JP6387228B2 - Piston ring for internal combustion engine - Google Patents

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 and can suppress the amount of wear of the piston material.

  The three piston rings used in an internal combustion engine, the top ring, the second ring, and the oil ring, are arranged to engage with piston 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 piston from moving, a heat transfer function that cools the piston by transmitting 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 piston ring groove of the piston when the piston reciprocates due to the explosion of fuel in the combustion chamber during the operation of the internal combustion engine. Further, since the piston ring is slidable in the circumferential direction in the piston ring groove, the piston ring slides in the piston ring groove. By the way, on the surface of the piston ring groove, a protrusion having a height of about 1 μm is formed by lathe processing for groove formation, and the protrusion is worn by collision and sliding with the above-described piston ring, The aluminum surface is exposed on the surface of the piston ring groove.
When this exposed aluminum surface comes into contact with the side surface of the piston ring by 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 progresses further, the piston groove wears rapidly, the piston ring adheres to the ring groove, the gas seal function of the piston ring decreases, and high-pressure combustion gas flows from the combustion chamber to the crank chamber. There is a problem that a phenomenon called so-called blow-by occurs that causes a decrease in engine output.

  Under such circumstances, various techniques for preventing the aluminum adhesion of the piston ring have been proposed so far. 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 and slides with a piston ring groove. Is 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 film. It describes a technique for effectively preventing adhesion of aluminum 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 when the temperature in the engine rises, the aluminum adhesion resistance is lowered. Therefore, in Patent Document 3, a polyimide film containing solid 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, in Patent Document 4, instead of the resin-based film, at least a silicon-like carbon (DLC) film containing at least silicon, and at least 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 W and 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 displacement 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 film as in Patent Document 3, the aluminum adhesion resistance is maintained for a long time 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.
Further, in the DLC film described in Patent Document 4, diamond is graphitized under a high temperature condition exceeding 260 ° C., and it is difficult to exhibit the original characteristics of the DLC film and maintain the aluminum adhesion resistance. .

  In addition to the long-term prevention of aluminum adhesion under the high temperature and high load conditions of this aluminum anti-adhesion coating, the attack on the piston material, which is the counterpart material, is reduced to reduce the wear amount of the piston material. It is also important.

  Therefore, 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 even under high temperature and high load conditions and can suppress the amount of wear of the piston material.

  The inventors diligently studied how to solve the above problems. As a result, a first film made of ceramics formed on the piston ring base material, and a second film made of resin or metal formed on the first film, the aluminum anti-adhesion film The present inventors have found that it is effective to have a two-layer structure having the present invention and have completed the present invention.

That is, the gist of the present invention is as follows.
(1) A piston ring for an internal combustion engine in which at least one of upper and lower side surfaces of a piston ring base material is coated with an aluminum anti-adhesion coating, wherein the aluminum anti-adhesion coating is formed on the piston ring base material. A first film made of ceramics and a second film made of resin or metal formed on the first film, the Vickers hardness HV of the first film and the first film A piston ring for an internal combustion engine, wherein the arithmetic average roughness Ra (μm) of the surface of one film satisfies the following formula (A):
Ra <−8.7 × 10 ⁻⁵ HV + 0.39 (A)

(2) The piston ring for an internal combustion engine according to (1), wherein the first coating has a Vickers hardness HV of 500 to 2800, and the second coating has a Vickers hardness HV of 20 to 300.

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

(4) The piston ring for an internal combustion engine according to any one of (1) to (3) , wherein the arithmetic average roughness of the surface of the first coating is 0.3 μm or less.

(5) The thickness of the first film is 0.1 μm or more, the thickness of the second film is 1 μm or more, and the total thickness of the first film and the second film is 20 μm or less. The piston ring for an internal combustion engine according to any one of (1) to (4) .

