SiC-W层状复合材料增韧机理分析

Analysis of Increscent Fracture Toughness for Laminated SiC-W Composites

为分析 Si C W层状复合材料增韧机理 ,对以 Si C陶瓷胶片为基体层 ,金属 W为夹层的 Si C W层状复合材料进行了力学性能测试 ,并用电镜法得到其断面显微结构照片。试验结果表明 :1)与 Si C单材料断裂韧性相比 ,Si C W层状复合材料的断韧性增大 ;2 )在基体层厚度不变 ,夹层厚度为 10～ 5 0μm时 ,Si C W层状复合材料的断裂韧性随夹层厚度的增加而增大 ,而抗弯强度随之下降 ;3)材料在不同方向断裂韧性不同。 Si CW层状复合材料裂韧性增大的原因是 :1)夹层晶体颗粒大于基体层的 ,其沿晶断裂形式延长了裂纹扩展路径 ;2 )断裂过程中有晶片拨出消耗了能量 ;3)

For analysis of increscent fracture toughness for laminated SiC W composites, Mechanical properties of laminated SiC W composites were tested. 1) The fracture toughness of Laminated SiC W composites is larger than SiC materials. 2) If the thickness of layer is increscent, then the fracture toughness of laminated SiC W composites is increscent and the resistance to bended strength is reducing in the range of thickness 10～ 50 μm. 3) Fracture toughness is different in the different directions. The reason of increscent fracture toughness for laminated SiC W composites are: 1) The crystallite in interlayer is bigger than base layer (SiC layer). The expansion path of crack is prolonged because the form of crack is along the crystallite interface. 2) the energy is depleted when the crystal slices are withdrawn out from the secondary laminated structure in fracture course. 3) The crack expansion is prevented by micro cracking in the secondary laminated structure.