Surface engineering is to change the morphology, chemical composition, structure and stress state of the solid metal surface and non-metal surface through surface coating, surface modification or multiple surface engineering techniques after surface pretreatment, so as to obtain the required System engineering of surface properties.

Surface engineering integrates basic theories, technologies and new achievements in many fields. Surface engineering technology has made a layer of coating or film on the surface of the base material, or imparted many special properties to the material through surface modification, so that the surface performance of the material is much better than that of the material base, which can not only greatly extend the application field of the base material, but also It solves the problem that materials cannot meet environmental requirements in many fields. Surface engineering technology plays an important and irreplaceable role in solving common problems encountered in human development such as resources, energy and environment.

Because surface engineering technology saves energy and materials, it protects the precious resources that mankind depends on for survival. At the same time, it also plays a very key role in environmental protection. Surface engineering technology in the 21st century will penetrate all walks of life, promote social civilization and improve the quality of life.

It uses heat sources such as flame, arc or plasma to heat a certain linear and powdery material to a molten or semi-melted state, and spray the accelerated droplets to the substrate at a high speed to form a coating. The coating has excellent properties such as wear resistance, corrosion, high temperature and heat insulation, and can repair the size reduction of parts caused by wear, corrosion or processing tolerances. The application of spraying technology mainly includes four aspects: long-term anti-corrosion, mechanical repair and advanced manufacturing technology, mold making and repair, and manufacturing of special functional coatings. At present, spraying technology has been widely used in almost all industrial fields and household products (such as non-stick pans, infrared health electric heaters, etc.).

At the end of the 20th century, spraying technology developed rapidly and was quickly promoted and used. From 1980 to 2000, the changes in the spraying market are shown in Table 1. By the end of the 20th century, plasma spraying was still dominant. It is worth noting that the rapid development of high-speed flame spraying (HVOF) will occupy 25% of the market, ranking second. Arc spraying technology, due to its good economy and superior coating performance than flame sprayed coatings, will partially replace flame spraying technology to the third place.