[0001] The present invention is concerned with certain novel solutions which are particularly
useful for bonding one material to another, notably one metal to another, according
to the process described and claimed in our copending Applications filed herewith.
[0002] A process is described and claimed in our copending application No. which involves
fusing into or onto a first metal or other electrically conductive material, a second
metal or electrically conductive material by the steps of :
placing the second conductive material in contact with an adjacent surface of the
first conductive material, the second conductive material being in the form-of a dissociable
solution; and
applying an interrupted electrical signal of a predetermined frequency to the first
and second materials, whereby the second material is fused to the first material.
[0003] According to the said process, the solution of the second material may be aqueous
or organic. Desirably an aqueous solution is used which has a pH of 0.4 to 14, the
amount of second material therein is in the range of 0.10 to 10% by weight of the
solution and the resistivity of the solution is in the range of 10 to 80 ohms cm.
[0004] Preferably both the first and second materials are metal, For example, the first
material may be iron or iron alloy and the second material may be molybdenum tungsten
or indium. A wide variety of ferrous and/or non-ferrous combinations are contemplated.
[0005] As indicated, the said process contemplate the use of a solution containing the metal
to be fused (hereinafter the "second metal") to another metal (hereinafter called
the "first metal"), it being understood that the term "metal" is intended to embrace
metal alloys as well as single metals.
[0006] It is to be noted that our copending applications also disclose another process for
fusing metals together wherein both metal components are in solid form. This other
process may be called "solid-to-solid" fusion for convenience. The present invention,
however, is only concerned with the solutions for use in the alternative process wherein
one of the metals to be fused is initially in solution form. This is called for convenience
"liquid-to-liquid" fusion.
[0007] Certain of the metal solutions disclosed in our copending applications and others
described herein are new and constitute the basis for the present invention. Broadly
described, these solutiosn are aqueous, have a pH of about 0.4 - 14, a resistivity
of 10 to 80 ohms cm and contain:.
(1) a compound of a dissociable polyvalent metal to be fused to the other metal;
(2) a compound which is capable of complexing with compound (1), compounds (1) and
(2) being either soluble in water or forming a complex which is soluble in water;
(3) a stabilizer which functions to keep (1) and (2) and the complex thsreof in solution;
and
(4) a catalyzer which functions to promote the speed of reaction and reduce the valency
of the polyvalent metal to a lower valence and to catalyze the complexing action between
(1) and (2). Acid and/or alkaline material may also be used to insure the appropriate
pH for the conditions of use and to help keep the metal compounds (1) and (2) in solution.
[0008] Certain of these solutions may include a sufficient quantity of an organic solvent
to ensure dissolution of the metal and/or the complex.
[0009] Certain other solutions may require conductivity enhancing agents. And depending
upon the end result desired, brightening agents may also be present. Wetting agents
or surfactants may also be provided.
[0010] By the use of these solutions it has been found possible to effect fusion of the
dissolved metal, using the process described in copending application No.
[0011] with a first metal with facility., economy and at ambient temperatures without the
attendant physical or chemical changes which usually occur with the usual fusion methods.
[0012] These and other objects and features of the present invention will be more apparent
from the following description and drawings in which certain specific embodiments
of these solutions are illustrative of the invention and in which:
Fig. 1 is a general perspective view of one embodiment of the apparatus in association
with which the solutions of the present invention are used;
Fig. 2 is a general perspective view of a second embodiment of an apparatus in accordance
with the solutions in accordance with the invention may be employed;
Fig. 3 is a schematic electrical circuit employed in the present invention;
Fig. 4 is a circuit diagram of an oscillator as employed in accordance with one embodiment
of the present invention;
Fig. 5 is a composite SEM photomicrograph with right-hand and left-hand halves, of
a copper matrix with which molybdenum has been fused using the process of the present
invention with a molybdenum solution. The left-hand half has a magnification xl250
and the right-hand half is a x8 enlargement of the marked area of the left-hand half;
Fig. 6 is a graph of an SEM/EPMA scan across the sample shown in Fig. 5 and shows
the fusion of molybdenum with copper;
Fig. 7 is a composite SEM photomicrograph, with right and left hand halves, of a steel
matrix with which molybdenum has been fused using the process of the present invention
with a molybdenum solution. The left hand half has a magnification xl250 and the right
hand half is a x8 enlargement of the marked area of the left hand half;
Fig. 8 is a graph of an SEM/EPMA scan across the sample shown in Fig. 7 and shows
the fusion of molybdenum with steel;
Fig. 9 is a composite photomicrograph, with right and left hand halves, of a copper
matrix with which tungsten has been fused using the process of the present invention
with a tungsten solution. The left hand half has a magnification xl250 and the right
hand half is a x8 enlargement of the marked area of the left hand half;
