High Velocity Oxygen Fuel Spraying (HVOF)

Definition - What does High Velocity Oxygen Fuel Spraying (HVOF) mean?

High Velocity Oxygen Fuel (HVOF) spraying is a thermal spraying coating technique used to enhance surface properties or dimensions of components. This coating provides longer life of equipment through significantly increasing the protection against erosion, wear resistance and corrosion. The first HVOF process is used in the detonation gun (D-gun) process.

It is a high-velocity thermal spraying process that is commonly used in the replacement of a hard chrome process. This process produces very thick, non-porous, hard-wearing coatings. It also produces outstanding bonding to the substrate material, and substantially improves resistance to wear and corrosion.

Corrosionpedia explains High Velocity Oxygen Fuel Spraying (HVOF)

High Velocity Oxygen Fuel (HVOF) spraying refers to a group of thermal spraying processes where spraying is done at supersonic speeds. HVOF is considered to be a smart technique due to its wide range of choices in terms of materials and processes. It has less of an impact on the environment in comparison to other conventional plating processes. The materials available for HVOF spray coating include metals and alloys, ceramics, plastics and composites.

HVOF coatings may produce a thick layer of up to 1/2" (12.7 mm). They are commonly used to coat for wear and corrosion protection on materials such as ceramic and metallic layers. The HVOF process can be successfully applied to deposit cermet materials (WC–Co, etc.) and other corrosion-resistant alloys (stainless steels, nickel-based alloys, etc.) on the substrate.

The process is similar to other thermal spray coating processes. First, the coating material is heated and excited by a gas stream to the equipment’s surface. This helps to attain better properties of coated materials. The gas stream is generated by combining and igniting oxygen and fuel (gas or liquid) in a heating chamber, and sending this high-pressure gas through a nozzle. Spraying powder is charged into this stream. This produces thin, overlapping platelets on the substrate surfaces.

In the HVOF processes, the temperature is not as important as the kinetic energy of particles. In HVOF processes, high-impact energy is used to produce dense coatings at relatively low temperatures.

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