JPH11246823A - Coating material for sliding part and piston ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating material for a sliding part, securing not only lubricating property but also abrasion resistance of itself even under a severe sliding condition for subjecting the same under a high temperature and a high load, preventing the occurrence of adhesion caused by a direct contact between a base material and an opposite material and the accompanying marked abrasion of the base material and/or the opposite material for a long period of time. SOLUTION: This coating material for a sliding part contains 50-90 wt.% polyimide-based heat resistant resin as a base material and each 5-45 wt.% at least molybdenum sulfide and antimony oxide as additive components, and uses the added molybdenum sulfide having 3-15 μm mean particle diameter in >=50 wt.%. Also the polyimide-based heat resistant resin as the base material has a net structure by blending a curing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating material for a sliding portion, and more particularly to a coating for a piston ring for an internal combustion engine and the like, which adheres to a base metal by direct contact with a mating material and deterioration of a lubricating state. The present invention relates to a covering material for a sliding portion which can be suitably used for preventing the occurrence of wear.

[0002]

2. Description of the Related Art The operating environment of an internal combustion engine has become severer year by year with the recent increase in performance of the engine.

[0003] Generally, the pistons of these internal combustion engines include:
A piston ring is installed to ensure the airtightness of the combustion chamber and to control the lubricating oil inside the cylinder. Particularly, in high-temperature, high-load conditions, the aluminum alloy used as the piston material is made of a piston ring. A phenomenon may occur in which the piston material is adhered to the surface of the combustion chamber and the piston material is worn, which may cause problems such as a decrease in airtightness of the combustion chamber and an increase in oil consumption.

In order to prevent this, in some engines, a solid lubricant or the like is applied to the upper and lower surfaces of the piston ring in order to prevent the direct contact between the piston ring base material and the piston and to improve the lubrication state. Is applied.

[0005] Conventionally, as a coating material for a sliding portion for such coating, for example, molybdenum disulfide (Mo) using an epoxy resin or a polyamideimide resin as a binder is used.
A solid lubricating film containing a solid lubricant such as S ₂ ), graphite, and polytetrafluoroethylene (PTFE) is known.

[0006]

However, such a conventional solid lubricating coating is excellent in friction reducing effect, but is required to be used under severe sliding conditions such as higher temperature and higher load (high surface pressure). On the other hand, the progress of wear of the coating itself becomes intense, and sufficient durability cannot be obtained. As a result, adhesion and wear between the piston ring base material and the piston may occur early. There was a problem.

[0007] Therefore, in the case of aluminum alloy pistons, under such severe conditions, it is necessary to adopt higher cost measures such as anodizing the sliding surface with the piston ring. Met.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the conventional problems described above, and not only has lubricity, but also has its own abrasion resistance under severe sliding conditions such as high temperature and high load. By providing a coating material for a sliding portion which can secure and prevent the occurrence of adhesion due to direct contact between the base material and the mating material and the accompanying significant wear of the base material and / or mating material for a long period of time, The aim is to realize unprecedented excellent anti-adhesion and wear resistance at low cost without using complicated mechanisms.

[0009]

In order to achieve the above object,
The present inventors have conducted detailed investigations on the friction and wear behavior of a sliding member coated with such a resin-bonded coating material. As a result, particularly under severe sliding conditions such as high temperature and high load, such a resin-bonded coating material was used. In order to further improve the anti-adhesion and abrasion prevention performance by forming the material, it has been found that it is particularly important to improve the wear resistance of the coating material itself in the area where the coating material is sliding with a single phase. .

Heretofore, in general, in the case of a resin-bonded coating containing molybdenum disulfide, the friction of the sliding portion is reduced, the dispersibility in the coating is further increased, and the base is partially exposed due to the effect of being embedded in the base recess. 1μ from the viewpoint of maintaining lubricity
Molybdenum disulfide particles having a relatively small particle size of about m have been frequently used.

However, from the characteristics of molybdenum disulfide, which exerts a lubricating effect by its own intragranular slip, a general coating using fine molybdenum disulfide particles with an emphasis on lubricity as described above has a particularly high output. High temperature, such as engine piston rings
When used under high load (high surface pressure) conditions, the abrasion resistance as described above tends to be insufficient.

The present inventors have also confirmed through experiments that under such conditions, particles having a certain size are more excellent in abrasion resistance of the coating itself.

Further, in the case of hitting and sliding at a higher surface pressure such as an engine with a supercharger, molybdenum disulfide having such a large particle diameter is used, and a hardener is added to a binder to form a coating film. It has been found that more excellent effects can be obtained by making stiffer.