Fig. 10 is a further SEM photomicrograph of the sample of Fig. 9 with a magnification
x10,000 of part of the marked area of Fig. 9;
Fig. 11 is a graph of an SEM/EPMA scan across the sample shown in Figs. 9 and 10;
Fig. 12 is a composite photomicrograph, with right and left hand halves, of a steel
matrix with which tungsten has been fused using the process of the present invention
with a tungsten solution. The left hand half has a magnification xl310 and the right
hand half is a x8 enlargement of the marked area of the left hand half;
Fig. 13 is a graph of an SEM/EPMA scan across the sample shown in Fig. 12 and shows
the fusion of tungsten with steel;
Fig. 14 is a composite photomicrograph with right and left hand halves, of a copper
matrix with which indium has been fused using the process of the present invention
with an indium solution. The left hand half has a magnification x1250 and the right
hand half is a x8 enlargement of the marked section of the left hand half;
Fig. 15 is a graph of an electron microprobe scan across the sample shown in Fig. 14;
Fig. 16 is a composite SEM photomicrograph, with right and left hand halves of a steel
matrix with which indium has been fused using the process of the present invention
with an indium solution. The left hand half has a magnification x625 and the right
hand half is a x8 enlargement of the marked section of the left hand half;
Fig. 17 is a graph of an SEM/EPMA scan across the sample shown in Fig. 16;
Fig. 18 is a composite SEM photomicrograph, with right and left hand halves, of a
copper matrix with which nickel has been fused using the process of the present invention
with a nickel solution. The left hand half has a magnification x1250 and the right
hand half is a x8 enlargement of the marked section of the left hand half;
Fig. 19 is a graph of an SEM/EPMA scan across the sample shown in Fig. 18;
Fig. 20 is a composite SEM photomicrograph with right and left hand halves, of a steel
matrix with which nickel has been fused using the process of the present invention
with a nickel solution. The left hand half has a magnification x1310 and the right
hand half is a x8 enlargement of the marked section of the left hand half;
Fig. 21 is a graph of an SEM/EPMA scan across the sample shown in Fig. 20;
Fig. 22 is a composite photomicrograh of a copper matrix with which gold has been
fused. The left hand half has a magnification x1310 and the right hand half is a x8
enlargment of the marked section fo the right hand half.
Fig. 23 is a graph of an SEM/EPMA scan across the sample shown in Fig. 22 showing
gold fused in the copper matrix;
Fig. 24 is a composite photomicrograph with right and left hand halves, of a steel
matrix with which gold has been fused using the process of the present invention with
a gold solution. The left hand half has a magnification x1310, the right hand half
is x8 magnification enlargement of the marked area of the left hand half;
Fig. 25 is a graph of an SEM/EPMA scan across the sample shown in Fig. 23 showing
gold fused in the steel matrix;
Fig. 26 is an SEM photomicrograph with a magnification x10,000 of a copper matrix
with which chromium has been fused using the process of the present invention with
a first chromium solution;
Fig. 27 is a graph of an SEM/EPMA scan across the sample shown in Fig. 26 and shows
the fusion of chromium with copper;
Fig. 28 is an SEM photomicrograph with a magnification x10,000 of a steel matrix with
which chromium has been fused using the process of the present invention with the
first chromium solution referred to above;
Fig. 29 is a graph of an SEM/EPMA scan across the sample shown in Fig. 28 and shows
the fusion of chromium with steel;
Fig. 30 is a composite SEM photomicrograph, with right and left hand halves, of a
copper matrix with which chromium has been fused using the process of the present
invention with a second chromium solution. The left hand half has a magnification
x625 and the right hand half is a x8 enlargement of the marked area of the left hand
half;
Fig. 30A is a further enlarged SEM photomicrograph of the enlarged area of Fig. 30
at a magnification of x10,000;
Fig. 32 is a graph of an SEM/EPMA scan across the sample shown in Fig. 30 and shows
the fusion of chromium with copper;
Fig. 33 is a composite SEM photomicrograph, with right and left hand halves, of a
steel matrix with which chromium has been fused using the process of the present invention
with a second chromium solution. The left hand half has a magnification x1250 and
the right hand half is a x8 enlargement of the marked area of the left hand half;
Fig. 33A is a further enlarged SEM photomicrograph of the enlarged area of Fig. 33
at a magnification of x10,000;
Fig. 34 is a graph of an SEM/EPMA scan across the sample shown in Fig. 32 and shows
the fusion of chromium with steel;
Fig. 35 is a composite photomicrograph with right and left hand halves, of a copper
matrix with which cadmium has been fused using the process of the present invention
with a first cadmium solution; the left hand half has a magnification x1310 and the
right hand half is a x5 enlargement of the marked area;
Fig. 36 is a graph of an SEM/EPMA scan across the sample shown in Fig. 35 and shows
the fusion of cadmium with copper;
Fig. 37 is a photomicrograph at xll,500 magnification of a steel matrix with which
cadmium has been fused using the process of the present invention with a second cadmium
solution;
Fig. 38 is a graph of an SEM/EPMA scan across the sample shown in Fig. 37 and shows
the fusion of cadmium with steel;
Fig. 39 is a composite photomicrograph with left and right hand halves, of a copper
matrix with which tin has been fused using the process of the present invention with
a first tin solution; the left hand half has a magnification of x655 and the right
hand half is a x8 enlargement of the marked area;
