Technical Field
[0001] This invention relates to a process for bonding abrasive particles to the surface
of a metal workpiece.
Background Art
[0002] The hardness and abrasive qualities of diamonds are well known, particularly those
of synthetically produced virgin polycrystalline diamond particles. Virgin polycrystalline
diamond particles are of particular interest because of their greatly increased number
of sharp points or cutting edges and lack of fracture planes.
[0003] Tools such as for sharpening and grinding have been prepared from natural and synthetic
diamond particles by bonding these particles together in the form of a sharpening
stone using a ceramic or polymeric matrix to bond the diamonds into a unitary structure.
However, this process consumes an excessive amount of diamond particles, and the ceramic
structure is also easily susceptible to fracture. For these reasons, such tools have
increasingly been prepared by bonding diamond particles to the surface of a metal
workpiece, while immersed in an electrolytic plating bath, by electrodeposition of
a metallic bonding matrix on to the workpiece and around the diamond particles.
[0004] Although tools produced according to this latter process have generally been more
durable and less expensive to make than the ceramically bonded tools, they have nevertheless
evidenced an inherent weakness in that the diamond particles tend to be pulled from
the metal workpiece by abrasive action during use of the tool. It has been found that
pulling out of the diamond particles can be minimised by controlling the hardness
of the metallic bonding matrix or by increasing the thickness and controlling the
hardness of the metallic bonding matrix. The hardness of a metallic bonding matrix
can be changed by changing the type of metal used and/or by heat treatment, for various
kinds of metals.
[0005] However, controlling the thickness and/or hardness of a metallic bonding matrix to
prevent pulling out of the diamond particles results in other disadvantages. For example,
if the metal bonding matrix is too thick and/or too hard for a given material to be
cut or ground, the diamond particles will wear down faster than the bonding matrix,
and the diamond particles will thus become co-planar with the bonding matrix. The
tool cutting edge thus becomes glazed and thereafter ceases to work efficiently for
purposes of grinding or cutting. When this happens, the tool must be re-dressed by
abrading or otherwise treating its grinding surface. This of course results in increased
cost and inconvenience to those using the tool.
[0006] Typically, glazing is caused by one of two conditions. If a given material is cut
or ground, minute particles (called "swarf") tend to fill in the crevices between
the diamond particles. Thus, one reason the cutting edge may become glazed is because
the swarf is not abrasive enough to erode away the bonding matrix at the same rate
as the diamond particles are being worn down. The other reason the cutting edge may
become glazed is because the metal bonding matrix is not slick enough, and thus swarf
will adhere to the bonding matrix and will fill in the crevices as described above.
[0007] It would, therefore, be an improvement in the art to provide a process whereby diamond
or other abrasive particles could be securely bonded to the surface of the workpiece
so as to prevent pulling out of the abrasive particles, while at the same time forming
a bonding matrix which would not be too hard or too thick, and which would be slick
enough to minimise the adherence of swarf to the matrix, thus minimising glazing of
the cutting edge of the workpiece as it wears.
[0008] French Patent Specification 1147811 discloses an embodiment of diamond coated tool
in which plural layers of diamond grains are interspersed by layers of electrolytically
deposited metallic support. The specification acknowledges the problem of having to
sharpen the surface of such tools in order to restore the cutting edge after wearing
down of the grains by uncovering the diamond grains from the deposited metal which
surrounds it, and proposes to overcome the problem by offsetting alternate layers
of diamond grains whereby as one grain is worn down an adjacent one in the layer below
appears. The offsetting is initiated by mechanically milling the surface of the tool
to produce regular hollows and ridges and during the subsequent electrolytic coating
two layers of diamond grains are coated on the surface, one layer substantially wholly
located within the hollows and a second layer located on the ridges. Said two layers
are subsequently wholly embedded in deposited metal as third and fourth layers of
grains are simultaneously coated over them, the grains in the third layer being aligned
with the grains in the first layer and offset from the grains in the second layer,
whereas the grains in the fourth layer are aligned with those in the second layer
but offset from those in the first and third layers.
