JPH09184079A - Wear resistant member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston ring with excellent wear resistance over a long period by forming a phosphate chemical conversion coating and a film containing solid lubricant grains on the surface of a piston ring for internal combustion engine. SOLUTION: After the surface, excluding outside peripheral surface, of a base material 1 of a piston ring of internal combustion engine, particularly a first compression ring 8, is previously subjected to surface conditioning treatment with Ti colloid, a first treating film 2 by phosphate such as manganese phosphate is formed. Subsequently, a second lubricant layer 3, composed of heat- and wear-resistant resin such as polyamideimide and dispersedly containing a solid lubricant such as MoS2 having 1-2μm average grain size, is formed on the above film 2 to 3-13μm thickness. By embedding the MoS2 grains, contained in the second film 3, among the crystalline grains in the surface of the first film 2, the falling of the Mo∫2 grains resulting from the wear of the surface film 3 with the lapse of time can be prevented. Moreover, the surface of a cylinder made of Al alloy, as a mating material of sliding, can keep excellent durability for a long period without requiring anodic oxidation treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear-resistant member, and more particularly, to a wear-resistant member which impactably contacts an aluminum alloy, for example, a piston ring for an internal combustion engine used in combination with an aluminum alloy piston. The present invention relates to a piston ring having a wear-resistant surface layer.

[0002]

2. Description of the Related Art In recent years, internal combustion engines of automobiles and the like have tended to increase output and rotate at high speed, and therefore, the pressure and heat load applied to a piston ring, especially a first pressure ring, have increased. In addition, since aluminum alloy pistons are widely used in internal combustion engines of automobiles and the like, adhesion wear described later tends to occur.

FIG. 11 is a sectional view showing the vicinity of a piston of a gasoline engine for an automobile. This gasoline engine is a four-cycle engine that repeats four strokes of intake, compression, combustion, and exhaust in the course of two reciprocations of the piston 11, and repeats the stroke. Rotate the crankshaft through. In FIG. 11, only the balancing weight 18 appears on the crankshaft.

FIG. 11 shows the last state of the compression stroke, in which the intake valve is in the closed state and already in the intake stroke.
Intake manifold 29, intake hole 2 of cylinder head 21
2, a mixed gas consisting of atomized gasoline and air is introduced into the cylinder bore, and the piston 11 moves backward (up).
Is compressed in the combustion chamber 25 by the pressure. When the ignition plug 24 is operated in this state, the mixed gas explosively burns and moves the piston 11 forward (down). Piston 11
The first pressure ring 12 and the second pressure ring 13 for maintaining airtightness with the cylinder liner 15 are arranged in order from the top.
In addition, an oil scraping ring 14 for supplying an appropriate amount of lubricating oil (oil) is fitted in each of the ring grooves. become.

The intake valve 23 is open only during the intake stroke, and the exhaust valve (not shown in the figure behind the intake valve 23) is open only during the exhaust stroke. The opening and closing of the valve is performed by the rocker arm 2 driven by the rotation of the cam 28.
7, the valve is constantly biased by the valve spring 26 in the direction of the closed state.

As shown in FIGS. 9 and 10, the piston rings 12, 13 and 14 are fitted on both sides of the ring grooves 11a and 11b of the piston 11 with a slight clearance.

In general, a wear-resistant member that comes into contact with a mating member has a low wear resistance from both sides, that is, the member itself has less wear due to the contact with the mating member and the wear of the mating member is small. desired. Therefore, in this specification, "wear resistance" means that, for example, in the case of a piston ring, both wear on the upper and lower surfaces thereof and wear on the piston in the ring groove are small.

When the piston 11 descends, the pressure rings 12 and 13 move into the ring grooves 11a and 11b as shown in FIG.
1 when the piston 11 is lifted up.
As shown in FIG. 0, it contacts the lower side surface of the ring grooves 11a and 11b. These abutments are repeated with high frequency, the piston ring being subjected to an impact with each abutment. This impact contact becomes more intense as the engine rotates at a higher speed. In addition, when the piston 11 reciprocates, the pressure rings 12, 1
Since 3 rotates irregularly in the ring groove, the upper and lower surfaces of the piston ring are further slid in addition to the impact contact with the side surface of the ring groove.

