高韧性炭/炭复合材料的制备及研究

Preparation and Research of High-Toughness C/C Composites

C/C复合材料是一种高性能新型复合材料,但是脆性大、韧性差的缺点限制了其广泛应用。因此,本研究利用化学气相渗透(CVI)法,设计并制备了三种C/C复合材料,基体炭分别为粗糙层、光滑层以及粗糙层/各向同性层带状结构热解炭,研究了C/C复合材料的微观结构、沉积机理、断裂行为和增韧机制。结果表明,三种C/C复合材料的抗弯强度分别为189.1、191.5、233.5 MPa。粗糙层和带状结构炭基体的C/C复合材料为假塑性断裂,而光滑层炭基体的C/C复合材料则是明显的脆性断裂。与粗糙层炭基体的C/C复合材料相比,带状结构炭基体的C/C复合材料通过不同结构热解炭之间的界面滑动,使得应变量增加了约70%,韧性得到了提升。因此,通过控制CVI工艺参数,实现带状结构热解炭制备,可以有效优化C/C复合材料的韧性。

C/C composites are a new type of high-performance composites,but their shortcomings of high brittleness and poor toughness limit their wide application.Therefore,in this study,three kinds of C/C composites were designed and prepared using the chemical vapor infiltration(CVI)method with matrix carbon:rough layer,smooth layer,and rough layer/isotropic layer band-structured pyrolytic carbon(PyC),respectively.And the microstructures,fracture behaviors,and toughening mechanisms of C/C composites were investigated.The results indicate that the flexural strength of the three C/C composites is 189.1,191.5,and 233.5 MPa,respectively.The C/C composites with rough layer and band-structured carbon matrix are pseudoplastic fractures.In contrast,the C/C composites with smooth layer carbon matrix are brittle fractures.Compared to the C/C composites with rough layer carbon matrix,the C/C composites with band-structured carbon matrix show a significant increase in toughness through interfacial sliding between the different structured pyrolytic carbon,which increases strain amount by about 70%.Therefore,the toughness of C/C composites can be effectively optimized by controlling the parameters of the CVI process to achieve band-structured pyrolytic carbon preparation.