JP2865419B2 - piston ring - Google Patents

Description

The present invention relates to a piston ring mounted on a piston for an internal combustion engine, and more particularly to wear resistance, scuffing resistance (seizure resistance), fatigue resistance, and corrosion resistance. It relates to a piston ring with improved overall characteristics and high overall performance.

[Conventional technology]

Due to severe operating conditions of piston rings mounted on pistons for internal combustion engines, excellent wear resistance, scuffing resistance (seizure resistance), heat resistance, fatigue resistance, corrosion resistance, etc. are required. .

Therefore, various surface treatments have been conventionally attempted on a piston ring base material made of, for example, steel for the purpose of mainly providing wear resistance required for the piston ring. In particular, hard chromium plating has been widely used because it has advantages such as excellent wear resistance and high scuffing resistance (seizure resistance) when a mating material is a cast iron cylinder. .

On the other hand, a piston ring in which a composite plating layer is provided on a piston ring base material surface in order to improve abrasion resistance and scuffing resistance has also been put to practical use.

[Problems to be solved by the invention]

However, in recent years, the thermal load applied to the piston ring has been increasing as the output of the internal combustion engine has been increased, the performance has been improved, and the exhaust gas treatment measures have been advanced. It has become difficult to obtain satisfactory performance in terms of scuffing properties.

That is, when a hard chrome plating is exposed to high temperatures, its hardness significantly decreases and cracks increase. The problem of the increase of the number has become remarkable.

Then, in order to solve such a problem, a piston ring having a nitriding layer provided on at least the outer peripheral sliding surface has been put to practical use.

However, in the piston ring subjected to the nitriding treatment, although the wear resistance is improved, the scuffing resistance is inferior to the hard chromium-plated piston ring. There is a problem that it is easy.

Further, in a piston ring having a composite plating layer provided on the surface of a piston ring base material (hereinafter sometimes referred to as a “composite plating ring”), it is necessary to increase the amount of P in a matrix in order to increase hardness. . The present inventor repeatedly studied the amount of P in the matrix, and as shown in FIG. 6, it was confirmed that the scuffing resistance was improved as the hardness increased. On the other hand, in this composite plating ring, it has also been confirmed that the toughness of plating decreases with an increase in the amount of P, and cracks and peeling are liable to occur in a plating layer whose thickness is increased in consideration of long life. . Therefore, in the conventional composite plating ring,
It is necessary to set the amount of P in the matrix to a low value in order to prevent the occurrence of the cracks and peeling and to improve the wear resistance and the scuffing resistance. Not always enough.

The present invention has been made based on the above circumstances,
An object of the present invention is to improve abrasion resistance, scuffing resistance (seizure resistance), heat resistance, fatigue resistance, corrosion resistance, etc., and to exhibit a high overall performance even under severe use conditions. Is to provide.

[Means for solving the problem]

The gist of the present invention to achieve the above object is to provide a piston ring mounted on a piston for an internal combustion engine, which has a composite dispersed plating layer on at least the outer peripheral sliding surface and has a physical vapor deposition layer on the composite dispersed plating layer. Having a film formed by a phase deposition method, wherein the composite dispersion plating layer contains boron.
Particle size in nickel alloy containing 0.1 to 10% by weight
0.1 to 10 μm hard particles are dispersed at a ratio of 5 to 30% by volume ratio, and the coating is a piston ring characterized by being composed of any of metal nitride, metal carbide and metal oxide, The piston ring according to claim 1, wherein the hard particles in the composite dispersion plating layer are at least one kind of particles selected from the group consisting of metal nitride particles, metal carbide particles, and metal oxide particles. 3. The piston ring according to claim 1, wherein a nitriding layer is formed on the entire peripheral surface of the base material on which the plating layer is formed. 3. A combustion chamber in the base material on which the composite dispersed plating layer is formed. 4. The piston ring according to claim 1 or 2, wherein a nitriding layer is formed on three sides of a side peripheral surface, a crankcase side peripheral surface, and a piston mounting surface.

