HVAF coatings are similar to and generally comparable to coatings produced by HVOF and Cold Spray. HVAF is a "warm spray" process that is cooler than HVOF, but hotter than Cold Spray. HVAF guns utilize axial powder injection into an air-fuel jet with a temperature of about 1900-1950°C. Therefore, the process is capable of effectively applying carbide-based materials, but since the air-fuel jet produces considerably less oxides than high temperature oxy-fuel jets, the HVAF process can also apply metals with almost zero oxidation, similar to Cold Spray. All common thermal spray powder materials may be applied with HVAF, except for ceramics... HVAF can apply metal, carbide, and metal alloy powders of 5 to 53 micron range, with -30+10 µm cut being the most common. The deposit efficiency (D.E.) is 50-75% for carbide powders, and 60-85% for metal powders... The theoretical limit of the HVAF jet velocity is 1400 m/s for pressure ranges that could be provided by regular 125 psi air..
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