JP2016156495A - Piston ring for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston ring for an internal combustion engine that can prevent aluminum coagulation from occurring for a long period under a high-temperature and high-load condition.SOLUTION: The piston ring 1 for an internal combustion engine includes a piston ring base material 11 over which an anti-aluminum coagulation coat 12 is coated. The anti-aluminum coagulation coat 12 is a composite coating that contains ceramics as a main component and is coated to at least one of upper and lower side faces 11a and 11b of the piston ring base material 11. The composite coating contains solid lubricant.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a piston ring for an internal combustion engine, and more particularly, to a piston ring for an internal combustion engine that can prevent aluminum adhesion over a long period of time even under high temperature and high load conditions.

  Three piston rings used in an internal combustion engine, a top ring, a second ring, and an oil ring, are arranged so as to engage with ring grooves provided on the surface of the piston, respectively, and combustion gas leaks from the combustion chamber to the outside. A gas seal function that prevents the oil from flowing, a heat transfer function that cools the piston by transferring the piston heat to the cooled cylinder wall, and a function that scrapes excess oil by applying an appropriate amount of engine oil as lubricating oil to the cylinder wall. Have.

These three piston rings repeatedly collide with the groove inner surface in the ring groove of the piston when the piston reciprocates due to the explosion of fuel in the combustion chamber during operation of the internal combustion engine. Further, since the piston ring is slidable in the circumferential direction in the ring groove, it slides in the ring groove. By the way, on the surface of the ring groove, a protrusion having a height of about 1 μm is formed by lathe processing for groove formation, and the protrusion is fatigued and destroyed by the collision and sliding with the above-described piston ring, The aluminum surface is exposed on the surface of the ring groove.
When the exposed aluminum alloy surface comes into contact with the side surface of the piston ring due to a collision and further slides, aluminum adhesion occurs, which is a phenomenon in which the aluminum alloy adheres to the side surface of the piston ring. This is particularly noticeable in the top ring located closest to the combustion chamber and placed under high temperature conditions.

  As this aluminum adhesion further progresses, the wear of the ring groove progresses rapidly, the gas seal function of the piston ring decreases, and a phenomenon called so-called blow-by occurs in which high-pressure combustion gas flows out from the combustion chamber to the crank chamber. This causes a problem that causes a reduction in engine output.

  In response to this situation, various techniques for preventing aluminum adhesion of piston rings have been proposed. For example, Patent Document 1 discloses a technique for improving conformability and preventing aluminum adhesion by providing a resin-based film containing carbon black particles on the side surface of a piston ring that collides with and slides on a ring groove. Have been described.

  Patent Document 2 discloses that one or two or more powders selected from the group consisting of nickel-based powder, lead-based powder, zinc-based powder, tin-based powder, and silicon-based powder are 10 to 80 with respect to the entire surface coating. It describes a technique for effectively preventing aluminum adhesion to the piston ring by providing a heat-resistant resin containing mass% on at least one of the upper and lower side surfaces of the piston ring.

  However, in the case of the coatings described in Patent Documents 1 and 2, there is a problem that the aluminum adhesion resistance decreases when the temperature in the engine rises. Therefore, in Patent Document 3, a polyimide coating containing hard particles and having a solid lubricating function is provided on at least one of the upper and lower side surfaces of the piston ring, so that even under high temperature conditions exceeding 230 ° C., for a long period of time. A technique for maintaining high aluminum adhesion resistance is described.

  Further, Patent Document 4 discloses a first diamond-like carbon (DLC) film containing at least silicon instead of a resin-based film, and at least W or W formed under the first DLC film. A technique for providing a piston ring having excellent aluminum adhesion resistance, scuff resistance, and wear resistance by providing a second DLC film containing Ni on the upper and lower side surfaces of the piston ring is described.

