Abstract: A rotary compressor comprises a housing having a cylindrical inner wall surface, a rotatable sleeve having an inner and outer surfaces and disposed in the housing for rotation about a first longitudinal axis, a rotor disposed in the sleeve for rotation about a second longitudinal axis which is offset from the first longitudinal axis, a plurality of vanes carried by the rotor to extend substantially in radial directions and having radially outer edges maintained in contact with the inner surface of the sleeve so that the sleeve is rotated as the rotor and the vanes rotate. One or each of the inner wall surface of the housing and the outer surface of the sleeve has a coating comprised of a wear-resistant resin dispersed with 10 to 120 volume part of a solid lubricant and 5 to 50 volume part of metal flakes for 100 volume part of the resin.

Abstract: A nitrided cast iron product comprising cast iron matrix material and graphite particles distributed in the matrix material, a nitrided layer formed in a surface of the cast iron product and having gaps between the graphite particles and the matrix material, the gaps being exposed to the surface of the product and filled with resin which has a resistance to dissolution under a temperature below 250.degree. C.

Abstract: The side housing of a rotary piston engine has an inner surface which has been subjected to a soft-nitriding treatment to form a layer of Fe-C-N type compounds and thereafter ground to provide a surface roughness of between 0.3 and 15 microns. An oil seal which slidably engages the inner surface of the side housing has a sealing lip constituted by a chromium plating. The arrangement provides an improved wear resistance of the oil seal.