三维碳/碳化硅复合材料的显微结构与力学性能

 利用三维碳纤维预制体，采用等温CVI法制备连续碳纤维增韧碳化硅陶瓷基复合材料。无热解碳界面层的复合材料，其力学性能随密度的增加而提高，但密度较高时却表现出脆性断裂特征。热解碳界面层的存在，有利于纤维的拔出，但由于其结晶程度较低，仍然存在纤维束内部的脆性断裂。

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF THREE DIMENSIONAL CARBON/SILICON CARBIDE COMPOSITES

Continuous carbon fiber reinforced silicon carbide composites were fabricated with three dimensional preform by isothermal/isobaric chemical vapor infiltration. For the composites without pyrolytic carbon interface, the mechanical properties were increased with the density which included flexural strength and modulus, compressive strength and modulus, fracture toughness, and shear stress. However, the high density composites exhibited brittle fracture behavior because of strong bonding between both carbon fiber/silicon carbide matrix and carbon fiber bundless/bundle. Pyrolytic carbon interface was beneficial to fiber pull out, but brittle fracture in the fiber bundle was also observed because of the poor crystallization of pyrolytic carbon interface.