The powder metallurgy process will inevitably involve the preparation of powder. The powder preparation process can be divided into three main categories, one is the rapid solidification atomization powder making technology, the other is the mechanical alloy powder making technology, and the other is It is a superfine powder preparation technology.
The powder metallurgy's rapid solidification atomization powder making technology is relatively straightforward, which is to crush liquid metal or alloy and then quickly condense, thereby obtaining powdery materials. This kind of powdering technology can effectively reduce the segregation of alloy components, so the obtained alloy powder composition is relatively uniform.
Due to the different atomization media used, the atomization methods used in powder metallurgy pulverization technology also have a variety of options, such as two-stream atomization, gas atomization, high-pressure water atomization, centrifugal atomization, vacuum atomization, etc. In the two-stream atomization, when the atomizing medium and the molten metal stream are sprayed through the nozzle, the two streams collide with each other, thereby breaking the stream and spraying powder.
In the gas atomization method, the gas pressure generally must reach 2-8 MPa, and the powder particles with smooth surface can be obtained on this basis and used in powder metallurgy. Since the water atomization method uses higher density water as the atomization medium, the condensation speed achieved is orders of magnitude higher than that of the general gas atomization method, so the powder shape obtained is generally irregular.
Mechanical alloying powdering technology is a method of preparing alloy powder or composite powder from element powder. It is completed in a high-energy ball mill and requires long-term grinding between powder particles and between powder particles and grinding balls. The powder will be broken and torn. The ultrafine powder preparation technology in powder metallurgy, due to the small particle size, the powder prepared by this technology has significantly different physical, chemical and mechanical properties.