In addition to the above, in particular the first pressure ring 12
Is exposed to a high temperature by the combustion gas and is placed in an extremely harsh environment. The aluminum alloy which is the material of the piston 11 is subjected to adhesive wear of the aluminum alloy (the aluminum alloy softens and is peeled off by the piston ring). This causes the wear on the side surface of the ring groove on the piston side. This wear is
This promotes the so-called blow-by in which the combustion gas blows through the ring groove, causing a decrease in engine output.

Conventionally, in order to solve the above-mentioned problems, hard anodizing is performed on the piston by anodic oxidation as a measure on the piston side, and phosphate conversion treatment is performed on the upper and lower surfaces of the piston ring as a measure on the piston ring side. That was being done. The former hard alumite treatment is effective in preventing cohesive wear, but is expensive. Although the formation of the manganese phosphate film by the latter is effective in preventing adhesion wear in the early stage of engine operation, the durability of the film is low, and a long-term effect of preventing adhesion wear cannot be expected.

In addition to the above countermeasures, a countermeasure of forming a heat-resistant and abrasion-resistant resin film containing a solid lubricant on at least the upper and lower surfaces of the piston ring by forming a phosphate film thereon has been proposed. No. 82552.
Further, a nitride layer is formed on at least the lower surface of the piston ring, and a heat-resistant and / or heat-resistant solid lubricant is formed on the lower surface of the nitride layer.
A measure for forming a wear-resistant resin film is disclosed in JP-A-1-307.
No. 568. Even in the measures disclosed in these publications, initially, the solid lubricant held in the heat-resistant and abrasion-resistant resin film is worn out or falls off, and the sliding function of the film is lost, Adhesive wear sometimes occurred.

[0012] The present invention has been made in view of the above circumstances, and even when used under severe contact conditions, the wear of the mating contact material is small and the wear of the mating contact material is small. It is an object of the present invention to provide a wear-resistant member exhibiting excellent wear resistance, particularly a piston ring.

[0013]

Means for Solving the Problems The present invention has been made to solve the above problems, and is provided on a substrate.
In a wear-resistant member having a laminated structure of a first coating layer formed by a phosphate conversion treatment and a second coating layer formed on the first coating layer and containing particles of a solid lubricant, a phosphate conversion coating is provided. A gap is formed between the crystal particles on the outermost surface of the processing film, and the gap has a width and a depth for burying the solid lubricant particles. More preferably, most of the large number of solid lubricant particles are buried in the gap.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, it is preferable that the first coating layer is a manganese phosphate chemical conversion treatment film capable of forming fine concave portions having a large depth / width ratio. When the solid lubricant particles in the second coating layer have an average particle size of 1 to 2 μm, and when the thickness of the second coating layer is 3 to 13 μm, the solid lubricant particles have a good embedding property. Desirable in terms of surface. The thickness is measured from the deepest part of the fine irregularities of the phosphate conversion coating by observing the surface layer cross section with an optical microscope. In the above embodiment, the second coating layer composed of molybdenum disulfide particles having an average particle diameter of 1 to 2 μm and a heat-resistant and abrasion-resistant resin containing and dispersing the molybdenum disulfide particles has a good lubrication function for the abrasion-resistant member and Maintain low friction function continuously. As the solid lubricant, besides molybdenum disulfide, a solid lubricant known in tribology such as tungsten disulfide, boron nitride (hBN), and graphite can be used.

The wear-resistant member according to the present invention is suitable as a member that comes into sliding contact with an aluminum alloy member. In this case, sufficiently durable sliding performance can be obtained for the aluminum alloy without anodizing. However, even if the piston is anodized, remarkable wear of the piston ring can be avoided. In particular, the surface layer according to the present invention is suitable as a surface layer formed on at least the upper and lower surfaces of the piston ring. As the binder of the lubricant layer, other appropriate binder resin, for example, epoxy, polyimide or polytetrafluoroethylene (PTFE) having a lubricating function can be used in addition to polyamideimide.

