ZrC-Cu-C/C复合材料的烧蚀性能及烧蚀机制

为了提高炭/炭(C/C)复合材料的耐烧蚀性能,以孔隙率为38%的C/C复合材料为坯体,Zr-Cu混合粉末为熔渗剂,采用反应熔渗法制备了ZrC-Cu-C/C复合材料。通过氧-乙炔焰烧蚀实验,研究了熔渗剂成分对复合材料高温耐烧蚀性能的影响。利用XRD、SEM和EDS对烧蚀前后ZrC-Cu-C/C复合材料的相组成和微观结构进行了分析。结果表明:ZrC-Cu-C/C复合材料烧蚀前主要存在C、ZrC和Cu相,有微量Zr残余;烧蚀20s后表面主要存在炭基体、ZrO_2、CuO、Cu_2O及残余的ZrC和Cu。随熔渗剂中Zr含量增加,复合材料的线烧蚀率和质量烧蚀率均呈现先减小后增大的趋势,以60%Zr-Cu(质量分数)为熔渗剂制备的ZrC-Cu-C/C复合材料的抗烧蚀性能最佳,其线烧蚀率和质量烧蚀率分别为0.0018mm·s~(-1)和0.0013g·s~(-1)。ZrC-Cu-C/C复合材料的烧蚀机制为以C的升华、ZrO_2的熔化及Cu的蒸发和汽化为主的热物理烧蚀、ZrC和C氧化的热化学烧蚀以及高压热流冲刷引起的机械剥蚀的综合作用。

Ablation property and mechanism of ZrC-Cu-C/C composites

In order to improve the anti-ablation property of carbon/carbon (C/C ) composites, ZrC-Cu-C/C composites were fabricated by reactive melt infiltration using C/C composites with the porosity of 38% as preforms and Zr-Cu mixed powders as reactive infiltrators.The effect of infiltrator composition on the ablation resistance of ZrC-Cu-C/C composites was investigated by the test of oxyacetylene flame ablation,and the phase composition and microstructure of the ZrC-Cu-C/C composites before and after ablation were analyzed by XRD,SEM and EDS.The results show that the composites are composed of C,ZrC,Cu and residual Zr before ablation,while there exist C matrix,ZrO2 ,CuO and Cu2 O as well as remnant ZrC and Cu in the surface after ablation for 20 s.Both the linear recession rate and mass loss rate of the composites decrease first and then increase with increasing the content of Zr in infiltrators.The ZrC-Cu-C/C composite fabricated with 60% Zr-Cu(mass fraction)exhibits the best anti-ablation property,whose linear recession rate and mass loss rate are 0.001 8 mm·s-1 and 0.001 3 g·s-1 ,respectively. The ablation mechanisms of the ZrC-Cu-C/C composite are the combination of thermo-physics ablation (based on sublimation of C,melt of ZrO2 and vaporization and sublimation of Cu),thermo-chemical ablation (oxidation of ZrC and C)and mechanical denudation (erosion of the flame).