High-velocity air fuel spraying, where propane, propylene or natural gas burns with compressed air to produce a fast but relatively cool jet. Particles reach velocities similar to or above HVOF while staying cooler, so carbides decarburize less and metallic coatings pick up very little oxide. Air costs far less than oxygen and deposition rates are high, which makes HVAF attractive for carbide coatings on large parts.
Switch the boiler tubes to HVAF, the carbide comes in denser and we stop paying for a tanker of oxygen a week.
Also heard as
- high-velocity air fuel
Related terms
HVOF
High-velocity oxygen fuel: burning fuel and oxygen under pressure to fire powder at supersonic speed.
WC-Co
Tungsten carbide in a cobalt binder, the most common wear-resistant thermal spray coating.
Chromium carbide
Cr3C2 carbide held in a nickel-chromium binder, a wear coating that keeps working at high temperatures.
Oxides
Thin oxide films formed on metal particles in flight, showing as dark stringers between splats.