[0016]

Conventionally, for example, in the surface layer disclosed in Japanese Utility Model Application Laid-Open No. 60-82552, the first phosphate chemical conversion treatment film has been used mainly for the purpose of improving adhesion by fixing a heat-resistant resin. Was not effective in preventing the solid lubricant in the heat-resistant and abrasion-resistant resin film from falling off the surface of the heat- and abrasion-resistant resin film.
Adhesion occurred on this surface.

On the other hand, the present invention focused on the size of the solid lubricant particles and the gaps between the phosphate conversion coating crystals as the underlayer. That is, phosphate crystals grown by a certain chemical conversion treatment grow from the substrate, and a large number of fine irregularities are formed on the outermost surface after the growth, and the size of the solid lubricant particles is made significantly smaller than the recess diameter or width. Similarly, if the size of the solid lubricant particles is made significantly smaller than the depth of the concave portion, the solid lubricant particles are embedded in the gaps between the crystals of the underlayer. With such a configuration, even if the surface layer of the present invention is worn over time, the solid lubricant hardly falls off and is removed, and the solid lubricant function is maintained close to the base surface, It is longer than before, preventing the occurrence of adhesive wear and improving the durability.

The crystal form of the phosphate chemical conversion treatment film is as follows.
Japanese Patent Publication No. 3-25514 discloses a leaf-like or rectangular parallelepiped one. However, it is difficult to embed solid lubricant particles between these crystal particles. The proportion is considered to be only a very small amount.

A specific method of forming the second coating layer is to mix the solid lubricant particles, the heat-resistant and abrasion-resistant resin and the solvent sufficiently, and then apply the mixed solution on the first coating layer. Then, drying is performed to evaporate the solvent, followed by baking of the heat-resistant resin to fix the solid lubricant to the chemical conversion film. At this time, it is preferable that the second coating layer has such a thickness as to completely cover the underlying phosphate crystal concave portions, and preferably has a thickness of 3 to 13 μm.

In the present invention having the above-described structure, there is a preferable relationship between the particle size of the solid lubricant and the gap between the chemical conversion treated crystals as the first layer of the underlayer. In other words, the finer the particle size of the solid lubricant is, the smaller the particle size of the solid lubricant is required because it is necessary to be embedded between the crystals of the underlayer. Agglomeration occurs in the medium, which tends to cause uneven distribution and increase the diameter of the aggregated particles. On the other hand, if the average particle size exceeds 2 μm, the number of solid lubricant particles that enter between the base crystal particles decreases, and the amount of the solid lubricant particles increases.

If the average particle size of the solid lubricant exceeds 2 μm, the solid lubricant in the second coating layer is in an unstable state, for example, the solid lubricant particles are not coated in the binder and project to the surface. In the process of repeated heavy collision and sliding with the mating member, impact concentrates on the tip of the solid lubricant particles, and as a result, the solid lubricant particles From the member, and sometimes a part of the second coating layer is exfoliated from the member.

A manganese phosphate film is suitable for forming a gap between crystals into which a solid lubricant having an average particle size of 1 to 2 μm can enter. Since the manganese phosphate chemical conversion coating forms crystals on the pyramid on the surface of the base metal iron, the particles of the solid lubricant easily enter into the gaps between the crystal surfaces, and the heat-resistant and wear-resistant resin layer has good adhesion. It is formed. By setting the average particle diameter of the solid lubricant to 1 to 2 μm, partial delamination of the second coating layer is prevented, and the wear proceeds entirely from the surface. It can withstand long-term use. In addition, as the binder resin of the second coating layer, for example, polyamideimide is preferable. Solid lubricants such as molybdenum disulfide are used in a total amount of 4% with the binder.
It is preferable that it is in the range of 0 to 60% by weight in order to balance low friction, lubricity and adhesion. The wear-resistant surface layer according to the present invention is suitable as a surface layer of a wear-resistant member in contact with an aluminum alloy member.

