receive. For this reason, the temperature of the heat-receiving member is prevented from easily rising even when the heat-receiving member has received heat, and thus the heat-receiving member of the present invention can demonstrate better performance in receiving heat by radiation heat transfer.

[0025] An exhaust pipe heat-releasing system according to claim 7 comprises: an exhaust pipe including a cylindrical base that contains a metal; and a heat-receiving member arranged over the exhaust pipe, the heat-receiving member being a heat-receiving member according to any one of claims 1 to 6.
The heat-receiving member of the present invention demonstrates excellent performance in receiving heat by radiation heat transfer. Hence, such a heat-receiving member arranged over the exhaust pipe can receive much radiation heat from the outer peripheral face of the exhaust pipe when the temperature of the exhaust pipe is increased by high-temperature exhaust gasses flowing through the exhaust pipe. Therefore, it is possible to prevent the temperature of the exhaust pipe from rising too high.

[0026] The exhaust pipe heat-releasing system according to claim 7 is provided with a surface-coating layer that is formed on the outer peripheral face of the base included in the exhaust pipe, and that contains a crystalline inorganic material and an amorphous binder.
Since provision of the surface-coating layer that contains a crystalline inorganic material and an amorphous binder leads to an increase in the emissivity of the outer peripheral face of the exhaust pipe, the amount of radiation heat from the outer peripheral face of the exhaust pipe is increased. The radiation heat from the outer peripheral face of the exhaust pipe is received by the heat-receiving member of the present invention which demonstrates excellent performance in receiving heat.
That is, improvement in the amount of radiation heat from the outer peripheral face of the exhaust pipe is combined with improvement in the amount of heat received by the heat-receiving member. As a result, it is possible to more effectively prevent the temperature of the exhaust pipe from rising too high.

[0027] In the exhaust pipe heat-releasing system according to claim 8, the exhaust pipe has an emissivity of 0.78 or more. The emissivity falling in such a range leads to improvement in the amount of radiation heat from the outer peripheral face of the exhaust pipe, thereby even more effectively preventing the temperature of the exhaust pipe from rising too high.

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment, not as such claimed)

[0028] Hereinafter, a first embodiment, which is one embodiment of a heat-receiving member and an exhaust pipe heat-releasing system, illustrative for aspects of the present invention but not claimed as such, is described with reference to drawings.
First, the heat-receiving member is described.
Fig. 2 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.
A heat-receiving member 1 illustrated in Fig. 2 includes a base 20 that contains aluminum or an aluminum alloy, and a surface layer 30 formed by anodizing the surface of the base 20.

[0029] The surface layer formed by anodizing the base has emissivity higher than the emissivity of aluminum. The emissivity (infrared emissivity) at a wavelength of 3 to 30 µm is, for example, 0.7 or more. The infrared emissivity can be measured by a radiometer (for example, an AERD produced by Kyoto Electronics Manufacturing Co., Ltd.).

[0030] The kind of aluminum or an aluminum alloy to be used as the base is not particularly limited so long as it can be anodized. For example, pure aluminum (1000 series), Al-Cu-Mg alloys (2000 series), Al-Mn alloys (3000 series), Al-Si alloys (4000 series), Al-Mg alloys (5000 series), Al-Mg-Si alloys (6000 series), Al-Zn-Mg alloys (7000 series), or the like can be used.

[0031] The shape of the base is not particularly limited, and can be, for example, a plate such as a flat plate, a curved plate, and a flexed plate. The shape can be set to any shape according to the shape of the place in which the heat-receiving member is to be used. The base may be formed by laminating a plurality of bases.
Further, the thickness of the base is not particularly limited either, and can be set to any thickness according to the amount of heat to be received by the heat-receiving member and the expected operating temperature of the heat-receiving member.
In the case where a heat-receiving member is to be provided in the exhaust pipe heat-releasing system of the present invention, the thickness of the base to be used in production of the heat-receiving member is desirably from 0.1 to 1.5 mm, more desirably from 0.3 to 1.0 mm, and even more desirably from 0.4 to 0.8 mm.
A thickness of less than 0.1 mm of the base may lead to insufficient strength. On the other hand, a thickness of more than 1.5 mm may lead to application of large compressive strain and large tensile strain to the surface layer upon deformation of the base.
In the case where the base is formed by laminating a plurality of bases, the thickness of the base is the sum of thicknesses of the laminated bases.

[0032] The thickness of the base is different before and after the anodization. Suppose that the surface of the base is taken as the reference position. When an oxide film with a thickness of ΔZ is formed on the upper side of the reference position by anodization, an oxide film with a thickness of ΔZ is to be simultaneously formed on the under side of the reference position by anodization, and thus the thickness of the base is to be decreased by Δ Z.
Accordingly, the thickness of the base used in production of the heat-receiving member can be presumed to be a thickness (ΔZ + T). The thickness (ΔZ + T) is obtained by measuring the thickness (2 × ΔZ) of the surface layer and the thickness (T) of the base in the heat-receiving member after the anodization, and by adding a half of the thickness of the surface layer, which is (ΔZ), to the measured thickness (T) of the base.

[0033] The surface layer is formed by anodizing the base, that is, by passing an electric current through an electrolytic bath with the base serving as the anode.
In the case of anodizing only one surface of the base, it is desirable that a masking tape or the like be put on the surface not to be anodized, for protection.
The thickness of the surface layer is desirably from 5 to 25 µm.
A thickness of less than 5 µm of the surface layer may decrease the emissivity. On the other hand, a thickness of more than 25 µm of the surface layer may increase the rigidity of the surface layer and thus increase the thermal stress applied to the adjacent base, thereby tending to generate a fissure in the base. Also, a thickness of more than 25 µm of the surface layer makes it difficult to perform electrolytic coloring. Further, a thickness of more than 25 µm of the surface layer is inefficient because it requires a longer time for anodization but does not lead to achievement of much effect of improving the emissivity.
The thickness of the base and the thickness of the surface layer can be measured by observing the cross-section of the heat-receiving member with a SEM or the like.

[0034] The electrolytic bath includes an acidic bath, an alkaline bath, and a bath of a non-aqueous solution such as a formamide series and a boric acid series. The acidic bath includes a bath of an aqueous solution in which one kind or two kinds or more of the following is/are dissolved: sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfosalicylic acid, pyrophoric acid, sulfamic acid, phosphomolybdic acid, boric acid, malonic acid, succinic acid, maleic acid, citrate, tartaric acid, phthalic acid, itaconic acid, malic acid, glycolic acid, and the like.
The alkaline bath includes a bath of an aqueous solution in which one kind or two kinds or more of the following is/are dissolved: sodium hydroxide, potassium hydroxide, sodium carbonate, potassium phosphate, ammonia water, and the like.

[0035] The current waveform at the time of electrolysis includes waveforms of direct current (DC), alternate current (AC), a superposition of AC and DC, a combination of AC and DC, an imperfectly-rectified wave, a pulse wave, a rectangle wave, or the like.
The electrolytic method includes a constant current method; a constant voltage method; a constant power method; a high-speed anodizing method based on a continuous current, an intermittent current, or current recovery; and the like.

[0036] The heat-receiving member of the present embodiment may have a micropore formed in the surface layer.
Fig. 3 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.
A heat-receiving member 2 illustrated in Fig. 3 has a large number of micropores 40 formed in the surface layer 30.
The micropores 40 are generated in the surface layer 30 when the thickness of the surface layer 30 formed by anodization becomes 10 to 20 nm. Further, as the anodization is continued on, the thickness of the surface layer 30 is increased and the depth of the micropores 40 is increased, whereby the plurality of deep micropores 40 are formed in the surface layer 30.

[0037] The heat-receiving member of the present embodiment may have a metal deposited in the micropores.
Fig. 4 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.
A heat-receiving member 3 illustrated in Fig. 4 has a metal 50 precipitated and deposited in the micropores 40 illustrated in Fig. 3 by electrolytic coloring.
Deposition of a metal in the micropores by electrolytic coloring further increases the emissivity of the surface layer.
Examples of the metal to be deposited in the micropores include metals such as Ni, Cu, Co, Pd, Sn, Pb, and Cd. A particularly desirable metal among these is Ni or Co because they can increase the emissivity of the surface layer.
Further, since use of Ni makes it easy to block the pore, Ni is more desirable.

[0038] Examples of a method of depositing a metal in the micropores include a method of passing an electric current through an electrolytic bath, which includes a metal, with the surface layer formed by anodization serving as the cathode, and the like.
The kind of electrolytic bath to be used to deposit a metal is not particularly limited. For example, in the case of depositing Ni, an electrolytic bath containing nickel sulfate can be used.

