JPH05255896A - Sliding-contact member excellent in wear resistance and producing device therefor - Google Patents

Abstract

PURPOSE:To obtain a sliding-contact member such as an engine cylinder excellent in resistance to wear and scuffing and initial fitness. CONSTITUTION:A first nickel plating layer 21 in which a hard grain 21 is dispersed and a second nickel plating layer 22 in which a solid lubricant 24 is dispersed are successively formed on the inner periphery of an aluminum-alloy cylinder liner 1. The amts. of the hard grain and solid lubricant grain are increased in the vicinity of the upper dead center 1a. The hard grain 23a, etc., exposed from the ground surface H of the first nickel plating layer 21 are firmly held by the second nickel plating layer 22, and hence the grain, etc., hardly fall off. Consequently, the area rate of the hard grain required by the sliding-contact surface is maintained, and the abrasive wear is also prevented. The initial fitness is improved by the solid lubricant contained in the second nickel plating layer 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding contact member such as an engine cylinder and a manufacturing apparatus therefor, and more specifically,
The present invention relates to a sliding contact member having a composite plating layer containing hard particles and excellent in wear resistance, and a manufacturing apparatus therefor.

[0002]

2. Description of the Related Art In recent years, internal combustion engines have been required to have a high compression ratio and a high rotation speed in order to improve their performance, and sliding contact parts such as piston rings and cylinders have higher wear resistance and scuffing resistance than ever before. In order to prevent abnormal wear and galling at the initial stage of operation, a material having good initial conformability is required. On the other hand, from the viewpoint of reducing the weight of parts and improving the cooling performance of the engine, light alloys such as aluminum alloys have come to be noticed in cylinder liners and the like.
It is used after being subjected to some kind of surface treatment, such as plating a hard material in order to compensate for the lack of wear resistance.

By the way, as a surface treatment for the inner peripheral surface of the cylinder, for example, as a means for improving initial conformability, a hard layer is plasma sprayed on a base material and a soft layer is laminated thereon ( JP-A-51-151414
(Japanese Patent Laid-Open No. 63-61756), an iron plating layer is formed on a base material, and a composite phosphate film is formed on the iron plating layer (Japanese Patent Laid-Open No. 63-61756), which improves scuffing resistance.
A thermal spray coating is formed on a base material, and the porosity is increased near the top dead center to utilize the oil trap effect of the pores (Japanese Patent Application Laid-Open No. 57-151043), which improves wear resistance. In which the vicinity of the top dead center is remelted by electron beam, rapidly solidified and hardened (JP-A-57-163139).
Japanese Patent Laid-Open No. 1-155061) and the like in which a wear-resistant coating is formed near the top dead center by a vapor phase method.

However, in the above, since the coatings of different materials are laminated, the adhesion of the coatings is insufficient, and it is difficult to increase the film thickness. In order to increase the porosity, particularly in the vicinity of the top dead center. There is a problem that the strength is insufficient and the wear of the coating is easily accelerated. In that case, it is necessary to grind the surface where two phases (near top dead center and other parts) are exposed, and the required processing accuracy is satisfied. There is a problem that it is difficult.

On the other hand, as a coating for improving the wear resistance and scuffing resistance of a cylinder, recently, a composite metal plating coating in which hard particles such as silicon carbide particles are dispersed in a metal plating coating has attracted attention, and is partially used. Is becoming popular. The coating in which the hard particles are dispersed has high hardness, and not only the wear of itself is small, but also the wear of the mating sliding parts is also excellent, and the scuffing resistance is also excellent. However, when grinding the liner surface, some hard particles are missing from the plating film, and hard particles crushed during grinding fall off from the film during sliding, which is required for the sliding contact surface. There is a problem in that the area ratio of the hard particles is not secured, seizure occurs, and the hard particles that fall off from the coating during sliding cause abrasive wear between the cylinder and the piston ring. Further, there is a problem that the composite metal plating film has poor compatibility in the initial stage of operation.

[0006]

DISCLOSURE OF THE INVENTION In view of the fact that the composite metal plating film in which hard particles are dispersed is extremely excellent in wear resistance and scuffing resistance, the present invention has the above-mentioned problems. The present invention has been made with the aim of solving all of the above problems at the same time, and also for the purpose of obtaining a sliding contact member which does not have the problems mentioned in the conventional example.

