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Vol.35, No.12, 1710 ~ 1716, 1997
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| Title |
| Effects of Reduction Temperature on the Reduced Powder Morphology and Sintering Behavior of Mechanically Mixed WO3-CuO Composite Powder |
| 이성 , 백운형 , 천병선 Seong Lee , Woon Hyung Baek , Byung Sun Chun |
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| Abstract |
| It is known fact that the presence of each element in insoluble system like W-Cu does not influence the mutual reduction process. Therefore, reduction is generally carried out at lower temperature in order to gain smaller particle size. However, in a nano sized mechanically mixed WO₃-CuO system, grain growth of tungsten particle and distinct solid state sintering are observed during reduction process. This implies the possibility of change of powder morphology by diffusion during reduction. This study is focused on scanning electron microscopy and dilatometry in order to investigate the effects of reduction temperature not only on the reduced powder morphology but also on the sintering behavior. It is observed that powder gets smaller and more round upto reduction temperature 980℃ due to breakage of composite powder and solid state sintering. As reduction temperature exceeds 980℃, the powder begins to grow once again. These results are well in agreement with the dilatometry experiments. In W-Cu system, sintered density is almost always determined by the rearrangement stage, which is determined by the powder size and its morphology. This dilatometry experiments show that the densification of reduced W-Cu powder is largely depended on the reduction temperature and shows the best at 980℃. |
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