[0039] Further, silicate or zirconium hydroxide may be deposited in the micropores by alternately immersing a heat-receiving member in acid or alkali and in a silicate aqueous solution or zirconium salt bath.

[0040] In the heat-receiving members as illustrated in Figs. 3 and 4, the micropores formed in the surface layer may be blocked by a general method such as a method of immersing a heat-receiving member in boiling water, a method of immersing a heat-receiving member in hot water that contains a metal salt, or the like.

[0041] Next, the exhaust pipe heat-releasing is described.
Fig. 5 is a cross-sectional view schematically illustrating an exemplary exhaust pipe heat-releasing system.
An exhaust pipe heat-releasing system 100 illustrated in Fig. 5 includes an exhaust pipe 101 having a cylindrical base 102 that contains a metal, and the heat-receiving member 1 arranged over the exhaust pipe 101.
The heat-receiving member 1 is arranged such that the surface layer 30 formed by anodizing the surface of the base 20 faces the outer peripheral face of the exhaust pipe 101.
In Fig. 5, the heat transferred from the outer peripheral face of the exhaust pipe 101 to the surface layer 30 of the heat-receiving member 1 is schematically shown by arrows.

[0042] The exhaust pipe 101 is a member that is connected to an internal combustion engine such as an engine and that allows high-temperature exhaust gases to flow therethrough.
Examples of the material of a base 102 that forms the exhaust pipe 101 include metals such as stainless steel, steel, iron, and copper, and nickel-based alloys such as Inconel, Hastelloy, and Invar. These metal materials have high heat conductivity, and therefore can contribute to improvement in heat-releasing properties of the exhaust pipe 101.

[0043] Further, these metal materials have high heat resistance, and thus can be suitably used in high-temperature conditions. By using these metal materials as the base of the exhaust pipe, the exhaust pipe is allowed to have excellent resistance to thermal shock, excellent processability, excellent mechanical properties, and the like.

[0044] The shape of the base 102 is not particularly limited as long as it is a cylindrical shape. The cross-sectional shape thereof may be a circular shape, or may be any other shape such as an elliptical shape and a polygonal shape.

[0045] The heat-receiving member 1 has the surface layer 30 with high emissivity, as described above. Hence, the heat-receiving member 1 can receive on the surface of the surface layer 30 much heat that is radiated from the outer peripheral surface of the exhaust pipe 101 upon an increase of the temperature of the exhaust pipe 101.

[0046] The shape of the heat-receiving member is not particularly limited as long as it does not disturb arrangement of the heat-receiving member over the exhaust pipe included in the exhaust pipe heat-releasing system. A shape may be acceptable for example in the case where the heat-receiving member corresponds to the heat insulator illustrated in Fig. 1 and the surface of the surface layer of the heat-receiving member faces the outer peripheral face of the exhaust pipe.

[0047] In the following, effects achieved by the heat-receiving member and the exhaust pipe heat-releasing system in the present embodiment are described.

(1) The heat-receiving member of the present embodiment has a surface layer formed by anodizing a surface of a base that contains aluminum or an aluminum alloy. The emissivity of the surface of the surface layer formed by anodization is higher than the emissivity of aluminum. When the emissivity of the surface of the surface layer is high, the heat-receiving member of the present embodiment, arranged with the surface layer thereof facing the heat source such as an exhaust pipe, can receive by radiation heat transfer a large amount of heat released from the heat source. That is, the heat-receiving member of the present embodiment demonstrates excellent performance in receiving, by radiation heat transfer, heat released from a heat source. Further, use of such a heat-receiving member makes it possible to promote heat release from the heat source.

(2) The heat-receiving members of the present embodiment may have micropores in the surface layer thereof, and a metal may be deposited in the micropores. When a metal is deposited in the micropores in the surface layer, the emissivity of that region can be more increased.

(3) The exhaust pipe heat-releasing system of the present embodiment includes an exhaust pipe having a cylindrical base that contains a metal, and a heat-receiving member arranged over the exhaust pipe.

The heat-receiving member demonstrates excellent performance in receiving heat by radiation heat transfer. Such a heat-receiving member arranged over the exhaust pipe can receive much radiation heat from the outer peripheral surface of the exhaust pipe when the temperature of the exhaust pipe is increased by high-temperature gasses flowing therethrough. Thus, it is possible to prevent the temperature of the exhaust pipe from rising too high.

[0048] Hereinafter, Examples are described which more specifically disclose the first embodiment. However, the present embodiment is not limited to these Examples.

(Example 1)

[0049] A plate (150 mm × 70 mm × 0.5 mm (thickness)) made of aluminum (A1050) was prepared as the base, and the surface thereof not to be anodized was protected by sticking a masking tape. Next, the plate was anodized so that a surface layer was formed on the surface of the plate. As a result, a heat-receiving member was produced.
At the time of anodization, the electrolytic bath used was a sulfuric acid bath with a concentration of 200 g/L, and the electrolyte temperature was set to 15°C. The electrolytic method used was a multistep electrolytic method in which a low voltage (20 V) was applied in the first half of the process and a high voltage (40 V) was applied in the second half of the process. Thereafter, the plate was washed to remove the electrolytic solution.
Part of the heat-receiving member after anodization was cut and the thickness of the surface layer formed by anodization was measured at five locations by SEM. The thicknesses thereof were in the range of 15 to 20 µm.
Also, micropores were formed in the surface layer.

(Example 2)

[0050] The surface layer of the heat-receiving member produced in Example 1 was then electrolytically colored, that is, nickel was deposited in the micropores in the surface layer.
The electrolytic bath used was a nickel sulfate bath. The electrolytic bath had a pH of within the range of 4 to 6, and a temperature of within the range of 5 to 30°C. The electrolytic treatment was performed by an alternate current of 5 to 60 V, with the surface layer of the heat-receiving member serving as the cathode and with a carbon rod serving as the anode. Then, blocking of the micropores was performed by immersing the heat-receiving member in deionized water and boiling the water for 15 minutes.

(Examples 3 to 5)

[0051] Heat-receiving members were produced by performing anodization, electrolytic coloring, and blocking in the same way as in Example 2 except that the thicknesses of the respective bases were set to 1.0, 2.0, and 5.0 mm.

(Comparative Example 1)

[0052] A base made of the same aluminum as in Example 1 without anodization and electrolytic coloring performed thereon was used as the heat-receiving member.

[0053] The heat-receiving members produced in the respective Examples and Comparative Example were each evaluated for the following points.

(i) Measurement of Emissivity

[0054] The emissivity of the base before anodization, the emissivity of the surface layer of the heat-receiving member after anodization, and the emissivity of the surface layer of the heat-receiving member after electrolytic coloring were each measured by a radiometer (AERD produced by Kyoto Electronics Manufacturing Co., Ltd., wavelength: 3 to 30 µm).

(ii) Measurement of Heat-receiving Performance

[0055] Fig. 6 is a cross-sectional view schematically illustrating a method of measuring heat-receiving performance of the heat-receiving member.
A heat-receiving performance measuring machine 200 illustrated in Fig. 6 includes a heater 201 that is surrounded by a heat insulating material 202. The heater 201 is connected to a not-shown power source through a power source cable 203, and the temperature of the heater 201 can be increased by turning the power on. The upper face of the heat-receiving performance measuring machine 200 is open so that putting the heat-receiving member 1, the effect of which is to be measured, on the open face forms a closed space around the heater 201.
The length shown by an arrow A in Fig. 6 indicates the long side (150 mm) of the heat-receiving member 1, and the length shown by an arrow B indicates the width (120 mm) of the closed space.

[0056] In measurement of the heat-receiving performance, the heat-receiving member 1 was placed on the upper face of the heat-receiving performance measuring machine 200 with the surface layer 30 facing the heater 201 side, and then the heater 201 was powered on.
Next, the amount of electricity was adjusted so that the amounts of the radiation heat and the input electricity would be equal when the temperature of the heater was 500°C, and the amount of electricity at this time was recorded.
The recorded amount of electricity was set to be the amount of heat received by the heat-receiving member.
It should be noted that the heat-receiving member of Comparative Example 1, which has no surface layer formed therein, was placed with the surface of the base facing the heater side.

[0057] Further, the temperature of the heat-receiving member was measured at five locations when the amounts of the radiation heat and the input electricity were equalized with the temperature of the heater being 500°C.
The measuring locations were the points shown by arrows C, D, E, F, and G, which were set by dividing at 30 mm intervals the width of 120 mm shown by the arrow B in Fig. 6.
Here, the measuring locations are aligned at the midpoint (35 mm) of the short side (70 mm) of the heat-receiving member, and therefore the location E in Fig. 6 corresponds to the center of the heat-receiving member.
Thereafter, the largest value and the smallest value among the temperatures measured at the five locations were derived, and then a value resulting from "the largest value - the smallest value" was used as an index that shows the variation of the temperature distribution inside the heat-receiving member.

