The high-velocity oxyfuel (HVOF) process was invented only 20 years ago, yet it has expanded the application possibilities for thermal spraying into areas that were once unattainable. In HVOF spraying, a combination of process gases such as hydrogen, oxygen, propylene, air, or kerosene are injected into the combustion chamber of the torch at high pressure and ignited. The resultant gas velocities achieve supersonic speeds. The powder is injected into the flame and also accelerated to supersonic speeds. The results are the densest thermal spray coatings available.
The HVOF process is the preferred technique for spraying wear-resistant carbides and is also suitable for applying wear-and/or corrosion-resistant alloys like Hastelloy, Triballoy, and Inconel®. Due to the high kinetic energy and low thermal energy the HVOF process imparts on the spray materials, HVOF coatings are very dense with less than 1% porosity, have very high bond strengths, fine as-sprayed surface finishes, and low oxide levels.
These properties have enabled HVOF sprayed coatings to become an attractive alternative to cladding and chrome plating.
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