[0007]

In order to achieve the above object, a sliding contact member according to the present invention comprises a first composite metal plating layer having hard particles dispersed and contained on a surface of a metal base material, and a first composite metal plating layer formed on the first composite metal plating layer. The present invention is characterized in that the first composite metal plating layer is provided with a second composite metal plating layer containing the same lubricant as the first composite metal plating layer and containing a solid lubricant dispersed therein. Hard particles include ceramic particles such as silicon carbide, and solid lubricants include tetrafluoroethylene (PTF).
E) and the like can be appropriately selected. In particular, this sliding contact member is suitable as a light alloy cylinder for an engine, and in this case, it is preferable to disperse a large amount of hard particles near the top dead center, and the composite metal plating layer is based on nickel. Preferably.

Further, the composite metal plating apparatus according to the present invention is for forming the composite metal plating layer on the inner peripheral surface of the tubular metal base material. That is, in a device for forming a composite metal plating layer containing dispersed particles on the inner peripheral surface of a base material while circulating a plating solution in which the particle is dispersed inside a cylindrical metal base material, a rod-shaped member is formed at the center of the base material. The above-mentioned positive electrode is provided, spiral fins are provided on the positive electrode, and the pitch of the fins is sparsely and densely provided, and it is suitable as an apparatus for manufacturing a cylindrical sliding contact member. In particular, when this composite metal plating apparatus is applied to the plating on the inner peripheral surface of the cylinder of the engine, the fin pitch is made dense near the top dead center. Further, in this apparatus, it is preferable to provide the fin with a rotating means.

[0009]

In the sliding contact member according to the present invention, for example, the base material is an aluminum alloy, and the composite metal plating layer (first composite metal plating layer) containing hard particles dispersed therein ensures wear resistance and scuffing resistance. The initial conformability is ensured by the composite metal plating layer (second composite metal plating layer), which is an upper layer thereof and contains solid lubricant particles dispersed therein. First
Since the base metal of the second composite metal plating layer is a similar metal, the adhesion of both layers is excellent.

Furthermore, another function of the second composite metal plating layer is to prevent the hard particles from falling off. That is, among the hard particles in the first composite metal plating layer, there are some hard particles that are only retained in the base plating layer and are likely to fall off.
In the case where the composite metal plating layer is formed and then subjected to a grinding process, as described above, a part of the hard particles in the first composite metal plating layer is lost due to the stress of the grinding process, It is inevitable that it will fall off easily or be crushed. However, in the present invention, since the second composite metal plating layer is formed thereon, the particles that are in a state of being easily dropped or the crushed hard particles are
It will be held firmly again by the same type of metal, and the hard particles can be prevented from falling off during sliding.

When the sliding contact member according to the present invention is applied to an engine cylinder, it is preferable that a large amount of hard particles be dispersed near the top dead center thereof. That is, near the top dead center of the cylinder, where the piston speed is close to zero and the lubricating oil is difficult to rotate in addition to being exposed to high pressure, it is easy for the oil film to run out, further improving wear resistance and scuffing resistance. This is because the abrasion resistance and the scuffing resistance in the vicinity of the top dead center can be easily increased by increasing the dispersion amount of the hard particles. Moreover, if the amount of dispersion of the solid lubricant near the top dead center is increased, the conformability thereof can be improved, and the lack of lubrication near the top dead center can be dealt with.

Moreover, since the second composite metal plating layer is formed by finishing grinding the first composite metal plating layer on the inner peripheral surface of the cylinder, the clearance between the inner peripheral surface of the cylinder and the piston ring is further reduced, and the seal is formed. You can improve your sex. Furthermore, by using a light alloy such as an aluminum alloy for the cylinder, it is possible to reduce the weight of components and improve the cooling performance of the engine.

In the composite metal plating apparatus of the present invention, the rod-shaped positive electrode provided in the central portion of the tubular metal substrate is provided with the spiral fin, so that the plating liquid flowing inside the tubular member is between the fins. Flow along the inner peripheral surface of the tubular member, and because the fin pitch is sparse and dense, the flow velocity is high in the dense pitch portion and the amount of particles dispersedly contained in the plating layer in that portion. Is relatively large. Therefore, when this composite metal plating apparatus is applied to an engine cylinder, it is possible to increase the dispersion amount of particles near the top dead center by making the fin pitch close to the top dead center close. it can. Further, when the rotating means is provided on the fin, more uniform plating can be performed, and there is also an effect of constantly eliminating bubbles adhering to the plated surface.

[0014]

The present invention will be described in more detail below by taking the case of applying the present invention to an aluminum alloy cylinder liner as an example. The first composite metal plating layer is a nickel plating layer containing silicon carbide particles dispersed therein, and the second composite metal plating layer is a nickel plating layer containing PTFE dispersed therein.