[Action]

The piston ring of the present invention has a coating made of any of metal nitride, metal carbide and metal oxide formed on the outer peripheral sliding surface by physical vapor deposition. As shown in FIG. 7, the piston ring of the present invention having this film formed by the physical vapor deposition method has a small amount of wear and a low aggressiveness against the cylinder as a mating material. By the way, if this film is formed directly on the surface of the piston ring base material, the scuffing resistance (seizure resistance) becomes insufficient when the film is worn and a part of the base material surface is exposed. Therefore, in the piston ring of the present invention, the above-described coating is provided on the composite dispersion plating layer provided on the piston ring base material surface. This composite dispersion plating layer
Hard particles with a particle size of 0.1 to 10 μm are dispersed in a nickel alloy containing 0.1 to 10% by weight of boron at a volume ratio of 5 to 30%, and have excellent wear resistance and scuffing resistance. Properties have been significantly improved. Therefore,
In the piston ring of the present invention, excellent wear resistance and scuffing resistance are compensated even if the above-mentioned film is worn and a part of the composite dispersion plating layer is exposed. In addition, a nitriding layer is provided on the entire peripheral surface of the piston ring base material surface or the peripheral surface on the combustion chamber side, the peripheral surface on the crankcase side, and the piston mounting surface, and the composite dispersion plating layer and the coating are formed on the nitriding layer. Are provided in this order, the wear resistance and corrosion resistance are further improved.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view of a piston ring according to one embodiment of the present invention.

As shown in FIG. 1, this piston ring has a composite dispersion plating layer 2 provided on a base material 1 on its outer peripheral sliding surface.
It has a coating 3 on it.

The base material 1 is preferably formed using, for example, a steel material.
It is desirable to use a steel material suitable for obtaining a nitrided layer exhibiting good wear resistance. Examples of such a steel material include a steel material containing 0.16 to 1.30% by weight of carbon and 12 to 19% by weight of chromium, or a steel material containing molybdenum and / or vanadium.

Composite dispersed plating layer 2 provided on base material 1
Has a particle size of 0.1 to 10 μm in a nickel alloy containing 0.1 to 10% by weight, preferably 0.5 to 6.0% by weight of boron.
m, preferably 0.3 to 3 μm hard particles in a volume ratio of 5 to 3 μm.
It is a plating layer dispersed at a ratio of 0%, preferably 5 to 15%.

Here, the content of boron increases the hardness of the plating base and improves the wear resistance, but the content of boron is 0.1% by weight.
If it is less than 10, the abrasion resistance may not be sufficiently improved, and if it exceeds 10% by weight, the plating base may be weakened.

Hard particles dispersed in the composite dispersed plating layer 2 include, for example, Si ₃ N ₄ , TiN, CrN, Cr ₂ N, ZrN, TiAl
Metal nitrides such as N and HfN; metal carbides such as TiC, SiC, Cr ₃ C ₂ and WC; metal oxides such as Cr ₂ O ₃ , ZrO ₂ and Al ₂ O ₃ ; metals such as TiB ₂ and ZrB ₂ Boride and the like. Among these, metal nitrides, metal carbides and metal oxides are preferred, and metal nitrides are particularly preferred. These hard particles may be used alone or in combination of two or more.

The particle diameter of the hard particles in the composite dispersion plating layer 2 is 0.1 μm.
If it is less than m, or if the content is less than 5% by volume, the abrasion resistance may not be sufficiently improved.
On the other hand, the particle diameter of the hard particles in the composite dispersed plating layer 2 is 10
If it exceeds μm, or if the content exceeds 30% by volume, the strength of the composite dispersed plating layer 2 decreases, and the wear of the mating material may further increase. Therefore, the particle size and content of the hard particles dispersed in the hard dispersion plating layer 2 need to be within the above ranges.

The thickness of the composite dispersion plating layer 2 is 3 to 50 μm, preferably
30 to 50 μm. If the thickness is less than 3 μm, the abrasion resistance and scuffing resistance may not be sufficiently improved. On the other hand, if it exceeds 50 μm, cracks and peeling are likely to occur.

The coating 3 on the composite dispersion plating layer 2 is made of any of metal nitride, metal carbide and metal oxide, and is formed by a physical vapor deposition (PVD) method.

Examples of the metal nitride used for the material for forming the film 3 include:
For example, Si ₃ N ₄ , TiN, CrN, Cr ₂ N, ZrN, TiAlN, HfN and the like can be mentioned.

