维氏压痕对常压固相烧结碳化硅陶瓷材料力学性能的影响

Effects of Vickers Cracks on the Mechanical Properties of Solid-phase-sintered Silicon Carbide Ceramics

为了研究维氏压痕裂纹对常压固相烧结碳化硅陶瓷(SSiC)材料力学性能的影响,通过扫描电镜观察了0.1～100 N的压痕载荷下产生的表面裂纹及裂纹剖面的状况,并测试了相应载荷下的力学性质,探讨了压痕法测量SSiC材料硬度、韧性等力学性质的适当压力载荷.结果表明,SSiC材料压痕裂纹起始的临界压力载荷介于0.1～0.2 N;当压痕载荷小于0.5 N时,裂纹尺寸小于5μm,SSiC材料的平均弯曲强度受影响程度较小.此外,当压痕载荷为10 N以上时,压痕法测得的维氏硬度值趋近定值,且所得到的裂纹是半圆形裂纹,因此,10 N为采用压痕法准确测量SSiC材料硬度及韧性的最低压痕载荷值.

In order to study the effects of Vickers cracks on the mechanical properties of solid-phase-sintered silicon carbide （SSiC for short） ceramics, the indentation cracks and the crack profiles were observed after loading 0.1-100 N loads on the SSiC samples by SEM. The critical indentation load for Vickers crack initiation in SSiC ceramics lies between 0.1 N and 0.2 N. Indentations by loads lower than 0.5 N have limited influence on bending strength. And if the indentation loads is higher than 10 N, the obtained hardness floats around 24.2 GPa and the cracks are half-coin type. The proper Vickers indentation load range for SSiC ceramic hardness and toughness tests are determined to be 10 N or above.