That is, the coating material for a sliding portion according to the present invention comprises, as described in claim 1, 50 to 90% by weight of a polyimide heat-resistant resin as a base material, and at least molybdenum sulfide and The composition contains 5 to 45% by weight of antimony oxide, and the molybdenum sulfide to be added has an average particle size of 3 to 15 μm and is 50% by weight or more. It is characterized by having a structure.

[0015] In an embodiment of the sliding portion covering material according to the present invention, as described in claim 2,
The curing agent can be a phenolic resin.

Similarly, in an embodiment of the sliding portion covering material according to the present invention, as described in claim 3,
Molybdenum sulfide having an average particle size of 3 to 15 μm and molybdenum sulfide having an average particle size of 0.5 to 2 μm can be mixed and used at a ratio of 1: 1 to 10: 1.

In the embodiment of the sliding portion coating material according to the present invention, as described in claim 4, graphite, tungsten sulfide,
It may contain one or more solid lubricants selected from fluororesins.

Similarly, in the embodiment of the sliding portion coating material according to the present invention, as described in claim 5, the polyimide heat-resistant resin used as the base material can be polyamide-imide. .

In the embodiment of the sliding portion covering material according to the present invention, as described in claim 6, the substrate has a thickness of 1 to 10 μm and a surface roughness of Rma as a base treatment.
x2 to 10 μm phosphating can be applied, in which case the phosphating is manganese phosphate as described in claim 7 Can be.

The piston ring for an internal combustion engine according to the present invention is, as described in claim 8, claimed in claims 1 to 7.
Wherein the coating material for a sliding portion is formed on at least one or both of the front and back surfaces orthogonal to the reciprocating direction of the piston.

[0021]

The coating material for a sliding portion of the present invention contains 50 to 90% by weight of a polyimide heat-resistant resin as a base material, and at least 5 to 45% by weight of molybdenum sulfide and antimony oxide as additive components. The molybdenum sulfide to be added has an average particle diameter of 3 to 15 μm and is used in an amount of 50% by weight or more, and a polyimide heat-resistant resin serving as a base material has a network structure by blending a curing agent. By using a polyimide-based resin having excellent heat resistance as the base material, the base material can withstand use in high-temperature sliding.

However, if the composition ratio in the coating is less than 50% by weight, there is a possibility that the bonding property of the coating is reduced and the durability becomes insufficient. On the other hand, if the content exceeds 90% by weight, the contents of molybdenum sulfide and antimony oxide, which are additive components, become too small, so that their effects cannot be utilized.

Molybdenum sulfide as an additional component is effective as a solid lubricant. However, if the amount is less than 5% by weight, a sufficient effect cannot be obtained. And the durability may be insufficient. If the average particle size of molybdenum sulfide is less than 3 μm, the lubricating property is advantageous, but the wear resistance of the coating material itself under sliding conditions of high temperature and high load (high surface pressure) is insufficient, and conversely, it exceeds 15 μm. In addition, the friction loss during sliding increases due to the large decrease in lubricity, and not only the durability of the coating is impaired due to the resulting frictional heat, but also in the case of grains larger than necessary, Becomes uneven, and peeling or the like is likely to occur due to a decrease in the binding property of the coating.

Therefore, in the sliding portion coating material of the present invention, the average particle size of the added molybdenum sulfide is 3 to 15 μm.
By making m the main component with 50% by weight or more, it is possible to have both necessary and sufficient lubricity and excellent wear resistance.

Further, by making the polyimide heat-resistant resin serving as the base material form a net-like structure by blending a curing agent, especially in a normal resin binder like a piston ring of a supercharged engine, Particle size 3
Even in the situation of intense beating and sliding at high temperatures where molybdenum sulfide particles exceeding μm can not be sufficiently retained, the compounded molybdenum sulfide particles can be retained firmly, significantly improving the durability of the coating. Let it. In addition,
Examples of the curing agent in this case include a resin compound having a hydroxyl group, but are not particularly limited.

Further, antimony oxide as an additional component is added as reinforcing particles for the coating, but this antimony oxide does not have too high hardness as compared with carbon fibers or the like generally used for resin composite materials. Also, since the particle shape is almost spherical and has no edge, even when a relatively soft metal such as aluminum is combined as the mating sliding member, the wear is not promoted. However, if the addition amount is less than 5% by weight, it is difficult to exhibit a sufficient effect of strengthening the film, and if it exceeds 45% by weight, the bondability of the film is reduced and the durability becomes insufficient. There is fear.

