| C/C composites are widely used as aeronautical materials because of their excellent thermodynamic properties.However,the easy oxidation of C/C composites in aerobic environment above 450℃affects their application in the field of high temperature.Therefore,the anti-oxidation and ablation resistance of the composite can be realized by the matrix modification technology.The sudden failure of the performance caused by the coating shedding can be effectively avoided,and the security of the composite can be improved.In this paper,C/C-ZrC-SiC composites were prepared by hydrothermal co-deposition.The effect of different heat treatment temperature,Zr/Si ratio,constructed of ZrC interface layer on fiber surface,in-situ growth of SiCnws on mechanical and ablation resistance of C/C-ZrC-SiC composites.The results are as follows:（1）C/C-ZrC-SiC composites were prepared by hydrothermal co-deposition.The effects of different heat treatment temperatures on the phase,microstructure,mechanical properties and ablation resistance of the composites were analyzed.The results showed that the C/C-ZrC-SiC composites with small particle size and uniform distribution of Zr and Si can be obtained by hydrothermal co-deposition.The C/C-ZrC-SiC composites heat-treated at 1600℃have the best mechanical properties which the maximum load is 154.5 N and the mass ablation rate is1.28×10-44 g·cm-2·s-11 and the linear ablation rate is 1.67μm·s-1,respectively.（2）C/C-ZrC-SiC composites with different Zr/Si ratios were prepared by hydrothermal co-deposition.The mechanical properties and ablation resistance of the composites with different Zr/Si ratios were studied.The results showed that the composite has the best ablation resistance when the molar ratio of Zr/Si is 2:1.The mass ablation rate and linear ablation rate are 0.6×10-44 g?cm-2?s-1 and0.13μm?s-1,respectively.This is because with the increase of ZrO2 content,the viscosity of ZrO2-SiO2 binary system increases exponentially.The smaller the Zr/Si ratio,the lower the viscosity of the ablative product and the easy to blowed away,which will lead to the poor corrosion resistance.High Zr/Si ratio will form porous and brittle zirconia layer,resulting in poor corrosion resistance.The optimum Zr/Si ratio balances the viscosity and fluidity of the ablative products.The oxide film is not only dense but also can withstand strong flame erosion.（3）The ZrC interface layer was successfully constructed on the fiber surface by microwave hydrothermal combined with carbothermal reduction,and the C/C-Zr-Si-O composite modified with ZrC interface layer was prepared by hydrothermal co-deposition.The microstructure and ablation resistance of the composite were studied,and the effect of ZrC interface layer during ablation was analyzed.The results showed that the ZrC interface layer is advantageous to protect the fiber during ablation.The mass ablation rate and linear ablation rate of C/C-Zr-Si-O composites are 1.12×10-44 g·cm-2·s-1 and 0.46μm·s-1,respectively.（4）In situ growth of SiC nanowires toughened C/C-ZrC-SiC composites prepared by hydrothermal co-deposition with rapeseed oil as solvothermal medium.The growth mechanism of SiC nanowires and its effect on mechanical properties and ablation resistance of the composites were investigated.The results showed that the CO atmosphere environment needed for the growth of SiC nanowires can be constructed by using oil as solvothermal medium,which is beneficial to the growth of SiC nanowires during the preparation process.SiC nanowire was grown by gas-solid mechanism.The maximum flexural load of C/C-ZrC-SiC composites toughened by SiC nanowires was 202.93 N,which was32.77%higher than that of CZS-1 without SiC nanowires.The mass ablation rate of tht composite is 3.22×10-44 g·cm-2·s-1.After the introduction of SiC nanowires,the peeling phenomenon between the ablation transition layer and the unheated composite can be effectively avoided.The erosion resistance and thermal shock resistance of the composites were improved. |
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