Cemented carbide sintering is the most basic and critical process in the production process. Traditional sintering methods include hydrogen sintering, vacuum sintering and hot isostatic pressing.
1.Hydrogen Sintering
Put the compact in a graphite boat, then fill it with alumina filler or graphite particle filler with a certain carbon content, put it into a continuous propelling molybdenum wire furnace, and sinter it under the protection of hydrogen. The sintering process is carried out under positive pressure, and the pores inside the product cannot be fully eliminated, leaving residual pores, and oxide impurities cannot be volatilized and removed well.
2.Vacuum Sintering
Vacuum sintering is the process of sintering and pressing in a negative pressure gas medium. Compared with hydrogen sintering, vacuum sintering can improve the purity of furnace gas, and the negative pressure can improve the wettability of the bonded relative hard phase. The method can exclude impurities and improve alloy purity, density and mechanical properties.
3.Hot Isostatic Pressing
This method can well eliminate the defects and pores between the particles inside the material, and improve the density and strength of the material. The main process is: first put the powder compact and the powder body (that is, the powder package) in the special container into the high-pressure container of the hot isostatic press, and then apply high temperature and high pressure to make the powder pressed and sintered into a dense parts or materials.
