Its basic processes are:
1. Preparation of raw material powder. At present, there are two kinds of pulverizing methods: mechanical method and physicochemical method. Mechanical comminution and atomization belong to mechanical method; physical and chemical methods are divided into electrochemical corrosion method, reduction method, reduction method, reduction-chemical method, vapor deposition method, liquid deposition method and electrolysis method. The most widely used methods are reduction, atomization and electrolysis.
2. Mixing: Mixing is the process of mixing various required powders in a certain proportion and homogenizing them into powder billets. Mixing methods are divided into dry, semi-dry and wet.
3. Forming embryo block: The purpose of forming is to make embryo block with a certain shape and size, and has a certain density and hardness. Many of them are directly shaped out of the final size and shape at one time. The forming methods are basically divided into pressure forming and non-pressure forming. Pressure moulding is the most widely used in pressure moulding.
4. Sintering of billets. Sintering is a key process in powder metallurgy process. The formed compacts are sintered to obtain the required final physical and mechanical properties. Sintering can be divided into unit system sintering and multicomponent system sintering. For solid phase sintering of unit system and multicomponent system, the sintering temperature is lower than the melting point of metal and alloy used; for liquid phase sintering of multicomponent system, the sintering temperature is generally lower than the melting point of refractory component, but higher than the melting point of fusible component. In addition to ordinary sintering, there are also some special sintering processes, such as loose-packed sintering, melt-immersion, hot-pressing and so on.
5. Post-treatment of powder metallurgical products. After sintering, various methods can be adopted according to the different requirements of products. Such as finishing, oil immersion, machining, heat treatment and electroplating.
It is the technology of making metal powder and making materials or products from metal powder by forming and sintering process. It is a branch of metallurgy and material science. Powder metallurgical products are widely used in many fields, from ordinary machinery to precision instruments, from hardware tools to large machinery, from electronic industry to motor manufacturing, from civil industry to military industry, from general technology to advanced high technology, the figure of powder metallurgical process can be seen.
