In the plasma spraying process, the material to be deposited ,typically as a powder, is introduced into a plasma jet stream. This plasma stream is created by disassociating gas molecules of hydrogen, argon, helium, or nitrogen in an electric arc. The energy from this reaction generates a gas stream that is at a temperature that exceeds 20,000° F which is capable of melting all materials that can be made into a powder. After the material is melted in the plasma gas stream, it is atomized ans propelled towards the surface being coated. There, the molten droplets flatten, rapidly solidify and form a deposit. There are a large number of technological parameters that influence the interaction of the particles with the plasma jet and the substrate and therefore the deposit properties. These parameters include feedstock type, plasma gas composition and flow rate, energy input, torch offset distance, substrate cooling, etc.
The former Miller Thermal group is still in Appleton WI and they are known as Thermach. They continue to build and improve on one of the cornerstones of Thermal Spray Equipment.