双脉冲固体火箭发动机中四向双基体炭/炭复合材料的非连续烧蚀行为OA

Four-directional dual-matrix C/C composites were fabricated from PAN-based carbon fibers using a combined approach of soft-hard hybrid weaving pre-form molding,chemical vapor infiltration(CVI)of pyro-lytic carbon(PyC),high pressure impregnation and car-bonization of pitch-derived carbon.The ablation resist-ance of the composites was evaluated by testing in a dual-pulse solid rocket motor,and their ablation behavi-or was investigated.The carbon rods formed by twisting and carbonizing fiber bundles,exhibited a hexagonal cross-section,surrounded by a dense PyC"wall"structure formed during the CVI process.The linear ablation rates of the com-posites after pulse I and pulse Ⅱ were 0.068 mm/s and 0.113 mm/s,respectively.A cellular-like PyC layer and nanowire struc-tures were deposited on the surface of the throat convergent section during the post-combustion cooling phase,while cracks and delamination occurred on and within the divergent section.The ablation of C/C composites under these conditions was a com-plex multi-mechanism process,including ultra-high temperatures,high-speed gas scouring,oxygen-containing thermochemical ablation,and thermal shock.This work elucidates the ablation behaviors of C/C composites under dual-pulse conditions and provides technical guidance and a theoretical basis for designing and fabricating C/C composites for extreme ablation environ-ments.