As a new useful engineering skill, there is no standard classification method, which is generally divided according to the type of heat source, the shape of spraying data and the function of coating. For example, according to the function of the coating, it can be divided into corrosion resistance, wear resistance, heat insulation and other coatings. According to the heating and bonding methods, it can be divided into spraying and spray melting: the former is that the body does not melt, and the coating and the substrate form a mechanical combination; The latter is the re-heating and remelting of the coating, and the coating and the substrate are mutually soluble and dispersed to form metallurgical bonding.

Plasma spraying is a kind of material surface strengthening and surface modification technology, which can make the base material surface have the properties of wear resistance, corrosion resistance, high temperature oxidation resistance, electrical insulation, heat insulation, radiation protection, wear reduction and sealing. The plasma spraying technology uses the plasma arc driven by DC as the heat source to heat the ceramic, alloy, metal and other materials to the molten or semi-molten state, and forms a solid surface layer on the surface of the pretreated workpiece by high-speed spraying. Plasma spraying is also used for medical purposes. Spray a layer of tens of microns on the surface of artificial bone as a method to strengthen artificial bone and enhance its affinity.

Plasma spraying technology has been widely used in traditional fields, such as wear-resistant coatings and corrosion-resistant coatings. Since the 1950s, its application fields have expanded from aviation and aerospace to steel industry, automobile manufacturing, petrochemical industry, textile machinery, shipbuilding and other fields. In recent years, the application and research of plasma spraying technology in high-tech fields such as nano-coating, functionally gradient materials, superconducting coatings, and biological functional coatings have gradually attracted people's attention.

In the atmosphere, as soon as the plasma flame leaves the nozzle, it will inhale a large amount of air from around. When the spray distance is 100mm, the air intake can account for more than 90% of the plasma. In the process of atmospheric plasma spraying, metal powder is seriously oxidized.

As a surface thermal protection coating, thermal barrier coating has excellent high temperature resistance, corrosion resistance and low thermal conductivity. It is widely used in aerospace, shipbuilding, automobile and other industrial fields. Plasma spraying is a commonly used process for preparing thermal barrier coatings.