Thermal spraying is a collective term for processes involving metal, metal alloy or metal compound in wire or powder form that is created by means of a plastic heat source and affixed through high kinetic energy. This creates a coating that strongly enhances the functions of the machine part. The selection of the surface layer can more or less be done independently of the underlying material so that the most optimal properties of the component can be added.
The following spray processes are distinguished:
- Combustion powder spray, the thermal energy originates from a combustion process (gas/oxygen)
- Arc wire spray, when energy comes from an electric arc
- Plasma spray, where the energy comes from ionization of highly pure gas mixtures
- HVOF spraying, the thermal energy originates from a combustion process (gas/oxygen) wich occurs under very high pressure
Thermal spraying is known as a cold process and can be applied to almost any type of surface. The base materials, regardless of the heat source doos not exceed 100º c so there isn’t any damage to the structure or shape. The applied coating has a lamellar structure which is mechanically connected to the substrate.
An exception to this is the group of alloys that receive an additional treatment where the coating and a temperature of 1.060º C become homogenous of structure and atomically connected with the substrate.