原料粉体纯度对SiC陶瓷材料显微组织及烧结行为的影响OA

In order to explore the effect of raw material powder purity on the microstructure evolution and sintering behavior of SiC ceramics,SiC ceramics were prepared by pressureless sintering with different purity SiC powders as raw materials and B4C and C as sintering aids.The sintering behavior of SiC powders with different purities,the microstructure,and the mechanical properties of ceramics were studied.The results show that improving the purity of SiC powder can reduce the sintering activation energy of the powder and decrease the emission of gases during the sintering process,which is beneficial for the sintering densification of SiC ceramics.Improving the purity of SiC powder can refine the grain size of SiC ceramics and enhance the uniformity of the microstructure.When the purity of the powder(mass fraction,the same below)reaches 98.80％,the average grain size of SiC ceramics is 5.2 μm.At this point,the relative density is 98.50％,flexural strength is(379±36)MPa,fracture toughness is(5.0±0.6)MPa·m1/2,and Vickers hardness of the ceramics is(26.4±0.6)GPa,respectively,which are 2％,57.2％,19.0％,and 16.3％higher than those of ceramics with a purity of 96.5％SiC powder.The improvement of the purity of SiC powder can reduce the internal pores of the material and refine the grains,which is the main reason for the improvement of the mechanical properties of SiC ceramics.