JPH10317122A - Sliding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding member excellent in wear resistance and seizure resistance, and capable of keeping the sufficient compact strength even when the thermal load is repeatedly applied in an engine by providing a film formed through the plasma thermal spraying of the metallic powder containing NiAl composite powder consisting of Al and Ni of the prescribed ratio and other powder to be added as necessary. SOLUTION: A basic material (substrate) of a sliding member includes an aluminum material such as Al to be regularly used for an engine parts. The NiAl composite powder consists of, by weight, 4-22% Al and 96-78% Ni. The composite powder is similar in material to a substrate layer, and large in the close tightening strength, and the compact strength by the thermal load in an engine is less deteriorated. As the powder to be added thereto iron or iron alloy power having self hardenability, concretely cast iron or high carbon steel is exemplified. The content in the metallic powder is preferably 15-75%. The wear resistance of the sliding member is thus further improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding member having excellent wear resistance and seizure resistance, which is used as a member of a sliding surface of an engine piston ring, a cylinder liner, a piston or the like.

[0002]

2. Description of the Related Art As a conventional sliding member, for example, Japanese Patent Application Laid-Open No. 60-93162 describes a sliding member in which a film is formed by spraying a powder obtained by mixing a molybdenum powder with an iron alloy powder. Have been. However, in general, a sliding member sprayed with an iron-based material is not sufficiently cooled during spraying. Molybdenum, like iron-based materials, also tends to have reduced adhesive strength due to deterioration of the film due to heat load. As described in the above publication, a sliding member obtained by spraying a powder obtained by mixing a molybdenum powder with an iron alloy powder is a material having excellent wear resistance, but has a property of being weak against heat load, so that it is used in an engine. In the application to parts used in, the reliability is poor when repeatedly exposed to a thermal load due to long-term use. Further, since molybdenum is an expensive material, it is economically difficult to mix a large amount of molybdenum.

On the other hand, Japanese Patent Application Laid-Open No. 60-125362 discloses a sliding member in which a film is formed by spraying a nickel-chromium alloy. However, when a nickel chromium alloy is sprayed, the hardness of the film is low and the scratch resistance is poor.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a sliding member which is excellent in abrasion resistance and seizure resistance and can maintain a sufficient adhesion strength even when repeatedly subjected to a thermal load in an engine. The purpose is to provide.

[0005]

The sliding member according to the present invention comprises:
Metal powder containing 25-100 parts by weight of a NiAl composite powder consisting of -22% by weight of Al and 96-78% by weight of Ni and 75-0 part by weight of other powders added as required (total 100 parts by weight) ) Having a film formed by plasma spraying (claim 1). The metal powder may include 25 to 85 parts by weight of the NiAl composite powder and 75 to 15 parts by weight of iron or iron alloy powder having self-hardening property. The above-mentioned metal powder is made of
It may contain 25 to 85 parts by weight of the iAl composite powder and 75 to 15 parts by weight of iron or iron alloy powder having a chilled portion due to quenching and having a particle size of 38 to 120 μm (claim 3).

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Substrate (base) of sliding member of the present invention
Examples of the material include aluminum, such as AC and ADC, which are commonly used for engine parts such as pistons and cylinder liners, as well as magnesium, titanium, iron, and alloys thereof.

The NiAl composite powder used in the present invention is:
It consists of 4 to 22% by weight of Al and 96 to 78% by weight of Ni, preferably 18 to 22% by weight of Al and 82 to 78%.
Consists of weight percent Ni. As the content of Al increases, the amount of intermetallic compound generated by heat during thermal spraying increases.
It is preferable that the content of l is as large as possible. If the Al content is less than 4% by weight, the effect of the intermetallic compound on the film properties is almost eliminated. Also,
If it exceeds 22% by weight, preparation of the composite powder becomes difficult.

The NiAl composite powder used in the present invention is:
Usually, since the material is similar to the material of the base layer of the ceramic sprayed layer, the adhesion strength is large, and there is almost no decrease in the adhesion strength due to the heat load in the engine. Further, since an intermetallic compound is generated by heat during thermal spraying, other Ni-based powders (H
_mv 200 to 250), the hardness is higher and H _mv 3
00 or more.

