Thermal Decomposition of <TEX>$beta$</TEX>$-Sialon by Graphite

,; ,; ,; ,; ,; ,; ,; ,

J. Korean Ceram. Soc. > Volume 24(5); 1987 > Article

Journal of the Korean Ceramic Society 1987;24(5): 453.

이연에 의한 $beta$$-사이알론의 열분해

최상흘, 이희철¹, 이종진, 서규식

인하대학교 무기재료공학과
¹인하대학교 화학공학과

Thermal Decomposition of $beta$$-Sialon by Graphite

ABSTRACT

β'-sialon(Z=2.7) specimens with <30%wt. graphite as a reducing agent were decomposed at 1350°up to 1,450℃ under the atmosphere of 90% N2-10%H2. The decomposition of β'-sialon was calculated from the change in Z-value, and the formation of new minerals was identified from X-ray diffraction patterns. The decomposition reactions of sialon were considered to yield a stable sialon close to β-silicon nitride and some aluminum compounds according to the following equations; β'-sialon(s)＋C(s)＋N2(g)→β2-sialon(metastable)＋β3-sialon(stalbe phase) β2-sialon(s)＋C(s)＋N2(g)→β3-sialon(s)＋AlN(s)＋α-Al2O3(s)＋15R(s)＋SiO(g)＋Al2O(g)＋CO(g) Z-value; β2( 3.5)>β'( 2.7)>β3( 0.5) The decomposition rate of sialon was controlled by two mechanisms ; One was characterized by the interface area of contact, corresponding to an apparent activation energy of 50.5Kcal/mol in the initial stage, and the other by the diffusion, corresponding to that of 104.3Kcal/mol in the final stage of the decomposition.