Thermal spray processes are a way of adding a protective layer to a part by spraying tiny particles onto it at high speed, which builds the coating up in layers, and this helps protect against heat and corrosion.

HVOF and HVAF

HVOF or High Velocity Oxygen Fuel, is known for making very strong coatings that don’t have many gaps, which is useful for parts that deal with friction or difficult conditions. HVAF is quite similar but it uses air instead of oxygen, which means that less heat is involved. With this, there’s less risk of oxidation and both are often used when you want a tough coating without making it too thick. The Health and Safety Executive has advice on safe manufacturing.

Plasma Spray

Plasma spray uses a very hot jet to melt and spray material onto a surface and this makes it good for ceramics and heat-resistant coatings. You’ll often hear it called thermal plasma spray, like the examples seen here, www.poeton.co.uk/surface-treatments/thermal-metal-sprays/plasma-coatings in industry guides. It’s a process that can handle different materials depending on what the part needs.

Arc Spray

Arc spray works by melting two metal wires with electricity and spraying the melted material onto a surface using air and this makes it fast and fairly low cost. It’s often used for coating large parts or adding material back onto worn areas.

Cold Spray

Cold spray doesn’t fully melt the material so it keeps temperatures low. This helps to avoid damaging the part and makes it useful for repairs or for parts that can’t handle high heat.