JP 2007-278495 A JP 2008-248986 A International Publication No. 2011/071049 Pamphlet JP 2003-014122 A

By the way, in recent years, downsizing of vehicles has progressed, and the amount of exhaust gas has been reduced in order to improve fuel efficiency. As a result, the temperature and pressure in the engine have been increasing. However, in the resin-based coating as in Patent Document 3, the coating wears out quickly under a high temperature condition exceeding 260 ° C. and a high load condition such that the pressure in the engine exceeds 10 MPa. It is difficult to maintain aluminum adhesion.
In addition, the DLC film described in Patent Document 4 is graphitized under a high temperature condition exceeding 260 ° C., and oxidation proceeds in an oxidizing atmosphere, and the original characteristics of the DLC film are exhibited and the aluminum adhesion resistance is maintained. It is difficult to do.

  Accordingly, an object of the present invention is to provide a piston ring for an internal combustion engine that can prevent aluminum adhesion over a long period of time under high temperature and high load conditions.

  The inventors diligently studied how to solve the above problems. As a result, it has been found that it is effective to make the aluminum anti-adhesion coating a composite coating that is formed on the base material for the piston ring and that contains ceramics as a main component and that contains a solid lubricant, thereby completing the present invention. It came to let you.

That is, the gist of the present invention is as follows.
(1) A piston ring for an internal combustion engine, wherein a piston ring base material is coated with an aluminum anti-adhesion coating, wherein the aluminum anti-adhesion coating is provided on at least one of the upper and lower side surfaces of the piston ring base material. A piston ring for an internal combustion engine, which is a composite coating composed mainly of coated ceramics, wherein the composite coating contains a solid lubricant.

(2) The Vickers hardness HV of the aluminum adhesion-resistant coating and the arithmetic average roughness Ra (μm) of the surface of the aluminum adhesion-resistant coating satisfy the following formula (A): Piston ring for internal combustion engines.
Ra <−8.7 × 10 ⁻⁵ HV + 0.39 (A)

(3) The internal combustion according to (1) or (2), wherein the Vickers hardness HV of the aluminum adhesion-resistant coating and the thickness h (μm) of the aluminum adhesion-resistant coating satisfy the following formula (B): Piston ring for engine.
H> -2.9 × 10 ⁻⁴ HV + 0.89 (B)

(4) The aluminum adhesive coating has any one of the above (1) to (3), in which the ceramic layer and the solid lubricant layer overlap each other in a cross section in the thickness direction. A piston ring for an internal combustion engine according to item.

(5) The piston ring for internal combustion engines according to any one of (1) to (4), wherein the aluminum adhesion coating has a Vickers hardness HV of 500 or more and 2800 or less.

(6) The piston ring for an internal combustion engine according to any one of (1) to (5), wherein a content of the solid lubricant is 1% by mass to 20% by mass with respect to the entire coating film.

(7) The piston ring for an internal combustion engine according to any one of (1) to (6), wherein the arithmetic average roughness of the surface of the aluminum adhesion-resistant coating is 0.4 μm or less.

(8) The piston ring for an internal combustion engine according to any one of (1) to (7), wherein the thickness of the aluminum adhesion-resistant coating is 0.1 μm or more and 20 μm or less.

(9) The ceramic constituting the aluminum-resistant adhesive coating is a group consisting of alumina, titania, yttria, zirconia, silica, magnesia, chromia, silicon carbide, chromium carbide, aluminum nitride, titanium nitride, silicon nitride, and chromium nitride. The solid lubricant comprised of at least one selected from the group consisting of molybdenum disulfide, tungsten disulfide, graphite (Gr), calcium fluoride, polytetrafluoroethylene (PTFE), polyimide (PI) Any one of (1) to (8), consisting of at least one selected from the group consisting of tin, copper, indium, silver, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and boron nitride. A piston ring for an internal combustion engine according to item.

  According to the present invention, the durability of the coating is improved by making the aluminum anti-adhesion coating stable at a high temperature and containing a hard ceramic as a main component, and the solid lubricant is contained in the coating to further counteract the coating. Since the aggressiveness is reduced, aluminum adhesion can be prevented for a long time under high temperature and high load conditions.

