Patent ID: 8410029

Claim:
A surface-oxide abrasion-resistant lubricant coating formed of two metal oxides that are produced as a result of a mixture of fine-particle powders of two respective soft metals, each having lower hardness and lower melting point than a base material of a sliding contact portion to be lubricated, the sliding contact portion being adapted to slidingly contact an object to be contacted and where the fine-particle powders are caused to be mixed by colliding the fine-particle powders against a surface of the sliding contact portion with a compressed gas containing oxygen to cause oxidation of the same at the surface of the sliding contact portion such that one of the two metal oxides has relatively higher hardness than the other; the surface-oxide abrasion-resistant lubricant coating including a high-hardness portion and a low-hardness portion which has relatively lower hardness than the high-hardness portion; the high-hardness portion being formed at a side of the base material of the sliding contact portion; the low-hardness portion being formed with a thickness of 0.1 μm to 2 μm at an interface which is located between the sliding contact portion that contacts the object to be contacted and a side of the object to be contacted and wherein the interface is a surface of the surface-oxide abrasion-resistant lubricant coating, the low-hardness portion having decreased friction resistance and shear resistance, and shear fractures concentrated to the low-hardness portion, the fine-particle powder of the soft metal that becomes a metal oxide of relatively higher hardness having a particle diameter smaller than the particle diameter of the fine-particle powder of the soft metal that becomes a metal oxide of relatively lower hardness; the low-hardness portion of the surface-oxide abrasion-resistant lubricant coating being formed of the metal oxides, one of the metal oxides having relatively higher hardness and the other having relatively lower hardness as a result of oxidation during colliding, and coverage of the metal oxide with relatively lower hardness at the low-hardness portion being at least 80%.