Flame spraying includes low-velocity powder flame, rod flame, and wire flame processes and high-velocity processes such as HVOF and the detonation gun (D-Gun) process.
In HVOF, a fuel gas (such as hydrogen, propane, or propylene) and oxygen are used to create a combustion jet at temperatures of 2500 to 3100 °C . The combustion takes place internally at very high chamber pressures, exiting through a small-diameter (typically 8 to 9 mm) barrel to generate a supersonic gas jet with very high particle speeds. The process results in extremely dense, well-bonded coatings, making it attractive for many applications. Either powder or wire feedstock can be sprayed, at typical rates of 2.3 to 14 kg/h.