| 가열이력 제어에 의한 $Si_3N_4$ 미분말 시편의 급속가열 |
| 이형직 |
| 강릉대학교 재료공학과 |
| Rapid Heating of Ultrafine $Si_3N_4$ Powder Compacts under the Controlled Thermograms |
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| ABSTRACT |
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The sintering and renitridation behaviors of ultrafine Si3N4 powder compacts, which were heavily oxidized and/or free-Si rich, were investigated with particular attentiion to microstructures. The specimens were heated without restoring to additives and pressure by controlling heating process attained a Xe image apparatus. The effect of particle size, free-Si contents, decomposition and renitridation, were investigated. When fired to 1$650^{circ}C$ within 15 sec and then immediately held at 135$0^{circ}C$ for 10min N2 atmosphere, significant densification took place in the limited region, in addition to decreasing oxygen contents to less than 0.3wt%. On the other hand, specimens decomposed due to overheating at the initial stage were rapidly renitridated at the relatively lower temperature of the holding stage. And, then, the activation energy for the renitridation was calculated to be 49kcal/mole. |
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