Fig. 40 is an SEM/EPMA scan across the sample of Fig. 39 and shows the fusion of tin
with copper;
Fig. 41 is a composite photomicrograph with left and right hand halves, of a copper
matrix with which tin has been fused using the process of the present invention with
a second tin solution; the left hand half has a magnification x326 and the right hand
half is x8 enlargement of the marked area;
Fig. 42 is an SEM/EPMA scan across the sample of Fig. 41 and shows fusion of tin with
copper;
Fig. 43 is a composite SEM photomicrograph with right and left hand halves, of a steel
matrix with which tin has been fused using the process of the present invention with
the second tin solution; the right hand half is a xl310 magnification and the left
hand half is x8 magnification of the marked area;
Fig. 44 is a SEM/EPMA scan across the sample of Fig. 43 and shows fusion of tin with
steel;
Fig. 45 is an SEM photomicrograph at a x5200 magnification of a copper matrix with
which cobalt has been fused using the process of the present invention with a first
cobalt solution;
Fig. 46 is an SEM/EPMA scan across the sample of Fig. 45 and shows fusion of cobalt
with copper;
Figs. 47 and 47A are photomicrographs of a copper matrix with which silver has been
fused using the process of the invention with a first silver solution;
Fig. 47 is a composite with the left hand side having a magnification of x625 and
the right hand side being an x8 enlargement of the marked area;
Fig. 47A is a further enlarged SEM photomicrograph of the enlarged area of Fig. 47
at a magnification x10,000;
Fig. 48 is an SEM/EPMA scan across the sample of 'Fig. 47 and shows fusion of silver
with copper;
Fig. 49 is an SEM photomicrograph at a magnification of x10,000 of a copper matrix
with which silver has been fused using the process of the present invention with a
second silver solution;
Fig. 50 is an electron microprobe scan across the sample of Fig. 49 and shows fusion
of silver with copper;
[0013] In those Figures which are graphs, of Figures 5 through 50, the vertical axis is
logarithmic while the horizontal axis is linear. And in these graphs the surface layer
has been taken as the point at which the concentration (wt%) of the matrix and the
element which has been fused therewith are both at 50% as indicated by the projections.
[0014] Referring now to drawings Figs. 1 and 2 these drawings illustrate in general perspective
view apparatus in accordance with the invention which is employed to carry out the
process of the invention.
[0015] In Fig. 1, which exemplifies a solid-to-solid process the number 10 indicates a power
supply and 11 an oscillator.
[0016] One side of the oscillator output is connected to an electrode 13 through a holder
12. Holder 12 is provided with a rotating chuck and has a trigger switch which controls
the speed of rotation of the electrode 13. The speed of rotation is variable from
5,000 to 10,000 rpm.
[0017] The electrode 13 is composed of the material to be fused with the matrix. The matrix
or substrate which is to be subjected to the process and which is to be treated is
indicated at 14. The matrix is also connected to the other side of the oscillator
output by a clamp 15 and line 16.
[0018] By these connections the electrode is positively charged and the matrix is negatively
charged when the signal is applied.
[0019] In Fig. 2 the corresponding components are correspondingly numbered. However, in
this embodiment the process employed may be characterized as a liquid to solid process.
In this apparatus the material to be fused is in the form of a solution and is held
in a reservoir 17. Reservoir 17 is connected by a tube 18 to an electrode 19. Electrode
19 is a plate provided with an insulated handle 20 through which one side of oscillator
11 output is connected. This output is led into a main channel 21 in electrode 19.
Channel 21 has a series of side channels 22 which open on to the undersurface of electrode
20. The flow from reservoir 17 is by gravity or by a pump and may be controlled by
a valve such as 23 on the handle 20. For further control, more even distribution of
the solution, and to prevent the inclusion of foreign matter the surface of electrode
19 is preferably covered by a permeable membrane such as cotton or nylon.
[0020] It has been found that to effect fusion that the application of 50,000 watts/sq.
cm. or alternatively the application of current of the order of 10,000 amps/sq. cm.
is necessary.
[0021] From a practical standpoint 10,000 amps/sq.cm. can not be applied constantly without
damage to the matrix to be treated.
[0022] However, it has been found practical to apply a pulsing signal of 2.5 microseconds
to 28.6 nanoseconds having a magnitude of 3 amps to the electrode and this causes
fusion to occur over an area of approximately 0.3 sq. mm.
[0023] To effect fusion over an area with the apparatus shown in Fig. 1 the electrode 13,
matrix 14 and the oscillator output are connected as shown.
[0024] The operator passes the rotating electrode 13 in contact with the upper surface of
the matrix over the matrix . surface at a predetermined speed to apply the electrode
material to the matrix and fuse it therewith.
[0025] It has also been found that the continuous application of an alternating signal generates
considerable heat in the substrate or matrix and to overcome this heat build-up and
avoid weldments the signal generated in the present apparatus is a half-wave signal
which permits dissipation of the heat.
[0026] As will be apparent to those skilled in the art each material, both the matrix and
the material to be applied have specific resistance characteristics. Thus with each
change in either one or both of these materials there is a change in the resistivity
of the circuit.
[0027] In Fig. 3, R
l = the resistance of the electrode, R
2 = the resistance of the matrix, and R
3 = the resistance of the circuit of 10 and 11.
