Z-pin增强CMC层间Ⅰ＋Ⅱ混合型断裂韧性

摘要

提出手工预缝纫方法将3K丝束的T300碳纤维引入预成型体,采用CVI工艺在预成型体和缝线处同时渗透SiC基体,制备了Z-pin增强平纹编织C/SiC陶瓷基复合材料。通过三点弯曲试验测定了Ⅰ＋Ⅱ混合型应变能释放率,分析了材料的裂纹扩展行为和Z-pin增强机理。结果表明：随着裂纹扩展长度的增大,Ⅰ＋Ⅱ型裂纹扩展阻力不断增大,相同裂纹扩展长度,增加Z-pin植入密度可以提高粘结强度,增大止裂作用。Z-pin增强平纹编织C/SiC陶瓷基复合材料裂纹扩展的耗能途径主要是层间界面剥离、Z-pin弹性剪切和拉伸变形。%A manual pre-stitching method was developed to introduce 3K T300 carbon fiber bundles into preforms.Plain woven ceramic matrix composites（CMCs） reinforced with Z-pins were manufactured by using chemical vapor infiltration（CVI） to infiltrate SiC matrix into plain woven preforms and carbon fiber sutures.Three-point flexure test was used to check mixed mode Ⅰ＋Ⅱ strain energy release rates for delamination of Z-pin reinforced plain woven C/SiC ceramic matrix composites.The delamination behaviors and reinforced mechanisms for the material were analyzed.The results show that crack growth resistance of mode Ⅰ＋Ⅱ delamination increases with increasing debonding length,and that at the same debonding length,bond strength and arrest action improve with increasing the density of Z-pin.Interlaminar interface debonding,elastic shear deformation and elastic tensile deformation of Z-pins are channels of the energy dissipation during delamination growth of Z-pin reinforced plain woven C/SiC ceramic matrix composites.