1 is a schematic cross-sectional view of a piston ring for an internal combustion engine according to the present invention in a state of being engaged with a ring groove. It is a schematic diagram of the engine simulation test apparatus used for the Example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a piston ring for an internal combustion engine according to the present invention engaged with a ring groove. The piston ring 1 for an internal combustion engine shown in this figure is a piston ring for an internal combustion engine in which a piston ring base material 11 is coated with an aluminum adhesion coating 12. Here, the aluminum adhesion-resistant coating 12 is a composite coating mainly composed of ceramics coated on at least one of the upper and lower side surfaces 11a and 11b of the piston ring base material 11, and the composite coating contains a solid lubricant. It is important to make it happen.

  As shown in FIG. 1, in a state where the piston ring 1 is engaged in the ring groove 21, the gap between the side wall of the cylinder 24 and the piston 20 is closed and the combustion gas and oil are sealed. The piston ring 1 follows the reciprocating movement of the piston 20 (movement in the direction of the arrow in the figure), and the vertical movement occurs in the ring groove 21, and the piston ring 1 and the upper surface 22 of the ring groove 21 and The collision is repeated with the lower surface 23. Since the piston ring 1 is slidable in the circumferential direction in the ring groove 21, the piston ring 1 repeats sliding while being in contact with the upper surface 22 and the lower surface 23 of the ring groove 21.

  Due to repeated collision and sliding between the piston ring 1 and the upper surface 22 and the lower surface 23 of the ring groove 21, protrusions (not shown) formed on the upper surface 22 and the lower surface 23 of the ring groove 21 are scraped. As a result, an aluminum alloy surface centering on the protrusion trace is generated. Here, in the present invention, the upper surface 22 and the lower surface of the ring groove 21 are formed while the aluminum adhesion coating 12 is mainly composed of ceramics having excellent heat resistance and oxidation resistance, while reducing the partner attack of the coating. 23, the aluminum surface is cut to form a surface in which primary silicon protrudes from the surface.

  During the operation of the internal combustion engine, the primary crystal protruding to the surface and the ceramic of the aluminum anti-adhesion coating 12 slide, but the solid lubricant contained in the aluminum anti-adhesion coating 12 (ie, ceramics) The friction coefficient of the aluminum adhesion coating 12 is lowered to further alleviate the attack on the piston material. Thereby, aluminum adhesion can be prevented over a long period of time under high temperature and high load conditions.

  In the present invention, “composite coating” means a coating containing a solid lubricant, and “based on ceramics” means that the composite coating contains 50% by mass or more of ceramics. It means that. Hereinafter, each structure of the piston ring 1 for internal combustion engines is demonstrated.

  The material of the piston ring base material 11 is not particularly limited as long as it has strength to withstand a collision with the ring groove 21. Steel, martensitic stainless steel, austenitic stainless steel, high-grade cast iron and the like are preferable. Moreover, in order to improve wear resistance, the side surface may be a base material subjected to nitriding treatment for stainless steel and hard Cr plating or electroless nickel plating treatment for cast iron.

  The ceramic constituting the aluminum adhesion-resistant coating 12 is at least selected from the group consisting of alumina, titania, yttria, zirconia, silica, magnesia, chromia, silicon carbide, chromium carbide, aluminum nitride, titanium nitride, silicon nitride, and chromium nitride. It can be a kind. Solid lubricants contained in the aluminum adhesion-resistant coating include molybdenum disulfide, tungsten disulfide, graphite (Gr), calcium fluoride, polytetrafluoroethylene (PTFE), polyimide (PI), tin, copper, and indium. , Silver, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and at least one selected from the group consisting of boron nitride.