[0028] Variations in R
l and R
2 will lead to variations in the frequency of the signal generated and the amplitude
of that signal.
[0029] As mentioned previously a signal having an amplitude of 3 amps is believed to be
the preferred amplitude. If the amplitude is greater decarbonizing or burning of the
matrix takes place and below this amplitude hydroxides are formed in the interface.
[0030] Fig. 4 is a schematic diagram of an oscillator circuit used in apparatus in accordance
with the present invention.
[0031] In that circuit a power supply 30 is connected across the input, and across the input
a capacitor 31 is connected. One side of the capacitor 31 is connected through the
LC circuit 32 which comprises a variable inductance coil 33 and capacitor 34 connected
in parallel.
[0032] LC circuit 32 is connected to one side of a crystal oscillator circuit comprising
crystal 35, inductance 36, NP
N transistor 37 and the RC circuit comprised of variable resistance 38 and capacitance
39.
[0033] This oscillator circuit is connected to output 50 through, on one side capacitor
40, and on the other side diode 41, to produce a halfwavesignal across output 50.
[0034] In the apparatus actually used the several components had the following characteristics:
31 = 1.2µ farad
32 = 0.3 picrofarad
33 = 0-25 millihenrys
35 = 400 - 30 Khz
36 = 20 millihenrys
37 = NPN
38 = 3.5 µ farads
39 = 0 - 500 ohms
40 = 400µ farads
41 = diode
[0035] To maintain the amplitude of the signal at 3 amps R
1 resistance 38 is varied; to vary the frequency inductance 33 is varied.
[0036] If C = the capacitance of the circuit of Fig. 3 and R
l, R
2 and R
3 are the resistances previously characterized it is believed that the optimum frequency
of the fusing signal F
o may be determined by the form
where L = R1.R2.R3
and C = capacitance of the circuit
L and C may be determined by any well-known method.
[0037] F
o depends on the material being treated and the material being applied but it is in
the range 400Hz - 35MHz. The frequency, it is believed, will determine the speed of
the process.
[0038] To fuse a predetermined area, the area is measured. Since each discharge will fuse
approximately 0.3 sq. mm. then the travel speed may be determined by the following
form:
and
[0039] A = area to be covered in sq.. mm.
[0040] F
l is the number of discharges per second.
[0041] As mentioned previously the resistances R
l and R
2 may be measured by any known means.
[0042] However it has been discovered that the measurement of resistance in the liquid phase
may not be stable. In this situation the resistance is measured in a standard fashion.
Two electrodes, 1 cm. apart and 1 cm. sq. in area are placed in a bath of the liquid
phase and the resistance was measured after a 20 second delay. After the variable
parameters have -been determined and the apparatus, matrix and probe have been connected
as shown in Figs. 1 and 3, the probe 13 is passed over the surface of the matrix in
contact therewith at the predetermined speed.
[0043] The speed of rotation is also believed to affect the quality of the fusion with a
rotation speed of 5,000 rpm the finish is an uneven 200 to 300 finish; with a speed
of rotation of 10,000 rpm the finish is a substantially 15 finish.
[0044] The apparatus of Fig. 2 is operated in the same manner as the apparatus of Fig. 1
and the process is essentially the same except for the use of a liquid with a solid
electrode.
[0045] In the following specific examples the use of the solutions in association with the
apparatus and in the process will be more clearly understood.
[0046] In each of these examples the electrode was so connected as will be apparent from
the description, so that when charged the electrode is positively charged and the
matrix is negatively charged.
[0047] With respect to the fusion of a second conductive chemical element into the solid
matrix of a first conductive chemical element, using a solution of the second conductive
chemical, with respect to each solution, the process was carried out at the ambient
temperature, 20°C, in the following manner.
[0048] The matrix 14 metal was connected into the circuit as previously described. The frequency
was determined in accordance with the formula previously set forth and the solution
in reservoir 17 applied by movement of the electrode over one surface of the first
metal for varying periods of time as determined by Form II. To ensure uniform distribution
of the second metal solution over the surface of the first metal the electrode was
covered with cotton gauze or nylon. It will be apparent that other materials may be
employed. This arrangement also served to limit contamination of the solution when
graphite electrodes were employed. They had a tendency to release graphite particles
in the course of movement.
[0049] The treated samples were then sawn to provide a cross-sectional sample, washed in
cold water, subject to ultrasonic cleaning, embedded in plastic and ground and polished
to produce a flat surface and an even edge. With other samples with the softer metals
where there was a tendency to lose the edge on grinding two cross-sections were secured
with the treated surface in face to face abutting relationship, embedded as before
and ground and polished.
[0050] Following embeddment the sample was etched using Nital for steel, the ferrous substrate,
and Ammonium Hydrogen Peroxide on the copper, the non-ferrous substrate.
[0051] During the course of some applications it was found that adjustments were sometimes
required in either the frequency, or speed of application. These were due to changes
in the solution composition or variations in the matrix.
[0052] A semiquantitative electron probe microanalysis of fused interfaces were performed
using an Energy Dispersive
X-Ray Spectroscopy (EDX) and a Scanning Electron Microscope (SEM).
