JPS6213440B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for applying a composite coating on an article by mixing particles in a metal matrix, and more particularly, it relates to a method for applying a composite coating on an article by mixing particles in a metal matrix. and particles simultaneously on an article.

Although the present invention primarily relates to electrodeposited coatings incorporating ceramic particles, the particles may also be cermets or metals. Such coatings are used to improve wear resistance, corrosion resistance, oxidation resistance, coefficient of friction (lubricity), scratch resistance, etc. In some cases, the substrate may be removed from the coating layer so that the coating layer itself becomes the final product. The method contemplated by the present invention includes the step of co-depositing metal from the bath and particles in a bath in which insoluble particles are dispersed. Although the method of the present invention can also be used for electroless plating, it is most suitable for electrodeposition.

According to the technique disclosed in British Patent No. 860291, the electrolyte containing particles is removed from the bottom of the bath;
The particles are reintroduced at the top of the bath so that gravity causes them to fall through the bath. The article to be coated forms a cathode and is rotated about a substantially horizontal axis such that falling particles are deposited on the current top of the article. This device has been found to have difficulty uniformly coating irregularly shaped portions of articles. British Patent No. 1218179 discloses that the article is suspended in a bath without movement, and that the particles are kept in suspension in the bath by circulating the solution, and that the particles are kept close to the surfaces on which electrodeposition occurs. A method is disclosed in which gas is introduced to form an upward flow of solution and gas. UK patent no.
In the apparatus disclosed in No. 1,329,081, the solution is stirred by moving a generally horizontal perforated stirrer generally up and down in the solution below the article to be coated. Although both of these methods are satisfactory in use, both require large volumes of solution and particles, which are expensive. Furthermore, maintaining a large volume bath uniformly requires considerable energy.

According to the invention, there is provided a method of coating an article with a metal layer mixed with particles, the article and the particles being placed in a hollow barrel having walls that are impermeable to the particles but permeable to the solution. and the hollow barrel is placed in a bath of a particle-free plating solution and the hollow barrel is rotated about a horizontal axis during plating, the article being supported within the hollow barrel. , the hollow barrel is rotated at a speed of 4 revolutions per minute or less, and the particles are carried upward inside the rotating hollow barrel and fall by gravity within the hollow barrel, containing a large amount of particles. A method is provided, characterized in that a stream of solution is allowed to flow gently over the surface to be plated. With this structure, the amount of particles used can be reduced and the proportion of particles can be increased. When expensive particles such as diamond particles are used, it is extremely advantageous to be able to reduce particle usage. To improve particle circulation, it is preferable to provide the barrel with co-rotating paddles. . The shape of the paddle is preferably a rib formed on the inner surface of the barrel so as to extend in the axial direction. Often the article to be plated is placed inside the barrel.
and is rigidly attached to the barrel. However, in some cases it may be necessary to support the article away from the barrel so that the article remains stationary, or to move the article around the axis of rotation of the barrel or around other axes at a speed different from that of the barrel. It is preferable to rotate it.

When the invention is used for electroless plating, the solution is of a suitable composition, such as a nickel-phosphorous electroless plating solution, and the diamond particles are placed in the barrel. When the method is used for electroplating, the solution is of a suitable composition, e.g. a cobalt plating solution, and chromium carbide particles are placed in the barrel between the anode in the solution and the article. Current is passed through it.

By using this method, a solution containing large amounts of particles can flow quietly without stagnation over the surface of the article to be plated.
The dispersion of a large amount of particles in the solution is carried out only in a limited area, ie within the barrel, and in other areas a large volume of solution containing no particles is used. Large volumes of solutions are preferred because their properties, such as temperature, concentration, uniformity, etc., can be more easily maintained uniformly than small volumes of solutions. The space outside the barrel is used for locating heaters, stirrers, etc., and also for locating the anode if electroplating is performed. In addition, in the conventional technology,
The anode was placed in a solution containing particles.

