Room temperature static and cyclic fatigue of ZrB₂-32 vol% SiC and ZrB₂-45 vol% SiC particulate ceramic composites has been studied. It was established that the presence of grain bridging plays an important role in the lifetime and time dependent mechanical performance of ZrB₂-SiC composites. It was also established that the cohesive strength of grain boundaries of the composites was a determining factor if grain bridging would occur during crack growth, as the grain boundaries strength would determine the pathway of the moving crack. Grain bridging was limited in ZrB₂-32 vol% SiC leading to the absence of a cyclic fatigue effect, while grain bridging indeed occurred in ZrB₂-45 vol%SiC contributing to a cyclic fatigue effect which limits the lifetime of the composite. Such differences were responsible for the occurrence of R-curve behavior in ZrB₂-SiC ceramic composites.

研究了ZrB ₂ -32 vol％SiC和ZrB ₂ -45 vol％SiC颗粒陶瓷复合材料的室温静态和循环疲劳。已经确定，晶粒桥接的存在在ZrB ₂ -SiC复合材料的寿命和时间相关的机械性能中起着重要的作用。还确定的是，复合材料晶界的内聚强度是裂纹扩展过程中是否会发生晶粒桥接的决定因素，因为晶界强度将决定运动裂纹的路径。ZrB ₂ -32 vol％SiC中的晶粒桥接受到限制，导致没有循环疲劳效应，而ZrB _2中确实发生了晶粒桥接-45 vol％SiC有助于循环疲劳效应，从而限制了复合材料的寿命。这些差异是ZrB ₂ -SiC陶瓷复合材料中R曲线行为的原因。