【摘要】 研究第二相粒子硼化锆及其加入量变化对碳化硅-硼化锆复相陶瓷的强度和韧性的影响,同时探讨其氧化行为。用光学、透射电镜和扫描电镜对复相陶瓷的微观结构、断裂行为进行分析讨论。实验表明,材料性能不仅取决于组成变化而且与工艺条件有关。在适当热压工艺条件下获得的性能表明,复相陶瓷（SiC-15vol.%ZrB₂）的断裂韧性比热压α-SiC要提高50％左右,达到6.5MPa·m^1/2,弯曲强度仍能达到560MPa。 抗氧化性能与单相热压SiC比较,SiC-15vol.%ZrB₂在1280℃时氧化加速进行,安全使用应低于1150℃。通过压痕裂缝扩展和拋光面上断裂时裂缝行进观察表明,裂缝分支和绕道可能是增韧的主要机制。更多还原

【Abstract】 The effects of second phase particles and changes of ZrB₂ contents on strength and toughness of SiC-ZrB₂ multiphase ceramic were studied. Oxidation behaviour of SiCZrB₂ was determined. Microstructure and fracture behaviour of multiphase ceramic were examined and analysized by metallography, TEM and SEM. It is pointed out by experimental results that properties of the material is not only depended on the composition but also on the processing condition.For the optimum hot-press condition, fracture toughness of SiC-15 vol.% ZrB₂ is about 6.5 MPa·m^1/2 which is about 50% higher than that of HP-SiC. Bending strength is still up to 560 MPa. Compared with HP-SiC, oxidation resistance of SiC-15 vol.% ZrB₂ increased greatly at 1280℃. For the sake of safety, the temperature should be lower than 1150℃.Analysis of toughening mechanism indicates that crack branching and bowing may contribute to the increase of toughness through crack propagation observed on the polished surface after indentation and SENB test.更多还原