材料期刊网

对SiC2/Al2O3陶瓷的低粘度、高固相体积分数浓悬浮体的制备以及凝胶注模成型后坯体的性能和显微结构进行了研究,着重分析了长径比不同的2种SiC晶须及其添加量对坯体性能的影响.结果表明,坯体的相对密度、抗弯强度与SiC晶须的长径比和添加量有关,浆料的粘度随着晶须长径比和添加量的增大而增加.坯体的抗弯强度随着晶须添加量的增加呈现一种先上升后下降的趋势.凝胶注模成型后坯体结构均匀、致密,相对密度为60%,抗弯曲强度达38.5 MPa.通过显微结构观察,裂纹偏转、晶须拔出和晶须桥连是晶须增强的主要机制.

Preparation of concentrated SiCw/Al2O3 slurry with low viscosity and high solid volume loading was studied.Two factors,the aspect ratio and the fraction of SiC whisker,which influenced the viscosity of the ceramic slurry,were investigated.The effect of the fraction of SiC whisker on the relative density and the fracture toughness of the green bodies formed by gelcasting of SiCw/Al2O3 ceramic slurry were discussed.The microstructure of the green bodies was observed by SEM.The results show that the viscostry of the ceramic slurry increased with the increasing of the aspect ratio and the fraction of SiCw.With the content of SiC whisker increasing,the bending strength showed a similar trend of increasing firstly but then decreasing for two whiskers.Hence,the optimal mechanical properties of 38.5 MPa for bending strength were obtained when the content of SiC whisker was 10 wt%.The pullout of rough whiskers,crack deflection and whisker bridging are responsible for the improvement on bending strength.However,the relative density decreased with the content of SiC whisker increasing.SEM micrographs of SiCw/Al2O3 composites show that SiC whiskers homogeneously distribute in Al2O3 matrix.