JPH08311696A - Formation of composite plated film having gradient composition - Google Patents

Abstract

PURPOSE: To provide a forming method of a composite plated film having a gradient composition capable of forming efficiently the composite plated film having the gradient composition excellent in adhesion and good in quality by a simple method. CONSTITUTION: A plating bath in which SiC particles 3 are dispersed uniformly in a prescribed dispersion concn. in a plating bath 4 consisting essentially of nickel sulfamate is used, and an anode 4 and a base material 1 (cathode) are arranged in the plating bath, and a direct power source is connected thereto. An agitating device 7 to uniformize the particle dispersion in the plating bath 4 is provided at a bottom surface of the plating bath 4. The composite plated film having the gradient composition in which the particle content is different in a film thickness direction of the plated film is formed on the base material 1 by controlling continuously the plating liq. temp. of the plating bath and the current density to be impressed to both electrodes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a composite plating film applied to shafts, bearings and the like which make up various mechanical devices.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a composite plating film for forming a composite plating film having a gradient composition in which the content of particles is different in the film thickness direction of the composite plating film on a base material, FIG. The method as shown in is used.

In this method, a composite plating film is formed on a substrate by electrolytic plating using three plating baths having different dispersed particle concentrations. First, the anode 55 and the base material 56 that is the object to be plated are placed in the plating bath 51 in which the particles 54 are dispersed in a high concentration. The base material 56 and the anode 55, which are the cathode, are connected to a DC power source 57, and when a predetermined current density is applied, as shown in FIG. 5A, a plating film having a high particle content is formed on the surface of the base material 56. 61 is formed.

Next, the base material 5 on which the plating film 61 is formed
6 is a plating bath 52 having a particle concentration lower than that of the plating bath 51.
5 and forming a plating film by the same method as shown in FIG.
As shown in (b), a plating film 62 having a particle content lower than that of the plating film 61 is formed on the plating film 61.

Further, when a plating film having a particle concentration lower than that of the plating bath 52 is used and a plating film is formed by the same method, as shown in FIG. 5C, the particle content is lower than that of the plating film 62. Plating film 63 is plating film 6
2 is formed on. In this way, the composite plating film 60 having a gradient composition in which the particle content decreases toward the surface layer of the film was formed.

[0006]

However, in the conventional forming method as described above, it is necessary to prepare many plating baths having different particle dispersion concentrations in order to have a more continuous gradient composition. In addition, the number of plating baths required plating work, which requires a lot of labor and time.

Further, when transferring the base material having the plating film formed thereon to the next plating bath, the base material has to be once taken out of the plating bath, which results in poor adhesion at the plating interface. The plating film formed by the method also has a problem that peeling easily occurs. In particular, when a tetrafluoroethylene resin (hereinafter referred to as PTFE) is used for the dispersed particles, it has excellent water repellency, and once it is taken out of the plating bath after forming the plating film, the plating film after that adheres well. There was a defect that it was not formed.

The present invention has been made in order to solve the above-mentioned problems, and a gradient composition composite capable of efficiently forming a high quality gradient composition composite plating film having excellent adhesion with a simple method. It is intended to provide a method for forming a plating film.

[0009]

In order to achieve this object, a method of forming a gradient composition composite plating film of the present invention uses a composite plating film having different particle contents in the thickness direction of the plating film. A method for forming a composite plating film formed on the surface of a base material, wherein the base material is immersed in a plating bath having a predetermined concentration in which particles are dispersed, and the temperature of the plating solution in the plating bath and the base material. By continuously controlling the current density of the current applied to the composite plating film having different particle contents in the thickness direction of the plating film, the composite plating film is formed on the surface of the base material.

Further, by gradually cooling the temperature of the plating solution in the plating bath from a predetermined temperature and gradually increasing the current density from a predetermined value, the content of particles becomes lower toward the surface layer of the film. Form a composite plating film.

Further, by gradually increasing the temperature of the plating solution in the plating bath from a predetermined temperature and gradually decreasing the current density from a predetermined value, the particle content increases toward the surface layer of the film. Form a composite plating film.

Further, the particles are made of silicon carbide (Si
C) Tetrafluoroethylene resin (PTFE) or a mixture thereof may be used.

[0013]

The gradient composition composite plating film of the present invention having the above structure is composed of one layer of the plating film, and the content of the particles is different in the thickness direction of the plating film. In addition, the adhesiveness is superior to that of a composite plating film having a gradient composition formed by stacking a plurality of plating films having different particle contents, and peeling is less likely to occur.

In the method for forming a gradient composition composite plating film of the present invention having the above-mentioned structure, the plating solution of the plating bath is prepared by immersing the substrate in a plating bath having a predetermined concentration in which particles are dispersed. By continuously controlling the temperature and the current density of the current applied to the substrate, a composite plating film having different particle contents in the film thickness direction of the plating film is formed on the surface of the substrate. A composite plating film having a gradient composition can be easily formed by a simple method.

