High-purity tungsten powder has the purity of at least 99.99%, with chemical purity from 99.99%~99.9999%; the content of impurity elements in it should be among (0.1～1000)×10-12, however, as for the some special elements like radioactive, alkali metal, heavy metals and gas elements ect., their content of will be special required respectively. The products of high-purity tungsten powder are high purity tungsten bar, rod, electrode, wire, sheet, plate, and pure tungsten and titanium tungsten sputter targets material ect..
Preparation of High-purity Tungsten Powder
The preparation methods of high purity tungsten powder are powder metallurgy, smelting and chemical vapor deposition method and others.。
1. Powder metallurgy method is heating tungsten powder up to a temperature below its melting point after formed, then going through migrate to realize the process of densification, and eventually obtained tungsten blank or some simple shape of tungsten products.
2. Melting method refers to the process of heating tungsten raw material to a temperature above its melting point to form a liquid phase and removing impurities, cooling, solidifying to realize densification; while according to the different means used, the specific methods are vacuum consumable arc melting, electron beam melting and plasma beam melting method.
3. Chemical vapor deposition method (CVD) refers to the process of reducing tungsten compound gas (typically of WF6) at a certain temperature in H2 atmosphere, then deposing tungsten on a particular substrate, and removing the base material after the deposition completed to obtain a dense tungsten blank or products.
Usage of High-purity Tungsten Powder
High-purity tungsten powder can be used in special high-temperature devices which has high require in the property and server life of the material, also used as pure tungsten added in precision alloy foundry; in addition, the high-purity tungsten powder and its silicide can be used for large scale integrated circuit as the resistance layer and diffusion barrier layer ect., and as door material and connecting material metal in metal-oxide-semiconductor transistors.