Thermal spraying, as the name suggests, is the process of applying a specially heated coating to a base material or substrate. This is typically in the form of a powder or a liquid that is fed through a plasma jet, heated to around 10,000K and sprayed onto the surface of the base material in an inert, controlled environment. Upon contact, the coating will begin to cool, contract, and mechanically adhere to the surface. Depending on its final application, the coating can be anything from 0.1mm to 10mm thick.
Table of Contents
ToggleIn addition to the plasma spray method, there are a few variations of thermal spraying that can be used to coat a surface. The arc spray method works by using two conductive wires, one positive and one negative. The wires are energised in a gun head by arcing against each other, creating molten material and by the use of compressed air, a jet is formed coating the substrate.
Wire frame spraying works by mixing a fuel, usually propane or acetylene, with oxygen. The resulting high temperature of the flame makes the coating molten as it passes through the gun.
Finally, there is HVOF spraying (high-velocity oxygen fuel coating ). As with the wire spray method, it mixes fuel with oxygen but in a combustion chamber. Once ignited, the gas it produces is forced through a nozzle at high speed, coating the surface. This method gives a high-density coating with very low porosity giving it an advantage in certain applications, especially where moisture is a factor. For more information on coatings, sites such as plasma spray provide detailed information.
All of these combinations added to the comprehensive choice of coating materials such as plastics, metal, alloys, ceramics and polymers mean that thermal spraying is unmatched in its versatility across a wide range of products and industries. For more in-depth technical analysis, see
Most of us imagine the renovation of worn parts when we think of thermal spraying and although this is certainly one of its applications, this is only the start. Aerospace industries are making increasing use of thermal sprayed products due to their high durability and temperature resistance. The thermal properties of material coated in this way mean it is much in demand as components in the green revolution. It is a thoroughly adaptable solution, ideal in a fast-changing world.