Wear resistant and self lubricating sprayed coatings - esp. for piston rings, using cobalt tungsten alloy and nickel-graphite powders

摘要

A wear-resistant and self-lubricating surfae layer is mfrd. esp. on the running surface of piston rings, using plasma- or flame-spraying plant, by spraying a metal powder mixt. consisting of a cobalt-tungsten alloy contg. 5-45% of metallically bonded graphite. The surface layer pref. consits of a cobalt-tungsten alloy contg. finely divided graphite powder, and a nickel-graphite powder is pref. mixed with the Co-W alloy. The surface layer may contain a homogeneous distribution of the graphite or the latter may decrease gradually from the outer surface inwards. The surface layer is superior to hard chromium coatings.