Thermal spraying technology is a method of using a heat source to heat the spray material to a melted or semi-melted state, and spraying and depositing it onto a pre-processing substrate at a certain speed to form a coating, with the purpose of giving the substrate surface special functions. The overall strength of the part is provided by the substrate, while the coating significantly improves its surface quality, such as corrosion resistance, wear resistance, and heat resistance. Therefore, thermal spray coating technology is widely used in the aerospace industry and power generation industry, such as the re-polishing of jet engines, gas turbines, compressors, and pump parts.

Cemented carbide is an alloy material prepared by powder metallurgy. It is a composite material composed of refractory metal compounds and bonding metals. Refractory metal compounds are WC, TiC, Ta(Nb)C, TaC, NbC, VC, Cr3C2, etc. The service life of cemented carbide is determined by its performance. After the composition is determined, the quality of performance and the length of life are mainly determined by its organizational structure. Organizational defects such as holes, inclusions, polycrystals, coarse grains, mixed materials, and cobalt pools in the alloy are the source of fracture of the alloy. Therefore, the metallographic organizational structure is particularly critical for the judgment of defects.

Microelectronic components are miniaturized electronic system chips and devices realized by microelectronic process technology. Metallographic analysis of microelectronic components is often referred to as "slice analysis". Micro-slices made by microscopic sectioning technology can be used for structural analysis of electronic components and inspection of surface and internal defects of electronic components.

Titanium is a relatively new metal that was used as an engineering structural material in the 1950s. The outstanding advantages of titanium are high specific strength, good heat resistance and excellent corrosion resistance. Titanium and titanium alloys have become important structural materials for aviation, shipbuilding and chemical industry.

Aluminum and aluminum alloys have low density, light weight, high specific strength, good electrical and thermal conductivity, and good corrosion resistance.

Copper is the earliest and most widely used metal material in human history. It not only has excellent electrical conductivity, thermal conductivity, and non-magnetic properties, but also has the characteristics of wear resistance, machinable, and decoration.

Because welding is simple, economical, safe and can simplify the manufacturing process of parts with complex shapes, welding technology has been widely used in the machinery manufacturing industry.

Cast iron is an iron-based alloy that is initially in a cast state and cannot withstand industrial deformation processing at any solid temperature. This definition can better define "steel" and "cast iron".