The coating material for a sliding portion according to the present invention comprises a molybdenum sulfide having an average particle size of 3 to 15 μm and an average particle size of 0.5 to 15 μm.
2 μm molybdenum sulfide can be used by mixing at a ratio of 1: 1 to 10: 1.
Molybdenum sulfide having an average particle size of 3 to 15 μm has an average particle size of 0.
By mixing and using 5 to 2 μm of molybdenum sulfide,
In particular, even when the base material is partially exposed due to the progress of the abrasion of the coating and a direct contact portion with the counterpart material occurs, the lubricating property is maintained by a sufficient amount of molybdenum sulfide particles remaining in the base concave portion, and It is possible to prevent adhesion and wear between the base material and the mating material for a longer time.

However, if the average particle size of the molybdenum sulfide to be mixed is less than 0.5 μm, such an effect is not only saturated, but also the time and cost required for pulverizing the particles are undesirably increased. Conversely, if the average particle size of the molybdenum sulfide to be mixed exceeds 2 μm, it will be difficult to obtain a sufficient filling effect on the underlayer.

The amount of molybdenum sulfide having an average particle size of 0.5 to 2 μm is desirably equal to or less than that of molybdenum sulfide having an average particle size of 3 to 15 μm for the reason described above. On the other hand, if the amount is less than 1/10, the amount of molybdenum sulfide particles buried in the concave portions of the base becomes too small, and it is difficult to expect a lubricating effect when the base is partially exposed.

Further, the coating material for a sliding portion according to the present invention contains at least one solid lubricant selected from graphite, tungsten sulfide, and a fluororesin as a lubricity improving component. Can be.

Particularly, in an environment where lubrication is severe, or
In the case where it is used in a site where low friction is required, the lubricity of the coating is further improved by appropriately adding these solid lubricants. Depending on the sliding conditions, the solid lubricant selected here may be graphite, which has particularly excellent heat resistance, tungsten sulfide, which exhibits well-balanced lubrication over a wide temperature range, and poly, which has a high friction-reducing effect at relatively low loads. By appropriately selecting and using a fluororesin such as tetrafluoroethylene (PTFE),
Lubricity can be provided more effectively.

In the coating material for a sliding portion according to the present invention, the polyimide heat-resistant resin used as the base material may be polyamide imide. Unlikely, it is soluble in solvents, so it is possible to select any coating method according to the purpose, such as spray coating or roller coating, by adjusting the composition with the solvent, and it is suitable for a wider range of sliding parts. Not only can it be a material excellent in the balance between sliding characteristics and heat resistance among polyimide resins in particular, so using polyamideimide as a base material makes it particularly suitable for high temperature sliding parts. .

Further, the coating material for the sliding portion according to the present invention is such that the base material is subjected to a phosphate treatment with a thickness of 1 to 10 μm and a surface roughness of Rmax 2 to 10 μm as a base treatment. In this case, the phosphate treatment may be a manganese phosphate treatment.

As described above, by performing the phosphate treatment as the base treatment, the adhesion strength to the base material is further improved, and the coating material for the sliding portion is more excellent in stability. In addition, by using a manganese phosphate treatment that provides a dense, high-strength, and heat-resistant treatment layer as the phosphate treatment, a more effective base treatment layer can be obtained, and the stability of the coating material can be improved. Is even higher.

However, the roughness of the phosphating layer is Rmax
If it is less than 2 μm, the effect of improving the adhesion strength tends not to be sufficiently obtained, and the effect of embedding molybdenum sulfide particles in the concave portions of the treatment layer decreases. Conversely, if the thickness exceeds 10 μm, it becomes difficult to form a uniform film when forming a coating material using the phosphate treatment layer as a base, which may cause early peeling and falling off of the film.

Further, if the thickness of the phosphating layer is less than 1 μm, the effect of the surface properties of the underlying metal becomes so great that the effect of stably improving the adhesion strength cannot be obtained. It becomes difficult to obtain a salt-treated layer, and the stability of the coating material when used as a base tends to be impaired.

In applying the coating material for a sliding portion of the present invention having the above-described excellent characteristics, the upper and lower surfaces of the piston ring for an internal combustion engine (front and back surfaces orthogonal to the reciprocating direction of the piston) are used. By forming and using on at least one surface, even under severe conditions such as high temperature and high load, generation of adhesion and wear between the piston ring base material and the piston is prevented for a long period of time.

