Pistons with wear resistant solid film lubricant coatings

摘要

Reciprocating engine parts which involve substantially continuous frictional contact are coated with a solid film lubricant having excellent wear characteristics and adhesion. The parts in question are pistons, and the area to which the wear resistant solid lubricant film is bonded is the piston skirt--i.e., all or a portion of the area below the piston rings. The lubricant film is composed of a polyimide of 2,2-bis[4- (4-aminophenoxy)phenyl]hexafluoropropane ("4-BDAF") and an aromatic tetracarboxylic acid (or dianhydride or ester thereof) containing from 25 to 125 parts by weight of fluorinated carbon per 100 parts by weight of the polyimide resin ("phr"), and preferably about 30 to about 100 phr of the fluorinated carbon.