为研究碳纤维(Cf)加入量对复合材料性能的影响,本研究以 Y2O3为烧结助剂,采用热压烧结技术制备了Cf/Si3N4复合材料,其中碳纤维加入量为0、2wt%和5wt%。选用乙醇作分散介质，通过球磨工艺可有效分散短切碳纤维。研究结果表明：碳纤维在复合材料中分散均匀,且材料中的晶粒在垂直于热压压力的方向呈现一定取向排列。高温烧结过程中,碳纤维与Si3N4或其表面的SiO2层发生反应,生成SiC中间层。适量碳纤维加入有助于提高复合材料的热导性能。当Cf加入量为2wt%时，Cf/Si3N4的热导率较高,为45.8 W/(mxK)；而不添加Cf的样品,其热导率为37.1 W/(mxK)。加入Cf后, Cf/Si3N4的断裂韧性有小幅提高,维氏硬度在16.6~16.8 GPa范围内变化。
To investigate the effects of carbon fiber (Cf) adding content on the propertiesof Si3N4, Cf/Si3N4 composites with 0, 2wt% and 5wt%ofshort carbon fibers were prepared by hot-press sintering method, using Y2O3as sintering additives. With long-time ball milling process, carbon fibers were well dispersed in mixed powders using ethanol as dispersion medium. Carbon fibers distribute uniformly in the composites and Si3N4grains grow to a certain degree in the vertical direction to the pressure of hot-press. The interfacial by-product silicon carbide (SiC) phase forms due to the reaction between added Cf and Si3N4 particles or SiO2 layer on surface of Si3N4 particles during high temperature sintering. The sample with 2wt% Cf addition achieves a higher value of thermal conductivity (45.8 W/(mxK)), while the thermal conductivity of Si3N4without Cf is only 37.1 W/(mxK). Therefore, the addition of Cf can improve the ther-mal conductivity of the composites. The fracture toughness of the composites has a slight increase with Cf adding. The measured hardness values for all samples are within a range of 16.6-16.8 GPa.
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