[0053] The surface of the embedding plastic was rendered conductive by evaporating on it
approximately 20 um layer of carbon in a vacuum evaporator. This procedure was used
to prevent buildup of electrical charges on an otherwise nonconductive material and
a consequent instability of the SEM image. Carbon, which does not produce a radiation
detectable by the EDX, was used in preference of a more conventional metallic coating
to avoid interference of such a coating with the elemental analysis.
[0054] Operating conditions of the SEM were chosen to minimize extraneous signals and the
continuum radiation and to yield at the same time the best possible spatial resolution.
[0055] The conditions typically used for the elemental analyses by EDX were as follows:
[0056] Energy calibration was tested using A1 kd emission at 1.486 keV and cu K at 8.040keV.
[0057] A standardless semiquantitative analysis was adopted for determination of elemental
concentration, using certified reference materials (NBS 478, 78% Cu - 27% Zn and NBS
479a, Ni, 11%, Cr 18%, Fe) to verify results. Multiple analysis of reference materials
were in excellent agreement with certified values from NBS. Average precision of +
1% was achieved. A size of analysed volume was calculated from the following equation
1:
where R(
x) is the mass range (th x-ray production volume) p = Density of analysed material
E
o = The accelerating potential E
c = A critical excitation energy.
[0058] The diameter of analysed volume was calculated for typical elements analysed and
was found to be as follows:
Ni 0.46
Cu 0.39
Fe 0.55
W 0.30
[0059] For assessment of the diffusion depth a static beam was positioned across the interface
at intervals greater than the above mentioned mass range. Ensuring thus the accuracy
of the analysis.
[0060] The results of elemental concentration were given in weight percentage (Wt%) for
each of the measured points across the fusion interface.
[0061] As mentioned previously the metal solutions disclosed in Serial No. 319,672 are new
and constitute the basis for the present invention. Broadly described, these solutions
are aqueous, have a pH of about 0.4-14, a resistivity of 10 to 80 ohms cm and contain:
(1) a compound of a dissociable polyvalent metal to be fused to the other metal;
(2) a compound which is capable of complexing with compound (1), compounds (1) and
(2) being either soluble in water or forming a complex which is soluble in water;
(3) a stabilizer which functions to keep (1) and (2) and the complex thereof in solution;
and
(4) a catalyzer which functions to promote the speed of reaction and reduce the valency
of the polyvalent metal to a lower valence and to catalyze the complexing action between
(1) and (2). Acid and/or alkaline material may also be used to insure the appropriate
pH for the conditions of use and -to help keep the metal compounds (1) and (2) in
solution.
[0062] Certain of these solutions may include a sufficient quantity of an organic solvent
to ensure dissolution of the metal and/or the complex.
[0063] Certain other solutions may require conductivity enhancing agents. And depending
upon the end result desired, brightening agents may also be present. Wetting agents
or surfactants may also be provided.
[0064] A variety of dissociable polyvalent metal compounds, usually metallic salts or acids,
may be used as component (1) provided they are soluble in the'solution medium. Typical
compounds include: sodium molybdate, sodium tungstate, indium sulphate, nickelous
sulphate, nickelous chloride, chloroauric acid, chromium trioxide, chromium sulphate,
chromic chloride, cadmium chloride, cadmium sulphate, stannous chloride, cobaltous
sulphate, silver cyanide, silver nitrate.
[0065] Normally component (1) will be used in an amount varying from 0.10 to 10% by weight
based on the total weight of the solution. However, it will be appreciated that other
amounts may be used, the particular amount used in any given situation depending on
other conditions of use.
[0066] Representative metal complexing agents useful as component (2) include, such as,
pyrophosphates, ethylene diamine tetracetic acid, citric acid, and potassium iodide
and the like. The pyrophosphates also serve as stabilizing agents.
[0067] This component will usually consist of from 3 to 10% of the weight of solution. However,
the amount can be varied and should be selected to give optimum complexing with (1).
[0068] A wide variety of stabilizers and catalysts may be used as components (3) and (4),
respectively. Typical stabilizers are the following: boric acid, citric acid or citrates,
pyrophosphates, acetates and aluminum sulphate; while suitable catalysts include:
metallic ions such as iron, nickel, antimony, and zinc, and organic compounds such
as dextrine, hydroquinone, gelatin, pepsin and acacia gum.
[0069] The amounts of these to components can be varied but usually each will fall in the
range of 0.01 to 0.5% by weight of the solution.
[0070] A wide variety of materials may be used to provide for the desired pH. Typical acids,
and bases include the following:
Acids: sulphuric, hydrochloric, hydrofluoric, orthophosphoric, citric and oxalic.
Bases: ammonium hydroxide, sodium hydroxide, potassium hydroxide and basic salts such
as alkali carbonates and bicarbonates.
[0071] Typical brighteners are formaldehyde and carbon disulphide. A surfactant or wetting
agent which is employed in some solutions is sodium lauryl sulphate. Others familiar
to those in the art may be substituted.
[0072] In some solutions a cnoductivity enhancing agent such as sodium sulphate may be employed.