The manufacturing process and manufacturing conditions are as follows. (1) After processing the inner peripheral surface of the cylinder liner (JIS AC8A aluminum alloy, inner diameter 80 mm, height 120 mm), degreasing trichlene. (2) Alkaline degreasing (caustic soda 100 g / l, 60
° C, 180 sec). (3) Acid treatment (40% nitric acid, 45 seconds). (4) Zinc substitution treatment (double zinc substitution with a commercially available substitution solution). (5) Strike nickel plating (nickel chloride 240
g / l, hydrochloric acid 120 g / l, water 850 ml / l, bath temperature 2
0 ° C., current density 10 A / dm ² ). (6) Nickel plating of silicon carbide particles dispersed (nickel sulfamate 350 g / l, nickel chloride 15 g / l, boric acid 45 g / l, sodium saccharin 3 g / l, average particle size of silicon carbide particles 1 to 5 μm, amount suspended in bath) 150 g /
1, bath temperature 60 ° C., PH 4, current density 20 A / dm ² ). (7) Honing process. (8) Alkali degreasing. (9) Acid treatment. (10) PTFE dispersed nickel plating (nickel sulfamate 500 g / l, nickel chloride 45 g / l, boric acid 35 g / l, dispersant Metaflon FS-20 (trade name)
25 g / l, Metaflon 1003 (trade name) 15 g /
1, bath temperature 45 ° C, PH4.2, current density 2A / d
m ² ). The reason for using the nickel sulfamate bath in the steps (6) and (10) is that the internal stress of the plating is small, the plating rate is high, and the bath management is easy.

Next, FIG. 2 shows an outline of the composite metal plating apparatus used in the above step (6). However, this device can also be used in the above step (10). A rod-shaped positive electrode 2 is arranged at the center of a cylinder liner 1 made of an aluminum alloy, and an anode bag 3 and a spiral non-conductive fin 4 are integrally attached around the positive electrode 2, and the plating chamber A is formed by these. Constitute. The pitch of the spiral fins 4 is such that the upper part (around the top dead center of the cylinder liner 1) is dense and the lower part is sparse.
The nickel caramel 5 that constitutes the anode is housed therein. The cathode side of the rectifier 6 is the cylinder liner 1
The anode side is connected to the positive electrode 2.

The upper and lower surfaces of the cylinder liner 1 are sealed at one ends of the circulation pipes 7 and 8, respectively.
The other end of is opened in the plating liquid tank 9. A liquid feed pump 10 is located in the middle of the lower circulation pipe 8. The plating bath 9
It is equipped with a stirring propeller 11 and a heater 12, and contains a composite plating solution containing silicon carbide particles dispersed therein. Positive electrode rod 2
Is rotatably supported by the side walls of the circulation pipes 7 and 8 and is rotatably driven by the motor 13.

Next, the operation of the composite metal plating apparatus will be described. The composite plating solution stirred in the plating solution tank 9 and uniformly dispersed with silicon carbide particles flows through the circulation pipe 8 due to the pressure of the liquid feed pump 10. It flows from below into the plating chamber A, rises while rotating between the spiral fins 4, flows out from above the plating chamber A, and returns to the plating solution tank 9 again through the circulation pipe 7. In the plating chamber A, the denser the pitch of the fins 4 is, the smaller the cross-sectional area of flow of the plating solution is, and the faster the flow rate of the plating solution is. The high flow rate means that the apparent volume ratio of the dispersed particles in the plating solution is high, and therefore the number of times the dispersed particles collide with the cathode surface increases and the amount of the dispersed particles deposited in the plating layer is increased. You can do a lot. In this embodiment, since the flow velocity near the top dead center of the cylinder liner 1 is high, the content of silicon carbide particles in the plated layer is increased there.

The rotation of the positive electrode 2 and the rotation of the fin 4 have the function of obtaining a uniform composite plating layer on the inner peripheral surface of the cylinder liner 1. That is, by rotating the fins 4, it is possible to prevent a shadow where plating is not formed on the inner peripheral surface of the cylinder liner 1 from occurring, and in addition, to remove air bubbles adhering to the inner peripheral surface of the cylinder liner 1, which is called a pit. It is possible to prevent the formation of crater-shaped recesses. Moreover, in the plating chamber A, the plating solution is directed from the lower side to the upper side, so that the bubbles can be removed smoothly. Of course, the fin 4 is rotated in the direction in which bubbles are likely to rise. Since this apparatus has a structure in which the plating solution is simply circulated, the low-capacity pump 10 can supply the plating solution.