(6) The second film is made of a resin containing hard particles, and the material of the hard particles is made of at least one selected from alumina, zirconia, ceria, silicon carbide, silicon nitride, cubic boron nitride, and diamond. The piston ring according to any one of (1) to (5) , characterized in that it is characterized in that

(7) The ceramic material is at least one selected from alumina, titania, yttria, zirconia, silica, magnesia, chromia, silicon carbide, chromium carbide, aluminum nitride, titanium nitride, silicon nitride, and chromium nitride, and the resin. These materials are polyimide, polyetherimide, polyamideimide, polysulfone, polyethersulfone, polyarylate, polyphenylene sulfide, polyetheretherketone, aromatic polyester, aromatic polyamide, polybenzimidazole, polybenzoxazole, aromatic At least one selected from annulate, aromatic polythiocyanurate, and aromatic polyguanamine, and the metal material is at least one selected from indium, lead, tin, copper, silver, and gold. Characterized the door, the (1) piston ring according to any one of - (6).

  According to the present invention, the aluminum anti-adhesion film has a two-layer structure made of ceramics, a Vickers hardness HV is relatively low, a conforming surface is formed by the second film made of resin or metal, and the Vickers hardness HV is compared. The first coating made of ceramic material is made durable by the aluminum adhesion coating, which prevents aluminum adhesion over a long period of time even under high temperature and high load conditions, and wear of the piston material The amount can be suppressed.

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 piston ring groove. It is an enlarged view of the aluminum adhesion coating part in the piston ring for internal combustion engines which concerns on this invention. 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 in a state engaged with a piston 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 covered with an aluminum adhesion coating 12. Here, as shown in FIG. 2, the aluminum adhesion-resistant coating 12 is formed on the first coating 12a made of ceramic and formed on the piston ring base material 11, and on the first coating 12a. In addition, it is important to have the second film 12b made of resin or metal.

  As shown in FIG. 1, the piston ring 1 closes the gap between the side wall of the cylinder 24 and the piston 20 while being engaged in the piston ring groove 21, and seals combustion gas and oil. The piston ring 1 follows the reciprocating motion of the piston 5 (the motion in the direction of the arrow in the figure), and the vertical motion occurs in the piston ring groove 21, so that the upper surface of the piston ring 1 and the piston ring groove 21. The collision is repeated between 22 and the lower surface 23. Further, since the piston ring 1 is slidable in the circumferential direction in the piston 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 piston ring groove 21.

  Projections (not shown) formed on the upper surface 22 and the lower surface 23 of the piston 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 piston ring groove 21. The aluminum surface centering on the protrusion trace is generated by cutting. In the present invention, aluminum is formed between the second film 12b and the upper surface 22 and the lower surface 23 of the piston ring groove 21 by the second film 12b made of resin or metal having a relatively low Vickers hardness (that is, soft). It is possible to effectively form a familiar surface in which the surface is shaved and the primary crystal silicon protrudes from the surface. Further, the first film 12a made of ceramics having relatively high Vickers hardness (ie, hard) has high durability even under high temperature and high load conditions, and prevents aluminum adhesion over a long period of time. be able to. In particular, the effect of configuring the second coating 12b with resin or metal is exhibited when the load received by the piston ring 1 is further increased in the future. For example, when the second coating 12b is configured with ceramics. In comparison, since the hardness and frictional force of the second coating 12b are small, the familiar surface can be satisfactorily formed even under conditions of receiving a higher load. Hereinafter, each structure of the piston ring 1 for internal combustion engines is demonstrated.

  The material of the base material 11 for piston rings will not be specifically limited if it has the intensity | strength which can endure the collision with the piston ring groove | channel 21. FIG. 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 Vickers hardness HV of the first coating 12a 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 12 is ensured, and the primary crystal silicon (Vickers hardness of the familiar surface) formed on the surface of the piston ring groove 21 is secured. About 1000), it is possible to suppress the aluminum adhesive film 12 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.

  The Vickers hardness HV of the second coating 12b is preferably 20 or more and 300 or less. Here, by setting the Vickers hardness to 20 or more, the tip of the convex portion on the surface of the piston material can be worn. Further, by setting the Vickers hardness to 300 or less, it is possible to prevent the wear from occurring on the flat portion of the piston material surface. That is, by setting the Vickers hardness to 20 or more and 300 or less, it is possible to selectively wear and flatten only local convex portions on the surface of the piston material.