(iii) Measurement of Thermal Distortion

[0058] Displacement of the location E in Fig. 6 in the measurement test of the heat-receiving performance in (ii) was measured by a non-contact type displacement meter.

(iv) Measurement of Fissures in Base

[0059] The heat-receiving members produced in the respective Examples and Comparative Example were tested by 500 cycles of a temperature cycle test in which a cycle of heating up to 250°C and cooling down to 25°C by water immersion was repeated. Then, the base after the temperature cycle test was visually observed to see whether a fissure was generated therein.

[0060] The evaluation results of the points (i) to (iv) with respect to the heat-receiving members produced in the respective Examples and Comparative Example are shown together in Table 1.
Table 1 shows the temperatures of the location E in Fig. 6. In Examples 1 to 5 and Comparative Example 1, the temperature was highest at the location E, namely at the center of the heat-receiving member.
With respect to generation of fissures, a heat-receiving member with a very small fissure generated therein is shown as "+", and a heat-receiving member with a large fissure generated therein is shown as "-".

[0061] 

[Table 1]

	Heat-receiving member				Evaluation result
	Thickness of base	Anodization	Electrolytic coloring	Emissivity	Temperature at location E	Highest temperature	Lowest temperature	Tempereature difference	Amount of heat reception	Amount of distortion	Fissure
	(mm)				(°C)	(°C)	(°C)	(°C)	(W/m2)	(mm)
Example 1	0.5	performed	not performed	0.780	448	448	418	30	2798	2.5	+
Example 2	0.5	performed	performed	0.814	452	452	423	29	2817	2.6	+
Example 3	1.0	performed	performed	0.814	452	452	421	31	2810	0.6	+
Example 4	2.0	performed	performed	0.814	43.8	438	419	19	2747	0.3	+
Example 5	5.0	performed	performed	0.814	418	418	407	11	2617	0.3	+
Comparative Example 1	0.5	not performed	not performed	0.050	315	315	299	16	1755	1.9	-

[0062] Here, the emissivity of the surface layer formed by anodization in Example 1 was considerably higher than the emissivity of the unanodized base in Comparative Example 1. Further, the amount of heat received by the heat-receiving member in Example 1 was larger than the amount of heat received by the heat-receiving member in Comparative Example 1.
Since the amount of electricity, which was measured as the amount of heat received, is equal to the amount of radiation heat from the heater as the heat source, the heat release from the heat source was found to be accelerated by use of a heat-receiving member with high emissivity as in Example 1.

[0063] Further, electrolytic coloring as in Example 2 made it possible to further increase the emissivity of the heat-receiving member, and in this case, the amount of heat received was further increased.

[0064] Example 2 and Examples 3 to 5 were compared to find out the effect of thickness of the base. In every Example, the emissivity of the surface of the heat-receiving member with a surface layer formed thereon was 0.814.
The highest temperature was observed at the location E in every Example, and when the thickness of the base was increased to 2.0 mm or to 5.0 mm, the highest temperature was decreased according to the increase thereof. Further, when the thickness of the base was increased to 2.0 mm or to 5.0 mm, the temperature difference between the highest temperature and the lowest temperature was decreased according to the increase of the thickness of the base.
The reason for a decrease in the temperature difference according to the increase of the thickness of the base has not been revealed. However, the reason is considered to be that the amount of heat transferred within the base by heat conduction is increased when the thickness of the base is large, and that the temperatures within the heat-receiving member thus tend to be equalized.

[0065] Furthermore, the amount of distortion in the heat-receiving member was decreased according to the increase of the thickness of the base. This is presumably because a large thickness of the base enhances the strength of the base and thereby tends not to generate a deformation of the base due to the thermal stress.

[0066] With respect to generation of fissures in the base, a very small fissure was observed in the base of the heat-receiving members in Examples 1 to 5.
On the other hand, a large fissure was generated in the base in Comparative Example 1. The large fissure in the base was presumably caused by the heat resistance of an unanodized aluminum base which is lower than the heat resistance of an anodized aluminum base.

(Second Embodiment, not as such claimed)

[0067] Next, a second embodiment, which is one embodiment of the heat-receiving member, illustrative for aspects of the present invention but not claimed as such, is described with reference to the drawings.
In the heat-receiving member of the second embodiment, the emissivity of one region far from the high-temperature part of the heat source is higher than the emissivity of another region.
Fig. 7 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.
A heat-receiving member 4 illustrated in Fig. 7 has the surface layer 30 that is formed by anodizing the surface of the base 20, and the surface layer 30 has a large number of the micropores 40 formed therein.
Part of one region in the surface layer 30 is electrolytically colored, and thus the micropores 40 in the region have the metal 50 deposited therein. Another region in the surface layer 30 is not electrolytically colored, and thus the micropores 40 in these regions do not have the metal 50 deposited therein.

[0068] In the heat-receiving member 4, the region on which electrolytic coloring was performed (high-emissivity region) has emissivity higher than the emissivity of the region on which electrolytic coloring was not performed, and the region on which electrolytic coloring was not performed (low-emissivity region) has emissivity lower than the emissivity of the region on which electrolytic coloring was performed.

[0069] Examples of the method of producing the heat-receiving member 4 include a method in which, after the surface layer has been formed by anodization in the same way as in the method of producing the heat-receiving member in the first embodiment, the region not to be electrolytically colored is masked at the time of the electrolytic coloring.
The masking can be carried out by a method such as sticking a masking tape on the region.
As a result, the masking allows the unmasked region to be a high-emissivity region, and allows the masked region to be a low-emissivity region.

[0070] Fig. 8 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.
A heat-receiving member 5 illustrated in Fig. 8 has the surface layer 30 formed by anodizing a part of the base 20. Another part of the base 20 is unanodized, and thus the surface of the base 20 is exposed.

[0071] In the heat-receiving member 5, the region with the surface layer 30 formed therein by anodization (high-emissivity region) has emissivity higher than that of the region with the surface of the base 20 exposed thereon. On the other hand, the region with the surface of the base 20 exposed thereon (low-emissivity region) has emissivity lower than that of the region with the surface layer 30 formed therein. The region with the surface of the base exposed thereon is arranged at a location close to the high-temperature part of the heat source.

[0072] Examples of the method of producing the heat-receiving member 5 include a method in which a region not to be anodized is masked and then anodized upon production of a heat-receiving member in the first embodiment.
The masking can be carried out by a method such as sticking a masking tape on the region.
As a result, the masking allows the unmasked region to be a high-emissivity region, and allows the masked region to be a low-emissivity region.

[0073] Fig. 9 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.
A heat-receiving member 6 illustrated in Fig. 9 has the surface layer 30 formed by anodizing a part of the base 20. Further, the surface layer 30 is electrolytically colored, and thus the micropores 40 have the metal 50 deposited therein. Another part of the base 20 is not anodized and thus the surface of the base 20 is exposed.

[0074] In the heat-receiving member 6, the anodized and electrolytically colored region (high-emissivity region) has emissivity higher than that of the region with the surface of the base 20 exposed thereon. On the other hand, the region with the surface of the base 20 exposed thereon (low-emissivity region) has emissivity lower than that of the anodized and electrolytically colored region.
In the heat-receiving member 6, the difference in the emissivity between the high-emissivity region and the low-emissivity region is larger than the difference in the emissivity between the high-emissivity region and the low-emissivity region in the heat-receiving member 4 and the heat-receiving member 5.

[0075] Examples of the method of producing the heat-receiving member 6 include a method in which a region not to be anodized is masked before anodization, and with the region being masked, the micropores are formed and the surface layer is then electrolytically colored.
More specifically, further anodizing the produced heat-receiving member 5 so as to form micropores in the surface layer and then further electrolytically coloring the surface layer results in production of the heat-receiving member 6.

[0076] In the heat-receiving member of the second embodiment, the size of the region with emissivity lower than that of the another region is desirably from 5 to 95% of the total surface area.
Further, the size of the area with emissivity lower than that of the another region is desirably larger than a size of 10 mm × 10 mm when the shape of the region is rectangular.
Also, the difference in the emissivity between the high-emissivity region and the low-emissivity region is desirably from 0.01 to 0.90.
Furthermore, a ratio (Y / X) of a length (Y) of the short side of the region with emissivity lower than that of the another region to a thickness (X) of the base is desirably 2 or more.

