Factors affecting sintering quality in metal powder injection molding

Factors affecting sintering quality in metal powder injection molding

Metal powder injection molding is a technology that uses metal powder as raw material to produce metal materials, composite materials, and various products after molding and sintering. The metal powder injection molding method is similar to ceramic production, so a series of new metal powder injection molding technologies can also be used to prepare ceramic materials. Due to the advantages of metal powder injection molding technology, it has become the key to solving new material problems and plays an important role in the development of new materials.

There are many factors that affect the performance of sintered materials, including the characteristics of the powder, molding, and sintering conditions. The elements of sintering conditions include heating rate, sintering temperature and time, cooling rate, sintering atmosphere, and pressure conditions.

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

The sintering atmosphere commonly used for metal powder injection molding is to reduce atmosphere, vacuum, hydrogen, etc. The sintering atmosphere directly affects the performance of the sintered body. Sintering in a reducing atmosphere can prevent block combustion and allow the reduction of surface oxides. For example, iron and copper based products typically use gas or ammonia, while hard alloys and stainless steel typically use pure hydrogen. Metal or Refractory metals, hard alloy containing Tic alloy and stainless steel can be used for vacuum sintering. Vacuum sintering can avoid harmful components. The liquid phase sintering method for metal powder injection molding may produce a small amount of liquid phase in the powder block when there are more than two components present in the powder block, which may sinter at the melting point of the components.

During the sintering process, pressure sintering applies pressure to the powder to accelerate 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, while improving the performance of the sintered body, some physical or chemical measures are taken to significantly reduce the sintering temperature and time.