液体冲压发动机燃烧室C/C-SiC复合材料的烧蚀行为及力学性能

Ablative behavior and mechanical properties of C/C-SiC composite materials for combustion chamber of liquid ramjet engines

采用固体粒子和不含固体粒子在不同含氧量下的液体冲压发动机对C/C-SiC复合材料燃烧室内层进行测试,研究两种实验条件下烧蚀严重区域和一般区域的烧蚀量、烧蚀行为及材料烧蚀后的力学性能。结果表明:在含固体粒子条件下,烧蚀严重区域烧蚀量较大,而一般区域也有一定的烧蚀量,均比不含固体粒子条件下相应区域烧蚀量大;C/C-SiC复合材料表面涂层先发生氧化反应,生成的SiO2玻璃态膜覆盖在涂层表面,阻挡了氧气的进入,有效地保护了基体材料。随着温度不断上升,材料发生主动氧化,气流的剥蚀和冲刷会加速该过程,使得SiO2难以附着在产品内表面上,SiC基体和碳纤维失去保护而被损耗。纤维变细,强度逐渐降低,纤维的增韧效果大幅减小,两种实验条件下C/C-SiC复合材料的弯曲强度和剪切强度均发生了下降,在颗粒冲刷下,材料的力学性能损失更加严重。

The C/C-SiC composite materials combustion chamber layer was tested with liquid ramjet engines with solid particles or without solid particles separately at different oxygen contents.The ablation amount,ablative behavior and mechanical properties of the material after ablation in critical and general areas were studied under two test conditions.The results show that under the condition of containing solid particles,the amount of ablation in the critical ablation area is large,and the amount of ablation in the general area is also large,which is larger than that of the corresponding areas without solid particles.The surface coating of C/C-SiC composites undergoes oxidation reaction first,and the resulting SiO2 glassy film covers the surface of the coating,blocking the entry of oxygen and effectively protecting the matrix material.As the temperature rises,active oxidation of the material occurs,and the process is accelerated by air erosion and scouring,making it difficult for SiO2 to adhere to the inner surface of the product,and the SiC matrix and carbon fiber are lost without protection.The fibers become thinner,the strength decreases gradually,and the toughening effect of the fibers is reduced greatly,so the bending strength and shear strength of the C/C-SiC composites decrease under two test conditions,and the mechanical property loss of the material is more serious under particles scouring.