[0077] In the following, effects of the heat-receiving member of the present embodiment are described.
In the present embodiment, in addition to the effects (1) and (2) described in the first embodiment, the following effects can be achieved.
(4) In the heat-receiving member of the present embodiment, there is a region with emissivity higher than that of another region. Since the region having higher emissivity than emissivity of the another region is more likely to receive heat by radiation heat transfer, the amount of heat to be received per unit area is large. The region having higher emissivity than that of the another region is thus a region in which the temperature tends to rise due to reception of heat. Accordingly, placing the region having higher emissivity than the another region at a location far from the high-temperature part of the adjacent heat source makes it more likely for the temperature of the heat-receiving member to rise even if the region is located far from the high-temperature part of the heat source; hence, generation of a low-temperature region inside the heat-receiving member can be prevented.
That is, generation of a temperature difference inside the heat-receiving member can be prevented. Further, generation of thermal stress and distortion in the heat-receiving member can be prevented.

[0078] (5) In the heat-receiving member of the present embodiment, micropores may be formed in the surface layer in the region far from the high-temperature part of the heat source, and a metal may be deposited in the micropores.
Deposition of a metal in the micropores in the surface layer makes it possible to increase the emissivity of the region. That is, placing the region with a metal deposited in the micropores formed in the surface layer thereof at a location far from the high-temperature part of the heat source makes it possible to more effectively prevent generation of a low-temperature region inside the heat-receiving member.

[0079] (6) In the heat-receiving member of the present embodiment, a region close to the high-temperature part of the heat source may include a region in which the surface of the base is unanodized and exposed.
Since the base is made of aluminum or an aluminum alloy, the emissivity of the region with the surface of the base exposed thereon is low. Placing the region with the surface of the base exposed thereon at a location close to the high-temperature part of the heat source makes it possible to prevent the temperature of the heat-receiving member from rising too high even if the region is located close to the high-temperature part of the heat source; hence, generation of a high-temperature region inside the heat-receiving member can be prevented. That is, generation of a temperature difference inside the heat-receiving member can be prevented.

[0080] Hereinafter, Examples are described which more specifically disclose the second embodiment. However, the present embodiment is not limited to these Examples.

(Example 6)

[0081] A base made of aluminum was anodized to form a surface layer on the base and to form micropores in the surface layer, in the same way as in Example 1.
Next, at the center (the location E in Fig. 6) of the anodized surface, a masking tape (851T, produced by Sumitomo 3M Limited.) with a size of 20 mm × 20 mm was stuck.
Subsequently, the surface layer was electrolytically colored in the same way as in Example 2, and thereby nickel was deposited in the micropores in the region without the masking tape stuck thereon.
Thereafter, the masking tape was removed, and then blocking was carried out in the same way as in Example 2.
A heat-receiving member produced thereby has a region on which electrolytic coloring was not performed, which is a "low-emissivity region", and a region on which electrolytic coloring was performed, which is a "high-emissivity region".

(Example 7)

[0082] At the center (the location E in Fig. 6) of the to-be anodized surface of the base that is of the same kind as the base used in Example 1, a masking tape with a size of 10 mm × 10 mm was stuck.
Then, the base was anodized in the same way as in Example 1, and a surface layer was formed by anodization on a region without a masking tape stuck thereon, and further, micropores were formed in the surface layer.
Subsequently, the surface layer was electrolytically colored in the same way as in Example 2, and thereby nickel was deposited in the micropores in the region without the masking tape stuck thereon.
Thereafter, the masking tape was removed, and then blocking was carried out in the same way as in Example 2.
A heat-receiving member produced thereby has a region on which anodization and electrolytic coloring were not performed, which is a "low-emissivity region", and a region on which anodization and electrolytic coloring were performed, which is a "high-emissivity region".

(Examples 8 and 9)

[0083] Heat-receiving members were produced by the same method as in Example 7 except that the respective masking tapes had a size of 20 mm × 20 mm and a size of 50 mm × 50 mm.

(Examples 10 to 12)

[0084] Heat-receiving members were produced by the same method as in Example 7 except that the bases each had a thickness of 1.0 mm and the respective masking tapes had a size of 10 mm × 10 mm, a size of 20 mm × 20 mm, and a size of 50 mm × 50 mm.

(Examples 13 to 15)

[0085] Heat-receiving members were produced by the same method as in Example 7 except that the bases each had a thickness of 2.0 mm and the respective masking tapes had a size of 10 mm × 10 mm, a size of 20 mm × 20 mm, and a size of 50 mm × 50 mm.

(Examples 16 to 18)

[0086] Heat-receiving members were produced by the same method as in Example 7 except that the bases each had a thickness of 5.0 mm and the respective masking tapes had a size of 10 mm × 10 mm, a size of 20 mm × 20 mm, and a size of 50 mm × 50 mm.

[0087] The heat-receiving members produced in the respective Examples were evaluated for the same points (i) to (iv) as in Example 1.

[0088] First, evaluation results of the heat-receiving members of Examples 6 to 9 each with the base having a thickness of 0.5 mm are shown together in Table 2. For comparison, the result of the heat-receiving member of Example 2 which had uniform emissivity on the surface thereof is also shown.

[0089] 

[Table 2]

	Heat-receiving member					Evaluation result
	Thickness of base	Low-emissivity region				Highest temperature	Lowest temperature	Temperature difference	Temperature at location E	Temperature decrease at location E	Amount of heat reception	Amount of distortion	Fissure
		Anodization	Electrolytic coloring	Emissivity	Size
	(mm)				(mm × mm)	(°C)	(°C)	(°C)	(°C)	(°C)	(W/m2)	(mm)
Example 2	0.5	N/A	N/A	N/A	N/A	452	423	29	452	0	2817	2.6	+
Example 6	0.5	performed	not performed	0.780	20 × 20	424	418	6	424	28	2674	2.3	+
Example 7	0.5	not performed	not performed	0.050	10 × 10	439	409	30	439	13	2709	1.2	+
Examples 8	0.6	not performed	not performed	0.050	20 × 20	402	379	23	379	73	2452	2.0	+
Example 9	0.5	not performed	not performed	0.050	50 × 50	392	359	33	359	93	2302	1.3	+

[0090] Table 2 shows the emissivities of the low-emissivity regions in the respective Examples. In Example 6 in which the heat-receiving members were anodized and the low-emissivity region thereof was not electrolytically colored, the emissivity was 0.780. In Examples 7 to 9 in which the low-emissivity regions in the heat-receiving members were not anodized nor electrolytically colored, the emissivity was 0.050, the same as that of the base.
Although Table 2 does not show the emissivities of the high-emissivity regions and the emissivity in Example 2, those emissivities correspond to the emissivities of the anodized and electrolytically colored regions, and thus those emissivities are all 0.814.

[0091] The heat-receiving member of Example 2 with uniform emissivity on the surface thereof had the highest temperature of 452°C at the location E in the heat-receiving member shown in Fig. 6, that is, at the center of the heat-receiving member.
On the other hand, the heat-receiving members of Examples 6 to 9, each of which had a low-emissivity region at the location E, had a temperature lower than the temperature of the heat-receiving member of Example 2 at the location E. Table 2 shows as "temperature decrease at location E" how many degrees the temperature dropped from the temperature at the location E in Example 2.

[0092] Further, Table 3 shows the temperatures measured at the locations C, D, E, F, and G shown in Fig. 6, for Example 2 and Examples 6 to 9. Furthermore, Fig. 10 shows the relationships between the locations of temperature measurement and the temperatures of the respective heat-receiving members, which were measured in Example 2 and Examples 6 to 9.

[0093] 

[Table 3]

	Heat-receiving member					Evaluation result
	Thickness of base	Low-emissivity region				Location C	Location D	Location E	Location F	Location G
		Anodization	Electrolytic coloring	Emissivity	Size
	(mm)				(mm × mm)	(°C)	(°C)	(°C)	(°C)	(°C)
Example 2	0.5	N/A	N/A	N/A	N/A	423	439	452	447	423
Examples 6	0.5	performed	not performed	0.780	20 × 20	418	419	424	418	418
Example 7	0.5	not performed	not performed,	0.050	10 × 10	410	426	439	434	409
Example 8	0.5	not performed	not performed	0.050	20 × 20	400	392	379	389	402
Example 9	0.5	not performed	not performed	0.050	50 × 50	390	367	359	363	392

[0094] Hereinafter, the evaluation results are described with reference to Table 2, Table 3, and Fig. 10.
In Example 6, the emissivity of the low-emissivity region is 0.780, and the difference between this emissivity and the emissivity of 0.814 of the high-emissivity region is 0.034. Such provision of a high-emissivity region and a low-emissivity region in the heat-receiving member decreases the temperature at the location E by 28°C; thus, the temperature difference between the highest temperature and the lowest temperature became 6°C, which made it possible to bring the temperature distribution within the heat-receiving member closer to the uniform distribution.

