细编穿刺C/C喉衬材料烧蚀微结构及损伤机理

Ablative microstructure and damage mechanism ofthe fine weave pierced C/C throat material

以碳纤维纱穿刺叠层正交铺放的无纬布所得的预制体,经沥青液相浸渍和碳化工艺的处理,得到了细编穿刺C/C喉衬材料,并在固体火箭发动机上测试了该喉衬的热环境烧蚀性能。分别采用扫描电子显微镜和显微电子计算机断层扫描仪观察了烧蚀后C/C喉衬表面和内部的微结构,研究了穿刺C/C材料烧蚀过程中微结构演变及损伤机制。结果表明,C/C喉衬经燃气冲蚀后,烧蚀面产生了裂纹型烧蚀损伤,且烧蚀裂纹的形成与烧蚀面编织结构密切相关:喉部区域,穿刺纱由于呈平铺态而被整体冲蚀剥落,其周围碳纤维束界面产生脱粘裂纹,形成深约1.2 mm的损伤层;而入口、出口区域的穿刺纱由于与铺层纤维呈交织态,烧蚀面仅有少量裂纹。穿刺纱对纤维束脱粘裂纹的诱导偏转,阻止了裂纹的深度扩展,烧蚀损伤仅发生在浅层区域。

The fine weave pierced C/C throat material was fabricated via the liquid pitch impregnation and carbonation of carbon fiber performs,in which the orthogonally laminated non-woven carbon cloths were pierced with carbon fiber bundles.The ablation performance of fine weave pierced C/C were tested under the thermal environment.The surface and internal microstructure of the ablated C/C throat insert was observed by SEM and microscopic computed tomography scanner(micro-CT)respectively,and the involution on the damage microstructure and mechanism of the C/C throat materials during the ablation were studied.The results show that the crack-type ablation damage is formed on the ablation surface of C/C throat.The formation of interfacial cracks is closely related to the weaving structure in the ablation zone.In the throat region,the pierced carbon fiber bundles are eroded and peeled off as a whole owing to its flat state.The debonding cracks propagate along the interface of fiber bundles,forming a damage layer about 1.2 mm deep.However,in the inlet and outlet regions,only a few interfacial cracks are formed on the ablation surface,which is attributed to the interweaving structure between the pierced carbon fiber bundles and the non-woven carbon cloth fibers.It is indicated that the induced deflection of the debonding crack of the pierced carbon fiber bundles prevent the propagation of cracks in depth,and the ablation damage occur only in shallow region.