Further, by gradually cooling the temperature of the plating solution in the plating bath from a predetermined temperature and gradually increasing the current density from a predetermined value, the content of particles becomes lower toward the surface layer of the film. Since the composite plating film is formed, it is possible to easily form the composite plating film of a type in which the content of the particles is gradually decreased toward the surface layer of the film with good quality.

Further, by gradually increasing the temperature of the plating solution in the plating bath from a predetermined temperature and gradually decreasing the current density from a predetermined value, the particle content increases toward the surface layer of the film. Since the composite plating film is formed, it is possible to easily form a high quality composite plating film of the type in which the content of particles is continuously increased toward the surface layer of the film.

Furthermore, silicon carbide (Si
C) When a tetrafluoroethylene resin (PTFE) or a mixture thereof is used, in the conventional method,
Although the adhesion was said to be poor, according to the method of the present invention,
Even when these particles are used, it is possible to form a high quality composite plating film having good adhesion.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the method for forming a composite plating film of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional view of a composite plating film having a gradient composition formed by the method for forming a plating film of this embodiment. As shown in FIG. 1, in a single-layer composite plating film 2 formed on a base material 1, a so-called gradient composition state in which the content of particles 3 gradually decreases toward the surface of the plating film is obtained. Are distributed in.

Nickel plating is generally used for the composite plating film 2. A wide variety of particles are used as the particles 3 depending on the application, but in general, silicon carbide (hereinafter referred to as SiC), silicon nitride (Si) for the purpose of improving wear resistance.
₃ N ₄ ), aluminum oxide (Al ₂ O ₃ ), diamond, etc. are used, and in order to improve slipperiness, PTFE,
Molybdenum disulfide (MoS ₂ ), boron nitride (BN), graphite fluoride ((CF) _n ) and the like are used.

This composite plating film 2 has a composition in which SiC particles are compound-dispersed for the purpose of imparting wear resistance to a shaft and a bearing, for example, by simply dispersing the particles uniformly throughout the film. The frictional force on the moving surface becomes too large and a good sliding state cannot be obtained. Therefore, by providing a gradient composition such that the content of SiC particles becomes higher as the plating film becomes deeper in advance, the friction coefficient between the shaft and the bearing at the initial wear stage at the start of operation is reduced, It has the effects of improving the familiarity of the sliding member and ensuring wear resistance after initial wear.

Next, a method of forming the composite plating film as described above will be described with reference to FIGS.

The method of forming the composite plating film of this embodiment is shown in FIG. In the present embodiment, a case will be described as an example in which the composite plating film 2 in which, for example, SiC particles are dispersed as the particles 3 is formed in the plating film containing nickel.

SiC particles 3 are uniformly dispersed at a predetermined dispersion concentration in a plating bath 4 containing nickel sulfamate as a main component. And the anode 5 in the plating bath 4
And a substrate 1 (cathode) which is an object to be plated are arranged, and these are connected to a DC power supply 6. Further, a stirrer 7 is provided on the bottom surface of the plating bath 4 in order to uniformly disperse the particles in the plating bath 4. Since the particles in the plating bath are uniformly dispersed by the stirring device 7, the plating bath 4 can be kept in a stable state.

Using the apparatus as described above, the temperature of the plating solution in the nickel sulfamate plating bath 4 is 40 to 60 ° C.
And the current density of the current applied to both electrodes is 0.5 to 10 A /
The results of investigating the content of the SiC particles 3 at that time after changing to dm ² are shown in FIGS. The plating bath 4 had a pH of 4.0 and the SiC particles 3 had a dispersed concentration of 80.
g / l, and the average particle size of the SiC particles 3 = 0.45 μm.

FIG. 3 (a) shows the temperature of the plating bath 4 and SiC.
The relationship with the content of the particles 3 is shown. From FIG. 3, it can be seen that the nickel sulfamate plating bath 4 has an appropriate operating temperature range of 40.
From 60 ° C. to 60 ° C., as the liquid temperature rises, the content of SiC particles 3 becomes 1 to 5 wt. It can be seen that it rises to about%.

FIG. 3B shows the relationship between the current density of the current applied to both electrodes and the content of the SiC particles 3. From FIG. 3B, when the current density of the current applied to both electrodes is increased from 0.5 to 10 A / dm ² , the content of the SiC particles 3 is 5 to 0.5 wt. It can be seen that the value drops to about%. The appropriate operating temperature range and the current density are appropriately set depending on the type of plating liquid used and the type of particles 3.

From the result of FIG. 3, the liquid temperature of the plating bath 4 was set to 60.
While continuously cooling from 40 ° C to 40 ° C, the current density of the current applied to both electrodes is 0.5 A / dm ² to 10 A / d.
By continuously increasing the m ² to m ² , it is possible to form the composite plating film 2 having a graded composition in which the content of the SiC particles 3 gradually decreases toward the surface layer.