[0073] It will be noted that in Examples II, III and IV which follow, ferrous and ferric
ions are provided in the solution. While the iron was apparently transferred concurrently
with molybdenum to the matrix there was no apparent material effect on the matrix
or molybdenum which was fused with it.
[0074] It has been found that the transfer of molybdenum into the matrix was enhanced by
the presence of the ferric and ferrous ions. The exact nature of the mechanism is
not known but it is believed that the presence of these iron ions forms complexes
which enhances the reduction of Mo
+6 to lower valency states.
[0075] Certain further solutions require second chemical conductive element complexing agents
which preclude precipitation of the second element. These agents were by way of example
citric acid, or sodium pyrophospate, or ethyldiaminetetracetic acid or their equivalents.
[0076] A suitable buffer is also provided in certain solutions, where required.
[0077] The water is always demineralized.
[0078] And for certain applications where the appearance of the product requires an elegant
appearance small quantities of brighteners such as formaldehyde, carbon disulphide,
benzene, sulphonic acid or their equivalents may be employed.
[0079] In these Examples, unless otherwise indicated the steel matrix was ASA 1018 and the
copper was ASTM B-1333 Alloy 110.
E X A M P L E I
[0080] Atlas A151 1020 steel was connected in the apparatus of Fig. 2 as the matrix 14 and
a 10% solution of ammonium molybdate in water was placed in reservoir 17.
[0081] The following were the characteristics and conditions of treatment:
[0082] The sample of Example I was subject to a thermal corrosion test. 25% sulphuric acid
was applied to the surface for 20 minutes at 325°C without any surface penetration.
EXAMPLE II
[0083] An aqueous solution of the following formulation was prepared:
[0084] The solution had the following characteristics:
[0085] The Mo
+6 concentration may be varied from 1.5% to 2.5% by weight; the pH from 7.2 to 8.2 and
the resistivity from 17 - 25 ohms cm.
REACTION CONDITIONS
[0086]
[0087] In the solutions set out in Examples II and III the presence of the ferrous and ferric
ions are believed to serve to reduce the Mo
+6 valency state to a lower valency state.
[0088] While iron is apparently concurrently transferred as illustrated in Fig. 6 the iron
has apparently no material effect on the characteristics of the matrix or the molybdenum.
[0089] An examination of the sample with an optical microscope shows a continuous coating
of molybdenum free from pitting and with a dark silver colour.
[0090] As shown in the table below and Fig. 6 an SEM/EPMA scan across the interface between
the matrix and the applied metal, molybdenum is seen to be fused to a depth of at
least 4 um with a surface deposit of approximately 1 um.
EXAMPLE III
[0091] An aqueous solution of the same formulation as Example II was prepared and applied
under the following conditions:
[0092] Examination under the optical microscope showed a continuous dark silver surface.
[0093] The photomicrograph Fig. 7, shows the deposition of a substantially uniform layer
of molybdenum 1 micron thick of uniform density.
[0094] As shown in Fig. 8 an SEM/EPMA scan across the interface between the substrate and
the applied metal shows molybdenum was present to a depth of at least 10 microns and
a molybdenum gradient as set out below in Table.
EXAMPLE III
[0095] An aqueous solution of the following formulation was prepared:
[0096] The solution had the following characteristics:
[0097] The W
+6 concentration may vary from 1.6% to 2.5%; the pH may vary from 7.5 to 8.5; and the
resistivity may vary from 18 ohms cm to 24 ohms cm.
Reaction Conditions
[0098]
[0099] As shown by the photomicrographs Figs. 9 and 10, the sample showed a uniform deposit
of tungsten approximately 1 micron thick. An SEM/EPMA scan showed fusion of tungsten
on copper to a depth of at least 5.0 microns, as can be seen in the Table below and
Fig. 11.
EXAMPLE V
[0100] An aqueous solution of the following formulation was prepared:
[0101] The solution had the following characteristics:
[0102] The concentration of tungsten may be varied from 1.6% to 2.5% by wt.; the pH from
7.5 to 8.5; and the conductivity from 18.8 ohms cm to 22.8 ohms cm.
Reaction Conditions
[0103]
[0104] An inspection of the sample by SEM/EPMA, Fig. 12, showed a deposit of tungsten of
approximately 0.5 um and as evident from Fig. 13 and the Table below tungsten was
detected at a depth of at least 3 um.
EXAMPLE VI
[0105] An aqueous solution of the following formulation was prepared:
[0106] The solution had the following characteristics:
[0107] The Indium concentration may vary from 0.2% to 2.2%; the pH from 1.60 to 1.68; and
the resistivity from 48.8 ohms cm to 54.8 ohms cm.
Reaction Conditions
[0108]
[0109] An examination of the sample under the optical microscope and the scanning electron
microscope showed a continuous surface free from structural faults as shown in Fig.
14.
[0110] As shown in the following Table and Fig. 15 and an
SEM/EPMA scan across the interface between the copper matrix and the indium layer showed
a deposit of approximately 1 um and fusion of indium to a depth of at least 4 um.