[0009] U.S. Patent Specification 3957593, on the other hand, concludes that it is better
to arrange the grains in one layer of single particle thickness than to pile particles
on top of each other on the tool surface because this helps the operator to control
more uniformlv the work being performed by the tool and to maintain close tolerances,
and because the ')Ingle layer thickness provides longer toollfe The U.S. Patent proposes
depositing the particles on the tool surface by mounting the tool blank on a mandrel
and inserting the assembly in a tank, the blank having been subjected to a standard
cleaning operation and having been dipped in a standard pickling solution followed
by washing and drying. The abrasive particles are poured into the tank in the space
between the tool surface and the sides of the tank, and are then compacted and brushed
into place. Electrolytic plating is then commenced as plating solution is directed
downwardly through the abrasive particles to provide a light layer of electrodeposited
metal, and subsequently an over- plating layer of metal is deposited leaving the single
layer of particles projecting therethrough. It will be noted that the particles in
the single particle layer are bonded by the deposited metal, substantially in contact
with the smooth surface of the tool. Accordingly there is a shear plane along the
smooth surface of the tool from which the deposited metal may be torn thereby causing
the particles to break away. It is an advantage of the method of the present invention
that the abrasive particles in a layer of single particle thickness on a tool surface
are less likely to be pulled from said surface during use.
Statement of Invention and Advantages
[0010] The present invention provides a process for bonding abrasive particles to the surface
of a metal workpiece by immersing the workpiece and the abrasive particles in an electrolytic
plating bath comprising an aqueous solution of metal ions and electrodepositing a
metallic bonding matrix on to the workpiece surface and around the abrasive particles
adjacent the surface, the process being characterised in that prior to such electrodeposition
the surface of the workpiece is etched to form cavities therein of dimensions such
that each cavity is capable of receiving a portion of one abrasive particle and, subsequently
to said etching step, the workpiece is at least partially embedded in a layer of the
abrasive particles in the plating bath and an electromotive force is imposed across
a metal anode in the plating bath and the workpiece whereby the abrasive particles
become individually partially embedded in the cavities of the etched workpiece surface
as the metal is plated on to the workpiece and around the embedded particles, and
in that subsequent to said electrodeposition step the workpiece is at least partially
immersed in a second plating bath comprising an aqueous solution of metal ions and
a second coat of metal is plated around the partially embedded abrasive particles.
Etching is believed to create small cavities in the workpiece surface, each cavity
being adapted to individually receive a portion of an abrasive particle, thereby providing
for a stronger mechanical bond between the particle/metal plated surface of the workpiece
by recessing at least a part of the abrasive particle below the shear plane.
[0011] By properly choosing the type and thickness of the second metal coating, as the abrasive
particles wear, the swarf will not significantly adhere to the matrix and the swarf
will evenly wear down the second coat of metal veneer, thus maintaining a cutting
edge so as to prevent glazing. The choice of type and thickness of the second metal
coating will therefore depend on the ultimate use of the tool. Heat treatment after
the second plating step can serve to control stresses in the plated surfaces and thereby
provide a stronger bonded surface on the workpiece to prevent pulling out of the abrasive
particles.
[0012] Partial or complete embedding of the etched workpiece in the layer of abrasive particles
ensures the even distribution of the particles during plating in the first-mentioned
plating bath. Such even distribution may also be enhanced by gentle rotation of the
workpiece, care being taken not to dislodge particles already bonded to the workpiece.
Figures in the Drawings
[0013] Two embodiments of apparatus for use in the process of the present invention will
now be described, by way of example only, with reference to the accompanying drawings,
in which:
FIGURE 1 is a schematic flow diagram demonstrating a first embodiment of apparatus
for carrying out the process of the present invention;
FIGURE 2 is a schematic cross-section of a workpiece that has been diamond plated
by the process of the present invention, and
FIGURE 3 is a schematic cross-section of an alternative plating bath to replace the
first plating bath shown in the apparatus of FIGURE 1.
Detailed Description of the Drawings
[0014] The invention is best understood by reference to the drawings wherein like parts
are designated with like numerals throughout. The process of this invention is applicable
to bonding any of a wide variety of abrasive particles, for example, diamond, boron
nitride, silicon carbide and the like. For convenience, the process of this application
will be described using diamond particles.
[0015] A workpiece that is plated with diamond particles in accordance with the present
invention advantageously incorporates the durability of diamond with the versatility
of a metal substrate. While natural diamond or static synthesis diamond grit can be
used, synthetically produced virgin polycrystalline diamond grit or particles are
particularly useful due to their increased surface irregularities as compared to natural
or static synthesis diamond particles.
