Abstract
Microstructural development of $Si_3N_4$/20 vol% SiC nanocomposites doped 2 wt% $Al_2O_3$ and 6 wt% $Y_2O_3$ as sintering additives were analyzed by sintering interruption. Density of samples was significantly increased between $1500^{\circ}C$ and $1700^{\circ}C$, and near full density was achieved at $1800^{\circ}C$. Transformation rate from $\alpha-Si_3N_4$ to $\betha-Si_3N_4$ was increased at $1700^{\circ}C$ and $1800^{\circ}C$, and then elongated matrix grains were appeared. Small size SiC particles had suppressive effect on densification rate and transformation of $Si_3N_4$ phase.
소결조제로 2 wt % $Al_2O_3$와 6 wt% $Y_2O_3$를 첨가한 $Si_3N_4/20$ vol % SiC 초미립복합 재료의 고온가압소결 중의 미세구조 발현과정을 sintering interruption법으로 관찰하였다. 밀도는 $1500^{\circ}C$와 $1700^{\circ}C$ 사이에서 빠르게 증가하였으며, $1800^{\circ}C$ 에서 이론밀도에 가깝게 치밀화하였다. 질화규소의 상전이 속도는 $1700^{\circ}C$와 $1800^{\circ}C$에서 증가하였으며, 길게 자란 기지상결정립들이 나타났다. 작은 입경의 SiC는 치밀화속도와 기지상 상전이를 억제하는 효과를 보였다.