EXAMPLE VII
[0111] The solution of Example VI was employed and applied to a steel matrix:
[0112] As shown in Figs. 16 and 17 an even continuous layer of Indium approximately 1 um
thick was deposited on the surface of the matrix. An SEM/EPMA scan, Fig. 16 across
the interface and the Table below indicated fusion to a depth of at least 3 um:
[0113] Fig. 18 shows a solid deposit of nickel of uniform density approximately 1.5 um thick.
As shown in the following Table and Fig. 19 an SEM/EPMA scan across the interface
between the matrix and the nickel layer shows nickel to be fused to a depth of at
least 4 um.
EXAMPLE VIII
[0114] An aqueous solution of the following formulation was prepared:
[0115] The solution had the following characteristics:
[0116] The nickel concentration may vary from 2% to 10%; pH from 3.10 to 3.50; and resistivity
from 17 ohms cm to 26 ohms cm.
Reaction Conditions
[0117]
EXAMPLE IX
[0118] The same solution as was formulated for Example X was prepared and applied to a steel
matrix:
[0119] As shown in Fig. 20 the nickel layer is continuous and substantially uniform in thickness
being about 1.5 um thick.
[0120] As shown in Fig. 21 and in the following Table nickel is shown to be fused to a depth
of at least 3 um.
EXAMPLE X
[0121] An aqueous solution of the following formulation was prepared:
[0122]
This solution had the following characteristics:
[0123] The pH may be varied from 3.70 to 11; the concentration of Au
+3 ions may vary from 0.1% to 0.5% by weight; and the resistivity from 40 ohms cm to
72 ohms cm.
REACTION CONDITIONS
[0124]
Observation with the optical and scanning electron microscope revealed a surface deposition
of gold approximately 1.5 um thick. The deposit was continuous and uniformly dense
as shown in Fig. 22.
[0125] An SEM/EPMA scan across the interface indicated fusion of gold to a depth of at least
3 um as shown on the Table below and Fig. 23.
EXAMPLE XI
[0126] An aqueous solution of the same formulation as that of Example X was prepared:
[0127]
Observation with the optical and scanning electron microscope revealed a surface deposition
of gold approximately 1.0 um thick. The deposit was uniformly thick and dense as shown
in Fig. 24.
[0128] An SEM/EPMA scan across the interface indicated fusion of gold to a depth of at least
4.0 um as shown on the table below and Fiq. 25.
EXAMPLE XII
[0129] An aqueous solution of the following formulation was prepared:
[0130]
This solution had the following characteristics:
[0131] The pH may be varied from 0.6 to 1.0; the concentration of Cr
+6 ions may vary from 3% to 20% by weight; and the resistivity from 11 ohms cm to 14
ohms cm.
REACTION CONDITIONS
[0132]
Observation with the optical and scanning electron microscope revealed a surface deposition
of chromium approximately 1 um thick. The surface of the layer was irregular but the
deposit appeared free of faults and was continuous as shown in Fig. 26.
[0133] An SEM/EPMA scan across the interface indicated fusion of chromium to a depth of
at least 3.0 um as shown on the table below and Fig. 27.
EXAMPLE XIII
[0134] An aqueous solution of the same formulation as employed in Example XII was prepared:
[0135]
Observation with the optical and scanning electrode microscope revealed a surface
deposition of chromium approximately 3.0 um thick. This is as shown in Fig. 28.
[0136] An SEM/EPMA scan across the interface indicated fusion of chromium to a depth of
at least 5.0 um as shown on the table below and Fig. 29.
EXAMPLE XIV
[0137] An aqueous solution of the following formulation was prepared:
[0138]
This solution had the following characteristics:
[0139] The pH may be varied from 2.5 to 3.5; the concentration of Cr
+3 ions may vary from 1.8% to 5% by weight; and the resistivity from 16 ohms cm to
20 ohms cm.
REACTION CONDITIONS
[0140]
Observation with the optical and scanning electron microscope revealed a surface deposition
of chromium approximately 0.5 um thick. The deposit was solid and continuous as shown
in Figs. 30 and 30A.
[0141] An SEM/EPMA scan across the interface indicated fusion of chromium to a depth of
at least 3.0 um as shown on the Table below and Fig. 32.
EXAMPLE XV
[0142] An aqueous solution of the same formulation as prepared for Example XVII was employed:
[0143]
Observation with the optical and scanning electron microscope revealed a surface deposition
of chromium approximately 1.0 um thick. The surface of the deposit appeared slightly
irregular but the deposit was solid and free of faults as shown in Figs. 33 and 33A.
[0144] An SEM/EPMA scan across the interface indicated fusion of chromium to a depth of
at least 3.0 um as shown on the table below and Fig. 34.
EXAMPLE XVI
[0145] An aqueous solution of the following formulation was prepared:
[0146]
This solution had the following characteristics:
[0147]
The pH may be varied from 10 to 10.2; the concentration of
Cd
+2 ions may vary from 0.2% to 0.5% by weight; and the resistivity from 28 ohms cm to
35 ohms cm.
REACTION CONDITIONS
[0148]
In this Example the solution employed was initially as set out above, applied in accordance
with the conditions identified as (1). A second solution, that set forth in Example
XVII, was then applied under the conditions identified as (2).
