What are the factors that affect the sintering quality of metal powder injection molding?

What are the factors that affect the sintering quality of metal powder injection molding?

Metal powder injection molding is a technology that uses metal powder (or mixture of metal powder and non-metallic powder) as raw material to produce metal materials, composite materials and various products after molding and sintering. Metal powder injection molding method is similar to ceramic production, so a series of new metal powder injection molding technology can also be used to prepare ceramic materials. Due to the advantages of metal powder injection molding technology, it has become the key to solve the problem of new materials and plays an important role in the development of new materials.

There are many factors that affect the properties of the sintered body, that is, the characteristics of the powder, molding and sintering conditions. The factors of sintering conditions include heating rate, sintering temperature and time, cooling rate, sintering atmosphere and pressure conditions.

The sintering temperature and time will affect the porosity, density, strength and hardness of the sintered body. High sintering temperature and long heating time will reduce the product performance, and even lead to product burning defects. At the same time, low sintering temperature or long heating time may reduce the performance due to the sintering process.

The sintering atmosphere usually used for metal powder injection molding is reducing atmosphere, vacuum, hydrogen, etc. The sintering atmosphere directly affects the properties of the sintered body. Sintering in reducing atmosphere can prevent block burning and allow reduction of surface oxides. For example, iron and copper-based products are usually decomposed with gas or ammonia, while cemented carbide and stainless steel are usually decomposed with pure hydrogen. Active metal or refractory metal, cemented carbide containing Tic alloy and stainless steel can be used for vacuum sintering. Vacuum sintering can avoid harmful components. Metal powder injection molding sintering method Liquid phase sintering When there are more than two components in the powder block, it may sinter at the melting point of the components, and a small amount of liquid phase will be produced in the powder block.

In the sintering process, pressure sintering exerts pressure on the powder to promote the densification process. Sometimes sintering and hot pressing are synonymous, but hot pressing refers to the process of directly obtaining products after powder forming and sintering.

At the same time, some physical or chemical measures are taken to significantly reduce the sintering temperature and time while improving the performance of the sintered body.

When the powder is introduced into the compaction process, the spark sintering generates an arc between the powder particles through DC and pulse power. Then the sintering process begins. In the sintering process, gradually increase the pressure to the workpiece, thus combining the molding and sintering of the two processes.