Briefly, the removal of the forming agent and the change in the sintered body during the calcination phase are:
Kunshan CNC Machining Kunshan Bojie Lien Precision Electronics Co., Ltd. reminds you to remove the molding agent. As the temperature increases, the molding agent gradually decomposes or vaporizes, eliminating the sintered body. At the same time, the molding agent is more or more Less carbon is added to the sintered body, and the amount of carbon added will vary depending on the type and amount of the molding agent and the sintering process.
The surface oxide of the powder is reduced. At the sintering temperature, hydrogen can reduce the oxides of cobalt and tungsten. If the molding agent is removed by vacuum and sintered, the carbon-oxygen reaction is not strong. The contact stress between the powder particles is gradually eliminated, the bonded metal powder begins to recover and recrystallize, surface diffusion begins to occur, and the strength of the compact is increased.
2, solid phase sintering
In general, the temperature required for the solid phase sintering stage is 800 ° C - eutectic temperature. At the temperature before the liquid phase appeared, in addition to the process that occurred in the previous stage, the solid phase reaction and diffusion were intensified, the plastic flow was enhanced, and the sintered body showed significant shrinkage.
3, liquid phase sintering
In general, the temperature required for the liquid phase sintering stage is 800 ° C - the eutectic temperature is also the sintering temperature.
When the sintered body exhibits a liquid phase, the shrinkage is quickly completed, followed by a crystallization transition to form the basic structure and structure of the alloy.
There is not much demand for the cooling problem, room temperature can be.
At this stage, the microstructure and phase composition of the tungsten steel fittings vary with the cooling conditions, and this feature can be utilized to heat treat the tungsten steel fittings to improve their physical and mechanical properties.