Fracture Resistance and Wear Properties of Silicon Nitride Ceramics

摘要

Six kinds of silicon nitrides with different microstructures were fabricated by changing the amount of sintering additives, Al_2O_3 and Y_2O_3. The hardness decreased with an increase in the amount of additives, whereas the indentation fracture resistance increased in the samples with large amount of additives due to the formation of coarse and elongated grains. The wear property of various Si_3N_4 ceramics was investigated in the sliding contact test without lubricant and was compared with the mechanical properties. The specific wear rate varied notably from 4×10~(-4) to 6×10~(-6) mm~(-3)N~(-1)m~(-1) depending on the compositions, which was difficult to explain directly from the hardness and fracture resistance. An indentation fracture model for material removal could correlate the wear properties with a function of hardness and fracture resistance of the materials, suggesting that the indentation model was likely to be valid for analyzing the wear behavior in this study.