[0016] Plating these diamond particles on to the surface of a metal workpiece provides a
tool with an abrasive surface useful for many grinding and lapping applications, for
example, those found in grinding wheels, lapping wheels, hones, tool sharpeners, etc.
[0017] In the foregoing applications, it is readily apparent that considerable stress is
placed on each diamond particle during use of the workpiece. This stress tends to
loosen and eventually break the diamond particles from the surface of the workpiece.
These stresses also tend to break apart and tear loose the metal with which the diamond
particles have been bonded to the surface of the workpiece. It has been found that
this latter problem may be alleviated to some degree by etching the workpiece surface
prior to plating with diamonds and metal so as to create cavities therein. The cavities
form a pocket to receive a portion of a diamond particle so that part of the diamond
particle is recessed out of the shear plane formed along the surface of the workpiece.
The cavities also assist in forming a stronger mechanical bond between the workpiece
and the plated surface.
[0018] According to the illustrated embodiment of the present invention, a layer of diamond
particles is bonded to the surface of a metal workpiece through electrodeposition
of nickel or other suitable metal to the workpiece. Diamond particles do not, in themselves,
electroplate on the metal workpiece but are entrapped by the metal as it is electroplated
thereon.
[0019] Uniform dispersion of diamond particles is assured by partially or totally embedding
the workpiece in a layer of the diamond particles in an electroplating bath while
an electromotive force imposed upon the bath assists in attracting the diamond particles
to the workpiece, thereby enhancing the predetermined population and uniform packing
of diamond particles on the workpiece surface. In this manner, the workpiece is surrounded
by diamond particles which may be uniformly plated on to the workpiece in a substantially
quiescent bath.
[0020] After a predetermined layer of diamond particles has been bonded to the surface of
the workpiece by the plating action of the metal, the workpiece is immersed in a second
plating bath. There, a second coat of only metal is deposited over the diamond/metal
surface. When the type and thickness of this second coating of metal is properly selected
for the intended application of the workpiece, the second coating of metal has the
surprising advantage of wearing down evenly as the abrasive particles wear. This helps
to prevent glazing of the cutting edge due to filling of the crevices between abrasive
particles. Furthermore, as this second coat of metal wears, the abrasive particles
will not loosen and pull out since they will remain firmly bonded to the cavities
of the workpiece surface by the remainder of the second coat and by the first coat
of metal.
[0021] The second plating step is then followed by heat treatment of the workpiece so as
to harden and toughen the metal and relax any stresses that may have developed during
any of the previous processing steps. Importantly, the temperature during heat treatment
is held below the decomposition temperature of the diamond particles to preclude thermal
decomposition.
[0022] Referring to FIGURE 1, a workpiece 10 is snown in an etching bath 14 comprising a
solution 15 of aqueous sulphuric acid. One suitable etching solution has a 60% sulphuric
acid concentration. To assist in the etching of workpiece 10, an electromotive force
indicated at 12 is imposed between workpiece 10 and a cathode 16 or even a metal vessel
13 containing the acid solution 15. A reverse DC current of about four amps at five
to six volts for six or seven minutes has been found adequate. To improve uniformity
in the etching process, workpiece 10 may be rotated either continuously or intermittently
in the bath with a rotatable shaft 18. Rotation of shaft 18 and workpiece 10 also
agitates the solution and minimises undesirable concentration of electrolytic action
of any one portion of the surface of the workpiece thereby assuring more uniform etching.
After etching, any remaining sulphuric acid is removed by rinsing workpiece 10 with
water.
[0023] For some types of workpieces, as for example those made from stainless steel or aluminium,
an oxide coating may readily form on the surface of the workpiece after it is removed
from the vessel 13 and rinsed. To prevent the formation of such oxide, it has been
found to be desirable for some types of material to plate a very thin metal veneer
coating on to the workpiece after it has been etched. This may be done by placing
the workpiece 10 in a bath similar to bath 40 described below for 6 to 10 seconds.
This will result in a very thin metal coating (approximately 2.5 x 10-
8 m) on the workpiece surface. This metal coating is sufficient to prevent oxide formation
but is still thin enough to permit portions of the abrasive particles to be partially
embedded in the cavities etched into the workpiece surface, as further described below.
The workpiece 10 is then placed in a first plating bath generally designated 20.