The "other powder added as necessary" in the metal powder used in the present invention is, for example, iron or iron alloy powder having self-hardening property, or quenched in a powder manufacturing process. Examples thereof include iron or iron alloy powder having a chill portion.

The iron or iron alloy powder having self-hardening property is
When the sliding member of the present invention is applied to a high-load engine that requires high wear resistance, it can be suitably contained in the metal powder. Here, iron or iron alloy powder having self-hardening means a powder having a property that particles are rapidly cooled and hardened during plasma spraying, for example, cast iron, high carbon steel, or Cr, Mo, Alloy steel containing elements such as Ni, Mn, and Si can be given.

The content of iron or iron alloy powder having self-hardening property is 0 to 75% by weight, preferably 15% by weight in the metal powder.
~ 75% by weight. When the content is less than 15% by weight, the abrasion resistance hardly changes as compared with the case where the content is 0, and the effect of addition is small. On the other hand, as the content increases, the abrasion resistance increases, but when the content exceeds 75% by weight, the adhesive strength decreases, and the decrease in the adhesive strength due to a heat load increases.

[0012] The particle size of the iron or iron alloy powder having a chill portion by being quenched in the powder manufacturing process is as follows:
It is preferably from 38 to 120 μm. This will be described below. Iron or iron alloy having a chilled part by being quenched in the powder manufacturing process is cooled at a much higher speed than during plasma spraying, so it undergoes melting and solidification processes during thermal spraying. Conversely, the hardness may decrease. For example, even if the powder has sufficient hardness (H _mv 600 or more) at the stage of powder before thermal spraying, when completely melted at the time of thermal spraying, the hardness is remarkably reduced to about H _mv 450. is there. Therefore, when a powder having a large particle size is used, the mixed powder can be taken into the matrix in an unmelted or semi-molten state.
As a result, the mixed powder can maintain sufficient hardness even in the film, and the abrasion resistance is improved. The particle size of the powder is large enough to prevent melting during thermal spraying,
Considering the two points of being small enough to be used as a normal thermal spray powder, 38 to 120 μm is preferred. The content of iron or iron alloy having a chill portion by quenching is 0 to 75% by weight, preferably 15 to 75% by weight in the metal powder, as in the case of the iron or iron alloy powder having self-hardening property. is there.

[0013]

EXAMPLES Example 1, Comparative Examples 1 and 2 Powders comprising Ni-20Al (Example 1), Ni-20Cr (Comparative Example 1), and Ni-19Cr-5Al (Comparative Example 2) were used. Under the conditions shown in Table 1, the test pieces were subjected to plasma spraying. In addition, “Ni-20Al” means 20
It means an alloy consisting of Al by weight and the balance of Ni. The test pieces after thermal spraying were compared by the Ogoshi type abrasion test under the conditions shown in Table 2. Table 3 shows the results of the Ogoshi type abrasion test and the hardness of the cross section of each coating.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3] Table 3 shows that the coating of Example 1 sprayed with the NiAl composite powder was Comparative Example 1 or Comparative Example 2 sprayed with another Ni-based material.
It can be seen that the abrasion resistance is superior and the hardness of the film is higher than that of the film No.

Example 2 Table 4 shows the change in the adhesion strength before and after the heat load when the mixing ratio of the iron alloy powder having self-hardening property to the NiAl alloy was changed. The heat load was carried out for 5 cycles of a process of holding at 220 ° C. for 30 minutes and then at room temperature for 30 minutes, and a process of holding at 220 ° C. for 30 minutes and then cooling with water.
Cycling was also used.

