显微结构对Sialon陶瓷室温疲劳短裂纹扩展行为的影响

Effect of Microstructure on Ambient Temperature Fatigue Short Crack-Growth Behavior in Sialon

本文采用不同相组成和不同显微结构的。α-β-Sialon复相陶瓷作为对比试样，以压痕裂纹模拟陶瓷材料本身固有的微小裂纹，通过四点弯曲试样，在相同力学参数条件下，结合扫描电子显微镜对疲劳断口的观察，研究了α-β-Sialon复相陶瓷的室温疲劳短裂纹扩展现象和微观机理．研究发现，长柱状β-Sialon晶粒含量多、长径比大的材料具有较高抵抗疲劳失效的能力·此外，疲劳断口表明，α-β-Sialon复相陶瓷疲劳短裂纹扩展的机制主要有：应力腐蚀、摩擦造成的晶粒桥接弱化和接触损伤．

The micromechanisms and characteristics of fatigue crack-growth in Sialon ceramics withdifferent microstructures were studied. Under cyclic loading, stress corrosion, wear degradation ofasperities through friction and indentation damage were used to explain the fatigue crack-growthbehavior. The samples of higher content of rod-like β-Sialon grains with larger aspect ratio,showed higher resistance to fatigue crack growth, thus higher reliability under cyclic loads at roomtemperature.