Abstract: A method of thermally spraying a coating onto the interior of a cylindrical surface which coating is graded between enhanced optimal machinability and enhanced wear resistance.

Abstract: A method of bonding a thermally sprayed coating to a non-roughened light metal (i.e. cast aluminum-based) surface. The method comprises the steps of (a) depositing a flux material (i.e. potassium aluminum's fluoride containing up to 50 molar % other fluoride salts) onto such cast surface which has been cleansed to be substantially free of grease and oils, such deposition providing a dry flux coated surface, the flux being capable of removing oxide on the cast surface and having a melting temperature below that of the cast surface; (b) thermally activating the flux in the flux coated surface to melt and dissolve any oxide residing on the cast surface; and (c) concurrently therewith or subsequent to step (b) thermally spraying metallic droplets or particles onto the flux coated surface to form a metallic coating that is metallurgically bonded to the cast surface.