  The Vickers hardness HV of the ceramic of the aluminum adhesion-resistant coating 12 is preferably 500 or more and 2800 or less. Here, by setting the Vickers hardness to 500 or more, sufficient hardness of the aluminum adhesion-resistant coating is secured, and the primary crystal silicon on the surface of the familiar surface formed on the surface of the ring groove (Vickers hardness of about 1000) Therefore, it is possible to suppress the aluminum adhesive coating from being significantly worn. Further, by setting the Vickers hardness to 2800 or less, it is possible to suppress the ratio of breaking the primary crystal silicon on the familiar surface layer and to prevent the piston material from being significantly worn.

  Further, the surface roughness of the aluminum adhesion resistant coating 12 is preferably 0.4 μm or less. The aluminum anti-adhesion coating 12 having such a surface roughness can suppress the attack of the piston material by suppressing the surface pressure even in contact with the ring groove, and can suppress an increase in the wear amount of the piston material. it can. In the present invention, the surface roughness of the ceramic means an arithmetic average roughness Ra based on JIS B0601 (1994), and is measured using a surface roughness measuring device.

Here, it is preferable that the Vickers hardness HV and the surface arithmetic average roughness Ra (μm) of the aluminum adhesion-resistant coating 12 satisfy the following formula (A).
Ra <−8.7 × 10 ⁻⁵ HV + 0.39 (A)
The inventors formed an aluminum-resistant adhesive coating 12 having various materials, Vickers hardness, surface roughness, and film thickness on the base material 11 for piston ring, and the aluminum-resistant adhesive of the piston ring 1 thus obtained. The performance and the wear amount of the piston material were evaluated. As a result, when the Vickers hardness HV and the arithmetic average roughness Ra of the surface of the aluminum adhesion-resistant coating 12 satisfy the above formula (A), the aluminum material has high aluminum adhesion resistance while suppressing the wear of the piston material. I found out. This is because the piston ring 1 and the upper surface 22 and the lower surface 23 of the ring groove 21 come into contact with each other by setting the arithmetic average roughness Ra of the surface to an appropriate value corresponding to the hardness of the aluminum adhesion-resistant coating 12. It is considered that the surface pressure between them can be reduced.

  Furthermore, the thickness of the aluminum adhesion-resistant coating 12 is preferably 1 μm or more and 20 μm or less. Here, by setting it to 1 μm or more, the film thickness of the film becomes sufficient with respect to the surface roughness of the ceramic, and the aluminum anti-adhesion film 12 can be made a homogeneous film to suppress self-abrasion. Moreover, by setting it as 20 micrometers or less, sufficient clearance in the ring groove 21 is ensured, and the function of the above-described piston ring can be executed.

Here, it is preferable that the Vickers hardness HV and the film thickness h (μm) of the aluminum adhesion-resistant coating 12 satisfy the following formula (B).
h> -2.9 × 10 ⁻⁴ HV + 0.89 (B)
As in the case of the above formula (A), the inventors suppress the wear of the piston material even when the Vickers hardness HV and the film thickness h of the aluminum adhesion resistant coating 12 satisfy the above formula (B). However, it has been found that it has high aluminum adhesion resistance. This is presumably because the wear of the piston material can be suppressed without wear of the aluminum-resistant adhesive coating 12 by setting the film thickness h to an appropriate value according to the hardness of the aluminum-resistant adhesive coating 12.

  The content of the solid lubricant contained in the aluminum adhesion resistant coating 12 is preferably 1% by mass or more and 20% by mass or less with respect to the entire coating. Here, by setting it to 1 mass% or more, the friction coefficient of the aluminum adhesion-resistant coating 12 can be further reduced, and the wear amount of the piston material can be further reduced. Moreover, by setting it as 20 mass% or less, it can prevent that the aluminum-resistant adhesion coating 12 itself wears out remarkably. Particularly preferably, the content is 5% by mass or more and 10% by mass or less.

