两种致密度2D-C/SiC层向动态压缩性能试验研究

Layer-directional dynamic compressive mechanical properties of two kinds of densifications 2D-C/SiC

对两种致密度的2D-C/SiC复合材料进行了层向动态压缩性能试验研究,两种致密度材料通过控制CVI(Chemical vapor infiltration)工艺参数得到。试验在SHPB装置上进行,使用改变波形整形器几何尺寸的方法基本实现恒应变率加载。试验结果表明:动态压缩应力-应变曲线呈明显的非线性,与静态试验相比两种致密度试样均有一定的应变率强化效果,即随着应变率的增加,抗压强度提高,失效应变减小,剪切损伤角增大。致密度提高后抗压强度明显增加但失效应变减小,且表现出脆性特征,剪切损伤角也明显增大。动态试验数据有较大的分散性,低、高致密度试样动态破坏强度的Weibull分布系数分别为8.36和5.27。SEM观察发现,低致密度试样纤维束断口不平整,高致密度试样断口相对平整;纤维束多发生整束剪断,动态条件下纤维破碎多于静态。

The tests for dynamic compressive mechanical properties of two kinds of densifications 2D-C/SiC were performed by using the SHPB system. The materials are made by controlling the parameters of CVI technics. The key issue to apply high strain rates to the 2D-C/SiC is to design the geometrical size of the shaper in the SHPB sys- tem. The experimental results of both the dynamic and static loading are successful. They show that the dynamic compressive stress-strain curve is distinctly non-linear. The mechanical properties of the two densifications 2D-C/ SiC are both strengthened under high strain rates, which are the higher failure strength, the lower failure strain and the larger shearing damage angle. The higher densification leads to the higher failure strength, lower failure strain and larger shearing damage angle. The dispersive dynamic experimental data are described by Weibull modules, which are 8.36 and 5.27 respectively for high and low densifications. From the SEM, a smooth ruptured surface is found for the high densification. More cracked fibers are observed under high strain rates.