Although the invention may be implemented in a variety of ways, one form of apparatus for carrying out the invention is described below with reference to the drawings. Further, specific examples of methods using the device will be explained.

The device shown in the drawings has a tank 1 containing an electrolyte bath 2. A framework 3 having a vertical part 4 and a horizontal part 5 extends above the bath to attach an S hook 6.
The frame 7 is supported by. Frame 7 suspends into bath 2 and carries bearings 8 on which trunnions 9 and 10 rotate. Trunnion has 6 walls 1
4 is attached to opposite end walls 11, 12 of a hexagonal hollow barrel 13. Each of the walls 14 includes a rectangular opening 15 closed by a composite cover. The structure of the cover 16 is shown in detail in FIG. Each cover includes a rectangular frame member 17 having a plurality of holes 18. Through hole 18, barrel 13
A stand 19 attached to a corresponding wall 14 of can pass through. The frame captures between itself and the wall 14 a sanderch member constituted by two outer layers 20 of porous neoprene and an inner layer 21 formed by filter paper. The 3 mm thick neoprene layer has a nominal pore size of 10 μm, while the filter paper has a nominal pore size of 2 μm.

The barrel is supported horizontally on the top of the frame 7 and the gear wheel 23 of the motor output shaft.
It can be rotated by an electric motor 22 connected to the trunnion 10 by an idler wheel 24 mounted on the upright part of the frame 7 and a gear wheel 25 mounted on the trunnion 10. The barrel includes a paddle 30.

As can be seen in FIG. 2, the inner end of the trunnion 9 extends axially into the barrel and terminates in a threaded plug 26. The mounting jig 27 that carries the member 28 to be coated is attached to the stopper 26.
In this case, the turbine stator blades have a platform at each end.

The device includes an air blower 31 connected by a flexible pipe 32 to a horizontal outlet pipe 33 at the base of the tank 1. The outlet pipe 33 has a plurality of openings on the upper surface, and when the blower 31 is operated, air can be blown into the solution to create bubbles.

Example Using the apparatus described, 5.08cm (2inches) x
A composite coating having a cobalt matrix containing chromium carbide particles was formed on a 2.54 (1 inch) by 0.32 cm (1/8 inch) stainless steel panel. Cobalt sulfide 450g/and foric acid 30g/
The tank was filled with a solution containing 12.5 g/m of sodium chloride. 10 ml of Canning's Antipit solution was added to this solution at 125 in the tank. Four anodes were supported within the bath with cobalt chips housed in titanium baskets surrounded by anode bags.

For panels to be coated, soak in cyanide cleaner for 2 minutes and then rinse with water, 50%
Pretreatment included etching in a sulfuric acid solution for 30 seconds followed by water rinsing, and nickel strike by plating in a nickel bath for 3 minutes at a current density of 3.9 mA per cm ² . The panel was secured in the plating barrel as described to the stator blades 28 shown in FIG. 2, and the panel was connected to the cathode. A sufficient amount of chromium carbide particles with an average particle size of 2 to 5 μm are present in the barrel volume at 2500 g/
was added to the barrel until . The panel to be coated and the opening in the barrel introducing the particles were closed by attaching a cover 16. The barrel is then completely immersed in the solution in the tank and rotated at a rate of 3 revolutions per minute while the composite plating is carried out under conditions of a voltage between 2.5-3V and a current density of approximately 2.7A per ^cm2 . It was held in The temperature of the solution was maintained at 50°C and the pH of the solution was 4.5-5. Thickness 0.05mm
After plating was allowed for a sufficient period of time, plating was stopped and the panels were inspected. It has a particle content of approximately 28.9% by weight and 35.2% by volume,
It was found that a highly retentive coating with a uniform particle distribution was formed on the panel. The panel volume was 6.

