| 저가의 $beta$-상 분말을 사용한 질화규소의 소결 및 기계적 특성 |
| 박우윤, 박동수, 김해두, 한병동 |
| 한국기계연구원 세라믹재료그룹 |
| Sintering and Mechanical Properties of Silicon Nitride Prepared with a Low-cost Silicon Nitride Powder |
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| ABSTRACT |
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A refractory grade low-cost silicon nitride powder was chemically analyzed, purified, and gas pressure sintered with the sintering additives. As-received powder contained a significant amount of free-Si, 0.72 wt% of Fe, 0.5 wt% of al and 0.31 wt% of Ca. Oxygen and carbon contents of the powder were 3.3 wt% and 0.4 wt%, respectively, and it consisted of 96% of $beta$-phase and 4% of $alpha$-phase. After lowering the Fe content and nitriding treatment, the powder was sintered with 6 wt% yttria and 2 wt% alumina for 1 h between 1823 K and 2123 K in order to examine the sintering behavior. Fully dense samples were obtained by sintering at 2123k for 2h. For comparison, a commercially available high-grade powder was also sintered at the same time. The low-cost powder showed much slower densification rate than the high-grade powder. Fully dense sample prepared from the low-cost powder contained a number of coarse grains with a low aspect ratio, and its hardness, fracture toughness, flexural strength and thermal shock resistance were not as good as those of the sample prepared with the high-grade powder. |
| Key words:
Low-cost silicon nitride, Sintering, Microstructure, Mechanical properties, Thermal shock |
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