用溶胶-凝胶法制备碳纤维三维编织物增强氧化铝基复合材料的研究

本文研究了溶胶－凝胶（Ｓｏｌ－ｇｅｌ）法制备碳纤维三维编织物增强氧化铝（Ａｌ２Ｏ３）基复合材料的成型工艺及其力学性能，研究了两种主要起始物Ａｌ（ＮＯ３）３、ＡｌＣｌ３配制的氧化铝溶胶对复合材料成型工艺和力学性能的影响。分别以Ａｌ（ＮＯ３）３和ＡｌＣｌ３为起始物，制备得到Ⅰ＃、Ｉ＃复合材料。研究表明，以Ａｌ（ＮＯ３）３为起始物配制的溶胶粘度较小，利于材料的致密化。经过溶胶浸渍、凝胶、裂解１３个周期后，Ⅰ＃材料的密度和室温三点弯曲强度分别为１．８６ｇ／ｃｍ３和１４５．２ＭＰａ，而ＩＩ＃材料的密度和室温三点弯曲强度分别为１．６３ｇ／ｃｍ３和１０４．１ＭＰａ，材料均呈典型的韧性断裂模式。用扫描电子显微镜（ＳＥＭ）观察试样的断口形貌，发现断口表面有大量的纤维拔出，纤维表现了较好的增韧效果。

Processing and Mechanical Properties of 3-Dimensional Braided Carbon Fiber Preform Reinforced Alumina Matrix Composites Prepared by Sol-gel Method

The processing and mechanical properties of 3 dimensional brainded carbon fiber preform reinforced alumina(Al 2O 3) matrix composites prepared by sol gel method were investigated. The influences of different sols prepared from Al(NO 3) 3 and AlCl 3 hydrolysis, respectively, on the processing and mechanical properties of composites were also studied. Composites I# and II# were prepared from the sols with Al(NO 3) 3 and AlCl 3 as starting material, respectively. The viscosity of the sol Prepared from Al(NO 3) 3 hydrolysis was lower than that from AlCl 3 hydrolysis, so the densification rate of composite I# was faster than that of composite II#. After 13 times of sol infiltration gelation pyrolysis, the density and the flexural strength of as fabricated composite I# reached 1 86g/cm 3 and 145 2MPa, respectively, while those of composite II# reached 1 63g/cm 3 and 104 1MPa, respectively. SEM observation of all the specimen fracture surfaces showed a large amount of fiber pull out. It illustrated that the carbon fiber played a role of toughening Al 2O 3.