  Such an aluminum adhesion-resistant coating 12 can be formed by various known methods in which ceramic fine particles or vaporized ceramic fine particles are directly laminated on the surface. Specifically, deposition is performed under appropriate deposition conditions using thermal spraying, chemical vapor deposition (CVD), physical vapor deposition (PVD), cold spraying, or the like. By performing the above, the piston ring according to the present invention can be manufactured.

  Also, solid lubricant is mixed with ceramic fine particles as fine particles, vaporized solid lubricant is directly laminated on the surface, or vaporized solid lubricant is mixed in an atmosphere near the surface to form ceramic fine particles. Thus, the aluminum adhesive film 12 can be contained.

  When the aluminum adhesion-resistant coating 12 is formed by thermal spraying, the powder composition is heated in the thermal spraying apparatus and sprayed at a high speed toward the side surface of the piston ring base material 11. Examples of the method of spraying the powder composition on the side surface of the piston ring base material 11 include a gas flame spraying method, a plasma spraying method, and a high-speed flame spraying method (HVOF), and the plasma spraying method is preferable.

  In the plasma spraying method, the gas between the anode and the cathode is turned into plasma by applying a high voltage between the anode and the cathode of the thermal spraying apparatus. Since the gas converted into plasma is heated and further expanded, it is ejected from the thermal spraying apparatus at a high temperature and at a high speed, and becomes a plasma jet flow. The powder composition supplied to the thermal spraying apparatus is heated and accelerated in the plasma jet stream, and sprayed toward the piston ring base material 11. Since the heated and accelerated particles are partially melted, they are flattened when they collide with the piston ring base material 11 and are layered on the side surfaces of the piston ring base material 11. To do. The particles deposited in layers are rapidly cooled by the piston ring base material 11 to form a sprayed coating.

  In the plasma spraying method, particles in the supplied powder composition can be heated to a higher temperature than other spraying methods, and the melting of each particle in the powder composition tends to be promoted. For this reason, in the cross section perpendicular to the sliding surface of the thermal spray coating obtained by plasma spraying (the cross section parallel to the thickness direction of the coating), the ceramic layer and the solid lubricant layer undulate like waves. However, they tend to form tissues that overlap (fold) and entangle with each other. Then, by forming the above structure in the cross section of the sprayed coating, chromium carbide is retained in the sprayed coating even after sliding, and the surface of the sprayed coating after sliding tends to be smooth. Therefore, the thermal spray coating obtained by the above plasma spraying is excellent in wear resistance and suppresses wear of the counterpart material.

  Thus, the piston ring according to the present invention can prevent aluminum adhesion over a long period of time under high temperature and high load conditions.

<Production of piston ring>
Examples of the present invention will be described below.
On the upper and lower side surfaces of the piston ring base material made of low chromium steel, various materials shown in Tables 1 to 4, the hardness of the ceramic material, the content of the solid lubricant material, the surface roughness of the film, and the film having the film thickness Formed. Here, in Invention Examples 1 to 63 and Comparative Example 5, a coating was formed by a known method of directly laminating ceramic fine particles or vaporized ceramic fine particles on the surface, and a piston ring was produced.
On the other hand, for Comparative Examples 1 and 2, a piston ring was produced by forming a film by spray coating a paint adjusted to each composition described later. Moreover, about the comparative example 3, the film was formed by the electroless-plating method and the piston ring was produced. Furthermore, about the comparative example 4, the film was formed by PVD method and the piston ring was produced.
The resin coating A of Comparative Example 1 is a polyimide resin coating containing 5% by mass of MoS ₂ powder (average particle size 2 μm) and 5% by mass of graphite powder (average particle size 2 μm). Furthermore, the resin coating B of Comparative Example 2 is a polyimide resin coating containing 10% by mass of Al ₂ O ₃ powder (average particle size 0.5 μm).

