Effect of <TEX>$Al_2O_3$</TEX> on Hot-Press of <TEX>${alpha}-SiC$</TEX> and Mechanical Properties

,; ,; ,; ,; ,; ,

J. Korean Ceram. Soc. > Volume 28(7); 1991 > Article

Journal of the Korean Ceramic Society 1991;28(7): 561.

알루미나의 첨가가 ${alpha}-SiC$의 가압소결 및 기계적 성질에 미치는 영향

이수영, 고재웅, 김해두

한국기계연구소 요업재료실

Effect of $Al_2O_3$ on Hot-Press of ${alpha}-SiC$ and Mechanical Properties

ABSTRACT

Submicron ${alpha}-SiC$ powder with $Al_2O_3$ addition was hot-pressed under the controlled heating and pressurizing schedule. $SiO_2$ layer on ${alpha}-SiC$ powder was effective for the sintering of ${alpha}-SiC$ powder when $Al_2O_3$ was used as an additive. Applying of pressure under the controlled schedule accelerated the rearrangment of SiC grains, yielding 98% of theoretical density of SiC even at $1900^{circ}C$. Flexural strength of the specimen containing 2 wt% $Al_2O_3$ was increased as increasing the hot-pressing temperature up to $2050^{circ}C$ and maximum value was 800 MPa, while the flexural strength of the specimen containing 10 wt% $Al_2O_3$ was decreased as increasing the hot-pressing temperature above $2000^{circ}C$ due to the formation of continuous grain boundary phase. Fracture toughness of the specimens was in the range of $3.5~4.5;MNm^{-3/2}$ regardless of the amount of $Al_2O_3$ addition.