掺杂难熔金属碳化物对炭/炭复合材料烧蚀微观结构的影响

详细分析和比较了3D炭／炭复合材料及其添加难熔金属碳化物的试样在三种烧蚀条件下的烧蚀结果、微观结构及形貌。SEM观察结果显示，纤维与基体间的界面优先烧蚀现象对纯炭／炭试样是普遍存在的，相反，对难熔金属碳化物掺杂的炭／炭试样而言，纤维却总是优先被烧蚀；纤维单丝相对基体优先烧蚀越明显，材料宏观烧蚀率越大。对纯炭／炭试样烧蚀表层区的TEM观察结果表明，在烧蚀过程中炭纤维和基体炭均发生明显的微观结构变化，具体表现为炭纤维的微晶尺寸显著长大，而基体炭原有层片区则出现柱状炭。烧蚀测试条件对材料宏观和微观形貌及烧蚀机理都有影响：

The effect of adding refractory metal carbides on the microstructure of carbon/carbon composites after ablation

The morphology and microstructure of a 3D carbon/carbon composite, and the corresponding composites doped with refractory metal carbides, were studied by SEM and TEM after ablation tests at various conditions. Results showed that in the case of composites doped with refractory metal carbides, the carbon fibers in the Z-direction were ablated faster than the matrix carbon. The bigger the difference of ablation rate between the carbon fibers and the matrix carbon, the greater the ablation rate of the bulk material. In contrast, in the carbon/carbon composite, the matrix carbon at the interface region was ablated faster than the carbon fibers. Micro- crystalline growth of carbon fibers and formation of columnar shaped carbon in the matrix carbon were commonly observed. Ablation conditions had a great influence on the morphology and the ablation mechanism.