[0095] In Example 8, the emissivity of the low-emissivity region was 0.05, which led to a large decrease in the temperature at the location E by 73°C. Comparison with Example 6 in which the area of the low-emissivity region is 20 mm × 20 mm, the same area as in Example 8, reveals that lower emissivity in the low-emissivity region more greatly increases temperature-decrease effects.

[0096] Comparison among Examples 7 to 9 each having the same emissivity of 0.05 in the low-emissivity region and having a different area of the low-emissivity region reveals that a larger area of the low-emissivity region leads to a larger temperature decrease at the location E.
Also, in each of Examples 8 and 9 in which the temperature decrease was large, the temperature was lowest at the location E within the heat-receiving member, and thus the line of the line chart of Examples 8 and 9 in Fig. 10 had a reverse shape of the line for Example 2.

[0097] Those results revealed that provision of a high-emissivity region and a low-emissivity region in the heat-receiving member makes it possible to prevent the temperature from rising too high in a certain region within the heat-receiving member, and to prevent the temperature from falling too low in a certain region. The results also revealed that appropriately adjusting the emissivities and sizes in the high-emissivity region and in the low-emissivity region makes it possible to adjust the temperature distribution inside the heat-receiving member.

[0098] Next, the evaluation results of Examples 10 to 12 in which the bases each had a thickness of 1.0 mm, Examples 13 to 15 in which the bases each had a thickness of 2.0 mm, and Examples 16 to 18 in which the bases each had a thickness of 5.0 mm are respectively shown in Table 4, 5, or 6.
For comparison, the result of the heat-receiving member of Example 3, 4, or 5 with uniform emissivity on the surface thereof is also shown. The respective values of "temperature decrease at location E" were calculated based on the temperature at the location E in Example 3, 4, or 5.

[0099] 

[Table 4]

	Heat-receiving member					Evaluation result
	Thickness of base	Low-emissivity region				Highest temperature	Lowest temperature	Temperature difference	Temperature at location E	Temperature decrease at location E	Amount of heat reception	Amount of distortion	Fissure
		Anodization	Electrolytic coloring	Emissivity	Size
	(mm)				(mm × mm)	(°C)	(°C)	(°C)	(°C)	(°C)	(W/m2)	(mm)
Example 3	1.0	N/A	N/A	N/A	N/A	452	421	31	452	0	2810	0.6	+
Example 10	1.0	not performed	not performed	0.050	10 × 10	443	410	33	443	9	2738	0.5	+
Example 11	1.0	not performed	not performed	0.050	20 × 20	405	387	18	387	65	2486	0.5	+
Example 12	1.0	not performed	not performed	0.050	50 × 50	394	362	32	362	90	2332	0.8	+

[0100] 

[Table 5]

	Heat-receiving member					Evaluation result
	Thickness of base	Low-emissivity region				Highest temperature	Lowest temperature	Temperature difference	Temperature at location E	Temperature decrease at loation E	Amount of heat reception	Amount of distortion	Fissure
		Anodization	Electrolytic coloring	Emissivity	Size
	(mm)				(mm × mm)	(°C)	(°C)	(°C)	(°C)	(°C)	(W/m2)	(mm)
Example 4	2.0	N/A	N/A	N/A	N/A	438	419	19	438	0	2747	0.3	+
Example 13	2.0	not performed	not performed	0.050	10 × 10	426	412	14	426	12	2669	0.4	+
Example 14	2.0	not performed	not performed	0.050	20 × 20	404	393	11	393	45	2495	0.4	+
Example 15	2.0	not performed	not performed	0.050	50 × 50	394	373	21	373	65	2363	0.4	+

[0101] 

[Table 6]

	Heat-receiving member					Evaluation result
	Thickness of base	Low-emissivity region				Highest temperature	Lowest temperature	Temperature difference	Temperature at location E	Temperature decrease at location E	Amount of heat reception	Amount of distortion	Fissure
		Anodization	Electrolytic coloring	Emissivity	Size
	(mm)				(mm × mm)	(°C)	(°C)	(°C)	(°C)	(°C)	(W/m2)	(mm)
Example 5	5.0	N/A	N/A	N/A	N/A	418	407	11	418	0	2617	0.3	+
Example 16	5.0	not performed	not performed	0.050	10 × 10	412	407	7	412	6	2585	0.3	+
Example 17	5.0	not performed	not performed	0.050	20 × 20	402	391	11	391	27	2480	0.3	+
Example 18	5.0	not performed	not performed	0.050	50 × 50	395	387	8	387	31	2440	0.4	+

[0102] From the results shown in Table 2 and Tables 4 to 6, effects exerted on the characteristics of the heat-receiving member by the thickness of the base were studied.
When the heat-receiving members of Examples with the respective bases having the same thickness are compared, the larger the size of the low-emissivity region, the larger the temperature decrease at the location E.

[0103] Comparison of the results of the heat-receiving members of Examples with the same sizes of the low emissivity regions and with different thicknesses of the bases showed that the larger the thickness of the base, the smaller the temperature decrease tended to be.
Although the reason for this has not been revealed, it is assumed that, since a larger thickness of the base leads to a larger amount of heat transferred inside the base by heat conduction, influences of an increase/decrease of the emissivity are thereby small.

[0104] Also, the larger the thickness of the base, the smaller the amount of distortion tended to be. The reason for this is considered to be that the mechanical strength of the base is increased as the thickness of the base is increased.

[0105] These results revealed that appropriately adjusting the emissivities and sizes of the high-emissivity region and the low-emissivity region according to the thickness of the base makes it possible to adjust the temperature distribution inside the heat-receiving member.

(Third Embodiment)

[0106] Now, a third embodiment, which is one embodiment of the heat-receiving member of the present invention, is described with reference to the drawings.
The heat-receiving member in the third embodiment has a plurality of cracks formed in the surface layer thereof.
Fig. 11 is a cross-sectional view schematically illustrating an exemplary heat-receiving member of the present invention.
A heat-receiving member 7 illustrated in Fig. 11 has the surface layer 30 formed by anodizing the surface of the base 20, and the surface layer 30 has a plurality of cracks 60 formed therein.

[0107] Fig. 12, Fig. 13, and Fig. 14 each are a scanning electron microscope photograph that shows a surface of a surface layer of an exemplary heat-receiving member of the present invention which has cracks in the surface layer.
In the surface layer shown in Fig. 12, a crack 61 has a zigzag shape as shown in the encircled region.
In the surface layer shown in Fig. 13, a crack 62 is in a state where at least one end thereof has stopped growing and thus is not connected to another crack, as shown in the encircled region; the cracks are separated from each other.
In the surface layer shown in Fig. 14, cracks 63 are formed as straight lines substantially parallel to each other in one direction, as shown by arrows.

[0108] The width of each crack is desirably from 0.01 to 15 µm.
A width of more than 15 µm might generate a fissure in the base.

[0109] Examples of the method of forming cracks in the surface layer include a method in which the heat-receiving member after anodization is bent so that it is distorted, and then the heat-receiving member is bent again so that it restores the original shape.

[0110] In the following, effects of the heat-receiving member of the present embodiment are described. In the present embodiment, the following effects can be exerted in addition to the effects (1) and (2) that have been described in the first embodiment.
(7) The plurality of cracks are formed in the surface layer of the heat-receiving member of the present embodiment. Therefore, part of thermal stress, which is applied between the base and the surface layer, is absorbed at the cracked part. As a result, the thermal stress applied between the base and the surface layer is prevented from becoming large. As a result, generation of a fissure in the base due to the thermal stress can be prevented.

[0111] (8) In the heat-receiving member of the present embodiment, the cracks may be separated from each other.
In the case where the cracks are separated from each other, the cracks absorb the thermal stress and grow upon application of the thermal stress to the surface layer, and thus make it possible to effectively prevent generation of a fissure in the base. Further, the continuous surface layer increases the rigidity and thus makes it easier for the heat-receiving member to maintain the shape.

[0112] (9) In the heat-receiving member of the present embodiment, at least one of the cracks may have a zigzag shape.
A zigzag shape of the crack generates resistance to the force applied in the direction parallel to the crack, and therefore makes it possible to effectively prevent generation of a fissure in the base.

[0113] Hereinafter, Examples are described which more specifically disclose the third embodiment of the present invention. However, the present embodiment is not limited to these Examples.

(Example 19)

[0114] A heat-receiving member was produced in the same way as in Example 2. Thereafter, the produced heat-receiving member was bended by hand to add distortion to the heat-receiving member. Then, cracks attributed from the distortion were observed.
The cracks had a zigzag shape, and had widths of 0.01 to 15 µm at five locations when measured by SEM.

