熔融渗硅法制备C／C-SiC复合材料弯曲性能研究

Study on flexural properties of the C/C-SiC composites by liquid silicon infiltration process

以针刺网胎无纬布为预制体，通过化学气相沉积（CVD）及树脂浸渍／炭化（IC）致密工艺，制备出不同密度C／C多孔体，经2500℃高温处理，在1800℃进行熔融渗硅（LSI），制备出C／C—SiC复合材料，对其弯曲性能进行研究。结果表明：C／C多孔体密度低时，熔融渗硅致密效率高，但所得C／C—SiC复合材料弯曲强度低（185MPa）；随着多孔体密度的增大，渗入的硅含量减少时，材料界面结合强度适中，弯曲强度增大（225MPa）；随着渗入硅含量进一步减小，界面结合减弱，弯曲强度降低（197MPa），表现出显著的韧性断裂特征。

C/C-SiC composites were produced by liquid silicon infiltration （LSI） at 1 800℃, using different density porous C/C with the preform of needled non-woven cloth and the mixed of CVD carbon, resin carbon heated at 2 500℃ in this paper. Its flexural properties were investigated. The results show that the lower the density of porous C/C is, the better the effects of LSI is, but the flexural strength of C/C-SiC composites is lower （185MPa）. The higher density of porous C/C preform with lower open porosity and small specific surface area is hard to infihrate liquid silicon into it, its flexural strength increases （225MPa） because the interface boning is appropriately strong. With the more decreasing of the contents of infiltration liquid silicon, the flexural strength of C/C -SiC composites decreases because the interface bonding is weakened, and the C/C-SiC composites show obviously non-brittle fracture behavior.