JPH11335806A - Production of sliding material for high temperature use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sliding material that stably exhibits a low coefft. of friction in the temp. range from room temp. to a high temp. and suppresses the wear of the material itself and its opposite material by forming a ceramic film on the surface of a metallic material by thermal spraying, impregnating a solid lubricant into the pores in the film and coating the surface of the film with the lubricant. SOLUTION: The metallic material used is, e.g. stainless steel, an Ni-base alloy or a Co-base alloy as an ordinary heat resistant alloy. The ceramic film is, e.g. a film of Cr3 C2 , WC, Cr2 O3 or Al2 O3 . The solid lubricant is used in the state of a solid lubricant dispersion prepd. by dispersing the lubricant in a solvent, generally water. The solid lubricant may be a generally used solid lubricant but potassium tungstate, potassium molybdate or boron nitride is preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-temperature sliding material in which a solid lubricant is combined with a ceramic sprayed film having wear resistance, low friction and high strength.

[0002]

2. Description of the Related Art Generally, a sliding material is required to have abrasion resistance and low friction, and a sintered metal or a composite material of a resin and a solid lubricant in which a solid lubricant such as graphite is dispersed in a metal base material is used. Although used, it has drawbacks such as poor heat resistance. Ceramics also have high-temperature hardness but a high coefficient of friction, so sintered compacts in which solid lubricants are dispersed have been developed.However, combining solid lubricants with inherently brittle ceramics further reduces the strength, It cannot be applied to members to which a load is applied. In this case, it is promising to coat a ceramic material on the surface of a metal material with high toughness, and there are a wide variety of ceramic films.However, there is no one that satisfies the property of combining abrasion resistance and low friction up to high temperatures. Is the current situation.

On the other hand, graphite, dihydrated molybdenum and Teflon are generally used as solid lubricants, but their heat resistance limits are low. For example, in an oxidizing atmosphere, the solid lubricant oxidizes due to a rise in temperature and loses its original lubricating properties. For example, graphite is oxidized from around 500 ° C. and consumed as carbon dioxide, and molybdenum disulfide is oxidized from around 400 ° C. to become molybdenum trioxide.

[0004] The inventors of the present invention have intensively searched for a high-temperature lubricant which is stable at a high temperature, and as a result, an oxide containing two or more metal elements (potassium tungstate or molybdate) has been found. By intercalating the frictional surface of the sliding part as a lubricant with a lubricant, it is possible to cause a slip under a stable friction coefficient from room temperature to a high temperature under a stable friction coefficient and to prevent seizure ( Japanese Patent Application No. 6-206563) and a high-temperature sliding material in which a heat-resistant alloy is combined with an oxide containing two or more metal elements (Japanese Patent Application No. 8-202004). However, for a member to which an impact load is applied, a higher strength sliding material for high temperature has been required.

[0005]

SUMMARY OF THE INVENTION In view of the state of the art, the present invention provides a high-temperature sliding material which exhibits a low coefficient of friction stably in a temperature range from room temperature to a high temperature and has little wear between itself and a mating material. It is intended to provide a manufacturing method.

[0006]

The present invention is characterized in that (1) a ceramic film is formed on the surface of a metal material by a thermal spraying method, and then pores and surfaces in the film are impregnated with a solid lubricant and coated. (2) The method for producing a high-temperature sliding material according to the above (1), wherein the solid lubricant is potassium tungstate or potassium molybdate, and (3) a solid. The method for producing a high-temperature sliding material according to the above (1), wherein the lubricant is boron nitride.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Metal materials used in the present invention include stainless steel, which is generally a heat-resistant alloy, and N
i-base alloys, Co-base alloys, etc. can be used. As the ceramics film, a Cr ₃ C ₂ system, WC
, Cr ₂ O ₃ , Al ₂ O _3, etc. ceramic films can be used. The solid lubricant is used in the form of a solid lubricant dispersion in which the solid lubricant is dispersed in a solvent, generally water. In the present invention, as the solid lubricant to be impregnated into the ceramic film, any of those conventionally known can be used, but it is particularly preferable to use potassium tungstate, potassium molybdate or boron nitride.

[0008]

EXAMPLES Hereinafter, specific examples of the present invention will be described to further clarify the effects of the present invention.

(Example 1) 20 mm × 20 made of stainless steel
Chromium carbide Cr _ThreeC_TwoAnd N
iCr mixed powder (average particle size: about 20 μm, mixing ratio: C
r_ThreeC_Two: NiCr = 80: 20) by plasma spraying
Was. Then, the surface is lapping-polished (roughness: 3μ)
m) in a saturated aqueous solution of potassium tungstate
Immersion, vacuum impregnation for about 3 hours,
Let dry for hours. This test piece (film thickness: 0.1 mm, K_Two
WO_FourImpregnation amount: about 1 mg.
5vol%) as a rotating piece (disk) and stainless steel
A dry friction test was performed using a friction partner material (ring). Contact
Tactile type is ring on disk type, surface pressure: 5MP
a, Sliding speed: 10 mm / sec. Also,
Heat the specimen directly with an infrared lamp while rubbing it for about 6
The temperature was raised to 00 ° C., and the change over time in the coefficient of friction was measured.
After the test, use the stylus-type surface roughness meter
And the wear depth of the disk was determined. Ring wear
The depth was measured with a micrometer.

The results in the atmosphere and in hydrogen gas are shown in Tables 1 and 2 below, respectively. The base material, which is a comparative material, has a high coefficient of friction of 1 or more, and has high wear. The comparative material obtained by spraying the mixed powder only has a lower coefficient of friction than this, but is close to 1, and has much wear on the mating material. On the other hand, the material of the present invention stably exhibits a low coefficient of friction of 0.6 or less in the temperature range from room temperature to high temperature, and has little wear between itself and the partner.

(Example 2) The same trial production and evaluation were performed by replacing potassium tungstate in Example 1 with potassium molybdate (saturated aqueous solution). The results are shown in Tables 1 and 2
Shown in

(Example 3) The same trial manufacture and evaluation were performed by replacing potassium tungstate in Example 1 with boron nitride (about 20% aqueous solution). Tables 1 and 2 also show the results.

[0013]

[Table 1]

[0014]

[Table 2] In Tables 1 and 2, the porosity, the coefficient of friction, and the wear depth indicate average values, respectively. Further, the porosity was controlled by changing the spraying distance, and the porosity was calculated from the area ratio of the pores in the cross-sectional structure photograph of the sprayed film.

The effect is the same as in Examples 1 and 2, except that hydrogen gas impregnated with boron nitride, which is not an oxide, has higher friction at high temperatures than impregnated potassium tungstate or potassium molybdate. It has the effect of having excellent wear characteristics.

[0016]

As is apparent from the above description of the method for producing a high-temperature sliding material of the present invention, the high-temperature sliding material obtained by the present invention has excellent friction and wear characteristics in a high temperature range. effective.

Claims (3)

[Claims] 1. A method for producing a sliding material for high temperature, comprising forming a ceramic film on a surface of a metal material by a thermal spraying method, and then impregnating and covering a pore and a surface of the film with a solid lubricant. 2. The method according to claim 1, wherein the solid lubricant is potassium tungstate or potassium molybdate. 3. The method according to claim 1, wherein the solid lubricant is boron nitride.