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采用低压化学气相渗透法制备了具有热解碳界面层的2.5维SiCf/SiC复合材料。研究了界面层厚度和基体制备工艺对材料力学性能的影响。结果表明:0.1μm厚的界面层使材料的弯曲强度提高了104.2%(从144增加到294MPa),材料表现为非灾难性断裂;界面层厚度进一步增加(到0.16μm),纤维的增强效果减弱,材料的断裂行为变差。基体制备温度由1050℃降到950℃时,材料强度增加了≈45%(从188增加到274MPa);制备压力由8kPa增加到16kPa时,气孔率升高,SiC基体晶粒形状由菱形变为球形。基体的球形晶粒有利于提高材料的承载能力,虽然复合材料的气孔率较高,但其弯曲强度却稍有增加。
A 2.5-dimensional SiCf / SiC composite with a pyrolytic carbon interface was prepared by low pressure chemical vapor infiltration. The effects of interfacial layer thickness and substrate preparation process on the mechanical properties were investigated. The results show that the flexural strength of the material increases by 104.2% (from 144 to 294 MPa) with a thickness of 0.1μm, and the material shows non-catastrophic fracture. The interfacial layer thickness increases further (to 0.16μm), and the reinforcing effect of the fiber is weakened , The fracture behavior of the material becomes worse. The material strength increased from ≈45% (from 188 to 274MPa) when the preparation temperature of the matrix decreased from 1050 ℃ to 950 ℃. When the preparation pressure was increased from 8kPa to 16kPa, the porosity increased and the grain shape of the SiC matrix changed from rhombus to spherical. The spherical grains of the matrix help to improve the bearing capacity of the material. Although the composite has higher porosity, its bending strength slightly increases.