High Velocity Oxygen Fuel (HVOF)
Available from Thermal Spray Depot
A HVOF system uses a combustible gas mixed with oxygen to create a flame inside of the spray gun at a temperature of approximately 5500°F. The resulting gases of combustion expand rapidly and can only exit out the nozzle of the gun resulting in a gas stream speed that exceeds the sound barrier. A sonic boom with aftershock diamond patterns is the evidence of this phenomena. This is the heat source to melt and accelerate the material to be sprayed. The material to be sprayed is in the form of a powder that is fed into the center of the flame where it is melted. Once it is melted in the flame, the liquid metal is atomized and accelerated to a high velocity from a combination of the pressure from the flame and compressed air that is injected around the flame. The atomized molten metal now forms a columned stream, similar in appearance to a spray paint pattern, except this is molten metal. The molten stream of metal is deposited on the component to be coated at a thickness of .0005" (.0127mm) per pass to .002" (.0254 mm) per pass. The variation of thickness per pass is depended on the material being sprayed and the amount of heat build up on the part being coated. This system is especially good for depositing tungsten carbide and chrome carbide.
A complete HipoJet 2700 includes the HVOF gun, HVOF gas flow panel, gas regulators, flash back arrestors, PF 700 powder feeder, gas control module, and a mobile cart. This compact system is easily moved to alternate locations.