Popis: |
Fracture resistance and fatigue behavior of two kinds of gas pressure sintered silicon nitride ceramics were studied. Indentation fracture, indentation strength and indentation and crack growth measurements, that are very useful to evaluate fractures from small cracks, were carried out to characterize crack growth resistance. The results indicated that the crack propagation resistance (R-curve behavior) is distinctively different between the two materials. From the observation of crack extension path, it was considered that the R-curve behavior is due to the grain bridging of elongated β-Si3N4 grains. |