Thermoelectric Conversion Characteristics of SiC Ceramics Fabricated from 6H-SiC Powder

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J. Korean Ceram. Soc. > Volume 27(3); 1990 > Article

Journal of the Korean Ceramic Society 1990;27(3): 412.

6H-SiC로부터 제작한 SiC 세라믹스의 열전변환 특성

배철훈, Kunihito Koumoto, Hiroaki Yanagida¹

동경대학공업부공업화학과
¹동경대학선단과학기술연구

Thermoelectric Conversion Characteristics of SiC Ceramics Fabricated from 6H-SiC Powder

ABSTRACT

Porous SiC ceramics were proposed to be promising materials for high-temperature thermoelectric energy conversion. Throughthe thermoelectric property measurements and microstructure observations on the porous alpha SiC and the mixture of $alpha$-and $beta$-SiC, it was experimentally clarified that elimination of stacking faults and twin boundaries by grain growth is effective to increase the seebeck coefficient and increasing content of $alpha$-SiC gives rise to lower electrical conductivity. Furthermore, the effects of additives on the thermoelectric properties of 6H-SiC ceramics were also studied. The electrical conductivity and the seebeck coefficient were measured at 35$0^{circ}C$ to 105$0^{circ}C$ in argon atmospehre. The thermoelectric conversion efficiency of $alpha$-SiC ceramics was lower than that of $beta$-SiC ceramics. The phase homogeneity would be needed to improve the seebeck coefficient and electrical conductivity decreased with increasing the content of $alpha$-phase. In the case of B addition, XRD analysis showed that the phase transformation did not occur during sintering. On the other hand, AlN addiiton enhanced the reverse phase transformation from 6H-SiC to 4H-SiC, and this phenomenon had a great effect upon the electrical conductivity.