FIGS. 2 and 3 are SEM images showing crystal grains 31 and 32 of the manganese phosphate layer formed by the chemical conversion treatment. FIG.
From FIG. 3, the manganese phosphate crystal particles have a form in which a large number of polyhedrons are arranged on the outermost surface of the first coating layer with their ridges facing upward, and the width between these ridges is 10 μm.
It can be seen that there are many gaps of a little less than μm.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a piston ring will be described below.

First, items common to the embodiments will be described.

FIG. 1 is an enlarged sectional view of the first pressure ring. The dimensions of the first pressure ring 8 are a nominal diameter of 78 mm, a width (B) of 1.5 mm, and a thickness (T) of 2.8 mm. The base 1 is made of a silicon chrome steel oil-tempered wire (S
WOSC-V equivalent material), and a manganese phosphate layer (first coating layer 2) is formed on a surface other than the outer peripheral surface of the base 1,
On the upper and lower surfaces, a lubricant layer (second coating layer 3) in which molybdenum disulfide particles are dispersed in a binder resin (polyamide imide) is formed on the first coating layer 2. A cylinder liner (see FIG. 9 and FIG.
The hard chromium plating layer 4 which is in sliding contact with 5) is formed. Note that the coating layer on the outer peripheral surface can be a nitride layer or a sprayed layer of molybdenum or the like instead of the hard chromium plating layer. The second pressure ring may have the same structure as that of FIG.

The first pressure ring 8 was manufactured as follows. The base 1 is made of a 1.5 mm × 2.8 mm short wire of the oil-tempered SWOSC-V material, and is formed by plastic working into a free state of a pressure ring having a nominal diameter of 78 mm. . First, a hard chromium plating layer 4 was formed on the outer peripheral surface by a conventional method, and then a manganese phosphate layer 2 was formed on the substrate 1 by a phosphate conversion treatment described below. At this time, the hard chromium plating layer 4 on the outer peripheral surface was masked, and the first coating layer 2 made of manganese phosphate was formed by the following procedure.

First, the substrate 1 is placed in a 16% aqueous solution of a mixture of sodium hydroxide and sodium carbonate (temperature: 50 to 90 ° C .; 90 ° C. in this example) for 3 to 7 minutes (in each of the following examples, 3 minutes).
) And degrease it.

Next, a mixed acid of sulfuric acid and phosphoric acid (mixing ratio 4:
6, temperature 15-35 ° C: 30 ° C, concentration 5 in each of the following examples
%) Was subjected to an immersion acid treatment to clean the surface.

Next, in order to adjust the surface of the substrate, a surface conditioner containing a titanium colloid-a manganese phosphate-based film-forming preparation PP = VMA, B (trade name, manufactured by Nippon Parkerizing Co., Ltd.)
Temperature 25-50 ° C: 45 ° C in each of the following examples)
The immersion treatment was performed for 70 seconds (60 seconds in each of the following examples).

Next, a manganese phosphate chemical conversion treatment solution—PF = M5 (trade name, temperature 82-85, manufactured by Nippon Parkerizing Co., Ltd.)
C) for 2-5 minutes (5 minutes in each of the following examples) to form a manganese phosphate layer. At this time, the concentration of the processing solution is such that the total acidity (TA) is 21 to 25 Pt (23 Pt in each of the following examples), the free acid ratio is 4 to 7 Pt (6 in each of the following examples), and the iron content is 0.4 to 3 g /. 1 (1 g / l in each of the following examples). Here, the total acidity and the free acid ratio were determined by titration with an indicator.

Next, a lubricant layer (second coating layer 3) formed by dispersing molybdenum disulfide having an average particle size of 0.8 to 8 μm using polyamideimide as a binder was formed on the upper and lower surfaces by coating. Molybdenum disulfide dispersion is 50% by weight
It is.

Finally, the hard chromium plating layer 4 on the outer peripheral surface is subjected to lapping to obtain a pressure ring 8 shown in FIG.

