聚合物先驱体组分对SiC/SiBCN复合材料性能的影响

以SiC纤维为增强相,SiBCN复相陶瓷先驱体为浸渍剂,采用聚合物先驱体浸渍裂解工艺制备了SiC/SiBCN复合材料。采用SEM和力学性能测试对SiC/SiBCN复合材料氧化前后组分、形貌及力学行为进行了分析。试验表明,随着SiBCN复相陶瓷先驱体中聚硼氮烷(PBN)含量的增加,先驱体陶瓷产率先增加后降低,SiC/SiBCN复合材料1000℃/20 h氧化后的弯曲强度保留率亦先增加后降低。这主要归因于SiBCN复相陶瓷先驱体中PBN含量的增加有利于先驱体分子交联程度增加,更容易形成稳定的三维网络结构。此外,材料孔隙率以及SiBCN复相陶瓷的氧化行为也成为影响SiC/SiBCN复合材料氧化稳定性的重要因素。

Effect of Polymer Precursor Components on the Properties of SiC/SiBCN Composites

SiC/SiBCN composites were prepared using SiC fiber as the reinforcing phase and SiBCN composite ceramic precursor as the impregnating agent.The composition,morphology and mechanical behavior of the SiC/SiBCN composites before and after oxidation were analyzed by SEM and mechanical properties tests.The results show that with the increase of PBN content in SiBCN composite ceramic precursors,the ceramic yield of precursor ceramics increases first and then decreases,and the flexural strength retention of SiC/SiBCN composites after 20 h oxidation at 1000℃ increases first and then decreases.This is mainly due to the fact that the increase of the PBN content in the SiBCN multiphase ceramic precursor is beneficial to the increase of the crosslinking degree of the precursor molecules,and thus it is easier to form a stable three-dimensional network structure.In addition,porosity and oxidation behavior of SiBCN multiphase ceramics also affect the oxidation stability of SiC/SiBCN composites.