[0115] The heat-receiving member produced in Example 19 was evaluated for the same points (i) to (iv) as in Example 1. The results thereof are shown together in Table 7. For comparison, the result of the heat-receiving member of Example 2 with no crack formed in the surface layer thereof is also shown.

[0116] 

[Table 7]

	Heat-receiving member					Evaluation result
	Thickness of base	Anodization	Electrolytic coloring	Crack	Emissivity	Temperature at location E	Highest temperature	Lowest temperature	Temperature difference	Amount of heat reception	Amount of distortion	Fissure
	(mm)					(°C)	(°C)	(°C)	(°C)	(W/m2)	(mm)
Example 2	0.5	performed	performed	not formed	0.814	452	452	423	29	2817	2.6	+
Example 19	0.5	performed	performed	formed	0.806	449	449	421	28	2784	1.9	++

[0117] The heat-receiving member produced in Example 19 had emissivity slightly lower than that of the heat-receiving member of Example 2. This decrease is considered to be due to inclusion of the surface of the base, which appeared at the cracked part, in the region the emissivity of which was measured.
In the heat-receiving member produced in Example 19, no fissure was observed in the base because of the cracks.
This result is shown as "++" in Table 7.

(Fourth Embodiment, not as such claimed)

[0118] Now, a fourth embodiment, which is one embodiment of the heat-receiving member, illustrative for aspects of the present invention but not claimed as such, is described with reference to the drawings.
The heat-receiving member of the fourth embodiment has surface layers formed by anodizing both respective surfaces of the base thereof.
Fig. 15 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.
A heat-receiving member 11 illustrated in Fig. 15 has the base 20 both surfaces of which are anodized, and the base 20 has a surface layer 30a on the upper surface, and has a surface layer 30b on the lower surface.
The surface layer 30a and the surface layer 30b respectively have micropores 40a and micropores 40b formed therein, and the micropores 40a and the micropores 40b respectively have a metal 50a and a metal 50b deposited therein.
That is, the structure of one side of the heat-receiving member is the same as that of the heat-receiving member illustrated in Fig. 4.

[0119] The heat-receiving member illustrated in Fig. 15 is an exemplary heat-receiving member of the present embodiment. As the surface layer of the heat-receiving member of the present embodiment, any of the surface layers of the heat-receiving members that have been described thus far can be employed.
Further, the conditions of the surface layer on the upper surface and lower surface may be different. Examples of such a structure include a structure in which the surface layer on the upper surface is electrolytically colored and the surface layer on the lower surface is not electrolytically colored, and the like.

[0120] Examples of a method of forming surface layers by anodizing both respective surfaces of the base include a method in which the base without masking performed thereon is immersed into an electrolytic bath such that both surfaces of the base touch the electrolytic bath, and the like. Alternatively, one surface of the base may be anodized at one time.

[0121] In the following, effects of the heat-receiving member of the present embodiment are described. In the present embodiment, changing the structure of the surface layer makes it possible to achieve the following effects on the respective surfaces in addition to achievement of the respective effects (1) and (2) and effects (4) to (9), the effects having been described in the first to third embodiments.
(10) In the heat-receiving member of the present embodiment, surface layers are formed by anodizing both respective surfaces of the heat-receiving member, and thus the emissivity of the both surfaces of the heat-receiving member is high. As a result, it becomes possible for the heat-receiving member to receive much heat on one surface and release much heat from the other surface. Therefore, the temperature of the heat-receiving member tends not to rise, which makes it possible to decrease the thermal stress generated in the heat-receiving member.
Further, the lower the temperature of the heat-receiving member, the larger the amount of heat that the heat-receiving member can receive; hence, the temperature of the heat-receiving member tends not to rise even at the time of heat reception, which makes it possible to produce a heat-receiving member that demonstrates excellent performance in receiving heat by radiation heat transfer.

[0122] In the following, Examples are described which more specifically disclose the fourth embodiment. However, the present embodiment is not limited to these Examples.

(Example 20)

[0123] A same base as the base used in Example 1 was immersed in an electrolytic bath without a masking tape being stuck on the base, and then both surfaces of the base were anodized to form respective surface layers on the both surfaces of the base. Then, micropores were further formed in the surface layers.
Other conditions of anodization were same as those in Example 1.

[0124] Next, a masking tape was stuck for protection on the surface layer formed on a surface of the base which was to be a heat-releasing face when the base is used as a heat-receiving member. Then, the surface layer was electrolytically colored in the same way as in Example 2 so that nickel was deposited in the micropores.
Thereafter, the masking tape was removed and blocking was carried out in the same way as in Example 2.
In a heat-receiving member produced as thus described, one of the surfaces was anodized and electrolytically colored and the other surface was only anodized.

(Example 21)

[0125] A heat-receiving member was produced in the same way as in Example 20 except that a masking tape was not stuck on the surface layer before electrolytic coloring in Example 20.
In a heat-receiving member produced as thus described, both faces were anodized and electrolytically colored.

[0126] The heat-receiving members produced in Examples 20 and 21 were evaluated for the same points (i) to (iv) as in Example 1. In Example 20, the heat-receiving member was placed such that the anodized and electrolytically colored surface faced the heaters and thus was used as a heat-receiving face. Further, the surface, which was only anodized, was arranged on the other side and set to be the heat-releasing face. In Example 21, the sides that the surfaces of the heat-receiving member would face were optionally determined.
Furthermore, Example 22 and Example 23 as described below were carried out.

(Example 22)

[0127] In Example 22, a same heat-receiving member as that produced in Example 20 was used in measurement of heat-receiving performance. However, unlike in Example 20, the heat-receiving member was placed in reverse, that is, the surface on which only anodization was performed was used as the heat-receiving face, and the surface on which anodization and electrolytic coloring were performed was used as the heat-releasing face.

(Example 23)

[0128] In Example 23, a same heat-receiving member as that produced in Example 2 was used in measurement of heat-receiving performance. However, unlike in Example 2, the heat-receiving member was placed in reverse, that is, the surface layer of the heat-receiving member was arranged on the farther side from the heaters and thus was used as the heat-releasing face, and the surface on which anodization was not performed was used as the heat-receiving face.
The results of evaluation of Examples 20 to 23 are shown together in Table 8. For comparison, the result of the heat-receiving member of Example 2 is also shown.

[0129] In each of Examples 20 to 22, since the emissivity is high both on the heat-receiving face and the heat-releasing face of the heat-receiving member, the amount of heat reception is more than 8700 W/m². This amount of heat reception is very large compared to the result of the heat-receiving member of Example 2 which has high emissivity only on the heat-receiving face.
That is, Examples 20 to 22 show that a large amount of heat release from the heat-receiving face by radiation heat transfer considerably increases the amount of heat reception of the heat-receiving member.
Further, the highest temperature of the heat-receiving member is low despite the large amount of heat reception, which shows that heat release from the heat-receiving member was promoted.
It should be noted that the amount of heat reception was small in Example 23 in which the heat-receiving member had high emissivity only on the heat-releasing face and had low emissivity on the heat-receiving face.
These results show that providing respective surface layers on both surfaces of the heat-receiving member by anodization so as to increase the emissivity on a heat-receiving face and a heat-releasing face makes it possible to produce a heat-receiving member which demonstrates excellent performance in receiving heat by radiation heat transfer.

(Fifth Embodiment)

[0130] Next, a fifth embodiment, which is one embodiment of the exhaust pipe heat-releasing system of the present invention, is described with reference to the drawings.
In the exhaust pipe heat-releasing system of the present embodiment, a surface-coating layer containing a crystalline inorganic material and an amorphous binder is formed on the outer peripheral face of the exhaust pipe described in the exhaust pipe heat-releasing system of the first embodiment.

[0131] Fig. 16 is a cross-sectional view schematically illustrating an exemplary exhaust pipe heat-releasing system of the present invention.
An exhaust pipe 151 that forms an exhaust pipe heat-releasing system 150 illustrated in Fig. 16 has a cylindrical base 102 that contains a metal; and a surface-coating layer 103 containing a crystalline inorganic material and an amorphous binder, which is formed on the outer peripheral face of the base 102.
Further, the heat-receiving member 1 is placed such that the surface layer 30 formed by anodization faces the surface-coating layer 103 of the exhaust pipe 151.
Arrows illustrated in Fig. 16 schematically show heat transferred from the surface-coating layer 103, which is formed on the outer peripheral face of the exhaust pipe 151, to the surface layer 30 of the heat-receiving member 1.

[0132] The surface-coating layer 103 has an emissivity of 0.78 or more at a wavelength of 3 to 30 µm. Provision of the surface-coating layer 103 with high emissivity on the outer peripheral face of the exhaust pipe 151 makes it possible to effectively release heat in the exhaust pipe 151 to the outside of the exhaust pipe 151 by radiation heat transfer.