[0024] Plating bath 20 may contain any suitable metal plating solution. In the illustrated
embodiment, plating bath 20 contains a nickel plating solution 22 which may be a standard
aqueous solution of nickel sulphate and nickel chloride heated to about 50°C. This
plating solution is well known in the art and is commonly referred to as a standard
Watts bath. Conventionally, the plating solution includes about 110 to 380 g/I nickel
sulphate and about 60 to 302 g/I nickel chloride in a boric acid buffer. Diamond particles
25 (see FIGURE 2) are provided as a layer 46 in the aqueous solution 22 at the bottom
of the bath 20 so as to facilitate uniform distribution of diamond particles 25 about
the workpiece 10 which is embedded in the layer 46. Diamond particles 25 may be of
any suitable size although the very fine particles (24 to 41 microns) are preferred
for sharpening tools and the like. Grinding wheels and related tools may require particle
sizes upwards of 24 mesh.
[0025] Workpiece 10 is mounted upon a shaft 32, which may be rotatable, and suspended in
plating bath 20. The workpiece may, if necessary, be rotated during plating to ensure
an even dispersion of the particles on the workpiece surface, but care should be taken
not to dislodge particles already bonded to the surface.
[0026] A nickel anode 34 is also suspended in plating bath 20 so as to be at least partly
immersed in the solution 22. An electromotive force 36 is applied between workpiece
10 and anode 34 with workpiece 10 connected so as to act as a cathode. In this manner,
workpiece 10 is plated with nickel metal ions. The plating action simultaneously entraps
diamond particles 25 on the surface of workpiece 10 and the plated nickel metal 23
(see FIGURE 2) serves to mechanically bond diamond particles 25 to the etched surface
of workpiece 10 as the particles 25 are individually embedded in the cavities 21 of
the etched surface. It has been discovered that the imposition of an electromotive
force 36 appears to cause an attraction between diamond particles 25 and workpiece
10 so as to more densely pack diamond particles 25 on the surface of workpiece 10.
For example, approximately six minutes has been found satisfactory to form a single
layer of 24 to 41 micron diamond.
[0027] The cavities 21 (FIGURE 2) created in workpiece 10 during the etching step greatly
assist in forming a strong bond between workpiece 10 and the first diamond/nickel
matrix 23. Many of the diamond particles 25 are partially recessed into the cavities
21 so as to limit their exposure to the shear plane formed along the diamond/metal
surface. The diamonds 25 thus secured have surprising resistance to shear and breakage
away from the workpiece 10.
[0028] It may be advantageous ta gently circulate the plating solution 22 through the layer
46 of abrasive particles, and this may be done, for example, by mechanical means (not
shown) such as a pump, by convection currents, or by gravity flow.
[0029] After suitably electroplating the diamond particles 25 to the surface of workpiece
10, workpiece 10 is removed from the plating bath and rinsed with water to remove
any unplated residue from bath 20. While not essential, it has been found desirable
to follow the rinsing step with an activation step wherein the diamond plated workpiece
is treated by dipping or rinsing in a 50% hydrochloric acid solution prior to immersing
the workpiece in a second plating bath 40. Surface activation is primarily used where
the workpiece surface has been oxidised. If care is taken to avoid drying of the workpiece
10 during the etching and electroplating process, activation can usually be avoided.
Prior to treatment in the second plating bath 40, the diamond adheres to the workpiece
10 as a soft pack.
[0030] With continued reference to FIGURE 1, the second plating bath 40 comprises an electroless
plating solution 42 of metal ions. The metal used may be nickel or any other suitable
metal selected in accordance with the hardness and thickness charactetistics desired
in an intended application for workpiece 10. Any suitable electroless plating solution
could be used such as solutions marketed by the Allied Kelite Division of Richardson
Chemical Co. (Product No. 794 A, B and HZ). The workpiece is held in this electroless
plating bath for sufficient time to achieve a suitable second coating of metal 27
(see FIGURE 2). For example, approximately 70 to 80 minutes has been found adequate
for many intended applications. The temperature in the electroless plating bath 40
is elevated to about 90°C or such other elevated temperature as may be recommended
by the manufacturer of the solution. It is pointed out that while electroless plating
is preferred, electrolytic plating may be used. Nickel plating has been found to deposit
about 2 x 10-
5 m nickel per hour in this bath and it is presently preferred to substantially interfill
the surface area around the diamonds 25 and/or cover the diamonds 25 adhering to the
workpiece.
