JP2006002254A - Piston ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sliding member (piston ring) coated with a film having excellent wear resistance, excellent scuffing resistance and an excellent no hostile to a mating material (the properties not increasing wear in a mating material). <P>SOLUTION: The problem is solved by coating the outer circumferential face 3 of the sliding member (piston ring) with a Cr-B-N alloy film 4 obtained by incorporating B into a Cr-N alloy. The Cr-B-N alloy film is preferably composed by a physical vapor deposition method, particularly, an ion plating method, a vacuum deposition method or a sputtering method. The B content is preferably 0.05 to 20 wt.%. Since the Cr-B-N alloy film 4 provided on the outer circumferential face 3 of the sliding member has excellent wear resistance, excellent scuffing resistance and an excellent no hostile to a mating material, the sliding member satisfying the performance to be required even if the sliding environment of the sliding member is made severe can be provided. Further, it is preferable that the whole circumferential face or at least the outer circumferential face 3 in the sliding member is provided with a nitriding layer 5, and the surface of the nitriding layer 5 is coated with the Cr-B-N alloy film 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piston ring which is a sliding member, and particularly, for example, a sliding for an internal combustion engine, which is excellent in wear resistance, scuffing resistance, and characteristics that do not increase wear of a mating material (hereinafter referred to as “counterattack”). The present invention relates to an improvement of a piston ring as a member.

  Conventionally, a sliding surface of a piston ring, which is a sliding member for an internal combustion engine, has been subjected to surface treatment for the purpose of wear resistance such as hard chrome plating treatment or nitriding treatment in order to improve its durability. ing.

  In recent years, however, internal combustion engines such as engines have become increasingly lighter and more powerful, so the piston ring sliding environment has become extremely harsh. It has become impossible to fully satisfy functions such as sex.

  Therefore, a sliding member such as a piston ring is required to have a coating or surface treatment with higher quality, for example, excellent wear resistance, scuffing resistance and opponent attack.

  In order to solve these problems, some internal combustion engines and parts have hard materials such as chromium nitride (CrN) and titanium nitride (TiN) made by PVD (physical vapor deposition) to improve wear resistance. The film is covered. However, these coatings are excellent in improving their own wear resistance, but sometimes there is a problem of increasing the wear of the cylinder liner which is the counterpart material.

  In view of the above points, an object of the present invention is to provide a piston ring that is a sliding member that is coated with a film that solves the drawbacks of conventional surface treatments and is excellent in wear resistance, scuffing resistance, and opponent attack. There is to do.

  The piston ring of the present invention has an outer peripheral surface formed by an ion plating method, a vacuum evaporation method or a sputtering method, and boron (B) is contained in a chromium (Cr) -nitrogen (N) alloy. It is covered with a BN alloy film, and the B content in the Cr-BN alloy film is 0.05 to 20% by weight. According to the present invention, the Cr-BN alloy film provided on the outer peripheral surface of the piston ring, which is a sliding member, is excellent in wear resistance, scuffing resistance and opponent attack. Even if it becomes severe, a sliding member that satisfies the required performance can be provided.

  Further, it is preferable that a nitride layer is provided on the entire peripheral surface or at least the outer peripheral surface of the piston ring, and the Cr—BN alloy film is coated on the nitride layer. According to the present invention, by providing a hard nitride layer on the surface of the piston ring that is a sliding member, it is further combined with the coating of the Cr—B—N alloy film to further improve wear resistance, scuffing resistance, and opponent attack. It can be set as the sliding member excellent in property.

  As described above, according to the piston ring which is the sliding member of the present invention, the Cr—B—N alloy film is provided on the sliding surface. Furthermore, it has more excellent effects and functions in wear resistance, scuffing resistance and opponent attack.

  The piston ring of the present invention can be sufficiently used for engines with high output and high temperature and high load that are expected to be developed in the future.

  FIG. 1 shows a configuration of a piston ring 1 which is an example of a sliding member for an internal combustion engine. (A) is an enlarged view of a portion Ia of (b), and (b) shows a partial fracture surface. 1 is a perspective view of a piston ring 1. FIG. A Cr—B—N alloy coating 4 is provided on the outer peripheral surface 3 of the base material 2 of the piston ring 1. The piston ring will be described below, but the sliding member is not limited to the piston ring, and may be, for example, an automobile part or a compressor part.

  As the base material 2 of the piston ring 1, stainless steel and stainless steel obtained by nitriding treatment are usually used. Nitrogen can be diffused and carburized on the surface layer of stainless steel by nitriding to form the hard nitrided layer 5, so that it is particularly preferred for the sliding member such as the piston ring 1. The nitriding treatment can be performed by a conventionally known method.

