材料期刊网

为了研究固体火箭发动机内高速高浓度冲刷条件下4D编织炭/炭复合材料的烧蚀行为,本文采用一种特别设计的小型实验发动机开展热试实验研究,分别测量获得了试验后炭/炭材料试件的炭棒和纤维束最大烧蚀率,并细分析了冲刷区域和非冲刷区域的烧蚀形貌和微观结构.结果表明:在核心冲刷区域,炭/炭材料试件表面出现了明显的凹坑;结合数值模拟结果可知当颗粒冲刷速度超过一定值后,机械剥蚀效应会大幅增加,是炭/炭材料烧蚀加剧的主导因素;和通常状态不同,在实验条件下,炭棒比纤维束更易受到两相流侵蚀;在颗粒的冲蚀作用下,炭棒表面形成了大量类陨石坑的孔洞,炭棒中的纤维头部几乎是平的,并且低于周围的基体;另外根据试验后试件的微观形貌,讨论了炭棒和纤维束之间界面的几种破坏模式,分析了界面易于被破坏的原因.

The ablation behavior of a four-directional carbon/carbon (C/C) composite was examined in a lab-scale solid rocket motor under a high flux of combustion products containing a high content of particulate alumina.The composite consisted of three braided carbon fiber bundles at 120° to each other in the XY plane and a hexagonal array of carbon rods in the Z direction, all in a pitch carbon matrix.The rods consisted of a unidirectional array of the same carbon fibers in a pitch carbon matrix The composite was placed in the rocket motor with its XY plane perpendicular to the gas flow and its ablation rate, ablation behavior and microstructure were investigated.The flow field of the combustion products was simulated by solving the Reynolds-averaged Navier-Stokes equations.A deep pit was formed on the surface of the composite, the center of which coincides with the simulated particle accumulation area.The mechanical erosion was significantly increased when the particle impact velocity exceeded 96.82 m/s.The carbon rods were more susceptible to erosion than the surrounding fiber bundles.The maximum ablation rates of the carbon rod and bundles were increased almost by an order of magnitude by increasing the particle impact velocity by a factor of two.Numerous crater-like pores on the ends of the carbon rods were formed by alumina particle impaction, and the tips of the fibers in the carbon rods were almost flat and lower than the surrounding matrix.Heating caused by the particle impact increased the thermal oxidization and hence the overall ablation rate of the composite.