Thermal spray processes improve the product’s resistance to heat, wear, corrosion and oxidation. It works by heating a material-usually in powder or wire form-and spraying it at high speed onto a surface, where it forms a coating.
Below are six processes that use thermal sprays, like poeton.co.uk/surface-treatments/thermal-metal-sprays/:
1. HVAF Spray
HVAF spraying is a relatively modern process that uses compressed air instead of pure oxygen to combust fuel. One of the biggest advantages of HVAF is the reduced oxidation of the coating material.
2. HVOF Spray
HVOF spraying is one of the most popular thermal spray techniques. It uses a mixture of fuel – such as kerosene, propane, or hydrogen – and oxygen to create a high-temperature, high-pressure flame.
3. Spray and Fuse
Spray and fuse is a two-step process. First, a coating material – usually a nickel-based alloy – is sprayed onto the surface using a flame spray technique. Then, the coating is heated and fused to create a metallurgical bond with the substrate.
4. Plasma Spray
Plasma spraying uses a high-temperature plasma jet, up to 15,000C, to melt coating materials to process materials with very high melting points, like ceramics.
5. Arc Spray
Arc spraying uses two electrically charged wires made of coating material and when the wires meet, an electric arc melts them – compressed air then propels the molten droplets onto the surface.
6. Flame Spray
Flame spraying is one of the oldest and simplest thermal spray processes, using a flame generated by burning fuel gases, such as acetylene or propane, to melt the coating material.
