界面相对3D-SiC/SiC复合材料静态力学性能及内耗特征的影响

采用先驱体浸渍裂解工艺制备无界面、SiC、PyC和PyC/SiC等界面相SiC/SiC复合材料,研究了SiC/SiC复合材料的微观结构及静态力学性能,并通过强迫振动法系统分析了界面相对复合材料内耗行为的影响。研究结果表明,引入界面相有效改善了复合材料的微观结构及力学性能,并降低了复合材料的内耗。其中, PyC/SiC复相界面中亚层SiC限制了PyC界面相与纤维的结合及塑性形变,提高了复合材料的力学性能;同时,界面相对SiC/SiC复合材料内耗行为有显著影响,材料内耗水平与界面剪切强度成反比。对比50和350℃时的材料内耗变化率发现,随界面剪切强度增大,材料内耗呈降低的趋势,且含有PyC的PyC/SiC界面复合材料具有较低的内耗变化率,说明PyC/SiC复相界面的SiC/SiC复合材料更适于高温振动环境。

Interface Type on the Static Mechanical Properties and Internal Friction of 3D-SiC/SiC Composites

Microstructure and static mechanical properties of 3D-SiC/SiC composites with different interfaces,such as PyC,SiC and PyC/SiC and without an interface were prepared via polymer infiltration and pyrolysis,and effect of interface type on the internal friction was investigted by means of forced vibration.The results showed that the microstructure and static mechanical properties of SiC/SiC composites with an interphase layer were superior to the composites without an interlayer,and the former also showed a lower internal friction than the later.The sub-layer SiC of the PyC/SiC interface limits the binding state and the plastic deformation of PyC interphase,beneficial to improving the mechanical properties of SiC/SiC composite.Meanwhile,The interface layer of SiC/SiC composites has a significant effect on the internal friction behavior,with interfacial shear strength inversely proportional to the internal friction.By comparing the change rate of internal friction of composites at 50 and 350℃,the overall trend of internal friction decreases with the increase of interfacial shear strength.In addition,as compared with the composite with PyC interface,the composite with PyC/SiC interface has a lower change rate of the internal fiction,indicating that PyC/SiC interface of SiC/SiC composites is more helpful for high temperature vibration environment.