JPH0430479B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a particle dispersion metal plating method, and in particular to a method for obtaining a composite plating with a high particle density using a small amount of particles when the particles to be dispersed are extremely fine. It can be used for manufacturing grain grindstones, etc. [Prior Art] If particles are dispersed (suspended) in a plating bath and plated, a composite plating containing the particles in the plating metal can be obtained. The composite plating layer obtained in this way has the respective characteristics of the plating metal and particles, so by appropriately selecting the combination of the plating metal and particles, it can have excellent hardness, abrasion resistance, lubricity, or heat-resistant strength. A composite plating layer can be obtained relatively easily. Conventionally, this property has been utilized to improve the strength and durability of the sliding part, for example, by forming a composite plating layer of nickel (Ni) or cobalt (Co) and wear-resistant particles on the surface of mechanical sliding members. To improve abrasion resistance, or add silver (Ag), palladium (Pd), gold (Au), platinum (Pt), etc. and titanium oxide (TiO ₂ ), silicon carbide (SiC), etc. to the surface of the electrical contact member. A composite plating layer is formed with particles to improve the wear resistance and arc damage resistance of the contact portion. When forming such a composite plating layer, conventionally, a body to be plated which also serves as a negative electrode and a positive electrode plate are placed in a plating bath, particles are added to the plating bath,
Thereafter, plating was carried out while dispersing the particles in the plating bath by taking measures such as strong stirring, air bubbling, or circulating the plating liquid in the plating bath using a liquid pump. [Problems to be Solved by the Invention] However, when the particles to be dispersed are extremely fine, it is difficult to obtain a composite plating layer with a desired particle density and uniform particle distribution using such conventional plating methods. It was difficult. That is, in order to obtain the desired composite plating layer, it is necessary to uniformly disperse the particles in the plating solution while maintaining the dispersion concentration or movement speed of the particles at appropriate values depending on the particle size, specific gravity, etc. However, if the particles to be dispersed are extremely fine, it may seem easy to disperse them by conventional stirring means, but on the other hand, depending on the form of the dispersed plating layer, it may be difficult to disperse the particles throughout the plating bath. It becomes difficult to achieve a uniformly dispersed state. This is because in the case of fine particles, the relative movement speed between the plating liquid and the particles is low, so if the movement of the plating liquid is stagnant, the fine particles tend to accumulate at that point, and once they have accumulated, it is difficult to redisperse them. This is because the plating liquid in the vicinity must be moved quite violently. Therefore, in general, the finer the particles, the more likely the particle adhesion density on the surface to be plated will vary, making it difficult to form a plating layer with a uniform particle content density. Incidentally, if relatively strong stirring is used, uniformity of the particle dispersion state can be obtained, but it becomes difficult to obtain the desired composite plating. Therefore, with conventional methods, it has not been possible to maintain the particles in an appropriate dispersed state so that they are uniformly retained in the plating layer. Additionally, in general, in order to achieve the desired particle density in the composite plating layer to be formed, the particle concentration in the plating solution must be above a certain value, but conventional methods involve dispersing particles throughout the plating bath. Therefore, a large amount of particles must be added to the plating bath. For this reason, for example, when manufacturing superabrasive grinding wheels, when the particles added are expensive such as diamond particles or cubic boron nitride (CBN) particles, the manufacturing cost is extremely high. becomes. An object of the present invention is to provide a particle-dispersed metal plating method that eliminates the above-mentioned drawbacks. [Means for Solving the Problems] In the particle-dispersed metal plating method according to the present invention, a columnar body is immersed in a plating bath with its axis substantially horizontal, and the entire circumference of the outer peripheral surface of the columnar body is covered with particles. The object to be plated is surrounded by a diaphragm that allows the plating liquid to pass through but not through the diaphragm, and this diaphragm is fixed to the columnar body, and the diaphragm forms a closed region including the outer peripheral surface, and the plating layer is to be formed in this region. A surface to be plated is arranged, a certain amount of the particles and particles having a larger diameter than the particles are enclosed in this region, and metal is deposited on the surface to be plated while rotating the columnar body around the axis. It is characterized by [Example] FIG. 1 is a cross-sectional view showing an example of an apparatus for carrying out the particle-dispersed metal plating method according to the present invention, and FIG. 2 is a cross-sectional view taken along the line -- in FIG. 1. An example of implementing the method according to the present invention using the apparatus shown in FIGS. 1 and 2 will be described below. In the figure, at least the surface of plating tank 2 filled with plating liquid 1 is made of nickel (Ni).
