Mechanical Properties of Hot-Pressed SiC with Rare-Earth Oxide

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J. Korean Ceram. Soc. > Volume 37(2); 2000 > Article

Journal of the Korean Ceramic Society 2000;37(2): 158.

희토류 산화물을 첨가한 일축가압소결 탄화규소의 기계적 특성

최철호, 이충선¹, 박광자, 조덕호¹, 김영욱²

기술표준원
¹요업기술원
²서울시리대학교 재료공학과

Mechanical Properties of Hot-Pressed SiC with Rare-Earth Oxide

ABSTRACT

Six different SiC ceramics with SiO2-Re2O3 (Re=Yb, Er, Y, Dy, Gd, Sm) as sintering additives have been fabricated by hot-pressing the SiC-Re2Si2O7 compositions at 1850$^{circ}C$ for 2 hr under a pressure of 25 MPa. The room temperature strneth and the fracture toughness of the hot-pressed ceramics were characterized and compared with those of the ceramics sintered with YAG (Y3Al5O12). Five SiC ceramics (Re=Yb, Er, Y, Dy, Gd) investigated herein showed sintered densities higher than 94% of theoretical. Tthe SiC-Re2Si2O7 compositions showed lower strength and comparable toughness to those from SiC-YAG composition, owing to the chemical reaction between SiO2 and SiC during sintering. SiC ceramics fabricated from a SiC-Y2Si2O7 composition showed the best mechanical properties of 490 MPa and 4.8 MPa$.$m1/2 among the compositions investigated herein.

Key words: Silicon Carbide, Silica, Rare-Earth Oxides, Mechanical Properties