[0031] After removal from the second or electroless plating bath 40, workpiece 10 is cleaned
with water, dried and then subjected to heat treatment, in a furnace 43 wherein workpiece
10 is heated to approximately 315°C for approximately one hour. Heat treatment between
340°C and 400°C for one hour yields a workpiece having a Rockwell C-Scale hardness
of 72. Hardness of 46 to 72 has been found desirable. The actual hardness achieved
is a function of the type of metal plated on to workpiece 10 in the second plating
bath 40 (which may be different to the metal plated in the first bath 20) and the
temperature and firing time of the heat treatment step.
[0032] The embodiment of first plating bath shown in FIGURE 3 for electroplating diamond
particles on to the etched surface of the workpiece 10 is similar to that described
in connection with FIGURE 1 in that the or each workpiece 10 is at least partly embedded
in a layer 46 of abrasive particles. In the embodiment shown in FIGURE 3 an enclosed
box generally designated 41 is provided in the first plating bath 20. The box 41 has
sides 44 and a base 45. Nickel anode 34 is placed in the bottom of box 41 and connected
to an electromotive force 36 as described previously. A port 48 permits plating solution
22 to enter the box 41. Alternatively, port 48 may be used as an exit for plating
solution 22 as hereinafter more fully described. A porous platform 50 is supported
by sides 44 of oox 41. A fine mesh net 52 is laid on top of porous platform 50 so
as to prevent the diamond particles 46 from falling through the holes 54 of platform
50.
[0033] A second platform 56 covers the diamond particles 46. Platform 56 has a plurality
of openings 58 through which workpieces 10 may extend so as to permit the etched portion
of each workpiece 10 to be embedded into the layer 46 of diamond particles. Importantly,
openings 58 are only large enough to permit a very small tolerance between each workpiece
10 and opening 58. This prevents diamond particles 46 from being carried out of the
openings 58 during the plating process. Each workpiece 10 is connected through a wire
60 of cable 62 to electromotive force 36.
[0034] In order to plate the workpiece 10, plating solution 22 is drawn through port 48
into box 41. Alternatively, plating solution 22 may be drawn through openings 58 and
may exit through port 48. Plating solution 22 may be circulated through box 41 by
a pump (not shown), by convection currents, or by gravity flow. The solution 22 and
metal ions formed from anode 34 then are passed through porous platform 50 and net
52, and through the layer of diamond particles 46. Nickel or other metal is plated
on to the workpiece 10 as the solution 22 circulates through box 41, and in this manner,
diamond particles 25 may be uniformly plated into the cavities 21 (see FIGURE 2) etched
into the surface of the workpiece 10 through the electrodeposition of metal on to
the workpiece and around the particles 25.
[0035] The treatments of the workpiece 10 in accordance with the invention, before and after
plating in the bath shown in FIGURE 3, may be identical to those discussed with reference
to FIGURE 1.
1. A process for bonding a single layer of abrasive particles to the surface of a
metal workpiece comprising immersing the workpiece and the abrasive particles in an
electrolytic plating bath comprising an aqueous solution of metal ions and electrodepositing
a metallic bonding matrix on to the workpiece surface and around the abrasive particles
adjacent the surface, the process being characterised in that prior to such electrodeposition
the surface of the workpiece (10) is etched to form cavities (21) therein of dimensions
such that each cavity is capable of receiving a portion of one abrasive particle (25)
and, subsequently to said etching step, the workpiece is at least partially embedded
in a layer (46) of the abrasive particles in the plating bath (20) and an electromotive
force is imposed across a metal anode (34) in the plating bath and the workpiece whereby
the abrasive particles become individually partially embedded in the cavities of the
etched workpiece surface as the metal (23) is plated on to the workpiece and around
the embedded particles, and in that subsequent to said electrodeposition step the
workpiece is at least partially immersed in a second plating bath (40) comprising
an aqueous solution of metal ions and a second coat of metal (27) is plated around
the partially embeddded abrasive particles.
2. A process according to claim 1 characterised in that the abrasive particles are
supported on a porous platform (50) in the first- .-nentioned plating bath.
3. A process according to claim 1 or claim 2 characterised in that the aqueous solution
in the first-mentioned plating bath is circulated around the portion of the workpiece
embedded in the layer of abrasive particles.
