C/C-SiC-ZrC-Al_(2)O_(3)复合材料的制备及抗烧蚀性能研究

Preparation and ablation resistance of C/C-SiC-ZrC-Al_(2)O_(3) composites

以葡萄糖为碳源,硅溶胶为硅源,氧氯化锆为锆源,硫酸铝为铝源,采用水热共沉积-碳热还原法制备了C/C-SiC-ZrC-Al_(2)O_(3)复合材料,并采用压汞仪测得了孔径分布,采用三点弯曲法计算出了抗弯强度。C/C-SiC-ZrC-Al_(2)O_(3)复合材料陶瓷基体相晶粒细小,分布均匀,其抗弯强度为169.1 MPa,比C/C-SiC-ZrC复合材料提高了21.9%,Al_(2)O_(3)有助于提高复合材料的力学性能。在等离子体火焰下烧蚀120 s后,质量烧蚀率和线烧蚀率分别为6.5×10^(-5)g/(cm^(-2)·s)和2.9×10^(-4) mm/s,分别比C/C-SiC-ZrC复合材料降低了69.3%和37.0%。Al_(2)O_(3)的加入有助于形成莫来石晶须,莫来石晶须作为增强相提高了熔融玻璃层的粘度,提高了熔融玻璃层抵抗冲刷的能力,熔融层的平整性得到了提升。粘度的提高也抑制了气相CO、SiO扩散时形成气泡的能力,熔融层的完整性得到了提高,进而抑制了氧化性气氛的向内扩散,提高了复合材料的抗烧蚀性能。

In this study,C/C-SiC-ZrC-Al_(2)O_(3)composites were prepared by hydrothermal co-deposition and carbo-thermal reduction method using glucose as carbon source,silica sol as silicon source,zirconium oxychloride as zirconium source,aluminum sulfate as aluminum source.The pore size distribution was measured by mercury porosimeter,and the flexural strength was calculated by three-point bending method.The ceramic matrix phase grains of C/C-SiC-ZrC-Al_(2)O_(3)composites are fine and evenly distributed.The flexural strength of C/C-SiC-ZrC-Al_(2)O_(3)composites is 169.1 MPa,which is 21.9%higher than that of C/C-SiC-ZrC composites.Al_(2)O_(3)contributes to improving the mechanical properties of the composites.The mass and linear ablation rates of the C/C-SiC-ZrC-Al_(2)O_(3)composites under the plasma flame for 120 s are 6.5×10^(-5) g/(cm^(2)·s)and 2.9×10^(-4) mm/s,respectively,which are 69.3%and 37.0%lower than those of the C/C-SiC-ZrC composites,respectively.In the ablation process,the addition of Al_(2)O_(3)contributes to the formation of mullite whiskers.Mullite whisker used as an enhancement phase improves the viscosity of the molten glass layer,the resist erosion ability of the molten glass layer and the smoothness of the molten layer are improved.The increase of viscosity inhibits the ability of forming bubbles during diffusion of gas phase CO and SiO,and improves the integrity of molten layer,further inhibits the inward diffusion of oxidizing atmosphere,and also improves the ablative resistance of composites.