Abstract: A wear-resistant titanium metal member includes a substrate having a carburized layer formed by plasma carburizing and a polished surface having a surface roughness Ra of 0.01 to 0.80 ?m formed on the surface of the carburized layer, a titanium oxide layer superposed on the polished surface, and an amorphous carbon (GLC) layer superposed on the titanium oxide layer. The GLC layer is rigid and has a flat and smooth surface, so that it is free of stress concentration. By adjusting the plasma carburizing temperature and the concentration of the carburizing gas, carbon ions can penetrate the polished surface and form the carburized layer under the polished surface.

Abstract: A method of carburizing treatment is proposed in which if carburizing is carried out at a low temperature, carbon will not turn amorphose and deposit on the surface of a titanium metal but reliably penetrate into between metallic atoms. It is a method of surface treatment of a titanium metal comprising the steps of heating the titanium metal to a temperature of 400-690° C. in a cleaning gas atmosphere containing hydrogen gas, subjecting the surface of the titanium metal to cleaning by applying a DC voltage of 200-1500 V, and plasma carburizing in an atmosphere comprising a carburizing gas having an atomic weight ratio of hydrogen atoms (H) to carbon atoms (C) adjusted to 1?H/C?9 at a pressure of 13-400 Pa and a temperature of 400-690° C. Ionization reaction in the gas is suppressed suitably. Because there exists no excessive carbon which is not used for carburization but turns soot or glass-like carbon, in the atmosphere during carburization, carburizing reaction progresses smoothly.

Abstract: Threaded parts for aircraft made of heat-resistant steel which will never seize even after subjected to large temperature fluctuations and vibrations for a long time. Thus they can be tightened sufficiently and also loosened for maintenance and inspection. The threaded parts are made of heat-resistant steel and having its surface subjected to carburizing so as to satisfy the following equations: 0≦X≦100, Y≧−10X+600, Y≦−6X+1000 where X is the depth (&mgr;m) from the surface of the threaded part and and Y is the Vickers hardness (HV).

Abstract: A method of forming a sufficiently thin, highly amorphous and homogeneous glass-like carbon film on the surface of a titanium metal with high efficiency. In this method, the surface of a titanium metal is polished by e.g. buffing with emery paper and alumina or chromium suspension as polishing agents to form a mirror surface. A dense and rigid titanium oxide film layer is formed on the mirror surface. The surface of the titanium oxide film is then subjected to plasma heating in an atmosphere containing a hydrocarbon gas under a gas pressure of 0.1-30 Torr at 400-1100.degree. C. to form a glass-like carbon film thereon.

Abstract: The surface of titanium is treated to reduce the friction coefficient and wear loss without sacrificing its corrosion resistance. Pure titanium or titanium alloy is subjected to plasma-carburizing in an atmosphere containing hydrocarbon gas at a pressure of 0.5 to 15 Torr and a temperature of 700.degree. to 1100.degree. C.