Effects of High Temperature Heat Treatment on the Microstructure and Tensile Properties of C/C Composites
In order to reduce the brittleness of C/C composites,a homemade thermal gradient chemical vapor deposition(TG-CVI)equipment was used to densify the unidirectional carbon fiber preforms to obtain dense C/C composites.The bonding strength of the interface and the graphitization of the matrix carbon were adjusted by high temperature heat treatment.The density of the composites was tested by the drainage method.Their tensile properties were tested with a universal material testing machine.The samples were treated with the visualization of graphene texture(VGT).The microstructure,interface and cross-sectional morphology of the composites were studied with a polarizing microscope(PLM)and a scanning electron microscope(SEM).Their phase composition was studied by X-ray diffraction(XRD).The results show that under the same deposition conditions,the graphitization of the carbon matrix of the heat-treated C/C composites increased,and both the interfacial bond strength and the tensile properties decreased.However,the initial brittle fracture of the composites changed to the proposed ductility and its elongation increased.
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