Now, FIG. 1 shows a schematic cross-sectional view of a cylinder liner 1 obtained by the above manufacturing process and manufacturing apparatus.
As shown in FIG. 1A, on the inner peripheral surface of the cylinder liner 1, a nickel plating layer 21 containing silicon carbide particles dispersedly contained.
(Hereinafter, referred to as the first composite plating layer 21), and PTFE
Nickel plating layer 22 (hereinafter referred to as the second
The composite plating layer 22 is used. ) Is formed, and the particles are densely dispersed near the top dead center 1a of the cylinder liner.

FIG. 1B shows an enlarged view of the sliding contact surface. On the cylinder liner substrate 30 made of aluminum alloy,
Zinc substitution layer 31 and strike nickel plating layer 3 in this order
2, first composite plating layer 21, and second composite plating layer 22
Are covered. The zinc substitution layer 31 and the strike nickel plating layer 32 are provided to improve the adhesion between the base material 30 and the first composite plating layer 21.

Since the first composite plating layer 21 is subjected to honing and the relatively soft nickel matrix is preferentially ground, the hard silicon carbide particles 23 are partially exposed from the nickel plating matrix on the ground surface H. The particles 23a crushed by the stress at the time of processing and particles (not shown) likely to fall off are also present in some of them. The second composite plating layer 22 is formed on the ground surface H of the first composite plating layer 21. Therefore, the crushed particles 2 in the first composite plating layer 21
3a and particles that are likely to fall off are again covered with the nickel plating base of the second composite plating layer 22 and firmly held. Incidentally, 24 is PTFE particles dispersed in the nickel plating base.

The plating thickness of the first composite plating layer 21 is preferably 100 μm or more before the honing process and 70 μm or more after the honing process from the viewpoint of durability. The dispersion amount of the silicon carbide particles 23 is 18 to 20 v near the top dead center.
and about 10 to 12 vol% near the bottom dead center.
The second composite plating layer 22 has a thickness of 5 to 10 μm.
That is, if the thickness is 5 μm or less, it is difficult to completely cover the silicon carbide particles 23 protruding from the first composite plating layer 21.
This is because if the thickness is more than μm, the plating is likely to be lost. The particle size of the precipitated PTFE particles is about 2 μm, and the dispersion amount is about 30 to 35% near the top dead center and about 10 to 15% near the bottom dead center if the lubricating ability near the top dead center is enhanced. However, it may be dispersed uniformly throughout.

When the cylinder liner 1 manufactured in this way is used, the second composite plating layer 22 first contributes to the initial familiarity because it has lubricity and is softer than the first composite plating layer 21. Initial wear is likely to proceed and easily conforms to the shape of the piston ring, thus ensuring sealing performance. As the initial wear progresses (for example, the position of the phantom line S in FIG. 1B), the silicon carbide particles 23 that are hard and hardly adhere to the mating material are exposed to support the load, which suppresses wear and prevents seizure. To do. Even in this state, since the silicon carbide particles 23 are retained by the nickel base of the remaining second composite plating layer 22, the silicon carbide particles 23 do not fall off, the area ratio of silicon carbide can be maintained, and the sliding surface with the piston ring can be maintained. It is possible to prevent abrasive wear.

(Abrasion test-1) Pin / shown in FIG. 3 (a)
A disc wear test method was used to test the relationship between the content of silicon carbide particles and wear resistance. According to the manufacturing process, a zinc substitution layer, a strike nickel plating layer, and a composite nickel plating layer containing silicon carbide particles were sequentially formed on a disk 40 made of AC8A aluminum alloy as a test piece, and then the surface was ground to obtain the composite nickel. The plating layer was 70 μm thick. In this test, the composite nickel plating layer containing the solid lubricant was not formed. The pin 41 facing the disc 40 is made of SUS440C nitrided as a material equivalent to a piston ring.
Its cross-sectional shape w × l is 3 mm × 5 mm, and its tip R is 2 mm
(FIG. 3 (b)). The pin 41 was pressed against the surface of the disk 40 rotating at a constant speed (peripheral speed 0.3 m / sec) with a load P of 5 Kgf. The lubrication conditions are
10W-30 as lubricating oil at 100 ° C, 300cc / m
It was in.

FIG. 4 is a graph showing the relationship between the wear height of the disk 40 and the silicon carbide content at a slip distance of 5 km. It can be seen that as the content increases, the wear height decreases, and the silicon carbide particles are extremely effective in improving wear resistance. FIG. 5 is a diagram showing the relationship between the surface roughness Ra and the test time. When the silicon carbide content is 20 vol%, the area ratio of silicon carbide that bears the load is high, so it takes time to reduce the surface roughness as compared with 10 vol%.
This indicates that the composite plating layer has high durability, and that it is highly necessary to form a composite metal plating layer containing a lubricant on the surface thereof in order to improve the initial conformability.