[0133] The material of the crystalline inorganic material contained in the surface-coating layer 103 is not particularly limited. An oxide of a transition metal is desirably used, and specific examples thereof include manganese dioxide, manganese oxide, iron oxide, cobalt oxide, copper oxide, chrome oxide and nickel oxide. Each of these may be used alone or two or more kinds of these may be used in combination.
These oxides of transition metals are suitably used for producing crystalline inorganic materials having high emissivity.

[0134] Examples of the amorphous binder include barium glass, boron glass, strontium glass, alumina-silicate glass, soda-zinc glass and soda-barium glass. Each of these may be used alone or two or more kinds of these may be used in combination.

[0135] Such an amorphous binder is a low-melting-point glass and its softening temperature is in the range of 400 to 1100°C. Accordingly, melting the amorphous inorganic binder to coat the outer peripheral face of the base of the exhaust pipe and then firing the base make it possible to easily form a robust surface-coating layer on the outer peripheral face of the base.

[0136] When the amorphous binder is a low-melting-point glass, the melting point thereof is desirably in the range of 400 to 1100°C.
When the low-melting-point glass has a melting point of less than 400°C, there is a case where the glass easily softens during use and extraneous matters adhere to the glass. On the other hand, when the melting point exceeds 1100°C, there is a case where the heating in formation of a surface-coating layer deteriorates the base.

[0137] In the surface-coating layer containing the crystalline inorganic material and the amorphous binder, with respect to a compounding amount of the crystalline inorganic material, a desirable lower limit is 10% by weight and a desirable upper limit is 90% by weight.
When the compounding amount of the crystalline inorganic material is less than 10% by weight, there is a case where the infrared emissivity is insufficient and the heat-releasing property in a high-temperature region is inferior. On the other hand, when the compounding ratio exceeds 90% by weight, there is a case where the adhesion between the heat-releasing layer and the base of the exhaust pipe is lowered.
With respect to the compounding amount of the crystalline inorganic material, a more desirable lower limit is 30% by weight and a more desirable upper limit is 70% by weight.

[0138] It is desirable that the surface-coating layer have a thickness of 0.5 to 10 µm.
When the surface-coating layer has a thickness of less than 0.5 µm, a sufficient heat-releasing property might not be ensured. On the other hand, when the surface-coating layer has a thickness exceeding 10 µm, cracks might appear on the surface-coating layer or the exhaust pipe might be deformed.

[0139] It is desirable that the surface-coating layer is formed on the entire outer peripheral face of the exhaust pipe because, in this case, the area of the surface-coating layer will be largest and the surface-coating layer will have a particularly excellent heat-releasing property. However, a surface-coating layer may be formed only on a part of the outer peripheral face of the exhaust pipe; particularly when the surface-coating layer is formed on the surface that faces the heat-receiving member, it may not be formed on other parts on the exhaust pipe.

[0140] Hereinafter, a method of producing an exhaust pipe to be used in the exhaust pipe heat-releasing system of the present embodiment is described in accordance with the order of processes.

[0141] (I) Using a cylindrical exhaust pipe processed into a predetermined shape as a starting material, cleaning is performed so as to remove impurities on a surface of the base of the exhaust pipe.
The cleaning is not particularly limited, and conventionally known cleaning may be used. More specifically, ultrasonic cleaning in alcohol solvent, and the like may be used.

[0142] Further, after the cleaning, roughening may be optionally performed on the surface of the base of the exhaust pipe in order to enlarge a specific surface area of the outer peripheral face of the base of the exhaust pipe or to adjust the maximum height Rz of the inner face of the base of the exhaust pipe. More specifically, roughening such as sandblasting, etching and high-temperature oxidation may be performed. Each of the treatments may be used alone or two or more kinds of these may be used in combination.

[0143] (II) Separately, a crystalline inorganic material and an amorphous binder are wet-mixed so as to prepare a raw material composition for a surface-coating layer.
More specifically, a powder of a crystalline inorganic material and a powder of an amorphous binder are prepared so that each has a predetermined particle size, a predetermined shape, and the like. Respective powders are dry-mixed at a predetermined compounding ratio to obtain a mixed powder. Then, water is added thereto and the mixture is wet-mixed by ball milling so as to prepare a raw material composition for a surface-coating layer.
The compounding ratio of the mixed powder and water is not particularly limited. However, around 100 parts by weight of water with respect to 100 parts by weight of a mixed powder is desirable. The reason for this is that a viscosity suitable for applying to the base of the exhaust pipe can be obtained. According to need, an inorganic fiber or an organic solvent may be blended to the raw material composition for a surface-coating layer.

[0144] (III) The outer peripheral face of the base of the exhaust pipe is coated with the raw material composition for a surface-coating layer.
As a method for coating with the raw material composition for a surface-coating layer, for example, spray coating; electrostatic coating; ink jet; transfer using a stamp, a roller or the like; brush coating and the like may be used.
In addition, the base of the exhaust pipe may be immersed in the raw material composition for a surface-coating layer so as to be coated with the raw material composition for a surface-coating layer.

[0145] At least one of plating such as nickel plating and chrome plating, oxidation of the outer peripheral face of the metal base, and the like may be performed before the coating of the outer peripheral face of a base of the exhaust pipe with a raw material composition for a surface-coating layer.
The reason for this is that there is a case where an adhesion property between a base of the exhaust pipe and a surface-coating layer is improved.

[0146] (IV) The exhaust pipe coated with the raw material composition for a surface-coating layer is fired.
More specifically, after the exhaust pipe coated with the raw material composition for a surface-coating layer is dried, a surface-coating layer is formed by firing.
The firing temperature is desirably set to the melting point of the amorphous binder or higher, and it is desirably 700 to 1100°C. The firing temperature depends on the kind of the blended amorphous binder. By setting the firing temperature to the melting point of the amorphous binder or higher, the exhaust pipe and the amorphous binder can be adhered solidly, so that a surface-coating layer solidly adhered to the base can be formed.
Through such processes, an exhaust pipe to be used in the exhaust pipe heat-releasing system of the present embodiment can be produced.

[0147] In the following, effects of the exhaust pipe heat-releasing system of the present embodiment are described. The exhaust pipe heat-releasing system of the present embodiment can achieve the following effects in addition to the effect (3) described in the first embodiment.
(11) The exhaust pipe heat-releasing system of the present embodiment is provided with a surface-coating layer that contains a crystalline inorganic material and an amorphous binder on the outer peripheral face of the base of the exhaust pipe.
Provision of a surface-coating layer containing a crystalline inorganic material and an amorphous binder increases the emissivity of the outer peripheral face of the exhaust pipe, thereby increasing the amount of radiation heat from the outer peripheral face of the exhaust pipe. Then, the radiation heat from the outer peripheral face of the exhaust pipe is received by the heat-receiving member of the present invention which demonstrates excellent performance in receiving heat.
That is, improvement in the amount of radiation heat from the outer peripheral face of the exhaust pipe is combined with improvement in the amount of heat received by the heat-receiving member, which more effectively prevents the temperature of the exhaust pipe from rising too high.

[0148] (12) The exhaust pipe of the exhaust pipe heat-releasing system of the present embodiment has an emissivity (emissivity of the surface-coating layer) of 0.78 or more. Emissivity of the exhaust pipe in such a range increases the amount of radiation heat from the outer peripheral face of the exhaust pipe. As a result, it is possible to still more effectively prevent the temperature of the exhaust pipe from rising too high.

(Other Embodiments)

[0149] In the case where the heat-receiving member of the present invention is used as a heat-receiving member for receiving heat from an exhaust manifold of an engine, the heat-receiving member may be arranged as a different member from a heat insulator.
Fig. 17 is an exploded perspective view schematically illustrating exemplary arrangement of the heat-receiving member of the present invention as a different member from the heat insulator.
In Fig. 17, the heat-receiving member 1 of the present invention is arranged between the exhaust manifold 111 and the heat insulator 118, with the surface layer 30 of the heat-receiving member 1 being on the exhaust manifold 111 side.
Even such arrangement of a heat-receiving member makes it possible to increase the cooling ability of an exhaust manifold.

BRIEF DESCRIPTION OF THE DRAWINGS

[0150] 

Fig. 1 is an exploded perspective view which illustrates a vehicle engine and a vicinity of an exhaust pipe connected to the vehicle engine.

Fig. 2 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.

Fig. 3 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.

Fig. 4 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.

Fig. 5 is a cross-sectional view schematically illustrating an exemplary exhaust pipe heat-releasing system.