On the contrary, the liquid temperature of the plating bath 4 is changed from 40 ° C to 60 ° C.
By continuously increasing the temperature to 10 ° C. and decreasing the current density of the current applied to both electrodes from 10 A / dm ² to 0.5 A / dm ² , the Si gradually increases toward the surface layer.
It is possible to form the composite plating film 2 having a gradient composition such that the content of the C particles 3 becomes high.

As described above, according to the method for forming the composite plating film of the present embodiment, unlike the conventional method, it is not necessary to repeat the plating operation by using a plurality of plating baths 4, and it is possible to perform a single plating operation. Since the work is sufficient, the workability is extremely improved, and the composite plating film excellent in the continuity of the gradient composition can be formed. Further, by controlling variously the liquid temperature of the plating bath 4 and the current density of the current applied to both electrodes, it is possible to easily prepare a composite plating film having a complicated content composition.

Further, the composite plating film 2 formed by the above method has a different content of the SiC particles 3 in the thickness direction of the plating film in one layer of the plating film, and is formed by the conventional method. Since it is not composed of multiple layers like the composite plating film,
Peeling is less likely to occur.

In the present embodiment, the particles 3 are made of Si.
Although the case where C is used has been described, as described above, a wide variety of particles can be selected according to the purpose in addition to this. Among them, the forming method of the present embodiment is extremely effective when forming a composite plating film containing PTFE. In other words, in the conventional forming method, it is necessary to frequently move the base material in and out of the plating bath, but in the case of a plating film containing PTFE, after the base material in the plating bath is once taken out of the bath. When it was returned to the bath again to form a plating film, the re-plating film had poor adhesion due to its excellent water repellency, and peeling and the like often occurred. On the other hand, in the forming method of the present embodiment, since the substrate can be carried out during the plating operation without being taken out of the bath even once, the above-mentioned poor adhesion does not occur, and a very good, high-quality graded composition is obtained. A composite plating film can be formed.

In this embodiment, the nickel sulfamate bath was used as the plating bath, but a Watts bath or the like can also be sufficiently used as the nickel plating bath. Also,
Not only nickel plating but also copper plating, chromium plating, zinc plating and the like may contain various particles.

[0034]

As is apparent from the above description, according to the gradient composition composite plating film of the present invention, it is composed of one layer of the plating film, and the content of the particles in the thickness direction of the plating film. Are different from each other, the adhesiveness is superior to the conventional gradient composition composite plating film formed by stacking a plurality of plating films having different particle contents, and peeling is less likely to occur.

Further, according to the method for forming a gradient composition composite plating film of the present invention, the substrate is immersed in a plating bath having a predetermined concentration in which particles are dispersed, and the temperature of the plating solution in the plating bath is adjusted. By continuously controlling the current density of the current applied to the base material, a composite plating film having different particle contents in the thickness direction of the plating film is formed on the surface of the base material. By the method, a composite plating film having a gradient composition can be easily formed. By controlling the temperature of the plating solution in the plating bath and the current density of the current applied to the substrate in various ways, it is possible to easily form a composite plating film having a complicated content composition.

Further, in the case of forming a gradient composition composite plating film containing PTFE, according to the forming method of the present invention, it is possible to carry out the plating process without exposing the base material to the outside of the bath, so that the adhesion property is improved. It is possible to form an excellent composite plating film of excellent quality.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a gradient composition composite plating film of this example.

FIG. 2 is an explanatory diagram of a method for forming a gradient composition composite plating film of this embodiment.

FIG. 3 (a) is a diagram showing the relationship between the temperature of the plating solution in the plating bath and the content of SiC particles. (B) It is a figure which shows the relationship between a current density and the content of SiC particles.

FIG. 4 is an explanatory view of a conventional method of forming a gradient composition composite plating film.

FIG. 5 is a cross-sectional view of a gradient composition composite plating film obtained by a conventional forming method.

[Explanation of symbols]

 1 Base Material 2 Gradient Composition Composite Plating Film 3 Particles 4 Plating Bath

Claims (4)

[Claims] 1. A method for forming a composite plating film, wherein a composite plating film having different particle contents in the thickness direction of the plating film is formed on the surface of a substrate, the method comprising: By continuously controlling the temperature of the plating solution in the plating bath and the current density of the current applied to the base material while the base material is immersed in the plating bath, And a composite plating film having different particle contents are formed on the surface of the base material. 2. The particle content decreases toward the surface layer of the film by gradually cooling the temperature of the plating solution in the plating bath from a predetermined value and gradually increasing the current density from a predetermined value. The method of forming a gradient composition composite plating film according to claim 1, wherein a composite plating film is formed. 3. The particle content increases toward the surface layer of the film by gradually increasing the temperature of the plating solution in the plating bath from a predetermined temperature and gradually decreasing the current density from a predetermined value. The method of forming a gradient composition composite plating film according to claim 1, wherein a composite plating film is formed. 4. The particle according to claim 1, wherein silicon carbide (SiC), tetrafluoroethylene resin (PTFE), or a mixture thereof is used for the particles. Method of forming a gradient composition composite plating film of.