  The ceramic material constituting the first film 12a is at least one selected from alumina, titania, yttria, zirconia, silica, magnesia, chromia, silicon carbide, chromium carbide, aluminum nitride, titanium nitride, silicon nitride, and chromium nitride. be able to. Among these, alumina, zirconia, chromia, and silica are particularly preferable because of high recombination between particles and easy formation of a uniform film.

  When the second film 12b is made of a resin, the resin material may be polyimide (Polyimid, PI), polyetherimide, polyamideimide (Polyamidimide, PAI), polysulfone, polyethersulfone (Polyethersulfone, PES), polyarylate ( Polyarylate, PAR), polyphenylene sulfide (PPS), polyether ether ketone (Polyetherethertone, PEEK), aromatic polyester, aromatic polyamide, polybenzimidazole (PBI), polybenzoxazole, polybenzoxazole, polybenzoxazole Rate, aromatic polythiocyanurate, aromatic polyguanamine It may be at least one selected. Of these, polyimide, polyamideimide, and polybenzimidazole are particularly preferable because the resin itself is a thermosetting resin having high hardness, low friction, and no thermoplasticity.

  Furthermore, when the 2nd membrane | film | coat 12b consists of resin, it is preferable that a hard particle is included. Thereby, a coating with a low friction coefficient and a high hardness can be obtained, the polishing ability of the second coating 12b is improved, and the wear resistance of the second coating 12b itself is also improved. The material of the hard particles can be at least one selected from alumina, zirconia, ceria, silicon carbide, silicon nitride, cubic boron nitride, and diamond. Of these, alumina, zirconia, and ceria are preferred because they are generally widely used and inexpensive materials.

  The hard particles have a particle size of 0.05 μm or more and 3 μm or less. Here, the reason why the thickness is 0.05 μm or more is to obtain an effective polishing ability in order to form a familiar surface at an early stage. The reason why the thickness is 3 μm or less is that the piston groove is not attacked more than necessary in the familiar surface shape. Preferably, it is 0.1 μm or more and 1 μm or less.

  Moreover, the addition amount of hard particles shall be 1 volume% or more and 20 volume% or less with respect to the volume of the 2nd membrane | film | coat 12b whole. Here, the reason why the content is 1% by volume or more is to obtain an effective polishing ability in order to form a familiar surface at an early stage. Further, the reason why the volume is 20% by volume or less is that the piston groove is not attacked more than necessary in forming the conforming surface. Preferably, it is 3 volume% or more and 10 volume% or less.

  When the second film 12b is made of metal, the metal material can be at least one selected from indium, lead, tin, copper, silver, and gold. Among these, tin is particularly preferable because it is compatible with the piston material and can be obtained at a low price.

The surface roughness of the first film 12a is preferably 0.3 μm or less. The first film 12 made of a ceramic material having such a surface roughness suppresses the surface pressure and reduces the attack of the piston material even when contacting the piston ring groove, and suppresses an increase in the wear amount of the piston material. can do. In the present invention, the surface roughness of the ceramic means an arithmetic average roughness Ra based on JISB0601 (1994), and is measured using a surface roughness measuring device. Furthermore, the surface roughness of the first film 12a is more preferably 0.03 to 0.1 μm. By setting it as this surface roughness, adhesiveness with the 2nd membrane | film | coat 12b improves, and the laminated structure which consists of the 1st membrane | film | coat 12a and the 2nd membrane | film | coat 12b can be maintained over a long term.
In the present invention, the second film 12b is formed on the first film 12a. In this state, the surface of the first film 12a does not exist, but the “surface roughness of the first film 12a” means This means the surface roughness of the first film 12a before the second film 12b is formed.

  Further, the surface shape of the second film 12b inherits the surface shape of the first film 12a as it is when the film thickness is about 3 μm, but the surface roughness is preferably 0.5 μm or less. Thereby, abrasion of the 2nd membrane | film | coat 12b itself at the time of conformity surface formation can be prevented.

