Why reduce the oxygen content of tungsten powder?
Nano-tungsten powder has the characteristics of small size effect, surface effect, quantum size effect and macroscopic quantum tunneling effect, so it has broad application prospects in catalysis, light filtering, light absorption, magnetic media and new materials. However, the use of powders is limited by the presence of a certain oxygen content.
Specifically, the embrittlement caused by oxygen in tungsten and cemented carbides is used for oxygen segregation on the crystal surface, which reduces surface energy and leads to intergranular fracture. From the macroscopic point of view, the increase of oxygen content will reduce the tensile strength of tungsten products and cemented carbide, resulting in cracking. Cracking tungsten products will reduce the comprehensive performance, such as shielding performance, impact resistance and so on.
Therefore, it is necessary to prepare spherical tungsten powder with low oxygen content. And for additive manufacturing applications, the lower the oxygen content, the more times the powder can be reused. In essence, it can reduce the use of raw materials, reduce the cost, and improve the quality of 3D printing products.
The factors affecting the oxygen content of spherical tungsten powder are particle size. Generally speaking, the smaller the particle size, the greater the oxygen content; On the contrary, the larger the particle size, the smaller the oxygen content. But in the actual production, in addition to the oxygen content, but also to consider particle size, carbon content and other factors.
Particle size is also the key factor that causes crack and fracture of carbide and tungsten products. Under normal circumstances, the larger the size of tungsten powder, the coarser the alloy grain, the more likely to crack.
As the key raw material of tungsten powder production, the quality of tungsten oxide is very important, which directly determines the particle size, particle size distribution, impurity element content and morphology of tungsten powder. Purple tungsten oxide is more suitable for ultrafine powder.