  The Cr—B—N alloy film 4 is preferably provided on the outer peripheral surface 3 of the piston ring 1. Since the outer peripheral surface 3 of the piston ring 1 comes into contact with a cylinder liner which is a counterpart material during the sliding, at least the outer peripheral surface 3 is provided with a Cr-BN alloy coating 4 to provide wear resistance and scuffing resistance. The piston ring 1 can be made excellent in performance and opponent attack. In addition, what was formed in surfaces other than the outer peripheral surface 3 may be sufficient, and it does not restrict | limit in particular. In addition, the Cr—B—N alloy film 4 is particularly excellent in attacking against other materials such as cast iron and aluminum alloy cylinder liners, and is particularly preferably applied in relation to these materials. .

  The Cr—B—N alloy film 4 is usually formed on the outer peripheral surface 3 of the piston ring 1 by a PVD (physical vapor deposition) method. Examples of the PVD method include an ion plating method, a vacuum deposition method, and a sputtering method. The thickness of the Cr—B—N alloy film 4 to be formed is not particularly limited, but is usually preferably in the range of 1 to 70 μm.

  The obtained Cr—B—N alloy film 4 preferably has a B content of 0.05 to 20% by weight. The Cr—B—N alloy film 4 formed by including B in the Cr—N alloy is excellent in wear resistance and scuffing resistance, and in particular, is excellent in attacking the opponent. When the B content is less than 0.05% by weight, the expected effects of scuffing resistance and opponent attack cannot be obtained. If the B content exceeds 20% by weight, the internal stress of the alloy film 4 is high, the toughness is reduced, cracks and delamination occur in the alloy film 4, and the function as a piston ring cannot be achieved. A particularly preferable range of the B content is 0.5 to 12% by weight.

  The Cr content constituting the Cr—B—N alloy film 4 is preferably in the range of 78.4 to 69.3 wt%, and the N content is in the range of 21.1 to 18.7 wt%. Preferably there is.

  Hereinafter, the present invention will be described more specifically with reference to examples.

  First, one side of a 18 mm × 12 mm × 6 mm steel plate was lapped, finished to a surface roughness of 1 μm or less, and used as a test sample. The sample was ultrasonically cleaned in advance in an organic solvent solution. Next, a Cr—B—N alloy film 4 was formed by an arc ion plating method according to the procedure described below.

(Procedure for forming a Cr-BN alloy film)
The sample was mounted in a chamber (vacuum vessel) of an arc ion plating apparatus and evacuated to 5 × 10 ⁻³ Torr. Gas adhering to or adsorbing to the sample surface was released by a heater built in the chamber. A Cr—B alloy having a predetermined composition was used as a target, an arc discharge was generated on the surface thereof, and Cr and B ions were released. The sample surface was sputter-cleaned (ion bombardment) by applying -800 V (volt) to the sample. Thereafter, nitrogen gas was introduced into the chamber in which arc discharge occurred, and a bias voltage of −50 V was applied to the sample to form 20 μm of Cr—B—N alloy film 4 on the sample surface.

  Formation of the Cr—B—N alloy film 4 with varying B content was performed by using Cr—B alloy targets having different compositions. Thus, a test sample (product of the present invention) on which a Cr—B—N alloy film 4 having a B content of 0.05% by weight, 10% by weight, 20% by weight, and 30% by weight was formed.

(Abrasion test)
Using the test sample produced by the above method, the wear resistance was evaluated under the following wear test conditions. As a comparative sample, a sample (comparative product) on which a partially commercialized Cr—N alloy film was formed was also evaluated.

  The abrasion resistance test uses an Amsler type abrasion tester, and a test sample and a comparative sample (both 18 mm × 12 mm × 6 mm) are fixed pieces, and the mating material (rotating piece) has a donut shape (outer diameter 40 mm, An inner diameter of 16 mm and a thickness of 10 mm) was used. The test sample and the comparative sample were set so that the formed alloy film was in contact with the donut-shaped rotating piece. The test results are shown in FIG. In addition, the abrasion resistance was compared with the amount of wear of the test sample (the product of the present invention) when the amount of wear of the comparative sample (comparative product) was 100 as a wear index with respect to the comparative sample (comparative product). Therefore, the smaller the wear index of the test sample (the product of the present invention) is, the smaller the amount of wear is, and thus the wear resistance is superior to the comparative sample (comparative product).