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

  Furthermore, the thickness of the first film 12a is preferably 0.1 μm or more. Thereby, the film thickness of the film becomes sufficient with respect to the surface roughness of the ceramic material, and a uniform film can be obtained, and the amount of wear can be reduced. The thickness of the second coating 12b is preferably (the surface roughness of the first coating 12a + 1 μm) or more. Thereby, a familiar surface can be formed only by the 2nd membrane | film | coat 12b. Furthermore, the total thickness of the first coating 12a and the second coating 12b is preferably 20 μm or less. Thereby, sufficient clearance in the piston ring groove 21 can be ensured, and the above-described function of the piston ring 1 can be executed.

Here, it is preferable that the Vickers hardness HV and the film thickness h (μm) of the first coating 12a 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 of the first coating 12a are high while suppressing the wear of the piston material even when the Vickers hardness HV and the film thickness satisfy the above formula (B). It has been found that it has aluminum adhesion resistance. This is presumably because by setting the film thickness h to an appropriate value corresponding to the hardness of the first coating 12a, the wear of the piston material can be suppressed without the first coating 12a being worn away.

  Such an aluminum adhesive film 12 can be formed by various known methods. Specifically, thermal spraying, chemical vapor deposition (CVD), physical vapor deposition (PVD), aerosol deposition, cold spray, sol-gel, etc. are used. The piston ring according to the present invention can be manufactured by performing film formation under appropriate film formation conditions.

In addition, in the said embodiment, although the aluminum-resistant adhesion film 12 has a 2 layer structure, it is not limited to a 2 layer structure, It can also comprise so that it may have 3 or more layers. For example, when the aluminum anti-adhesion coating 12 is composed of three layers, the first coating formed on the piston ring base material is the hardest, the second coating formed on the first coating, and the third coating The film and the surface layer are configured such that the hardness of the film decreases. However, when the second film is provided in order to improve the adhesion between the first film and the third film, it is not necessary to configure the hardness of the second film according to this guideline.
The surface roughness of the film is preferably 0.3 μm or less for the first film and 0.5 μm or less for the third film. Although it does not specifically limit about a 2nd membrane | film | coat, It is preferable to have an appropriate surface roughness so that the surface roughness of a 3rd membrane | film | coat may become the said range.
Further, the thickness of the coating is preferably 0.1 μm or more only for the first coating, 1 μm or more for the second coating and thereafter, and the third coating (the surface roughness of the second coating + 1 μm or more), and the entire coating is 20 μm. The following is preferable.
Furthermore, the materials of the second film and the third film may be the same or different, but the outermost film (that is, the third film) is made of the resin or metal described herein. .
Furthermore, when the second film is an intermediate layer for bringing the first film and the third film into close contact with each other, a composite film of the first film and the third film is used.
These guidelines are the same when the aluminum adhesion-resistant coating 12 is composed of four or more layers.

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

<Production of piston ring>
Examples of the present invention will be described below.
Films having the materials, Vickers hardness, surface roughness, and film thickness shown in Tables 1 to 3 were formed on the upper and lower side surfaces of the piston ring base material made of low chromium steel. Here, the film made of any one of Al ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ and TiO ₂ is formed by an aerosol deposition method using Cr ₂ O ₃ , MgO, 3Al ₂ O ₃ -2SiO ₂ , 2MgO-SiO _2. and the _Al 2 _O 3 film comprising either -40% TiO ₂ are spraying method, _SiC, by Si _{3 N} 4, film made of any one of SiO 2, _AlN CVD method, TiN, CrN, CrC and DLC A film made of any of the following: PVD method, PAI, PBI, PI, PAR, resin film A and resin film B are spray methods, PEEK, PPS and PES are fluid immersion methods, Cu, Ag, Au, Sn, In and Ni were each formed by a plating method. Therefore, for example, in the case of Invention Example 1, the first film made of SiC was formed by the CVD method, and the second film made of Sn was formed by the plating method.
In Table 1, Invention Examples 14 to 16 have the first film made of two types of ceramics, and the first film of Invention Example 14 is a mixture of Al ₂ O ₃ and SiO ₂ in a ratio of 3: 2, invention. The first coating of Example 15 is a mixture of MgO and SiO ₂ in a ratio of 2: 1. The first coating of Invention Example 16 is obtained by adding 40% by mass of TiO ₂ to Al ₂ O ₃ . The film is obtained by adding 40% by mass of TiO ₂ to Al ₂ O ₃ .
Moreover, the resin film A of Comparative Example 1 is a polyimide resin film 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 film B of Invention Example 24 and Comparative Example 2 is a polyimide resin film containing 10% by mass of Al ₂ O ₃ powder (average particle size 0.5 μm).
Furthermore, the aluminum-resistant adhesive film of Comparative Example 5 is made of Al ₂ O ₃ and has a one-layer structure.