Further, as the metal carbide, for example, TiC, SiC, Cr
₃ C ₂ , WC, etc. Further metal oxides, for example, Al ₂ O ₃ , Cr ₂ O ₃ , Zr
O _{2 and the} like.

Among these forming materials, preferred are metal nitrides, and particularly preferred are titanium nitride (TiN) and chromium nitride (Cr ₂ N).

The film 3 is formed by a physical vapor deposition (PVD) method such as an ion plating method, a sputtering method, and a vacuum deposition method.
Method).

Here, a physical vapor deposition method (PVD method) is used to form the film 3.
The reason why is adopted is that it is possible to form a film 3 which is excellent in abrasion resistance, hardly wears a mating material, and has high adhesion strength to the composite dispersed plating layer 2.

The thickness of the coating 3 is usually 0.3 to 30 μm, preferably 3 to 30 μm.
1010 μm. If the thickness is less than 0.3 μm, the abrasion resistance is not sufficiently improved, and the effect of reducing the abrasion of the mating material may not be sufficiently exhibited. On the other hand, 30μ
If m is exceeded, cracks are likely to occur.

In addition, as shown in FIG. 2, the coating 3 may be provided on the composite dispersion plating layer 2 on the base material 1 on which the nitriding layer 4 is formed on the entire peripheral surface, or in FIG. As shown, even if the coating 3 is formed on the composite dispersion plating layer 2 on the base material 1 on which the nitriding layer 4 is formed on three sides of the combustion chamber side peripheral surface, the crankcase side peripheral surface, and the piston mounting surface. Good.

As described above, when the nitriding layer 4 is provided on the entire peripheral surface of the base material 1, the peripheral surface on the combustion chamber side, the peripheral surface on the crankcase side, and the piston mounting surface, the wear resistance and corrosion resistance are further improved.

FIG. 4 is a graph showing the amount of wear in each of the embodiment product and the conventional piston ring.

Here, the product A has a nitriding layer 4 having a thickness of 90 μm on the entire peripheral surface of the steel piston ring base material 1, and a thickness of Ni-B-Si ₃ N ₄ on the nitriding layer 4. It has a composite dispersion plating layer 2 having a thickness of 30 μm and a thickness of 3 μm formed on the composite dispersion plating layer 2 by employing the ion plating method.
2 has a film 3 made of a TiN film, and has the structure shown in FIG. 2. The product B has the same structure as the product A except that the film 3 is made of a Cr ₂ N film having a thickness of 3 μm. Have. Comparative product A is a conventional piston ring having a hard chromium plating layer having a thickness of 100 μm on the outer peripheral sliding surface, and comparative product B is Ni-P-Si ₃ with a reduced amount of P on the outer peripheral sliding surface. 1 is a conventional piston ring having a 90 μm thick composite plating layer made of N ₄ . The abrasion amount is a value measured after mounting on a piston of a diesel engine for passenger cars having a displacement of 2000 cc and performing continuous high-speed operation for 100 hours.

As shown in FIG. 4, it can be seen that the product A and the product B have improved abrasion resistance as compared with the product A and the product B.

FIG. 5 is a graph showing the adhesion strength of the actual products A and B and the comparative product B. This adhesion strength was measured by measuring the peeling angle using a torsional peeling tester.

As shown in FIG. 5, the peeling angles of the products A and B were larger than the peeling angle of the comparative product B, and it was confirmed that the adhesion strength was significantly improved.

In addition, actual products were tested for the products A and B to evaluate the occurrence of cracks and peeling after 600 hours of continuous high-speed operation, and no cracks and peeling occurred in the products A and B. Products A and B were confirmed to have sufficient film strength and adhesion strength. Note that a diesel engine for passenger cars with a displacement of 2000 cc was used in the actual machine test.

Further, the results of tests on the wear resistance, counterpart aggressiveness and seizure resistance of the piston ring according to the present invention are shown below.

(Abrasion resistance and counterpart aggression) Abrasion resistance test and counterpart aggression test were carried out on Examples A and B and Example C of the present invention. Here, the product C is provided with a 90 μm-thick nitridation layer on a steel piston ring, and the Ni-W-Cr ₃ C ₂ thickness 3
It has a composite dispersion plating layer of 0 μm, and further has a coating of a 3 μm thick TiN film formed on the composite dispersion plating layer by employing an ion plating method.