[0149] Observation with the optical and scanning electron microscope revealed a surface
deposition of cadmium approximately 4 um thick. This deposit was not homogenous as
shown in Fig. 35 but an
SEM/EPMA scan across the interface indicated fusion of cadmium to a depth of at least
9 um as shown on the Table below and Fig. 36.
EXAMPLE XVII
[0150] An aqueous solution of the following formulation was prepared:
[0151]
This solution had the following characteristics:
[0152] The pH may be varied from 3.2 to 3.5; the concentration of Cd
+2 ions may vary from 1% to 4% by weight; and the resistivity from 45 ohms cm to 55
ohms cm.
REACTION CONDITIONS
[0153]
Observation with the optical and scanning electron microscope revealed a surface deposition
of cadmium approximately 1 um thick. The surfce of the deposit was irregular but it
was solid and continuous as seen from Fig. 37.
[0154] An SEM/EPMA scan across the interface indicated fusion of cadmium to a depth of at
least 4 um as shown on the Table below and Fig. 38.
EXAMPLE XVIII
[0155] An aqueous solution of the following formulation was prepared:
[0156]
This solution had the following characteristics:
[0157] The pH may be varied from 11.2 to 12.7; the concentration of Sn
+2 ions may vary from 2% to 5% by weight; and the resistivity from 6.2 ohms cm to 10.3
ohms cm.
REACTION CONDITIONS
[0158]
Observation with the optical and scanning electron microscope revealed a surface deposition
of tin approximately 1.2 um thick. The deposit was uniformly thick and homogenous.
This is shown in Fig. 39.
[0159] An SEM/EPMA scan across the interface indicated fusion of tin to a depth of at least
4 um as shown on the table below and Fig. 40.
EXAMPLE XIX
[0160] An aqueous solution of the following formulation was prepared:
[0161]
This solution had the following characteristics:
[0162] The pH may be varied from 9 to 9.7; the concentration of Sn
+2 ions may vary from 0.4% to 1% by weight; and the resistivity from 30 ohms cm to 36
ohms cm.
REACTION CONDITIONS
[0163]
Observation with the optical and'scanning electron microscope revealed a surface deposition
of tin approximately 4 um thick.
[0164] This deposit appears to comprise a lower uniform and substantially homogenous layer
of approximately 1 um thick and an outer slightly porous layer approximately 3 um
thick as shown in Fig. 41.
[0165] An SEM/EPMA scan across the interface indicated fusion of tin to a depth of at least
5 um as shown on the Table below and Fig. 47.
EXAMPLE XX
[0166] An aqueous solution of the same as prepared for Example XIX was employed:
[0167]
Observation with the optical and scanning electron microsccpe .revealed a surface
deposition of tin exceeding 2 um thick. This layer was porous but continuous as shown
in Fig. 43.
[0168] An SEM/EPMA scan across the interface indicated fusion of tin to a depth of at least
2 um as shown on the table below and Fig. 44.
EXAMPLE XXI
[0169] An aqueous solution of the following formulation was prepared:
[0170]
This solution had the following characteristics:
[0171] The pH may be varied from 4.5 to 6.5; the concentration of Co+2 ions may vary from
2% to 6% by weight; and the resistivity from 25 ohms cm to 30 ohms cm.
REACTION CONDITIONS
[0172]
Observation with the optical and scanning electron microscope revealed a surface deposition
of cobalt approximately 6.5 um thick. This layer was uniform and continuous as shown
in Fig. 45.
[0173] An SEM/EPMA scan across the interface indicated fusion of cobalt to a depth of at
least 20 um as shown on the Table below and Fig. 46.
[0174] It was evident by visual inspection and from the previous experiments that the deposit
of cobalt was above the 10 um level was extremely dense.
EXAMPLE XXII
[0175] An aqueous solution of the following formulation was prepared:
[0176]
This solution had the following characteristics:
[0177] The pH may be varied from 11.2 to 11.7; the concentration of Ag
+1 ions may vary from 1% to 3% by weight; and the resistivity from 8 ohms cm to 13 ohms
cm.
REACTION CONDITIONS
[0178]
Observation with the optical and scanning electron microscope revealed a surface deposition
of silver approximately 5 um thick. The structure is shown in Figs. 47 and 47A.
[0179] An SEM/EPMA scan across the interface indicated fusion of silver to a depth of at
least 3 um as shown on the Table below and Fig. 48.
EXAMPLE XXIII
[0180] An aqueous solution of the following formulation was prepared:
[0181]
This solution had the following characteristics:
[0182] The pH may be varied from 1.5 to 2; the concentration of Ag
+1 ions may vary from 0.5% to 2.5% by weight; and the resistivity from 6 ohms cm to
12 ohms cm.
REACTION CONDITIONS
[0183]
Observation with the optical and scanning electron microscope revealed a surface deposition
of silver approximately 2 um thick. The structure was as shown in Fig. 49.
[0184] An SEM/EPMA scan across the interface indicated fusion of silver to a depth of at
least 2.00 um as shown on the Table below and Fig. 50.
[0185] From the foregoing examples it will be seen that through the medium of these solutions
a second metal in the solution may be fused with a first metal.