Influence of Whiskers' Shape and Size on Mechanical Properties of SiC Whisker-Reinforced Al2O3
Influence of Whiskers' Shape and Size on Mechanical Properties of SiC Whisker-Reinforced Al2O3
复制标题
晶须形状和尺寸对SiC晶须增强Al2O3力学性能的影响
DOI：
10.2109/jcersj.99.52
复制
发表时间：
1991
影响因子：
1.1
通讯作者：
Y. Tanabe
中科院分区：
文献类型：
--
作者：
E. Yasuda;T. Akatsu;Y. Tanabe
对于晶须增强陶瓷复合材料，人们提出了多种增韧机制。然而，目前还不清楚哪种机制是导致增韧的主要原因。在本文中，我们试图用拔出机制来解释增韧行为。建立了基于裂纹扩展能量平衡和晶须拔出摩擦能的模型，对实验结果进行了分析。采用7种不同尺寸和形状的碳化硅晶须制备了碳化硅晶须/氧化铝复合材料。测定了这些复合材料的断裂韧性KIc、有效断裂能γef和四点弯曲强度σf等力学性能随晶须尺寸或晶须体积分数的变化关系。详细观察了这些复合材料的断口和裂纹扩展路径。得到了γff与R2/LW之间的线性关系(r：晶须半径，LW：晶须长度)。γEf也与晶须体积分数呈线性关系。这些结果似乎支持本文提出的晶须拔出模型。(KIc)2与R2/LW、晶须体积分数和γEff呈线性关系。晶须补强增韧后，复合材料的四点弯曲强度没有得到改善。据推测，长晶须会在陶瓷基体中引入较大的缺陷。
For whisker reinforced ceramic composites, many toughening mechanisms are proposed. However, it is not clear yet which mechanism mainly contributes to the toughening. In this paper, we tried to explain the toughening behavior by the pull-out mechanism. A model based on the energy balance of crack propagation and frictional energy during whisker pulling-out was constructed for analyzing experimental results. Seven types of SiC whiskers with various sizes and shapes were used for fabricating SiC whisker/Al2O3 composites. Mechanical properties of these composites such as frature toughness KIC, effective fracture energy γeff and 4-point bending strength σf, were measured as a function of whisker dimension or whisker volume fraction. Fractured surfaces and crack propagation paths in these composites were observed in detail. A linear relationship between γeff and r2/lw was obtained (r: radius of whiskers, lw: length of whiskers). γeff also had a linear relationship with the whisker volume fraction. These results seem to support the whisker pull-out model proposed here. (KIC)2 showed linear relationships with r2/lw and whisker volume fraction as well as γeff. Four-point bending strengths of these composites were not improved in spite of toughening by whisker reinforcement. It is presumed that long whiskers cause to introduce large defects into ceramic matrix.