陶瓷的断裂韧性与缺口半径　Ⅰ.断裂韧性测试技术

Fracture Toughness of Ceramics and Notch Radius Ⅰ. Fracture Toughness Testing Technique

本文用一种新的简单方法制备了不同半径的尖缺口，用单边切口梁试件测试了不同缺口半径氧化铝陶瓷的断裂韧性.对七种不同测试方法测得的、同一种材料的断裂韧性进行了对比，讨论陶瓷材料断裂韧性的最佳测试方法和测试中对缺口半径的要求.

The dependence of Kic on the notch-root radius was tested with the notch radius as small as a few micrometers in a polycrystalline alumina ceramics. The results show that the fracture toughness decreases as the notch radius decreases, when the notch radius approximately equal, to or lowcr than the average grain diameter, the fracturc tonghness becomes constant, this implies that the critical notch tip radius has the same sizc as the average grain diameter. The fracture toughness of a same alumina was also tested by seven different methods, i.e. bridge indentation, compressive cyclic fatigue, precrack before sintered and polished sharp notch methods with the SENB specimens; wedgc press and precrack before sintered methods with DCB specimens; indentation method with disc. The results show that SENB specimens with polished sharp notch or compressive cyclic fatigue precrack yield the true KIC value.