| Lots of engineering components have been produced by the powder metallurgy, especially for high melting point materials such as refractory metals and ceramics. Reduction in sintering temperature and/or sintering time results in reduced energy consumption and improved material properties in the powder metallurgy. Tungsten is a refractory metal and it is hard to obtain a full density sintered body. Main objective of this study is to make a high density tungsten sintered body at the reduced sintering temperature. Sintering is an interfacial phenomenon between contacting particles and it is a thermally activated process. In this regard, interface activations by both process and metallurgical aspects were considered. In the former process aspects, pulsed current directly passing through conductive particle surface makes Joule heating, micro-arcing, and electro-migration which are advantageous for enhancing mass flow during sintering. In the latter, it is well-known that the sintering temperature of nano-particles can be markedly reduced by the size effect. Tungsten nano-particles were synthesized by the pulse wire explosion process and then they were blended with micro-sized tungsten particles. In such a case, it could be proved that nano-particles existing at the interfaces between micro-particles played a homogeneous sintering activator when compared with other conventional irregular micro-particles and spheroidized micro-particles. |
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