模压压力对SiC/SiC复合材料力学性能及力学行为的影响

采用热模压辅助聚合物先驱体浸渍裂解工艺制备了国产近化学计量比SiC纤维增强SiC陶瓷基复合材料，通过阿基米德排水法和SEM技术对SiC/SiC复合材料致密化过程进行表征，采用弯曲强度、拉伸强度和断裂韧性对SiC/SiC复合材料力学性能和力学行为进行评价。研究表明，热模压压力是影响材料结构和性能的重要因素，热模压在提升材料致密度的同时，亦造成纤维的损伤。随着热模压压力的增加，SiC/SiC复合材料力学性能先增加后降低。热模压压力适中时，致密度增加因素占优，材料力学性能较为优异；热模压压力较大时候，热模压操作对纤维性能的损伤因素逐渐凸显，基体致密化和纤维损伤两种作用机制相当。

英文摘要:

SiC fiber reinforced SiC ceramic matrix composites with near stoichiometric ratio were prepared by the polymer precursor impregnation pyrolysis combined with hot molding process. The densification process of SiC/SiC composites was characterized by Archimedes drainage method and SEM technology. The mechanical properties and behaviors of SiC/SiC composites were evaluated by testing the bending strength, tensile strength and fracture toughness. Results showed that the hot molding pressure is an important factor affecting the structure and properties of SiC/SiC composites, and the hot molding pressure not only increased the density of SiC/SiC composites, but also caused fiber damage. With the increase of hot molding pressure, the mechanical properties of SiC/SiC composites increased first and then decreased. When the hot molding pressure was moderate, the density increase factor was dominant and the mechanical properties of the material were excellent. When the hot molding pressure was high, the damage factors of hot molding on fiber properties were gradually prominent, and the two mechanisms of matrix densification and fiber damage were similar.

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