| Hypersonic spacecrafts need withstand extreme conditions at re-entry in Earth's atmosphere. Especially, the nose tip and leading edge need operate at ultra-high temperature and high heat flux for long time in oxidized environment, so that it is necessary to develop new thermal protection materials. On the base of ultra-high temperature materials research abroad and at home, this dissertation investigated ultra-high temperature carbon matrix composites. New ultra-high temperature composites C/C-ZrB2(ZrC, TaC) were fabricated by introduction of ceramic powder (ZrB2, ZrC, TaC) using slurry brushing process, and introduction of carbon matrix using polymer infiltration and pyrolysis method. We studied the influence of precursor, crosslinking, infiltrating and puncture techniques on the composites structure and property.We chose furan resins, phenolic resins and pitch as the source of carbon, and investigated the influence of crosslinking and infiltrating on the composites structure and property. The C/C-ZrB2 composites were prepared by infiltration-crosslinking-pyrolysis process by using furan resins, only to find that the resins will expand and shrink in process of crosslinking and pyrolysis, thus leading to poor adherence between layers and poor performance of the composites. The C/C-ZrB2 composites prepared by infiltration-pyrolysis furan resins display high densification, good mechanical properties and oxidation resistance.The composites prepared by using phenolic resins, on the other hand, can enhance densification effectively through infiltration-crosslinking-pyrolysis process, thus improve significantly mechanical properties, oxidation resistance and ablated resistance. The composites prepared by infiltration-pyrolysis process showed low density, poor mechanical, oxidation resistance and ablated resistance properties.The C/C-ZrB2 composites were also prepared by infiltrating pitch of molten and solution. The sample from melt pitch has good integration performance, while that from solution has lower density and poor mechanical properties. However, the melting infiltration process requires high temperature and high pressure equipment, and thus high cost. In conclusion, phenolic resins is the suitable precursor for polymer infiltration and pyrolysis process, and the composites prepared by infiltration-crosslinking-pyrolysis process is first-rank.We investigated the influence of ceramic content on the composites (C/C-ZrB2, C/C-ZrC, C/C-TaC) structure and property. The density of C/C-ZrB2 composites increases when the content of ZrB2 increase, while linear recession rates in oxyacetylene torch test decrease first and increase later. Among all samples ZB10 sample (10vol% ZrB2) has the best integration performance with 250.37MPa flexural strength and 13.84MPa·m1/2 fracture toughness. After being oxidated at 1200°C for 30min, its mass retention and strength retention were 90.65% and 85.14%, respectively. Meanwhile, it also shows best ablation resistance. After being ablated in oxyacetylene torch for 60 seconds, the sample showed mass loss rate of 0.01802g/s and linear recession rate of 0.0122mm/s. ZC15 sample (15vol% ZrC) shows the relatively excellent integration performance with 217.54MPa flexural strength and 12.00MPa·m1/2 fracture toughness. After being oxidated at 1200°C for 30min, its mass retention and strength retention were 90.91% and 82.04%, respectively. It also has better ablation resistance with the mass loss rate of 0.01827g/s and linear recession rate of 0.0193mm/s. The density of C/C-TaC composites increases when the content of TaC increase. TC15 sample (15%vol TaC) has the best integration performance with 260.99MPa flexural strength and 13.21MPa·m1/2 fracture toughness. After being oxidated at 1200°C for 30min, its mass retention and strength retention were 92.12% and 75.03%, respectively. It also presents relatively good ablation resistance with mass loss rate of 0.02510g/s and linear recession rate of 0.0290mm/s.The influence of puncture process on the composites performance was investigated. Puncture process can enhance densification of C/C-ZrB2(TaC, ZrC) composites, reduce the opening porosity, improve shear strength. At the same time, puncture process can also decrease high heat flux erosion and keep integration performance during ablation. Contrast with un-punctured sample, the linear recession rate of C/C-ZrBB2 composites was reduced to 0.0075mm/s from 0.0135mm/s.
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