  At this time, the wear amount of the rotating piece as the counterpart material was measured to evaluate the opponent aggression. Similarly to the wear resistance of the opponent, the wear amount of the rotating piece when the comparative sample (comparative product) is used is 100, and the wear amount of the rotating piece when the test sample (product of the present invention) is used, FIG. 3 shows comparison as an index with respect to the amount of wear when a comparative sample (comparative product) was used. Therefore, the smaller the opponent attack (index) when using the test sample (the product of the present invention) is, the less the wear of the counterpart material is greater than when using the comparative sample (comparative product). It will be excellent.

Wear test conditions;
Test machine: Amsler type wear tester Method: Immerse almost half of the rotating piece in oil, contact the fixed piece,
Wear test with load.
Opponent material: FC25 (HRB98)
Lubricating oil: Bearing oil Oil temperature: 80 ° C
Peripheral speed: 1m / sec (478rpm)
Load: 150kg
Time: 7 hours
Wear amount measurement: Wear amount (μm) is measured with a step profile by a roughness meter.

(Scuffing resistance test)
Using the above test sample (product of the present invention) and comparative sample (comparative product), scuffing resistance was evaluated under the following scuffing test conditions. The test results are shown in FIG. The scuffing resistance was compared with the scuff generation load of the comparative sample (comparative product) as 100 and the scuff generation load of the test sample (product of the present invention) as a scuff index relative to the comparative sample (comparative product). Therefore, as the scuff index of the test sample (product of the present invention) is larger than 100, the scuff generation load increases and the scuffing resistance is superior to that of the comparative sample (comparative product).

Scuffing test conditions;
Tester: Amsler type wear tester Method: Lubricant is attached to the test piece and a load is applied until scuffing occurs.
Opponent material: FC25 (HRB98)
Lubricating oil: No. 2 spindle oil Oil temperature: Resulting peripheral speed: 1 m / sec (478 rpm)
Load: Until scuffing Time: Result

(Peelability test)
Using the above-mentioned test sample (product of the present invention) and comparative sample (comparative product), the peel resistance was evaluated under the following peel test conditions. The test results are shown in FIG. The peel resistance is defined as the peel resistance (index) of the test sample (compared product) with respect to the test sample (the product of the present invention) when the number of peeled samples of the comparative sample (compared product) is 100. Compared. Accordingly, if the peel resistance (index) of the test sample (the product of the present invention) is smaller than 100, the peeling occurs less frequently than the comparative sample (comparative product), and therefore the peel resistance is poor. . An NPR impact test apparatus is shown in FIG.

Peel test conditions;
Testing machine: NPR impact testing device (Japanese Patent Laid-Open No. 36-19046,
An improved testing machine for quantitative test equipment of plating adhesion.
Method: 43.1 mJ (44 kg / mm) per time on the PVD alloy film surface
The impact energy is applied and evaluated by the number of times until peeling occurs.
Presence or absence of peeling: The surface was magnified 15 times and observed and evaluated.

(Test results)
A test sample (product of the present invention) in which a Cr-BN alloy film 4 having a B content of 0.05% by weight was formed has a decrease in wear index and opponent attack (index) and an increase in the scuff index. Excellent wear resistance, scuffing resistance and opponent attack.

  In addition, the test sample (product of the present invention) in which the Cr-BN alloy film 4 having a B content exceeding 20% by weight had a low peel resistance (index) and was inferior in the peel resistance.

  Therefore, the test sample (product of the present invention) in which the Cr content of the Cr-BN alloy film 4 having a B content of 0.05 wt% or more and 20 wt% or less is provided with wear resistance, scuffing resistance, opponent attack resistance and resistance to attack. It was excellent in any peelability.

They are the expanded sectional view (a) of an example of the sliding member (piston ring) for internal combustion engines of this invention, and the perspective view (b) which showed the partial fracture surface. It is a graph which shows abrasion resistance (wear index) and scuffing resistance (scuff index). It is a graph which shows peeling resistance (peeling resistance index) and opponent aggression property (partner aggression index). It is the schematic showing the peelability test using an NPR type impact test device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston ring 2 Base material 3 Outer peripheral surface 4 Cr-BN alloy film 5 Nitrided layer 11 Indenter 12 Gold

Claims (1)

The outer peripheral surface is formed by an ion plating method, a vacuum deposition method or a sputtering method, and B is coated with a Cr—B—N alloy film contained in the Cr—N alloy,
The piston ring, wherein the B content in the Cr-BN alloy film is 0.05 to 20% by weight.

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