The test was performed by using an Amsler type abrasion tester, in which almost half of the rotating piece was immersed in oil and brought into contact with a fixed piece to apply a load. The test conditions are as follows.

Mating material: FC25 (H _RB 98) Lubricating oil: 10W30 Oil temperature: room temperature Friction speed: 0.89m / sec (500rpm) Load: 100kg Time: 40 hours Wear measurement: Wear measured by a step profile using a roughness meter (μm ) Measured.

It should be noted that the Amsler-type testing machine was temporarily stopped at 20 hours after the start of the test, and the abrasion resistance and the aggressiveness to the partner were measured.

 The test results are as shown in FIG.

As shown in FIG. 7, it can be seen that the products A and B are superior to the comparative product C in abrasion resistance and aggressiveness to the other party.

(Seizure resistance test) The same test products A, B and comparative product C used in the wear resistance test and the counter-attack test were subjected to the following test conditions using a rotating disk type sliding friction wear tester under the following test conditions. An adhesion test was performed.

Partner material: FC25 (H _RB 98) Lubricating oil: SAE # 30 (50%) + white kerosene (50%) Oil volume: 0.02 l / min Oil temperature: 50 ° C (tank temperature) Friction speed: 3.75m / sec (300 rpm) Surface pressure: After running-in for 20 minutes under the test condition of 25 kg / cm ² or more,
The supply of the lubricating oil was stopped, and after 2 minutes from the surface pressure of 30 kg / cm ² , the surface pressure was increased by 10 kg / cm ² , and the surface pressure at which scuffing occurred was defined as the scuffing occurrence limit surface pressure.

 The test results are as shown in FIG.

As is clear from FIG. 8, the seizure resistance of the product A is almost the same as the seizure resistance of the comparative product C, but the seizure resistance of the product B is better than that of the comparative product C. It turns out that there is.

〔The invention's effect〕

According to the present invention, abrasion resistance, scuffing resistance, etc. are provided on a specific composite dispersed plating layer, which is improved as compared with the conventional composite plating layer. Since the outer peripheral sliding surface is provided with a specific coating that has excellent coating strength and adhesion strength, various properties such as wear resistance, seizure resistance, fatigue resistance, and corrosion resistance have been improved. A piston ring with high overall performance can be provided.

[Brief description of the drawings]

1 to 3 are partial cross-sectional views each showing an example of the piston ring of the present invention. FIG. 4 is a graph showing test results of a wear resistance test for each of the piston ring of the present invention and a conventional product. 5 is a graph showing the test results of the adhesion strength test, FIG. 6 is a graph showing the relationship between the P content in the composite plating layer and the surface pressure at which seizure occurs, and FIG. 7 is a graph showing the relationship between the piston ring of the present invention and the conventional product. FIG. 8 is a graph showing the test results regarding the wear characteristics and the counterpart aggressiveness of each, and FIG. 8 is a graph showing the test results regarding the seizure resistance. 1 ... base material, 2 ... composite dispersion plating layer, 3 ... film, 4
... A nitrided layer.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16J 1/00-10/04

Claims (4)

(57) [Claims] 1. A piston ring to be mounted on a piston for an internal combustion engine, wherein the piston ring has a composite dispersion plating layer on at least an outer peripheral sliding surface, and a film formed by physical vapor deposition on the composite dispersion plating layer. The composite dispersed plating layer has hard particles having a particle size of 0.1 to 10 μm dispersed in a nickel alloy containing boron at a ratio of 0.1 to 10% by weight at a volume ratio of 5 to 30%, A piston ring, wherein the coating is made of one of a metal nitride, a metal carbide and a metal oxide. 2. The piston ring according to claim 1, wherein said hard particles in said composite dispersion plating layer are at least one kind of particles selected from the group consisting of metal nitride particles, metal carbide particles and metal oxide particles. 3. The piston ring according to claim 1, wherein a nitriding layer is formed on the entire peripheral surface of the base material on which the composite dispersion plating layer is formed. 4. A nitriding layer is formed on three surfaces of a combustion chamber side peripheral surface, a crankcase side peripheral surface, and a piston mounting surface of a base material on which the composite dispersed plating layer is formed. The piston ring according to 1.