(Abrasion test-2) As in the abrasion test-1,
The scuffing resistance of the sliding contact member according to the present invention was tested using the pin / disk wear test method. As the test piece, a disk used in the abrasion test-1 (conventional example) and a disk having a composite nickel plating layer containing a solid lubricant (PTFE) formed thereon (example) were prepared. The content of silicon carbide particles is 20 vol% in each case, and the content of PTFE particles in the plating layer in the examples is 30 vol%. The opposing pins were the same as in Abrasion Test-1.

In this test, the pin 41 is pressed against the surface of the disk 40 rotating at a constant speed to increase the test load P stepwise, while the horizontal torque applied to the pin 41 is constantly measured and the torque is P. When it exceeds × 0.2,
That is, it was determined that scuffing occurred when the friction coefficient exceeded 0.2. As shown in FIG. 3 (c), the test load P initially started at 10 Kgf and was 10 Kg every 30 seconds.
Increased by f. The peripheral speed of the disc 41 and the lubrication conditions were the same as those in the abrasion test-1.

The test results are shown in FIG. In the conventional example, scuffing occurred at 50 kgf, whereas in the example of the present invention, scuffing did not occur up to 100 kgf, and scuffing resistance was greatly improved.

[0030]

As described above, in the sliding contact member of the present invention, since the hard particles in the first composite metal plating layer are firmly held by the second composite metal plating layer, they do not easily come off, and The required area ratio of hard particles can be maintained. Therefore, scuffing is less likely to occur,
Moreover, it is possible to prevent abrasive wear. Further, the second composite metal plating layer containing the solid lubricant improves the initial conformability of the sliding contact member. As described above, according to the present invention, it is possible to obtain a sliding contact member that effectively utilizes the wear resistance and scuffing resistance originally possessed by the composite metal plating layer containing hard particles.

When the sliding contact member of the present invention is applied to a light alloy cylinder and the amount of hard particles dispersed near the top dead center is increased, the wear resistance and scuffing resistance near the top dead center can be easily achieved. It is possible to improve the sex. Further, according to the composite metal plating apparatus of the present invention, such a cylinder can be easily obtained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a cylinder liner according to the present invention, and FIG. 1 (b) is an enlarged view of a main part thereof.

FIG. 2 is a schematic view of a composite metal plating apparatus according to the present invention.

FIG. 3 is an explanatory diagram of a pin / disk wear test method.

FIG. 4 is a diagram showing the relationship between wear height and silicon carbide particle content.

FIG. 5 is a diagram showing the relationship between surface roughness Ra and wear test time.

FIG. 6 is a diagram showing a scuffing generation load.

[Explanation of symbols]

 1 Cylinder Liner 2 Electrode Bar 4 Fin 9 Plating Liquid Tank 21 First Composite Metal Plating Layer 22 Second Composite Metal Plating Layer 23 Hard Particle 24 Solid Lubricant Particle H Ground Surface

Claims (7)

[Claims] 1. A first composite metal plating layer in which hard particles are dispersedly contained on a surface of a metal base material, and a second composite metal in which a solid lubricant is dispersed and contained on the first composite metal plating layer and a metal similar to that of the first composite metal plating layer. A sliding contact member comprising a plated layer. 2. The sliding contact member according to claim 1, wherein the second composite metal plating layer is laminated on the ground surface of the first composite plating layer. 3. The sliding contact member according to claim 1, wherein the sliding contact member is an engine light alloy cylinder having a large amount of hard particles dispersedly contained near the top dead center. 4. The sliding contact member according to claim 1, wherein both the first composite metal plating layer and the second composite metal plating layer are based on nickel. 5. An apparatus for forming a composite metal plating layer containing dispersed particles on the inner peripheral surface of a base material while circulating a plating solution containing dispersed particles inside a tubular metal base material, the center of the base material. A composite metal plating apparatus, characterized in that a rod-shaped positive electrode is provided in the portion, spiral fins are provided on the positive electrode, and the fin pitch is sparse and dense. 6. The composite metal plating apparatus according to claim 5, wherein the fin is provided with a rotating means. 7. The composite metal plating apparatus according to claim 5, wherein the cylindrical metal base material is an engine cylinder, and the fin pitch is dense near the top dead center.