Examples 1 to 7 As shown in Table 1 below, molybdenum disulfide (MoS ₂ )
Was changed, and a pressure ring was manufactured according to the above-described procedure (Examples 1 to 6). In addition to these, the average particle size is 1.5 μm instead of molybdenum disulfide as a solid lubricant.
Using graphite (graphite) (dispersion amount 50% by weight)
Other than that produced the pressure ring similarly to the above (Example 7).

Comparative Example 1 For the purpose of comparison, a zinc phosphate chemical conversion treatment chemical (Palbond 880 manufactured by Nippon Parkerizing Co., Ltd.) was used.
The same processing was performed. (Below)

[0036]

[Table 1]

FIG. 4 is a sketch of an SEM image of a lubricant layer (second coating layer 3) according to Example 3, and FIG. 5 is a sketch of an SEM image of a lubricant layer (second coating layer 3) according to Example 6. It is. 4 and 5, reference numeral 20 denotes a binder resin (polyamide imide), and reference numeral 10 denotes molybdenum disulfide particles, all of which are embedded between manganese phosphate crystals.

With respect to the piston ring manufactured as described above, a wear test was performed to evaluate the material correlation between the piston ring and sliding and impact contact with the piston in the ring groove.

FIG. 6 is a schematic sectional view showing a main part of the test apparatus.

The tester is constituted by a vertically moving part 5 for hitting and a rotating part 6 opposed to the vertically moving part. Vertical moving part 5
Is moved up and down by a crank mechanism (not shown) driven by a motor. The rotating unit 6 can be continuously rotated or inverted around a central axis of the vertical rotating shaft 6a by driving a motor. A disk 7 made of an aluminum alloy of a piston material is horizontally fixed to the lower end of the vertically moving portion 5, and the disk 7 is heated to an arbitrary temperature by a heater built in the vertically moving portion 5. . A piston ring 8 is horizontally fixed to the upper surface of the rotating portion 6 by fitting, and faces the disk 7.

With such a structure, the rotating part 6 rotates and the vertical moving part 5 moves up and down by the crank mechanism. The upper surface of the piston ring 8 is hit by the lower surface of the disk 7, and the piston and the ring groove of the piston are formed. The state of the collision and the sliding contact with the piston ring fitted to is reproduced. The hitting load can be set arbitrarily by a hydraulic mechanism (not shown) from below the rotating unit 6, and the number of hits per unit time and the rotation speed can be set arbitrarily.

The pressure ring 8 having been subjected to the above-described treatment is assembled in the above-described test machine, and the aluminum alloy for piston (A
An abrasion test was performed with the disk 7 made of C8A-T6) under the following conditions. Lubrication: dry hitting load: 150 kgf Number of hits: 8 times / sec Rotation speed: continuous one direction 2.0 mm / sec Disk temperature: 280 ° C

FIG. 7 shows the test results. FIG. 7 shows a pressure ring (Comparative Example 2) in which a normal manganese phosphate coating layer is provided on the upper and lower surfaces and a lubricant layer is not provided, and a manganese phosphate of Comparative Example 2 is shown for comparison with the present embodiment. The results of the same test as described above for the pressure ring (Comparative Example 3) in which the layer was subjected to chromium oxidation treatment to form a chromate film are also shown.

As is clear from FIG. 7, the piston ring according to the present embodiment has less wear of the piston ring and the disk (made of aluminum alloy for the piston) in both cases than the piston rings according to any of the comparative examples. It turns out that it shows excellent durability. The durability is particularly remarkable when the average particle size of the solid lubricant is in the range of 1 to 2 μm.

FIG. 8 shows an SEM image of the upper surface after the wear test of the piston ring according to the third embodiment. In FIG. 8, most of the molybdenum disulfide particles 10 (presenting glossy black) enter the gaps (presenting dark gray) between the manganese phosphate crystal particles 9 (presenting light gray) and filling the gaps. Is observed. On the other hand, in the piston ring according to Example 6, since the particle diameter of molybdenum disulfide is large, the proportion of the particles embedded in the gaps between the crystal particles of manganese phosphate is small, and the particles simply bonded by the binder Is overwhelmingly large. As a result, the lubricant layer slightly peels off from the underlying manganese phosphate layer. However, compared to the piston ring according to the comparative example,
An improvement in wear resistance is observed.

