Composition for lubricating film, sliding member using the composition for lubricating film, and method of manufacturing the composition for lubricating film

Abstract

A composition for a lubricating film includes molybdenum disulfide particles which are dispersed, and a binding resin, and is a composition for coating a surface of a base material made of metal with a lubricating film in which the molybdenum disulfide particles are bound together by the binding resin. The composition for a lubricating film contains 50 mass % to 70 mass % of the molybdenum disulfide particles with respect to a total amount of the molybdenum disulfide particles and the binding resin. An average particle size of the molybdenum disulfide particles is in a range of 0.1 μm to 3.0 μm.

What is claimed is: 
     
         1 . A composition for a lubricating film, comprising:
 molybdenum disulfide particles which are dispersed; and   a binding resin, wherein   the composition for the lubricating film is a composition for coating a surface of a base material made of metal with a lubricating film in which the molybdenum disulfide particles are bound together by the binding resin,   the composition for the lubricating film contains 50 mass % to 70 mass % of the molybdenum disulfide particles with respect to a total amount of the molybdenum disulfide particles and the binding resin, and   an average particle size of the molybdenum disulfide particles is in a range of 0.1 μm to 3.0 μm.   
     
     
         2 . The composition for the lubricating film according to  claim 1 , wherein
 the binding resin is a polyamide-imide resin.   
     
     
         3 . A sliding member, in which the surface of the base material is coated with the lubricating film formed of the composition for a lubricating film according to  claim 1 . 
     
     
         4 . The sliding member according to  claim 3 , wherein
 a plurality of dimples are formed on the surface,   a projecting valley depth of the surface is in a range of 0.4 μm to 1.0 μm, and   a center-line average roughness of the surface is in a range of 0.4 μm to 1.0 μm.   
     
     
         5 . The sliding member according to  claim 3 , wherein
 the sliding member is a piston of an internal-combustion engine, and   the lubricating film is formed on a surface of a skirt section of the piston.   
     
     
         6 . A method of manufacturing a sliding member, in which a surface of the base material is coated with a lubricating film formed of the composition for a lubricating film according to  claim 1 . 
     
     
         7 . The method according to  claim 6 , comprising:
 forming a plurality of dimples, the dimples being formed by propelling hard particles against the surface of the base material through shot peening to allow the surface to have a projecting valley depth in a range of 1.5 μm to 2.0 μm and a center-line average roughness in a range of 1.5 μm to 2.0 μm, the hard particles being harder than the base material; and   forming the lubricating film on the surface on which the dimples are formed, with the composition for a lubricating film.   
     
     
         8 . A method of manufacturing a piston using the sliding member as the piston, according to the method of manufacturing a sliding member according to  claim 7 , the method further comprising:
 after forming the plurality of dimples on the surface of a skirt section of the piston, coating the surface of the skirt section, on which the dimples are formed, with the lubricating film.