Aluminum adhesion resistance of the piston rings of Invention Examples 1 to 47 and Comparative Examples 1 to 5 was evaluated. For that purpose, the engine simulation test apparatus shown in FIG. 3 was used. The engine simulation test apparatus 30 shown in FIG. 3 has a mechanism in which the piston 32 reciprocates up and down and the piston ring 33 rotates. The test is performed by the heater 31, the temperature controller 34, and the thermocouple 35. Thus, the piston 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 the piston ring film and the occurrence of aluminum adhesion were examined. The obtained results are shown in Tables 1-3. In addition, the evaluation criteria of the film remaining amount are as follows.
A: 0.8 μm or more ○: 0.4 μm or more and less than 0.8 μm Δ: 0 μm to less than 0.4 μm ×: No film

The evaluation of aluminum adhesion performance was confirmed visually. The obtained results are shown in Tables 1-3. 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 1-3. 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 1-3. The evaluation criteria for the amount of wear are as follows.
◎: Excellent ○: Good △: Relatively good ×: Bad Here, the overall evaluation is that the film remains, there is no aluminum adhesion, and the piston material wear amount is less than 0.5 μm ◎, there is no film, aluminum A film with adhesion and a piston material wear amount of 3.0 μm or more was marked with ×, and the others were marked with ◯ or △. A film having no x in all evaluation items was marked with ◯, and a film having x in 1-2 in all evaluation items was marked with Δ.

<Evaluation of aluminum adhesion resistance>
As shown in Tables 1 to 3, aluminum adhesion did not occur in all of the piston rings of Invention Examples 1 to 47. In invention examples 30, 35 and 36, the film thickness of the first film was thin, and the film disappeared after the test and aluminum adhesion occurred, but this was extremely negligible and could be ignored. It was about.
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 film remained after the test, and aluminum adhesion occurred, but it was very slight.
Further, in Comparative Example 4, the amount of remaining film was large, and aluminum adhesion did not occur.
Furthermore, in Comparative Example 5, the amount of remaining film was large, and aluminum adhesion did not occur.

<Evaluation of piston material wear>
As shown in Tables 1 to 3, for the inventive examples except the inventive examples 30, 35, 36, 40, 44 and 47, the piston wear amount was very small, less than 0.5 μm. Inventive Examples 44 and 47, in which the surface roughness of the first film was relatively large, the amount of wear was slightly high. Inventive Examples 30, 35, and 36 in which the first film was relatively thin, although the amount of wear was small, it was not as high as Inventive Examples 1 to 29. Furthermore, the amount of wear was a little large for Invention Example 40 in which the film thickness of the second film was relatively thin.
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 amount of wear was slightly large, and in Comparative Example 4, the amount of wear was large.
Further, in Comparative Example 5, although the amount of wear of the piston material was small, it was not as high as Invention Examples 1 to 29.

  Table 2 shows the relationship between the film thickness of the film and the amount of wear of the piston material. Invention Examples 31 to 34, 37 to 39 in which the Vickers hardness and film thickness of the first film satisfy the formula (B). About 41 and 41, it turns out that it has high aluminum adhesion-proof performance, suppressing abrasion of piston material. Invention Examples 1 to 29 shown in Table 1 also satisfy the formula (B), and it can be seen that the aluminum material has high aluminum adhesion resistance while suppressing wear of the piston material.

