Chen Hua-Hui, Cao Jing-Jing, Hong Hai-Ping, Zheng Nan, Ren Jie, Wang Chang-An
Department of Materials Science and Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China.
College of Mechanical and Equipment Engineering, Hebei University of Engineering, Handan 056038, China.
J Nanosci Nanotechnol. 2021 Oct 1;21(10):5235-5240. doi: 10.1166/jnn.2021.19354.
transformed carbon fibers/Al₂O₃ ceramic matrix nanocomposites with Cao-MgO-SiO₂ sintering agent were prepared by hot-pressed sintering technology in vacuum. In the sintering process, pre-oxidized polyacrylonitrile fibers (below named as pre-oxidized PAN fibers) were used as the precursors of transformed carbon fibers. The micro/nanostructure of composites and interface between transformed carbon fibers and matrix were investigated, as well as the properties of composites. The results showed that the composites could be sintered well at a relatively low temperature of 1650 °C. During the sintering, the precursors, pre-oxidized PAN fibers, were transformed into carbon fibers, and the transformed carbon fibers had the graphitelike structure along the fiber axial direction. The carbon atoms arrangement in the surface layer of the fiber was more orderly than the core. A typical diffraction peak of carbon fiber at 26°, which corresponded to the (002) crystal plane, was observed, and the inter-planar spacing was approximately 0.34 nm. The CaO-MgO-SiO₂ sintering agent formed MgAl₂O₄ and CaAl₂Si₂O phases in the interface between transformed carbon fibers and matrix, therefore improving the interface bonding, and thereby modifying the mechanical properties of the composites.
采用真空热压烧结工艺制备了添加CaO-MgO-SiO₂烧结剂的转化碳纤维/Al₂O₃陶瓷基纳米复合材料。在烧结过程中，预氧化聚丙烯腈纤维（以下简称预氧化PAN纤维）用作转化碳纤维的前驱体。研究了复合材料的微观/纳米结构、转化碳纤维与基体之间的界面以及复合材料的性能。结果表明，复合材料在1650℃的相对低温下能够良好烧结。在烧结过程中，前驱体预氧化PAN纤维转化为碳纤维，转化后的碳纤维沿纤维轴向具有类石墨结构。纤维表层的碳原子排列比芯部更有序。观察到碳纤维在26°处有一个典型的衍射峰，对应于（002）晶面，面间距约为0.34nm。CaO-MgO-SiO₂烧结剂在转化碳纤维与基体的界面处形成了MgAl₂O₄和CaAl₂Si₂O相，从而改善了界面结合，进而改善了复合材料的力学性能。
