The Microstructure of the Reaction -Bonded <TEX>$Si_3N_4$</TEX> Formed in the Various Atmosphere

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J. Korean Ceram. Soc. > Volume 23(5); 1986 > Article

Journal of the Korean Ceramic Society 1986;23(5): 61.

질화분위기에 따른 반응결합 질화규소의 미세구조변화

박지연, 김종희

한국과학기술원 재료공학과

The Microstructure of the Reaction -Bonded $Si_3N_4$ Formed in the Various Atmosphere

ABSTRACT

The gas mixtures ($H_2$/$N_2$, He/$N_2$) having a high thermal conductivity allow the heat generated by the nitriding exotherm to be dissipated from the compact in to the nitriding atmosphere permitting a more accurate control of temperature and produces a more uniform microstructure. In order to observe the effect of the mixed gas atmosphere on the microsturcture of RBSN. the specimen was nitrided in the mixed gas atmosphere which was containe up to 50vol% $H_2$ or He for 0-12 hrs at 135$0^{circ}C$. The addition of hydrogen to nitrogen gas resulted in the growth of a-needle at the early stage of nitrding increase of the reaction rate and a finer and more uniform microstructure. in case of the addition of helium the behaviour of reaction was similar to the one with pure nitrogen. As the amount of helium was increased a coarse microstructure was formed.