Key factors for sintering:
(1) Sintering temperature and time
The sintering temperature and time affect the porosity, density, strength and hardness of the sintered body. If the sintering temperature is too high and the time is too long, the performance of the product will be reduced, and even over-burning defects of the product will occur; if the sintering temperature is too low or the sintering time is too short, the performance of the product will be degraded due to under-burning.
(2) Sintering atmosphere
The sintering atmospheres commonly used in powder metallurgy include reducing atmosphere, vacuum, hydrogen atmosphere, etc. The sintering atmosphere also directly affects the properties of the sintered body. Sintering in a reducing atmosphere prevents burnout of the compact and reduces surface oxides. For example, iron-based and copper-based products often use producer gas or decomposed ammonia, and cemented carbide and stainless steel often use pure hydrogen. Vacuum sintering can be used for active metals or refractory metals (such as beryllium, titanium, zirconium, tantalum), hard alloys containing TiC and stainless steel. Vacuum sintering can avoid the adverse effects of harmful components (H2O, O2, H2) in the atmosphere, and can also reduce the sintering temperature (generally reduce100-150°C).