4. A process according to any one of claims 1 to 3 characterised in that the second
plating step is preceded by the removal of the workpiece from the first-mentioned
plating bath and subjecting the workpiece to an aqueous rinse.
5. A process according to claim 4 characterised in that the rinsed workpiece is exposed
to an acid wash prior to immersion or partial immersion in the second plating bath.
6. A process according to any one of the preceding claims characterised in that the
workpiece is heat treated at a temperature below the decomposition temperature of
the abrasive particles, so as to harden the metal plating, after the workpiece is
removed from the second-mentioned plating bath.
7. A process according to any one of the preceding claims characterised in that the
second-mentioned plating bath comprises an electroless plating bath.
8. A process according to any one of the preceding claims characterised in that the
workpiece is rotated in the first-mentioned plating bath as metal is plated on to
the workpiece.
9. A process according to any one of the preceding claims characterised in that a
thin metal coating is plated on to the workpiece surface between etching and plating
in the first-mentioned plating bath, to prevent formation of oxide on the workpiece
surface.
10. A process according to any one of the preceding claims characterised in that the
metal ions in the first- and second-mentioned plating baths are different.
1. Procédé pour lier une couche unique de particules abrasives à la surface d'une
pièce d'oeuvre en métal, procédé dans lequel on immerge la pièce d'oeuvre ainsi que
les particules abrasives dans un bain de placage électrolytique comportant une solution
aqueuse d'ions métalliques, et dans lequel on dépose par électrolyse une matrice de
liaison métallique sur la surface de la pièce d'oeuvre et autour des particules abrasives
adjacentes à cette surface, procédé caractérisé en ce que, préalablement à ce dépôt
électrolytique, la surface de la pièce d'oeuvre (10) est attaquée chimiquement pour
constituer sur elle des cavités (21) de dimensions telles que chaque cavité soit capable
de recevoir une partie d'une particule abrasive (25) puis, après cette attaque chimique,
la pièce d'oeuvre est au moins partiellement enrobée dans une couche (46) de particules
abrasives dans le bain de placage (20) tandis qu'une force électromotrice est appliquée
par l'intermédiaire d'une anode métallique (34) sur le bain de placage et la pièce
d'oeuvre, grâce à quoi les particules abrasives vont être individuellement partiellement
enrobées dans les cavités de la surface ainsi attaquée chimiquement de la pièce d'oeuvre
en ce que le métal (23) est plaqué sur la pièce d'oeuvre et autour des particules
enrobées, et après ce dépôt électrolytique, la pièce d'oeuvre est au moins partiellement
immergée dans un second bain de placage (40) comportant une solution aqueuse d'ions
métalliques et une seconde couche de métal (27) est plaquée autour des particules
abrasives partiellement enrobées.
2. Procédé selon la revendication 1, caractérisé en ce que les particules abrasives
sont supportées sur une plateforme poreuse (50) dans le bain de placage mentionné
en premier lieu.
3. Procédé selon la revendication 1 ou la revendication 2, caractérisé en ce que la
solution aqueuse dans le bain de placage mentionné en premier lieu, est mise en circulation
autour de la partie de la pièce d'oeuvre enrobée dans la couche de particules abrasives.
4. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé en ce que
le second placage est précédé par l'enlèvement de la pièce d'oeuvre du bain de placage
mentionné en premier lieu, et que cette pièce d'oeuvre est soumise à un rinçage aqueux.
5. Procédé selon la revendication 4, caractérisé en ce que la pièce d'oeuvre ainsi
rincée est soumise à un lavage acide avant son immersion ou son immersion partielle
dans le second bain de placage.
6. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce
que la pièce d'oeuvre est traitée thermiquement à une température inférieure à la
température de décomposition des particules abrasives de façon à durcir le placage
métallique après que la pièce d'oeuvre ait été enlevée du bain de placage mentionné
en second lieu.
7. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce
que le bain de placage mentionné en second lieu comporte un bain de placage non électrolytique.
8. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce
que la pièce d'oeuvre est mise en rotation dans le bain de placage mentionné en premier
lieu tandis que le métal est plaqué sur cette pièce d'oeuvre.
9. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce
qu'un fin revêtement métallique est plaqué sur la surface de la pièce d'oeuvre, entre
l'attaque chimique et le placage dans le bain de placage mentionné en premier lieu,
afin d'éviter la formation d'oxyde sur la surface de la pièce d'oeuvre.