A series of experiments using the method and apparatus described in the aforementioned British Patent No. 1218179, using the conditions of the example above, and gradually increasing the amount of particles incorporated into the solution was carried out to reduce the amount of particles from 400g/ If you do a lot,
It showed that the proportion of particles in the coating hardly increased. At levels above 400 g/g, the proportion of particles was found to be 23%. In a series of experiments using the apparatus shown in FIGS. 1 to 4 and carrying out the method described in the example above, the following results were obtained.

Amount of particles mixed in the bath Particle content ratio (wt%) 400 17 500 20 600 22.6 700 23.1 1000 24.9 1500 26.5 2500 28.9 3000 33.2 The limitations of the present invention arise from the method disclosed in British Patent No. 1218179. It can be seen that this does not occur with the method disclosed in the specification.

Example The above device is 5.08 cm (2 inches) x 2.54 cm
It was used to non-electrically apply a composite coating having a nickel-phosphorous matrix containing diamond particles to a 1 inch by 1/8 inch stainless steel panel. In the tank,
Known under the trade name NIKLAD-794, it is a British manufacturer.
It was filled with a non-electroplating nickel-phosphor plating solution sold by Reamanufacturing Limited, BUXTON, DERBYSHIRE. The bath is 794A diluted to 80ml and 150ml/
It was made with equal amounts of 794B diluted to

The panels to be coated underwent the same pretreatment as mentioned in the example and were installed in the barrel in a similar manner. Diamond particles were added to the barrel in sufficient quantity to give a barrel capacity of 35 g/barrel. This amount is more than four times the nickel component for the same amount of solution. The barrel is then closed and completely submerged in the solution in the tank, at a rate of 3 minutes per minute.
Rotated by rotation. To initiate non-electrical deposition, a voltage of 2 volts was applied between the article and the anode for 5 to 10 seconds and then switched off. Non-electrical deposition continued for 1 hour. As a result, the panel was found to have a 20 micron thick, homogeneous and strongly adherent deposited layer 20 containing 20 to 25 volume percent diamond particles in a nickel-phosphorous matrix. Under similar conditions, deposited layers made using the method and apparatus disclosed in the aforementioned GB 1218179 contained only 15 to 20 volume percent diamond particles.

[Brief explanation of the drawing]

Figure 1 is a schematic front view of an apparatus for performing a composite coating deposition method with a part of the tank wall cut away to show the inside of the apparatus, Figure 2 is an enlarged view of the drum of the apparatus shown in Figure 1, and Figure 3 is an enlarged view of the drum of the apparatus shown in Figure 1. End view of the drum shown in Figure 2, No. 4
The figure is an exploded view of the composite cover of the barrel. 1...tank, 2...electrolyte bath, 3...framework, 6...S hook, 7...frame,
9, 10...Trunion, 13...Barrel, 15
...Rectangular opening, 16 ... Cover, 18 ... Hole, 2
2...Motor, 31...Blower, 34...Anode.

Claims (1)

[Scope of Claims] 1. A method of coating an article with a metal layer mixed with particles, the article and the particles being placed in a hollow barrel having walls that do not allow the particles to pass through but allow a solution to pass through. and placing the hollow barrel in a bath of a particle-free plating solution and rotating the hollow barrel about a horizontal axis during plating, wherein the article is supported within the hollow barrel. The hollow barrel is rotated at a speed of not more than 4 revolutions per minute, and the particles are carried upward inside the rotating hollow barrel and fall by gravity within the hollow barrel, discharging a large amount of particles. A method characterized in that a stream of the containing solution is allowed to flow gently onto the surface to be plated. 2. A method according to claim 1, characterized in that the hollow barrel has a paddle rotating therewith. 3. A method according to claim 1 or 2, characterized in that the article is supported by and rotates with the hollow barrel. 4. Claims 1 to 3, characterized in that said solution is an electrolytic plating solution, and a current is passed between said article and an anode placed outside said hollow barrel. The method described in any one of the above. 5. The method of claim 4, wherein the particles are chromium carbide particles and the solution is a cobalt plating solution.