Fig. 6 is a cross-sectional view schematically illustrating a method of measuring heat receiving performance of a heat-receiving member.

Fig. 7 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.

Fig. 8 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.

Fig. 9 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.

Fig. 10 is a view showing the relationships between the locations of temperature measurement and the temperatures of the respective heat-receiving members which were measured in Example 2 and Examples 6 to 9.

Fig. 11 is a cross-sectional view schematically illustrating an exemplary heat-receiving member of the present invention.

Fig. 12 is a scanning electron microscope photograph that shows a surface of a surface layer of an exemplary heat-receiving member of the present invention which has cracks in the surface layer.

Fig. 13 is a scanning electron microscope photograph that shows a surface of a surface layer of an exemplary heat-receiving member of the present invention which has cracks in the surface layer.

Fig. 14 is a scanning electron microscope photograph that shows a surface of a surface layer of an exemplary heat-receiving member of the present invention which has cracks in the surface layer.

Fig. 15 is a cross-sectional view schematically illustrating an exemplary heat-receiving member.

Fig. 16 is a cross-sectional view schematically illustrating an exemplary exhaust pipe heat-releasing system of the present invention.

Fig. 17 is an exploded perspective view schematically illustrating exemplary arrangement of a heat-receiving member of the present invention as a different member from a heat insulator.

EXPLANATION OF SYMBOLS

[0151] 

1 to 11

Heat-receiving member

20

Base (base of heat-receiving member)

30, 30a, 30b

Surface layer

40, 40a, 40b

Micropore

50, 50a, 50b

Metal

60, 61, 62, 63

Crack

100, 150

Exhaust pipe heat-releasing system

101, 151

Exhaust pipe

102

Base (base of exhaust pipe)

103

Surface-coating layer

110

Engine

111

Exhaust manifold (exhaust pipe)

118

Heat insulator

Claims

1. A heat-receiving member, which is adapted to be arranged over an exhaust pipe and to receive heat energy released from an internal combustion engine, comprising:

a cylindrical base that contains aluminum or an aluminum alloy; and

a surface layer that is formed by anodizing a surface of the base,

characterized in that a plurality of cracks having zigzag shape or straight lines substantially parallel to each other is formed in the surface layer by bending the heat-receiving member so that it is distorted, and then bending it again so that it restores the original shape.

2. The heat-receiving member according to claim 1,
wherein
the heat-receiving member has a first region and a second region,
the first region is located farther from a high-temperature part of the exhaust pipe than the second region, and
the first region has emissivity higher than emissivity of the second region.

3. The heat-receiving member according to claim 2,
wherein
a micropore is formed in said surface layer in the first region, and a metal is deposited in said micropore.

4. The heat-receiving member according to claim 2,
wherein
the second region includes a region in which the surface of the base is unanodized and exposed.

5. The heat-receiving member according to any one of claims 1 to 4,
wherein
said cracks are separated from each other.

6. The heat-receiving member according to any one of claims 1 to 5,
wherein
a surface layer is also formed on a surface on the reverse side of said surface of the base.

7. An exhaust pipe heat-releasing system comprising:

an exhaust pipe including a cylindrical base that contains a metal; and

a heat-receiving member arranged over said exhaust pipe;

and a surface-coating layer that is formed on the outer peripheral face of the base included in the exhaust pipe, and that contains a crystalline inorganic material and an amorphous binder,

said heat-receiving member being a heat-receiving member according to any one of claims 1 to 6.

8. The exhaust pipe heat-releasing system according to claim 7,
wherein
said exhaust pipe has an emissivity of 0.78 or more.

Ansprüche

1. Wärmeaufnehmendes Element, das geeignet ist, über einem Abgasrohr angeordnet zu werden und Wärmeenergie aufzunehmen, die von einem Verbrennungsmotor freigesetzt wird, mit:

einer zylindrischen Basis, die Aluminium oder eine Aluminiumlegierung aufweist; und

einer Oberflächenschicht, die durch Anodisieren einer Oberfläche der Basis ausgebildet ist,

dadurch gekennzeichnet, dass mehrere Risse mit Zickzack-Form oder geraden Linien im Wesentlichen parallel zueinander in der Oberflächenschicht durch derartiges Biegen des wärmeaufnehmenden Elements, dass es verzerrt wird, und dann erneutes Biegen, so dass die ursprüngliche Form wieder hergestellt ist, ausgebildet sind.

2. Wärmeaufnehmendes Element nach Anspruch 1, bei dem das wärmeaufnehmende Element einen ersten Bereich und einen zweiten Bereich aufweist,
der erste Bereich weiter weg von einem Hochtemperaturteil des Abgasrohrs als der zweite Bereich ist, und
der erste Bereich ein höheres Emissionsvermögen als das Emissionsvermögen des zweiten Bereichs aufweist.

3. Wärmeaufnehmendes Element nach Anspruch 2, bei dem eine Mikropore in der Oberflächenschicht in dem ersten Bereich ausgebildet ist und ein Metall in der Mikropore abgeschieden ist.

4. Wärmeaufnehmendes Element nach Anspruch 2, bei dem der zweite Bereich einen Bereich aufweist, in dem die Oberfläche der Basis nicht-anodisiert und freiliegend ist.

5. Wärmeaufnehmendes Element nach einem er Ansprüche 1 bis 4, bei dem
die Risse voneinander getrennt sind.

6. Wärmeaufnehmendes Element nach einem der Ansprüche 1 bis 5, bei dem
eine Oberflächenschicht auch auf einer Oberfläche an der entgegengesetzten Seite der Oberfläche der Basis ausgebildet ist.

7. Abgasrohrwärmefreisetzungssystem mit:

einem Abgasrohr mit einer zylindrischen Basis, die ein Metall aufweist; und

einem wärmeaufnehmenden Element, das über dem Abgasrohr angeordnet ist; und

einer Oberflächenbeschichtungsschicht, die an der Außenrandfläche der Basis, die in dem Abgasrohr enthalten ist, ausgebildet ist und ein kristallines anorganisches Material und ein amorphes Bindemittel aufweist,

wobei das wärmeaufnehmende Element ein wärmeaufnehmendes Element nach einem der Ansprüche 1 bis 6 ist.

8. Abgasrohrwärmefreisetzungssystem nach Anspruch 7, bei dem
das Abgasrohr ein Emissionsvermögen von 0,78 oder mehr aufweist.

Revendications

1. Organe récepteur de chaleur, prévu pour être disposé par-dessus un tuyau d'échappement, et pour recevoir de l'énergie thermique dégagée par un moteur à combustion interne, comprenant:

une base cylindrique qui contient de l'aluminium ou un alliage d'aluminium, et

une couche de surface qui est formée par anodisation d'une surface de la base,

caractérisé en ce que plusieurs fissures présentant une forme en zigzag ou selon des lignes droites sensiblement parallèles entre elles sont formées dans ladite couche de surface en pliant l'organe récepteur de chaleur de telle sorte qu'il soit déformé, puis en le pliant à nouveau pour qu'il reprenne la forme primitive.

2. Organe récepteur de chaleur selon la revendication 1, dans lequel
l'organe récepteur de chaleur présente une première région et une seconde région,
la première région est située plus loin que la seconde région, d'une partie à haute température du tuyau d'échappement, et
la première région présente une émissivité supérieure à celle de la deuxième région.

3. Organe récepteur de chaleur selon la revendication 2, dans lequel
des micropores sont formés dans ladite couche de surface dans la première région, et un métal est déposé dans lesdits micropores.

4. Organe récepteur de chaleur selon la revendication 2, dans lequel
la deuxième région comprend une région dans laquelle la surface de la base n'est pas anodisée, et est exposée.

5. Organe récepteur de chaleur selon l'une quelconque des revendications 1 à 4, dans lequel lesdites fissures sont séparées les unes des autres.

6. Organe récepteur de chaleur selon l'une quelconque des revendications 1 à 5, dans lequel
une couche de surface est également formée sur une surface de la face opposée de ladite surface de la base.

7. Système de dégagement de chaleur de tuyau d'échappement comprenant:

un tuyau d'échappement comprenant une base cylindrique qui contient un métal, et

un organe récepteur de chaleur disposé par-dessus ledit tuyau d'échappement,

et une couche de revêtement de surface qui est formée sur la face périphérique extérieure de la base incluse dans ledit tuyau d'échappement, et qui contient un matériau inorganique cristallin et un liant amorphe.

ledit organe récepteur de chaleur étant un organe récepteur de chaleur selon l'une quelconque des revendications 1 à 6.

8. Système de dégagement de chaleur de tuyau d'échappement selon la revendication 7, dans lequel
ledit tuyau d'échappement présente une émissivité de 0,78 ou plus.

Drawing