原位合成MoSi_2反应烧结SiC-MoSi_2复合材料

Reaction-bonding preparation of SiC - MoSi_2 composites using in-situ synthesized MoSi_2

将Mo粉和Si粉按1:2的摩尔比,在聚乙烯球磨罐中球磨混合4h,然后与SiC粉按不同的比例配料,加入少量的Al_2O_3微粉和活性炭粉,再共磨混合24h;然后在20MPa的压力下压制成型,在1650℃下、氮气气氛中烧结,保温1h后自然冷却至室温。采用XRD、SEM和EDAX等手段对反应产物的物相组成、组织结构和微区成分进行了分析,结果表明:原位合成MoSi_2反应烧结SiC-MoSi_2复合材料由SiC、MoSi_2以及少量的残余硅组成;其显微组织结构疏松,颗粒堆积呈蜂窝状。根据实验结果,讨论了复合材料显微结构的形成机制,并着重对MoSi_2颗粒聚集区中的空心粒子及其周围分散的小气孔的形成机制进行了阐述。

The powders of Mo and Si were mixed in atomic ratio of Si/Mo = 2 in a polythene pot for a period of 4 h. These powders were blended with SiC,AI2O3 and activated carbon in the desired ratio in the polythene pot for a period of 24 h. Forming pressure of the mixture powder was 20 MPa. The compacted specimens were fired in argon atmosphere at 1650 ℃.then cooled in the natural condition after holding in the sintering temperature for 1 h. The microstructure and phase composition of the in-situ synthesized MoSi2 -SiC composites were studied. The results indicate that there are silicon carbide and molybdenum disilicide and a little of remained silicon phase in the composites. The particles in the composites are weakly jointed,and packed up in shape of honeycomb. According to the experimental result,the forming mechanism of micro-structure was discussed,especially that of hollow particles of MoSi2.