[0038]

According to the present invention, as described in claim 1, 50 to 90% by weight of a polyimide heat-resistant resin as a base material and at least molybdenum sulfide and oxidized Molybdenum sulfide to be added contains 5 to 45% by weight of antimony and has an average particle size of 3 to 15 μm in an amount of 50% by weight or more. Not only has sufficient lubricity, but also excels in the sliding conditions of high temperature and high load (high surface pressure) without increasing the aggression to the mating material. Wear resistance, and especially in severe conditions such as piston rings in turbocharged engines where harsh tapping occurs at high temperatures. Significantly excellent effect that it is possible to prevent the adhesion and wear between the substrate metal and the mating member is brought over.

In the coating material for a sliding portion according to the present invention, as described in claim 2, the polyamideimide heat-resistant resin having a chain structure is formed by using a phenol resin as the curing agent. The formation of a network structure in conjunction with each other has the significant effect of being further strengthened.

Further, in the sliding portion covering material according to the present invention,
As described in claim 3, the average particle size is 3 to 15 μm.
Molybdenum sulfide and molybdenum sulfide having an average particle size of 0.5 to 2 μm are mixed and used at a ratio of 1: 1 to 10: 1. Even when a direct contact portion with the mating material occurs, sufficient lubricity is maintained, and it is possible to prevent the occurrence of adhesion and wear between the base material and the mating material for a longer period of time. The remarkable effect is brought about.

Further, in the sliding portion coating material according to the present invention, as described in claim 4, at least one solid selected from graphite, tungsten sulfide, and fluororesin as a lubricity improving component. By including a lubricant, it is possible to effectively impart more excellent lubricity, particularly when used in a severely lubricated environment or a site where low friction is required. Has a remarkable effect.

Further, in the sliding portion covering material according to the present invention, as described in claim 5, the polyimide heat-resistant resin used as the base material is polyamide imide, so that it can be used according to the purpose. Coating method can be selected and applied to a wide range of sliding parts, and its excellent sliding characteristics and heat resistance have the remarkable effect that it can be more suitably used as a high-temperature sliding member. Brought.

Further, in the sliding portion coating material according to the present invention, as described in claim 6, the base material has a thickness of 1 to 10 μm and a surface roughness Rmax of 2 to 10 μm as a base treatment.
m, by having been subjected to a phosphate treatment, it is possible to further enhance the adhesion to the base metal,
It becomes possible to make a coating material with even higher stability,
As described in claim 7, by setting the phosphate treatment to be a manganese phosphate treatment, it is possible to obtain a denser, higher-strength, and superior heat-resistant base treatment layer, A remarkably excellent effect is obtained in that the stability of the coating material can be further increased.

In applying the coating material for a sliding portion according to the present invention having such excellent characteristics, the present invention is applied to claim 8.
As described in the above, by forming and using at least one of the front and back surfaces orthogonal to the reciprocating direction of the piston of the piston ring for an internal combustion engine, a high-power engine, particularly an engine with a supercharger, etc. Even under severe conditions such as high temperature and high load (high surface pressure), adhesion and abrasion between the piston ring base material and the piston, and the progress thereof, are at unprecedented levels for a long period of time. This has a remarkably excellent effect that it is possible to prevent such a phenomenon.

[0045]

Next, examples will be described in more detail with reference to comparative examples.

(Examples 1 to 4) First, polyamideimide (PAI) was used as a polyimide heat-resistant resin as a base material.
And dissolved in n-methyl-2-pyrrolidone and xylene as a solvent, and the polyamideimide (20% by weight of a phenol resin added as a curing agent) was used as a solvent. Molybdenum disulfide (MoS ₂ ) having an average particle size of 7 μm and an average particle size of 1
μm molybdenum disulfide (MoS ₂ ), antimony oxide (Sb ₂ O ₃ ), graphite, polytetrafluoroethylene (PTFE), and tungsten disulfide (W
S ₂ ) was added to prepare a coating material solution.

[0047]

[Table 1]

Next, after surface adjustment such as degreasing is performed on the upper surface of the piston ring base material made of spring steel, the surface roughness R
A manganese phosphate treatment with a maximum of about 4 μm and a thickness of about 4 μm is performed, and the solution adjusted as described above is spray-coated and dried, and then heated and fired at about 180 to 220 ° C., as shown in FIG. Thus, a test piece of the piston ring 1 in which the upper surface of the piston ring substrate 1b was coated with the sliding portion coating 1c having a thickness of about 10 μm was prepared.

(Comparative Examples 1 to 8) The same polyamideimide (PAI; however, no curing agent was added in Comparative Examples 1 to 4) used in the above Examples was prepared by using n-methyl-2-pyrrolidone and xylene as solvents. After dissolving, the average particle size was 7 μm so that the composition shown in each column of Comparative Examples 1 to 8 in Table 1 was obtained.
m of molybdenum disulfide (MoS ₂ ) and an average particle size of 1 μm
Molybdenum disulfide (MoS ₂ ), antimony oxide (Sb ₂ O ₃ ), graphite, polytetrafluoroethylene (PTFE), and tungsten disulfide (WS)
₂ ) was blended to prepare a coating material solution.

