Investigation of Loss Weight and Densification of SiC-Al_2O_3-Y_2O_3 Ceramic Composite on Sintering

摘要

α-SiC, Al2O3 and Y2O3 powders were all used as raw materials. The SiC-Al2O3-Y2O3 ceramic composites were made by pressureless liquid phase sintering technology. The effects of sintering temperature, loss weight and coordination number on sintering densification were studied. The reason for producing loss weight on sintering was analysed. The results show that the primary reason for producing loss weight on sintering in SiC-Al2O3-Y2O3 ceramic composite was that chemical reactions between SiC and Al2O3 are happened during sintering, and given out volatile gases. If sintering temperature is excessively lower, grain size would be finer, and coordination number would be higher, well then material would be on no sintering densification. If sintering temperature is excessively higher, grains would grow up, though small coordination number would benefit to make pore eliminate and shrink, but coarse microstructure would also block gliding and resetting of grains, together affected by expansion stress from volatile gas, the material densification would instead go down. Only under the sintering process of 1850 ℃ for 30 min, material densification is better, and the mechanical property of ceramic composites is also improved.