关键词: 碳纤维, 抗拉强度, 断裂, 涂层

Abstract: In the paper,with the help of the CVD method,the author acquired uniform SiC coating,C+SiC composite coating,Si coating and C-Si gradient coating on the surface of carbon fibers (CF);studied the influence of the coating on the tensile strength of CF; analysed the phase structure of the coating and studied the fracture process and fracture texture.Experimental results show that the tensile strength of the coated CF is lower than that of the acetone treated CF;that the sequence of the tensile strength magnitude of the coated CF is from the C-Si gradient coated CF to the C+SiC composite ccated CF,tO the SiC coated CF,and to the single Si coated CF;and that the phase structures of all coatings on the surface of CF are noncrvstalline,The author further proved "the turbostratic graphite structure" of the PAN Ⅱfiber,The characterizations of appearance of the fracture of PAN fiber are the step form wave form,buckle form, car arm form,etc,respectively.The appearance of the fracture of the C-Si gradient coated CF,the C+ SiC composite coated CF and the SiC coated CF is in the flat cutting form; the fracture mechanism is that the craze spreads throngh the CF. But the appearance of the fracture of the single Si coated CF is in the pull-out form; the fracture mechanism is that the craze spreads along the interface of the coating,the CF is split.

Key words: carbon fiber, tensile strength, fracture, coating