A columnar body 3 made of another conductive material and having a cylindrical outer shape is rotatably installed. In this embodiment, the columnar body 3 itself also serves as the body to be plated, and the outer peripheral surface of the columnar body 3 is the surface to be plated. That is, a rotating shaft 4 whose surface is insulated at least is attached to the columnar body 3 along its axis, and both ends of the rotating shaft 4 are rotatably supported by the side walls of the plating tank 2. , and one end of the rotating shaft 4 is connected to a drive motor (drive mechanism) disposed outside.
It is connected to the rotating shaft of 5. Thereby, when the drive motor 5 is operated, the columnar body 3 is rotationally driven. Further, two disk bodies 6 made of acrylic or other non-conductive material are coaxially attached to both sides of the columnar body 3 and have a diameter larger than the outer diameter of the columnar body 3. A diaphragm 7 such as a filter cloth or a cation exchange membrane that allows the plating solution to pass through but not to pass particles larger than a certain size is installed between the disk bodies 6 so as to cover the outer peripheral surface of the columnar body 3 at regular intervals. This forms a closed area 8 including the plated surface. Further, two anode plates 9 made of nickel or the like are provided near the columnar body 3. Furthermore, an electric contact brush (cathode energizing means) 10 is provided at one end of the rotating shaft 4, and although not shown, the electric contact brush 10 is used to inject at least the electrically conductive surface of the columnar body 3 from the outside. This columnar body 3 is electrically connected so that it can be energized.
The surface of constitutes the cathode. Therefore, as shown in a partially enlarged cross-sectional view in FIG.
The particles 11 are enclosed on the surface of the columnar body 3 constituting the cathode by energizing the anode plate 9 and the electric contact brush 10 while rotating the columnar body 3.
A composite plating layer containing the following can be formed. Next, a description will be given of an example in which a superabrasive grindstone was actually produced by implementing the particle dispersion metal plating method according to the present invention using the above-mentioned apparatus. First, the surface of the columnar body 3 was plated under the following processing conditions to form a composite plating layer. (A) Column 3 a Dimensions Diameter...100mm Width...80mm Area of plating surface...240cm ² (Cover both widthwise ends of columnar 3 with masking tape) b Polished glossy surface of stainless steel (SUS-304) Before plating, polish and degrease using precipitated calcium carbonate c. Rotation speed...10 rpm (B) Diaphragm 7 a. Material...Cation exchange membrane (Neoseptor C66) b. Distance from plating surface...10 mm (volume of area 8 =
270cm ³ ) (C) Dispersed particles a Type...Diamond (artificial) b Particle size...3/6μ c Dispersion amount...113.5g d Dispersion concentration...50g/l (D) Dispersed particles a Type...Glass beads b Particle size... 1000-3000μm c Dispersion amount...2.7g d Dispersion concentration...10g/l (E) Composition of plating liquid (sulfamic acid nickel plating liquid) a Ni sulfamic acid...450g/l b NiCl ₂ ...5g/l c H ₃ BO ₃ ...30g /l d Anti-pitting agent…small amount (PH; 4.2) (F) Plating conditions a Bath temperature…50℃ b Cathode current density…1.0A/dm ² c Plating time…2 hours Once the composite plating layer is obtained, Next, the diaphragm 7 was removed from the columnar body 3, the remaining diamond particles were collected, and then a single metal plating layer was applied over the composite plating layer to embed and fix the diamond particles. In this case, the plating conditions are such that the cathode current density is
The plating conditions were the same as those described above except that the plating rate was 2 A/dm ² and the plating time was 10 minutes. After this plating process is completed, the composite plating layer obtained from the surface of the columnar body 3 is peeled off and the length is
A superabrasive grinding wheel sheet of 300 mm, width 80 mm, thickness 50 μ, diamond particle content of 42 Vol%, and extremely uniform particle distribution was obtained. Note that this grindstone sheet did not contain any glass beads 12 at all. As described above, according to the method according to this embodiment, the diamond particles 11 and the glass beads 12 are enclosed in the narrow region 8, and the particles 12 and the particles 11 are stirred together by rotating the columnar body 3. Therefore, as the columnar body 3 rotates, the plating liquid 1 between the columnar body 3 and the diaphragm 7 rotates, and accordingly circulates around the particles 11 and glass beads 12.
