Abstract: A method of fluxing a cast light-weight metal substrate for thermally adhering sprayed metallic coatings thereto, comprising: (a) preparing the substrate to be clean of grease and oil and to have a uniform and homogeneous surface energy; (b) electrostatically depositing a dry flux powder coating onto such prepared surface; and (c) thermally depositing melted metal onto and across the flux coated surface to further thermally activate the flux if not already activated, for stripping away any substrate oxides and to thermally metallurgically bond the deposited molten metal to the substrate.

Abstract: A plasma transferred wire arc thermal spray apparatus and method producing an extended-arc and supersonic plasma jet stream for applying a dense metallic coating on a substrate, such as a concave internal surface of a bore. The apparatus includes a plasma generating torch assembling having a cathode and an anode nozzle surrounding the cathode and a wire feeder which continuously feeds the tip of a wire feedstock opposite a constricted nozzle orifice and wherein the wire feedstock is maintained at the same positive electrical potential as the nozzle. Plasma gas is directed into the nozzle, preferably generating a vortex flow around the cathode and exiting the restricted nozzle orifice. The improved apparatus includes a pilot power supply and a high voltage or high frequency power supply which initiates the electric arc and the constricted plasma arc and a separate main power supply which extends the constricted plasma arc to the wire tip.

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.

Abstract: Method of depositing an Fe.sub.x O comprising coating onto a light metal substrate by use of wire-arc thermal spraying that propels atomized droplets by use of atomizing gases, comprising: preparing at least one surface of the light metal substrate to present an exposed essentially non-oxidized substrate surface; and thermally spraying melted droplets of a steel feedstock wire onto the prepared surface by use of propellant gases to deposit a composite coating, the gases being controlled as to content to regulate the exposure of the droplets to oxygen so that Fe.sub.x O is substantially the only iron oxide formed during spraying, x being 0.5-1.5.