气相硼催化石墨化炭纤维对其力学性能和微观结构的影响

摘要

Boron-catalyzed graphitization of carbon fibers was conducted in a boron-doped graphite crucible at 2 000℃, in which boron diffused from the crucible to the carbon fibers to act as the catalyst. The microstructures, boron contents and mechanical prop-erties of the resulting carbon fibers were characterized by Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy and mechanical tests. Results indicate that boron has a significant impact on the fiber microstructure. Raman spectra indicate the presence of distortions in the graphitic layers. The tensile modulus of boron-doped carbon fibers obviously increases with boron content and the tensile strength is also higher than that of the original car-bon fibers at boron concentrations between 0. 58 to 0. 68 at.%.%采用间接法将硼引入炭纤维( CF)中，即先将硼引入石墨坩埚中，然后将CF放到坩埚中，升温进行石墨化处理，石墨坩埚中的硼扩散出来，进入纤维中，借助硼的催化石墨化特性，从而制备出硼掺杂石墨纤维。研究硼含量对炭纤维力学性能的影响。利用X射线光电子能谱、X射线衍射、拉曼光谱、扫描电子显微镜、高分辨透射电子显微镜对所制石墨纤维中的硼含量、结构和形貌进行表征和分析。结果表明：石墨纤维中的硼含量可控，硼的催化石墨化作用，提高了CF的石墨化度，由于硼的固溶特性引入了一些缺陷，使得CF的微结构和力学性能发生变化；通过调控CF中的硼含量(0.58%-0.68%)，能够在CF强度不损失的情况下提高其模量。