高温高压下金刚石/碳化硅体系烧结反应机理研究

Reaction mechanism of diamond-silicon carbide systems under high pressure and high temperature

本文研究了微米级金刚石与硅粉在高温（800-1 200℃）高压（5.1 GPa）下的反应机理。通过对金刚石与硅粉反应过程的研究,发现微米级金刚石与硅粉在硅熔点以下发生了反应;并指出高温高压下微米金刚石与硅粉的反应分为两个阶段：硅未熔化前的金刚石与硅的反应,硅熔化后的金刚石与硅、石墨与硅的反应。最后提出了一种新的合成金刚石/碳化硅复合材料的工艺,即采用高压熔渗法合成金刚石/碳化硅复合材料时,在温度略高于硅熔点之后保温一段时间,再升温到合成材料的设定温度,可以合成出结构更加均匀的、高质量的金刚石/碳化硅复合材料。

The reaction mechanism of micron diamond and silicon powder at 800~1200 ℃ and 5.1 GPa was studied.Based on the phase composition analysis,it is found that micron diamond and silicon have reacted below the melting point of silicon.The authors proposed that,the reaction of micron diamond and silicon powder under HT-HP was realized through two steps.The first step is the reaction between diamond and silicon under the melting point of silicon;The second step is the reaction between silicon and diamond,and that between silicon and graphite above the melting point of silicon.Finally,a new technique for synthesizing diamond / SiC composite materials——infiltration sintering at HP is presented,by this method we firstly hold temperature above the melting point of silicon for a certain time,then rising the temperature to the set sintering temperature of composite materials,at last we can get more uniformly structured diamond / silicon carbide composite materials.