Although the embodiment of the present invention has been described above, various modifications can be made to the above embodiment based on the technical idea of the present invention.

[0047]

The wear-resistant surface layer according to the present invention comprises a first coating layer made of phosphate and a second coating layer containing a solid lubricant formed on the first coating layer. Since it has a laminated structure, even when it is used in combination with a mating member made of aluminum alloy, cohesive wear of the aluminum alloy does not occur, and wear of the aluminum alloy member and wear of the wear-resistant surface layer are both small.

In addition, since the solid lubricant that has entered the gaps between the phosphate crystal grains suppresses the progress of wear of the wear-resistant member, excellent wear resistance is maintained over a long period of time, and excellent durability is maintained. Is guaranteed.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a pressure ring according to an embodiment of the present invention.

FIG. 2 is a sketch of an SEM image of a manganese phosphate layer.

FIG. 3 is a sketch of an SEM image of a manganese phosphate layer.

FIG. 4 is a sketch of an SEM image of a lubricant layer of Example 3.

FIG. 5 is a sketch of an SEM image of a lubricant layer of Example 6.

FIG. 6 is a sectional view showing a main part of the wear tester.

FIG. 7 is a cliff showing the results of the wear test in comparison with a comparative example.

FIG. 8 is a sketch of an SEM image of a lubricant layer after a wear test in Example 3.

FIG. 9 is an enlarged partial sectional view showing the positional relationship between the piston and the piston ring in the ring groove when the piston is raised.

FIG. 10 is an enlarged partial sectional view showing a positional relationship between a piston and a piston ring in a ring groove when the piston is lowered.

FIG. 11 is a sectional view around a piston of a gasoline engine.

[Explanation of symbols]

 1. . . 1. Base of pressure ring . . 2. Manganese phosphate layer (first coating layer) . . 3. Lubricant layer (second coating layer) . . Hard chrome plating layer 7. . . 7. Aluminum alloy disc . . Pressure ring 9. . . Manganese phosphate crystal particles 10. . . Molybdenum disulfide particles 11. . . Aluminum alloy piston 11a, 11b, 11c. . . Ring groove 12. . . First pressure ring 13. . . Second pressure ring 14. . . Oil scraping ring 15. . . Cylinder liner 20. . . Binder resin (polyamide imide) 31. . . Manganese phosphate crystal particles 32. . . Manganese phosphate crystal particles

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location F02F 5/00 F02F 5/00 N F16J 9/26 F16J 9/26 C

Claims (10)

[Claims] 1. A first coating layer formed on a substrate and comprising a phosphate conversion coating, and a second coating layer formed on the first coating layer and containing particles of a solid lubricant. In the wear-resistant member having the laminated structure of the above, a gap is formed between the crystal particles on the outermost surface of the phosphate chemical conversion treatment film, and the gap has a width and a depth for burying the solid lubricant particles. A wear-resistant member characterized by the above-mentioned. 2. The wear-resistant member according to claim 1, wherein most of the plurality of solid lubricant particles are buried in the gap. 3. The wear-resistant member according to claim 1, wherein the phosphate chemical conversion treatment film is made of manganese phosphate. 4. The solid lubricant has an average particle size of 1 to 2 μm.
The wear-resistant member according to any one of claims 1 to 3, wherein 5. The wear-resistant member according to claim 1, wherein the solid lubricant is molybdenum disulfide. 6. The wear-resistant member according to claim 1, wherein the mating member that slides is an aluminum alloy. 7. The wear-resistant member according to claim 6, wherein the aluminum alloy is not anodized. 8. The first coating layer and the second coating layer,
The wear-resistant member according to claim 7, wherein the wear ring is formed on at least upper and lower surfaces of a piston ring mounted on an aluminum alloy piston. 9. The wear-resistant member according to claim 2, wherein the substrate is subjected to a surface conditioning treatment with a titanium colloid before the phosphate conversion treatment. 10. The wear-resistant member according to claim 4, wherein the thickness of the second coating layer is 3 to 13 μm.