High-velocity oxy-fuel coating

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High-velocity oxy-fuel (HVOF) coating is a thermal spray technique used to deposit protective coatings on a substrate.

A blend of fuel (gaseous or liquid) and oxygen is injected into a torch and burned. The combustion products flow through a nozzle that accelerates the flow to a speed up to 1500 m/s. A powder feed stock is injected into the gas stream, which accelerates the powder up to 800 m/s. The stream of hot gas and powder is directed towards the surface to be coated. The powder partially melts in the stream, and deposits upon the substrate. The resulting coating has low porosity as and a high bond strength.

HVOF coatings may be as thick as 12mm (1/2"). It is typically used to deposit wear and corrosion resistant coatings on materials. Ceramic and metallic powders can be deposited using HVOF. Common powders include WC-Co, Chromium carbide, MCrAlY, and alumina.