Cemented carbides are metal materials made of carbides of one kind or several kinds of refractory metals and binding metals with powder metallurgy method.

Cemented carbide sintering is to compress the powder into blanks, put them to the sintering furnace, heat to certain temperature (sintering temperature), keep for some time (preservation temperature) and cool them to get cemented carbides with required performances.

The sintering process of cemented carbides can be divided into four basic phases:
1: Removing molding agent and pre-sintering phase, which will take on the following changes:
Removing molding agent: As the temperature rises in the beginning phase, the molding agent is gradually dissolved or vaporized and discharged from the sintered body. Meanwhile, the molding agents will more or less increase carbon to the sintered body. The increasing amount will changes as the types, amount and sintering process differ.
Oxides on the surface of powder are reduced. At sintering temperature, hydrogen can reduce cobalt oxide and tungsten oxide. If vacuum molding agent removing and sintering are carried out, carbon and oxygen reaction is not so fierce. The contact stress between powder grains is eliminated gradually and the binding metal powder begins restoration and recrystallization; surface expansion begins and compression strength is improved.

2: Solid Phase Sintering Phase (800℃-eutectic temperature)
At the temperature before liquid phase occurs, solid phase reaction and expansion are increased, plastic flowing is strengthened and sintered body is shrinking obviously besides of carrying out processes occurred in last phase.

3: Liquid Phase Sintering Phase (temperature-sintering temperature)
When the liquid phase appeared in the sintered body, the shrinking will be finished quickly. Then crystallization will occur to form basic organization and structures.

4: Cooling Phase (sintering temperature-room temperature)
In this phase, the alloy organization and phase elements will take on some changes as the cooling conditions differ, which can be made use of to carry out cemented carbide thermal treatment to improve its physical mechanical performances.