微量Al 掺杂对2D C/ SiC 性能的影响

以二维编织碳纤维碳布为预制体,采用聚铝碳硅烷(PACS)为聚合物前驱体,应用化学气相渗透(CVI)结合聚合物浸渗-裂解(PIP)工艺制备微量Al掺杂2D C/SiC复合材料。研究微量Al掺杂对C/SiC微观结构、力学、热膨胀和氧-乙炔焰烧蚀性能的影响。结果表明:掺杂微量Al未改变C/SiC的微观结构和热膨胀性能,也未降低其韧性和强度;但微量Al掺杂提高了C/SiC的抗烧蚀性能,含微量Al的SiC氧化形成微量Al熔于SiO2的固熔体,微量Al提高了SiO2的黏度和致密度,减小SiO2挥发,较未掺杂Al的C/SiC相比,线烧蚀率降低了26%。

Effects of Adding a Small Amount of Al on Properties of 2D C/ SiC

Two-dimensional(2D) C/SiC composites were fabricated by chemical vapor infiltration(CVI) combined with polymer impregnation and pyrolysis(PIP) using polyaluminocarbosilane(PACS) as precursor.Properties including microstructure,mechanical properties and thermal expansion of the composites were investigated.The ablation properties of C/SiC composites were investigated by the oxyacetylene torch flame.The results show that adding a small amount of Al has little effect on microstructure,coefficient of thermal expansion(CTE),flexural strength and toughness of composites.However,the addition of a small amount of Al into C/SiC composite effectively enhances its ablation resistance.SiC reacts with oxygen to form a silica film,which causes Al melt into silica.Al doping can not only increase the viscosity of silica,but also reduce the activity of silica.Compare with the no addition of Al into C/SiC composites,the linear ablation rate decreased by 26%.