Next, after surface adjustment such as degreasing is performed on the upper surface of the piston ring base material made of spring steel, the surface roughness R
A manganese phosphate treatment with a maximum of about 4 μm and a thickness of about 4 μm is performed, and the solution adjusted as described above is spray-coated and dried, and then heated and baked at about 180 to 220 ° C., as in the example. Then, a test piece of the piston ring 1 was prepared in which the upper surface of the piston ring base 1b was covered with the sliding portion covering material 1c having a thickness of about 10 μm.

(Adhesion Wear Test) Examples 1-4 and Comparative Example 1
Test piece of each piston ring 1 created in ~ 8
As shown in FIG. 2, a single piece adhesion wear test was performed on the cut material 2 from the actual aluminum alloy piston under the conditions shown in Table 2 (test temperature was set by the heater 3), and the sliding surface was used. The time until the occurrence of adhesion at 1 s was compared. Table 3 shows the results.

[0052]

[Table 2]

[0053]

[Table 3]

As is clear from Table 3, Example 1 of the present invention
Comparative Examples 1-4, Comparative Examples 1-4, in which no curing agent was added to the polyamideimide as the base material, average particle diameters of 3-
Comparative Examples 5 and 6 in which the compounding ratio of 15 μm molybdenum sulfide is out of the range of the present invention, Comparative Example 7 in which the composition ratio of the base material is out of the range of the present invention, and Comparative Example 8 in which antimony oxide as reinforcing particles is not added. As compared with the above, the durability time until the occurrence of adhesion was greatly improved, and it was found that the resin-bonded coating material had an excellent performance which could not be obtained.

Further analysis on this point revealed that the sliding portion covering material 1c obtained in the example of the present invention was made of polyamide-imide (PAI) as a polyimide-based heat-resistant resin.
And a phenol resin as a curing agent, a reaction as shown in the following chemical formula 1 occurs.

[0056]

Embedded image

As described above, it was confirmed that the chain-structured polyamide imides (PAIs) were tied to each other to form a network structure, which was further strengthened.

[Brief description of the drawings]

FIG. 1 is a partially enlarged sectional explanatory view of a piston ring showing an embodiment of the present invention.

FIG. 2 is an explanatory cross-sectional view showing an outline of a single adhesion wear test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piston ring 1b Piston ring base material 1c Covering material for sliding part 1s Sliding surface 2 Cutting material from piston (partner material) 3 Heater

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F16J 9/26 F16J 9/26 C // (C09D 179/08 161: 06) (72) Inventor Masahiko Shioda Yokohama, Kanagawa 2 Takaracho, Kanagawa-ku, Nissan Inside Nissan Motor Co., Ltd.

Claims (8)

[Claims] 1. A heat-resistant polyimide-based resin as a base material in an amount of 50 to 90% by weight, and at least 5 to 45% by weight of molybdenum sulfide and antimony oxide as additive components.
A coating material for a sliding portion, characterized in that a polyimide-based heat-resistant resin serving as a base material has a network structure by the addition of a curing agent, in which a material having a thickness of 15 μm or more is used in an amount of 50% by weight or more. 2. The sliding part covering material according to claim 1, wherein the curing agent is a phenol resin. 3. A 1: 1 mixture of molybdenum sulfide having an average particle size of 3 to 15 μm and molybdenum sulfide having an average particle size of 0.5 to 2 μm.
The sliding portion coating material according to claim 1, wherein the coating material is used by mixing at a ratio of 10 to 10: 1. 4. The method according to claim 1, wherein the lubricating component contains at least one solid lubricant selected from graphite, tungsten sulfide, and fluororesin.
4. The coating material for a sliding portion according to any one of items 3 to 3. 5. The coating material for a sliding portion according to claim 1, wherein the polyimide heat-resistant resin used as the base material is polyamideimide. 6. A base material having a thickness of 1 to 10 μm as a base treatment.
The coating material for a sliding portion according to any one of claims 1 to 5, wherein a phosphate treatment having a surface roughness Rmax of 2 to 10 m is performed. 7. The coating material for a sliding part according to claim 6, wherein the phosphate treatment is a manganese phosphate treatment. 8. An internal combustion, wherein the coating material for a sliding portion according to any one of claims 1 to 7 is formed on at least one of front and back surfaces orthogonal to a reciprocating direction of a piston. Engine piston ring.