Light alloy piston for IC engine - has hard wearing surface layer of aluminium oxide deposited electrolytically

摘要

The piston is made of aluminium or aluminium alloy. It has a crown (1) and a cylindrical side (2) with grooves (3) for piston rings. The skirt below the rings has bearings (4) for a gudge on pin which carries the connecting rod (5). The surfaces of the crown, cylindrical side and grooves are covered with a hard wear resisting layer. This layer consists of aliminium oxide obtained by an iodisation. A specialised electrolytic process gives an extremely this surface layer which is hard and wear resisting and is firmly bonded to the parent metal of the piston. Alternatively a thermal spray process can give a thicker layer.