10. Procédé selon l'une quelconque des revendications précédentes, caractérisé en
ce que les ions métalliques sont différents dans les bains de placage mentionnés en
premier et en second lieu.
1. Verfahren zum Verbinden einer einzigen Schicht von Schleifpartikeln mit de Oberfläche
eines metallenen Werkstückes, gemäß dem das Werkstück und die Schliefpartikel in ein
elektrolytisches, aus einer wässrigen Lösung von Metallionen bestehendes Galvanisierungsbad
zu tauchen sind, wobei durch Galvanisieren auf der Oberfläche des Werkstücks und um
die Schleifpartikel, die auf der Oberfläche anliegen, eine metallische Bindungs-Matrix
geschaffen wird, dadurch gekennzeichnet, daß vor dem Galvanisieren in die Oberfläche
des Werkstücks (10) Hohlräume (21) eingeätzt werden, die von ihren Dimensionen her
so beschaffen sind, daß jeder Hohlraum ein Teil eines Schleifpartikels (25) aufnehmen
kann, daß anschließend an den Arbeitsschritt 'Ätzen' das Werkstück zumindest Teilweise
mit einer Schicht (46) der Schleifpartikel im Galvanisierungsbad (20) umgeben sowie
eine elektromotorische Kraft zwischen eine Metallanode (34) und das Werkstück an das
Galvanisierungsbad gelegt wird, wodurch die Schleifpartikel einzeln teilweise in die
Hohlräume der geätzten Oberfläche des Werkstücks eingelagert werden, indem eine Metallschicht
(23) auf das Werkstück und um die eingelagerten Partikel galvanisch aufgebracht wird,
und daß anschließend an den Arbeitsschritt 'Galvanisieren' das Werkstück zumindest
teilweise in ein zweites Galvanisierungsbad (40) getaucht wird, das aus einer wässrigen
Lösung von Metallionen besteht, und eine zweite Metallschicht (27) um die teilweise
eingelagerten Schleipartikel aufgebracht wird.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Schliefpartikel (25)
auf eine poröse Plattform (50) aufgebracht werden, die sich in dem erstgenannten Galvanisierungsbad
(20) befindet.
3. Verfahren nach Anspruch 1 oder Anspruch 2, dadurch gekennzeichnet, daß die wässrige
Lösung in dem erstgenannten Galvanisierungsbad (20) um das von der Schicht der Schleifpartikel
umgebene Werkstück (10) zirkuliert.
4. Verfahren nach den Ansprüchen 1 bis 3, dadurch gekennzeichnet, daß das Werkstück
(10) vor dem zweiten Galvanisieren aus dem erstgenannten Galvanisierungsbad entnommen
und mit Wasser abgespült wird.
5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß das abgespülte Werkstück
vor dem Eintauchen oder teilweisem Eintauchen in das zweite Galvanisierungsbad (40)
in ein Säurebad gebracht wird.
6. Verfahren nach den Ansprüchen 1 bis 5, dadurch gekennzeichnet, daß das Werkstück
bei einer Temperatur unterhalb der Zersetzungstemperatur de Schleifpartikel einer
Hitzebehandlung unterzogen wird, um, nachdem das Werkstück dem zweiten Galvanisierungsbad
entnommen wurde, die aufgebrachte Metallschicht zu härten.
7. Verfahren nach einem oder mehren der vorhergehenden Ansprüche, dadurch gekennzeichnet,
daß als zweites Galvanisierungsbad (40) ein stromloses Bad verwendet wird.
8. Verfahren nach den Ansprüchen 1 bis 7, dadurch gekennzeichnet, daß das Werkstück
im ersten Galvanisierungsbad während des Aufbringens der Metallschicht einer rotatorischen
Bewegun unterworfen wird.
9. Verfahren nach den Ansprüchen 1 bis 8, dadurch gekennzeichnet, daß zwischen dem
Ätzvorgang und der Beschichtung im erstgenannten Galvanisierungsbad ein dünner Metallüberzug
auf die Oberfläche des Werkstücks aufgetragen wird, um eine Oxydbildung an der Oberfläche
des Werkstücks zu vermeiden.
10. Verfahren nach den Ansprüchen 1 bis 9, dadurch gekennzeichnet, daß im erst- und
zweitgenannten Galvanisierungsbad verschiedene Metallionen verwendet werden.