A Reaction Engineering Study on SiC Whisker Growth Control by High Temperature Masking of Substrate Surface

点击翻译按钮获取中文摘要

For the development of a low cost mass production process of SiC whiskers a new process concept was developed, where previous knowledge was summarized and systematically applied for the selective growth of thick whiskers. In this work fundamental data were taken for the development. In the present experiment constructed was a vertical tube reactor mounted with a continuous feeder, a continuous SiO gas radiator(1400ﾟC)and a SiO whisker growth section(1400-1600ﾟC)in which the substrates with implanted catalyst particles were placed. The composition of catalysts, gas flow rate, SiO generation rate and growth direction in relation with the gravity were investigated. Successful holding of a catalyst drop of 50 gm in diameter was established when SiO_2/C Composite particles and CH_4+Ar gas were fed in a rate of 0.0258/min and 400 ml/min, respectively. After 10 hours obtained was a linear whisker of 25mum thick and lOOmum long. However, for instance, most of the whiskers grown from 37 catalysts drops placed on a substrate had defects and kinks. To cope with such problems fundamental data were collected regarding operating factors. From SCM photographs of the products the following information was obtained :(1)By the presaturation of catalyst drops the induction period of whisker growth can be shortened and both evaporation loss of catalyst and secondary nucleation can be prevented ; (2)Increased SiO concentration and decreased gas flow rate improve the whisker growth rate ; and(3)The effect of gravity is not very significant. Although the very factor that controls the kink formation has not yet made clear, it was confirmed that thick and long SiC whiskers can be raised on the substrate SiO radiation system from the presaturated catalyst with the present continuous