Synthesis of Silicon Carbide Whiskers (I) : Reaction Mechanism and Rate-Controlling Reaction

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J. Korean Ceram. Soc. > Volume 35(12); 1998 > Article

Journal of the Korean Ceramic Society 1998;35(12): 1336.

탄화규소 휘스커의 합성(I) : 반응기구의 율속반응

최헌진, 이준근

Synthesis of Silicon Carbide Whiskers (I) : Reaction Mechanism and Rate-Controlling Reaction

ABSTRACT

A twt -step carbothermal reduction scheme has been employed for the synthesis of SiC whiskers in an Ar or a H2 atmosphere via vapor-solid two-stage and vapor-liquid-solid growth mechanism respectively. It has been shown that the whisker growth proceed through the following reaction mechanism in an Ar at-mosphere : SiO2(S)+C(s)-SiO(v)+CO(v) SiO(v)3CO(v)=SiC(s)whisker+2CO2(v) 2C(s)+2CO2(v)=4CO(v) the third reaction appears to be the rate-controlling reaction since the overall reaction rates are dominated by the carbon which is participated in this reaction. The whisker growth proceeded through the following reaction mechaism in a H2 atmosphere : SiO2(s)+C(s)=SiO(v)+CO(v) 2C(s)+4H2(v)=2CH4(v) SiO(v)+2CH4(v)=SiC(s)whisker+CO(v)+4H2(v) The first reaction appears to be the rate-controlling reaction since the overall reaction rates are enhanced byincreasing the SiO vapor generation rate.

Key words: Silicon Carbide Whiskers, Two-step Carbothermal Reduction, Reaction Mechanism, Rate-Controlling Reaction