Aluminum adhesion resistance of the piston rings of Invention Examples 1 to 63 and Comparative Examples 1 to 5 was evaluated. For this purpose, the engine simulation test apparatus shown in FIG. 2 was used. The engine simulation test apparatus 30 shown in FIG. 2 has a mechanism in which the piston material 32 reciprocates up and down and the piston ring 33 rotates. The test is performed using the heater 31, the temperature controller 34, and the thermocouple. 35, the piston material 32 was heated and controlled. The test conditions were a surface pressure of 13 MPa, a ring rotation speed of 3 mm / s, a control temperature of 270 ° C., a test time of 5 hours, and nitrogen gas and a fixed amount of oil were injected at predetermined intervals. After the test, the remaining amount of coating on the piston ring and the presence or absence of aluminum adhesion were examined. The obtained results are shown in Tables 1 to 4. In addition, the evaluation criteria of the film remaining amount are as follows.
◎: 80% or more remains with respect to the initial film thickness ○: 40% or more but less than 80% remains with respect to the initial film thickness △: Less than 40% remains with respect to the initial film thickness ×: No film

The evaluation of the aluminum adhesion performance was confirmed visually. The obtained results are shown in Tables 1 to 4. In addition, the evaluation criteria of aluminum adhesion performance are as follows.
◎: Aluminum adhesion not occurred ○: Aluminum adhesion occurred but very slight ×: Aluminum adhesion occurred

The amount of wear of the piston material was calculated by measuring the shape of the surface of the piston material after the test and calculating the depth from the reference surface. The obtained results are shown in Tables 1 to 4. The evaluation criteria for the amount of wear are as follows.
A: Less than 0.5 μm O: 0.5 μm or more and less than 1.0 μm Δ: 1.0 μm or more and less than 3.0 μm ×: 3.0 μm or more

The performance of the piston ring was comprehensively evaluated from the evaluation results of the aluminum ring anti-adhesion performance of the piston ring and the wear amount of the piston material. The obtained results are shown in Tables 1 to 4. The criteria for comprehensive evaluation are as follows.
◎: Excellent ○: Good △: Relatively good ×: Bad Here, the overall evaluation is that the film remains 80% or more with respect to the initial film thickness, there is no aluminum adhesion, and the wear amount of the piston material is less than 0.5 μm. The film is ◎, the film is 40% or more and less than 80% of the initial film thickness, aluminum is not adhered, the piston material wear amount is 0.5 μm or more and less than 1.0 μm, ○, the film is not present, the aluminum The coating with a wear amount of the piston material of 3.0 μm or more was marked with ×, and the coatings other than that were marked with Δ.

<Evaluation of residual coating amount and aluminum adhesion resistance>
As shown in Tables 1 to 4, aluminum adhesion did not occur in all of the piston rings of Invention Examples 1 to 63. Moreover, about the invention examples except invention examples 40-43, 46, 47, 52, 53, and 63, the film residual amount was as much as 80% or more with respect to the initial film thickness. On the other hand, in Comparative Examples 1 and 2, no film remained after the test, and aluminum adhesion occurred. In Comparative Example 3, as in Comparative Examples 1 and 2, no coating remained after the test and aluminum adhesion occurred, but it was very slight. Furthermore, in Comparative Examples 4 and 5, the remaining amount of the film was large, and aluminum adhesion did not occur.

<Evaluation of piston material wear>
As shown in Table 1, with respect to the inventive examples other than the inventive examples 30, 35 to 37, 40, 41, 46, 52 and 58, the piston wear amount was less than 1.0 μm and was small. Moreover, about the invention example 58 with comparatively little content of solid lubricant material, the abrasion amount was a little large with 1.0 to 3.0 micrometer.
On the other hand, in Comparative Examples 1 and 2, the wear amount was as large as 3 μm or more. In Comparative Example 3, the wear amount was slightly small, but in Comparative Examples 4 and 5, the wear amount was large.