[0018]

[Table 4]

A method for measuring the adhesion strength will be described with reference to FIG. First, a cut piece of 30 × 30 mm was cut out as a test piece, and this was used as Sample 1. The test is performed three times for each sample. As shown in FIG.
_A pair of upper and lower test jigs 3 and 4 each having a length of 40 mm is used. The upper and lower surfaces of the sample 1 on which the thermal spray coating 2 is formed are
Adhere to the test jigs 3 and 4. The test jigs 3 and 4 are pulled outward (in the direction of the arrow), and the peeling load required to peel off the thermal spray coating 2 is measured. The value obtained by dividing the peeling load by the peeling area is defined as the adhesion strength.

However, when the adhesion is good, the load required for peeling off the thermal spray coating becomes very large. Therefore, the measuring apparatus shown in FIG. 2 is used. 2, a sample 1, a thermal spray coating 2, and an adhesive 5 are the same as those in FIG. Using the test jigs 6 and 7, the test jig 6 to be bonded to the thermal spray coating 2 is used.
The diameter d of the tip portion is set to 12 mm, the bonding area is reduced, and the thermal spray coating 2 is peeled off with a small load. In the method of FIG. 1, the peeling area when calculating the adhesion strength is equal to the area of the test jigs 3 and 4, whereas in the method of FIG. The value of the area that has been pulled and peeled is also taken as the value.

Examples 3 to 6, Reference Example 1 High carbon steel powder having self-hardening properties but not having a chilled portion by quenching (Example 3) or high carbon containing 3% by weight of molybdenum (Mo) Made of steel, the hardness of the particles is _Hmv6
Iron alloy powder (Examples 4 to 6) having a hardness of not less than 00, having self-hardening properties, and having a chilled portion due to rapid cooling, and NiA
After the metal powder obtained by mixing the composite powder was plasma-sprayed on the test piece under the conditions shown in Table 2, an Ogoshi type abrasion test was performed under the conditions shown in Table 5. Here, the iron alloy powder which was not classified (Example 4) was classified into 38 μm by classifying.
Those excluding particles less than m (Examples 5 and 6) were used.
As Reference Example 1, a test was performed in the same manner as in Example 3 except that iron powder was not included.

[0022]

[Table 5]

[0023]

[Table 6]

From Table 6, it can be seen that abrasion resistance is improved by plasma spraying a mixture of NiAl composite powder and iron or iron alloy powder. When a powder having a sufficient hardness at the particle stage, such as an iron alloy, is used, abrasion resistance is further improved by spraying a powder having a particle size larger than NiAl (10 to 44 μm) serving as a matrix. This can be seen by comparing Example 4 and Example 5. Further, it can be seen by comparing Example 5 and Example 6 that the higher the mixing ratio of the iron or iron alloy powder, the better the wear resistance.

[0025]

The sliding member of the present invention is excellent in wear resistance and seizure resistance, and can be applied to a cylinder inner wall, a piston and the like. In addition, when iron or iron alloy powder having self-hardening property or metal powder further added with iron or iron alloy powder of a specific range of particle diameter having a chill portion due to quenching is used for plasma spraying, wear resistance is reduced. More improved,
It can be applied to high-load engines and the like.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a method for testing the adhesion of a thermal sprayed coating.

FIG. 2 is a conceptual diagram showing a method for testing the adhesion of a thermal sprayed coating.

[Explanation of symbols]

 Reference Signs List 1 Sample 2 Thermal spray coating 3 Test jig 4 Test jig 5 Adhesive 6 Test jig 7 Test jig

Claims (3)

[Claims] 1. A metal containing 25 to 100 parts by weight of a NiAl composite powder composed of 4 to 22% by weight of Al and 96 to 78% by weight of Ni and 75 to 0 parts by weight of other powders added as necessary. A sliding member having a coating formed by plasma spraying a powder. 2. The sliding member according to claim 1, wherein the metal powder comprises 25 to 85 parts by weight of the NiAl composite powder and 75 to 15 parts by weight of iron or iron alloy powder having self-hardening property. 3. The method according to claim 1, wherein the metal powder comprises 25 to 85 parts by weight of the NiAl composite powder, and 75 to 120 μm of iron or iron alloy powder having a chill part due to rapid cooling.
2. The sliding member according to claim 1, comprising 15 parts by weight.