When the particles 11 are fine, the particles 11 tend to accumulate on the inner surface of the diaphragm 7, but the glass beads 12 move at a different speed than the particles 11 due to the difference in particle size, so the glass beads 12 and the particles 11 do not move at a different speed. By repeating the collision, the movement of particle 11 is disturbed, and particle 1
1 and improves its dispersibility. Further, the particles 11 and the glass beads 12 are evenly rolled up along the inner surface of the diaphragm 7 over the entire length of the columnar body 3 in the axial direction, and then fall onto the surface to be plated on the upper side of the columnar body 3 and are evenly attached thereto. Therefore, together with the above-mentioned dispersion effect, the distribution of the particle adhesion density on the surface to be plated in the axial direction of the columnar body 3 and the particle adhesion density distribution in the circumferential direction of the columnar body 3 become uniform, and the particle adhesion density distribution on the surface to be plated in the axial direction of the columnar body 3 becomes uniform. A plating layer in which the particle content density is highly uniform can be easily formed. Furthermore, in this method, particles adhere to the surface to be plated mainly on the upper side of the columnar body 3, and some of the particles are temporarily fixed to the surface to be plated by the metal that sequentially precipitates. The cycle in which excess particles that are not temporarily fixed fall from the surface, metal is sequentially deposited around the temporarily fixed particles, and the particles are embedded is repeated, so by adjusting the rotation speed of the columnar body 3. , glass beads 1
It is possible to select the conditions under which the glass beads 12 fall from the surface to be plated without being sufficiently temporarily fixed, and only the fine particles 11 are incorporated into the plating layer.
It is easy to form a plating layer that does not contain Furthermore, since the particles 11 only need to be sealed in a narrow area between the diaphragm 7 and the columnar body 3, it is possible to sufficiently increase the particle concentration near the surface to be plated with a small amount of particles used. A plating layer with a high content can be formed at low cost. In addition, although the above-mentioned example shows the case where a superabrasive grinding wheel is manufactured by the method according to the present invention, the present invention is not limited to this, and products other than the grinding wheel, such as BN, MoS ₂ or (C ₂ F) It can also be used as an effective means for producing lubricating members and other products consisting of a plating layer containing self-lubricating powder such as n. [Effects of the Invention] In the particle-dispersed metal plating method of the present invention, as the columnar bodies rotate, the plating liquid between the columnar bodies and the diaphragm rotates, and the particles and large-diameter particles also circulate accordingly. If the particles are fine, they tend to accumulate on the inner surface of the diaphragm, but large particles move at a different speed due to the difference in particle size, so large particles tend to collide with fine particles. It repeatedly disturbs the movement of particles, prevents local accumulation of particles, and enhances their dispersibility. In addition, the particles and large-diameter particles are evenly rolled up along the inner surface of the diaphragm over the entire length of the columnar body in the axial direction, and then descend to the surface to be plated on the upper side of the columnar body and adhere evenly. Coupled with the dispersion effect of A plating layer with a highly uniform particle content density can be easily formed over the period. Furthermore, in this method, after the particles adhere to the surface to be plated mainly on the upper side of the columnar body, some of the particles are temporarily fixed to the surface to be plated by the metal that sequentially precipitates. Excess particles that were not temporarily fixed fall from the surface, metal is sequentially deposited around the temporarily fixed particles, and the particles are embedded.The cycle is repeated, so by adjusting the rotation speed of the columnar body, By accurately adjusting the residence time of large particles and particles on the surface to be plated, the large particles fall from the surface to be plated before they are sufficiently temporarily fixed, and only the fine particles form the plating layer. The conditions for incorporating can be selected, and it is easy to form a plating layer that does not contain large-diameter particles. Furthermore, since the particles only need to be encapsulated in the area between the diaphragm and the columnar body, it is possible to sufficiently increase the particle concentration near the body to be plated with a small amount of particles used, making it possible to achieve the desired particle content. Another effect is that the plating layer can be formed at low cost.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of an apparatus for carrying out the particle dispersion metal plating method according to the present invention, FIG. 2 is a cross-sectional view taken along the line - in FIG. 1, and FIG. It is a diagram. 1... Plating liquid, 2... Plating tank, 3... Column body, 4... Rotating shaft, 6... Disc body, 7... Diaphragm,
8...Region, 9...Anode, 10...Electric contact brush (cathode current supply means), 11...Particle, 12...Large diameter particles.

Claims (1)

[Scope of Claims] 1. A particle dispersion metal plating method in which a plating layer containing the particles is formed on a plated object by dispersing particles in a plating bath and plating the particles, comprising: The columnar body is immersed horizontally, and the entire circumference of the outer peripheral surface of the columnar body is surrounded by a diaphragm that allows the plating liquid to pass through but not the particles, and this diaphragm is fixed to the columnar body. A closed region containing the particles is formed, and the surface to be plated of the object to be plated in which the plating layer is to be formed is arranged in this region, and a certain amount of the particles and particles with a larger diameter than the particles are enclosed in this region. . A particle dispersion metal plating method, characterized in that metal is deposited on the surface to be plated while rotating the columnar body around an axis.