  Table 2 shows the relationship between the surface roughness of the coating and the amount of wear of the piston material. Invention examples 28, 29, 31 to 34, in which the Vickers hardness and surface roughness of the coating satisfy the formula (A), About 38 and 39, it turns out that it has the high aluminum adhesion-proof performance, suppressing abrasion of piston material. Invention Examples 1-27 shown in Table 1, Invention Examples 42-45, 47-51 and 53-57 shown in Table 3, and Invention Examples 59-62 shown in Table 4 also satisfy the formula (A). It can be seen that the aluminum material has high adhesion resistance while suppressing the wear of the piston material.

  Further, Table 3 shows the relationship between the film thickness of the coating film and the amount of wear of the piston material. Invention Examples 42 to 45, 47 to 51 and 53 in which the Vickers hardness and film thickness of the coating film satisfy the formula (B). About -57, it turns out that it has the high aluminum adhesion-proof performance, suppressing abrasion of piston material. Invention Examples 1-27 shown in Table 1, Invention Examples 59-63 shown in Table 4, and Invention Examples 28, 29, 31-34, 38 and 39 shown in Table 2 also satisfy the formula (B). It can be seen that the aluminum material has high adhesion resistance while suppressing the wear of the piston material.

<Comprehensive evaluation>
Evaluation of comparatively good or better was given to all of Invention Examples 1 to 63. In particular, the aluminum anti-adhesion coating is a coating containing ceramics as a main component and containing 1% by mass to 20% by mass of a solid lubricant, and the Vickers hardness and surface roughness of the aluminum anti-adhesion coating are expressed by the formula (A ) Or when the Vickers hardness and film thickness satisfy the formula (B), a piston ring having high aluminum adhesion resistance while suppressing wear of the piston material was obtained. I understand.
On the other hand, Comparative Examples 1 and 2 provided with the resin film were inferior in both aluminum adhesion resistance and piston material wear. Further, Comparative Example 3 provided with a nickel coating, Comparative Example 4 provided with a DLC coating, and Comparative Example 5 provided with an alumina coating have good or excellent aluminum adhesion resistance, and piston material wear characteristics. Is also excellent, but not as good as the present invention.

  According to the present invention, the durability of the coating is improved by making the aluminum anti-adhesion coating stable at a high temperature and containing a hard ceramic as a main component, and the solid lubricant is contained in the coating to further counteract the coating. It is useful for the automobile parts manufacturing industry because it can reduce aggressiveness and prevent aluminum adhesion over a long period of time under high temperature and high load conditions.

1,33 Piston ring 11 Piston ring base material 11a Upper side surface 11b of piston ring base material Lower side surface of piston ring base material 12 Aluminum adhesive coating 20 Piston 21 Ring groove 22 Ring groove upper surface 23 Ring groove Lower surface 24 Cylinder 30 Engine simulation test device 31 Heater 32 Piston material 34 Temperature controller 35 Thermocouple

That is, the gist of the present invention is as follows.
(1) A piston ring for an internal combustion engine, wherein a piston ring base material is coated with an aluminum anti-adhesion coating, wherein the aluminum anti-adhesion coating is provided on at least one of the upper and lower side surfaces of the piston ring base material. A composite coating comprising a coated ceramic as a main component, the composite coating containing a solid lubricant, the Vickers hardness HV of the aluminum anti-adhesion coating and the arithmetic average roughness of the surface of the aluminum anti-adhesion coating Ra (μm) satisfies the following formula (A): A piston ring for an internal combustion engine.
Record
Ra <−8.7 × 10 ⁻⁵ HV + 0.39 (A)

(2) The piston ring for an internal combustion engine according to (1 ) , wherein the Vickers hardness HV of the aluminum adhesion-resistant coating and the thickness h (μm) of the aluminum adhesion-resistant coating satisfy the following formula (B): .
H> -2.9 × 10 ⁻⁴ HV + 0.89 (B)

(3) The internal combustion coating according to (1) or (2) , wherein the aluminum adhesive coating has a structure in which a layer made of the ceramic and a layer made of the solid lubricant overlap each other in a cross section in the thickness direction. Piston ring for engine.

