An investigation on the in situ synthesis-sintering and mechanical properties of MoSi2-xSiC composites prepared by spark plasma sintering

Composites of MoSi2-x wt.% SiC (x = 5, 10, 15, 20) prepared using spark plasma sintering. The effect of temperature on the in-situ synthesis-sintering was investigated between 1100 degrees C and 1500 degrees C. X-ray diffraction patterns showed that at 1100 degrees C the reactions were incomplete and elementary diffraction peaks of Mo, Si and C still exist. With an increase in temperature from 1100 to 1300 degrees C the reactions were performed completely. The study showed that the sintering ability at higher temperature at the presence of enough mechanical pressure was better because the heat released from the reaction between Mo, Si and C causes higher temperature than the melting point of Si (1410 degrees C). Consequently the silicon would melt during the heating process. The molten Si can strengthen the interconnections and it has higher diffusion rate. Therefore, due to the liquid phase sintering and at the presence of mechanical pressure, the sintering ability at higher temperature is better than lower temperature. Scanning electron microscopy showed that with the addition of carbon, there was no silica phase in the microstructure of the synthesized samples, due to the formation of SiC Therefore, it can be noted that the addition of carbon leads to better mechanical properties due to elimination of silica phase. (C) 2014 Elsevier Ltd. All rights reserved.