碳纤维表面改性增强Fe3Al-Al2O3复合材料的制备及组织性能

采用溶胶-凝胶分散和热压烧结制备了短切碳纤维（CF_s）/Fe₃Al-Al₂O₃复合材料。分别通过电化学镀Cu和化学气相沉积SiC对CF_s表面修饰和改性，研究了Cu镀层和SiC涂层对CF_s/Fe₃Al-Al₂O₃复合材料显微组织、相组成、力学性能及断裂行为的影响。结果表明，未修饰的CF_s在Fe₃Al-Al₂O₃基体中受到严重侵蚀，CF_s/Fe₃Al-Al₂O₃复合材料致密度低，抗弯强度仅为239.0 MPa，与Fe₃Al-Al₂O₃强度相当；表面镀Cu可有效保护CF_s不被侵蚀，同时提高了CF_s/Fe₃Al-Al₂O₃复合材料的烧结致密性和界面结合强度，从而明显提高了复合材料的断裂强度，但断裂过程中纤维拔出较短；CF_s表面沉积SiC的CF_s/Fe₃Al-Al₂O₃复合材料组织均匀致密，表面涂层完整，且与纤维及基体之间结合力相当，断裂过程中，涂层既可随纤维一起拔出基体，也可与CF_s分离而留在基体之中，SiC涂层与纤维及基体之间的弱相互作用很大程度上促进了纤维脱黏和拔出，从而促进CF_s/Fe₃Al-Al₂O₃复合材料韧化所需的渐进破坏机制。 

Preparation and microstructure of Fe3Al/Al2O3 composites reinforced by surface modified carbon fiber

The short carbon fiber (CF_s)/Fe₃Al-Al₂O₃ composites were prepared by a sol-gel dispersing method and a subsequent hot-pressing process. The Cu coating and SiC coating applied to CF_s were fabricated by electrochemistry and in-situ reaction method, respectively. The effects of Cu coating and SiC coating applied to carbon fiber on the microstructure, phase composition, mechanical properties and fracture behavior of CF_s/Fe₃Al-Al₂O₃ composites were investigated. The results show that the CF_s/Fe₃Al-Al₂O₃ composites fabricated from the as-received CF_s exhibit low density and the flexural strength is only 239.0 MPa comparable with matrix due to the CF_s severely eroded in Fe₃Al-Al₂O₃ matrix. The Cu coating applied to CF_s can effectively protect CF_s eroded by matrix, improve sintering compactness and cause strong bonding between the fiber and matrix that cause high flexural strength, however, the length of fibers extending from the matrix is short during the fracture process. The CF_s/Fe₃Al-Al₂O₃ composites fabricated from SiC coating exhibite homogeneous microstructure, the coating onto fiber is integrated and soft bondings between fiber and matrix result in the fiber with SiC coating extending from matrix or SiC coating remained in the pull-out holes. The weak interaction between the fiber with SiC coating and matrix greatly promotes fiber debonding and extending from matrix to promote toughening and progressive failure mechanisms in the CF_s/Fe₃Al-Al₂O₃ composites.