(4) The piston ring for an internal combustion engine according to any one of (1) to (3) , wherein the aluminum adhesion coating has a Vickers hardness HV of 500 or more and 2800 or less.

(5) The piston ring for an internal combustion engine according to any one of (1) to (4) , wherein a content of the solid lubricant is 1% by mass or more and 20% by mass or less with respect to the entire coating film.

(6) The piston ring for an internal combustion engine according to any one of (1) to (5) , wherein the arithmetic average roughness of the surface of the aluminum adhesion-resistant coating is 0.4 μm or less.

(7) The piston ring for an internal combustion engine according to any one of (1) to (6) , wherein the aluminum adhesion-resistant coating has a thickness of 0.1 μm or more and 20 μm or less.

(8) The ceramic constituting the aluminum anti-adhesion coating is composed of alumina, titania, yttria, zirconia, silica, magnesia, chromia, silicon carbide, chromium carbide, aluminum nitride, titanium nitride, silicon nitride, chromium nitride. The solid lubricant comprised of at least one selected from the group consisting of molybdenum disulfide, tungsten disulfide, graphite (Gr), calcium fluoride, polytetrafluoroethylene (PTFE), polyimide (PI) Any one of (1) to (7) , consisting of at least one selected from the group consisting of tin, copper, indium, silver, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and boron nitride. A piston ring for an internal combustion engine according to item.

Claims (9)

A piston ring for an internal combustion engine in which an aluminum adhesion coating is coated on a piston ring base material,
The aluminum adhesion-resistant coating is a composite coating composed mainly of ceramics coated on at least one of the upper and lower side surfaces of the piston ring base material, and the composite coating contains a solid lubricant. Piston ring for internal combustion engines. 2. The piston for an internal combustion engine according to claim 1, wherein the Vickers hardness HV of the aluminum adhesion-resistant coating and the arithmetic average roughness Ra (μm) of the surface of the aluminum adhesion-resistant coating satisfy the following formula (A): ring.
Ra <−8.7 × 10 ⁻⁵ HV + 0.39 (A) The piston ring for an internal combustion engine according to claim 1 or 2, wherein a Vickers hardness HV of the aluminum adhesion-resistant coating and a thickness h (µm) of the aluminum adhesion-resistant coating satisfy the following formula (B).
H> -2.9 × 10 ⁻⁴ HV + 0.89 (B)   The internal combustion engine according to any one of claims 1 to 3, wherein the aluminum adhesion coating has a structure in which a layer made of the ceramic and a layer made of the solid lubricant overlap each other in a cross section in the thickness direction. Piston ring for use.   The piston ring for an internal combustion engine according to any one of claims 1 to 4, wherein the aluminum adhesion coating has a Vickers hardness HV of 500 or more and 2800 or less.   The piston ring for an internal combustion engine according to any one of claims 1 to 5, wherein a content of the solid lubricant is 1% by mass or more and 20% by mass or less with respect to the entire coating film.   The piston ring for an internal combustion engine according to any one of claims 1 to 6, wherein an arithmetic average roughness of the surface of the aluminum adhesion-resistant coating is 0.4 µm or less.   The piston ring for an internal combustion engine according to any one of claims 1 to 7, wherein the aluminum adhesion-resistant coating has a thickness of 0.1 µm or more and 20 µm or less.   The ceramic constituting the aluminum anti-adhesion coating is selected from the group consisting of alumina, titania, yttria, zirconia, silica, magnesia, chromia, silicon carbide, chromium carbide, aluminum nitride, titanium nitride, silicon nitride, and chromium nitride. The solid lubricant comprising at least one kind and contained in the aluminum adhesion-resistant coating is molybdenum disulfide, tungsten disulfide, graphite (Gr), calcium fluoride, polytetrafluoroethylene (PTFE), polyimide (PI), tin, The internal combustion engine according to claim 1, comprising at least one selected from the group consisting of copper, indium, silver, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and boron nitride. Piston ring for use.

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