2D-C/C复合材料及其石墨化制品烧蚀特性分析

Ablation characteristics of 2D-C/C composites and their graphitized products

以液化石油气为碳源，2D炭纤维织物为基体，通过1000℃-1100℃积热解炭，制备了沉积态2D—C／C复合材料。通过对沉积态2D—C／C复合材料在2800℃热处理10h制备了石墨态2D—C／C复合材料。采用小型发动机烧蚀实验对两种复合材料的烧蚀性能进行了测试和评价；通过比较两种复合材料的孔隙分布、基体和纤维的结合强度以及热导率，解释了它们不同的烧蚀特性和烧蚀机理。结果表明：沉积态2D—C／C复合材料由于孔隙分布少、基体和纤维结合强度大、面间热导小，烧蚀主要由热化学反应（氧化）控制，烧蚀表面平整，烧蚀率为0．033mm／s。石墨态2D—C／C复合材料由于孔隙分布多、基体和纤维结合强度小，烧蚀主要由氧化和机械剥蚀控制，烧蚀表面出现烧蚀坑，烧蚀率为0．046mm／s。

2D-C/C composites were prepared by pyrocarbon deposition at 1000-1 100℃ using liquefied petroleum gas as the carbon source and a 2D carbon fiber weave as substrate. Graphitized samples were obtained by heat treatment at 2 800 ℃ for 10 h. An engine torch test was used to evaluate the ablation properties of the two kinds of composites. A comparison of the pore size distribution, the cohesion strength between matrix and fiber, and the thermal conductivity of the two composites was used to explain their ablation characteristics and mechanism. Results show that for the 2D-C/C composites, the ablation mechanism is controlled by a thermo-chemical reaction （oxidation）, the ablated surface is even and the ablation rate is 0.033 mm/s because of its low porosity, large cohesion strength and low out-of-plane thermal conductivity. For the graphitized 2D-C/C composites, the ablation mechanism is dominated by both oxidation and mechanical wearing with a few macroscopic pits on the ablated surface and the ablation rate is 0.046 mm/s, which is caused by their large porosity and low cohesion strength.