  Further, Table 3 shows the relationship between the surface roughness of the coating and the amount of wear of the piston material, and the inventive examples 42, 43, and 45 in which the Vickers hardness and the surface roughness of the first coating satisfy the formula (A) and About 46, it turns out that it has high aluminum adhesion-proof performance, suppressing abrasion of piston material. Invention Examples 1 to 29 shown in Table 1 also satisfy the formula (A), and it can be seen that the aluminum material has high aluminum adhesion resistance while suppressing wear of the piston material.

<Comprehensive evaluation>
For all Examples 1 to 49, an evaluation of excellent or relatively good or better was given. In particular, when the Vickers hardness and surface roughness of the first film satisfy the formula (A), or when the Vickers hardness and film thickness satisfy the formula (B), excellent evaluation is given, That is, it can be seen that a piston ring having high aluminum adhesion resistance performance while suppressing wear of the piston material was obtained.
On the other hand, Comparative Examples 1 and 2 provided with a resin film were inferior in both aluminum adhesion resistance and piston material wear.
In Comparative Example 3 provided with the nickel film and Comparative Example 4 provided with the DLC film, the aluminum adhesion resistance was good or excellent, but the piston material wear characteristics were slightly inferior.
Further, Comparative Example 5 showed high aluminum adhesion resistance. Moreover, although the abrasion amount of piston material was also small, it was not as much as invention examples 1-29 grade | etc.,.

  According to the present invention, the aluminum adhesion-resistant film has a two-layer structure, the Vickers hardness HV is relatively low, the familiar surface is formed by the second film made of resin or metal, and the Vickers hardness HV is relatively low. Since the first film made of ceramics has durability of the aluminum adhesion-resistant film, aluminum adhesion can be prevented over a long period of time even at high temperatures, and the wear amount of the piston material can be suppressed. Useful in the automotive parts manufacturing industry.

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

Claims (7)

A piston ring for an internal combustion engine, in which at least one of the upper and lower side surfaces of the piston ring base material is coated with an aluminum anti-adhesion film,
The aluminum adhesion-resistant film includes a first film made of ceramics and formed on the piston ring base material, and a second film made of resin or metal formed on the first film. A piston ring for an internal combustion engine, characterized in that the Vickers hardness HV of the first coating and the arithmetic average roughness Ra (μm) of the surface of the first coating satisfy the following formula (A).
Ra <−8.7 × 10 ⁻⁵ HV + 0.39 (A)   The piston ring for an internal combustion engine according to claim 1, wherein the first coating has a Vickers hardness HV of 500 or more and 2800 or less, and the second coating has a Vickers hardness HV of 20 or more and 300 or less. The piston ring for an internal combustion engine according to claim 1 or 2, wherein the Vickers hardness HV of the first coating and the thickness h (µm) of the first coating satisfy the following formula (B).
H> -2.9 × 10 ⁻⁴ HV + 0.89 (B)   The piston ring for an internal combustion engine according to any one of claims 1 to 3, wherein the arithmetic average roughness of the surface of the first coating is 0.3 µm or less.   The thickness of the first film is 0.1 μm or more, the thickness of the second film is 1 μm or more, and the total thickness of the first film and the second film is 20 μm or less. The piston ring for internal combustion engines as described in any one of 1-4.   The second film is made of a resin containing hard particles, and the material of the hard particles is at least one selected from alumina, zirconia, ceria, silicon carbide, silicon nitride, cubic boron nitride, and diamond. The piston ring as described in any one of Claims 1-5.   The ceramic material is at least one selected from alumina, titania, yttria, zirconia, silica, magnesia, chromia, silicon carbide, chromium carbide, aluminum nitride, titanium nitride, silicon nitride, and chromium nitride, and the resin material is , Polyimide, polyetherimide, polyamideimide, polysulfone, polyethersulfone, polyarylate, polyphenylene sulfide, polyetheretherketone, aromatic polyester, aromatic polyamide, polybenzimidazole, polybenzoxazole, aromatic polycyanurate, At least one selected from aromatic polythiocyanurate and aromatic polyguanamine, and the metal material is composed of at least one selected from indium, lead, tin, copper, silver, and gold. The symptom, the piston ring according to any one of claims 1 to 6.

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