Thermal spraying

The thermal spray processes are surface coating processes. According to the normative definition (DIN EN 657 ) are there additional materials, the spray additives so called, from, to or melted inside or outside a spray burner, accelerated in a gas stream in the form of spray particles and propelled onto the surface of the component to be coated. The component surface is in this case (as opposed to welding ) not melted and thermally loaded only to a small extent. A layer formation takes place because the spray particles more or less flattened, mainly adhere through mechanical interlocking remain process-and material-dependent upon striking the component surface and layer by layer to build the spray layer. Quality characteristics of spray coatings are low porosity, easy access to the component, cracks and homogeneous microstructure. The layer properties achieved are significantly influenced by the temperature and the speed of the spray particles at the time of impact with the surface to be coated. The surface state (purity, activation, temperature) also exerts significant influence on quality characteristics such as adhesion.

Energy for the presence or melting of the spray additive material used electric arc ( arc spraying ), plasma jet ( plasma spraying ), oxy-fuel flame or fuel high-velocity oxygen flame ( conventional and high-velocity flame spraying), fast, preheated gases ( cold spray ) and laser beam (laser beam spraying). According to EN 657 DIN standard, the spray process are classified according to these criteria.

The purpose of this procedure is the coating of metallic and non-metallic materials with metals, oxide ceramic materials and carbide materials ( composites or generally ) for the purpose of modification and the targeted adjustment of the surface properties. Important industries in which thermally sprayed coatings are used, are the automotive industry, the paper and printing industry, the aviation and aerospace industry, waste industry, power generating industry and the general mechanical and plant engineering. The main application fields are the (combined ) wear and corrosion protection, protection from hot gas corrosion, thermal insulation or the adaptation of friction and sliding properties.

Thermal spray processes

• Schmelzbadspritzen
• Arc spraying ( wire arc spraying )
• Plasma spraying to atmosphere
• Under protective gas
• Under low pressure (vacuum)

• Powder flame spraying
• Wire flame spraying
• Plastic flame spraying

• With gaseous fuel
• With liquid fuel