Sintering is a key step in the decision carbide microstructure and properties, but also directly affect the performance of the tungsten carbide knives material. During the sintering process is important to note two issues, the sintering temperature control and control of grain size. How to reach the alloy at the sintering temperature as low as possible and fully dense grain growth during sintering is the development direction of the reasonable control of sintering technology. The following summarizes several new tungsten carbide knives sintering technology.
1. Spark Plasma Sintering
Spark Plasma Sintering (SPS) is a new tungsten carbide knives sintering technology, which directly between the particles pass through the heating pulse current sintering. In the SPS sintering process, a plasma discharge electrode through the instant when the pulse current generated by the DC, so that the individual particles inside the sintered body itself generates Joule heat uniformly and surfactant particles, the use of self-heating within the particles is sintered. This discharge direct heating, high thermal efficiency, the discharge point can be dispersed to achieve uniform heating, and therefore easy to prepare a homogeneous, dense, high-quality sintered body. Due to the fast heating rate, skip the surface diffusion process, effective control of tungsten carbide knives materials grain size.
2. Microwave Sintering
By interaction with the microwave microwave sintering the sintered material sintered tungsten carbide knives material inside atoms, molecules or ions kinetic energy increases, so the sintered material decreases the activation energy, the diffusion coefficient is increased, enabling low temperature rapid sintering, i.e. fines already too late to grow by sintering, is an effective means to create fine-grained materials. Microwave sintering has several advantages: significant reduction in the sintering temperature up to 500 ℃; reduce energy consumption; shorter sintering time and increase density, grain refinement. But the microwave sintering process prone to thermal runaway effect, the sintered body is heated unevenly, thus affecting product performance.
3. Other sintering methods
In addition to the above-described sintering technology, there are some new sintering technology has been developed. Such as laser sintering, two stages of sintering, hot extrusion sintering sintering methods. Forging sintering can effectively eliminate the gap by high temperature plastic powder. The sintering process can be refined grains to some extent, to obtain a dense tungsten carbide knives materials.