Study On Go Interface Based Reinforcement Preparation And Carbon/Carbon Composite

Carbon/carbon(C/C)composites reinforced by carbon fiber and pyrolytic carbon matrix of C/C composites in the process of service,the interface debonding collapse,frequent burst phenomenon,caused by the instability of heterosexual component performance and size,etc.,in view of the present C/C composite material damage evolution problem of serving in harsh conditions,this study will be introduced to the interface design of carbon fiber in C/C composites reinforced precast body in order to improve the mechanical properties of composite materials.In this thesis,the interface of GO was grafted onto the carbon fiber modified by functional groups by chemical grafting method.Nanofiber-carbon fiber preforms were constructed by the high specific surface area and abundant functional groups of GO,and C/C composites were prepared by chemical vapor deposition densification.The main conclusions are as follows:The effect of the introduction of GO interface on the microstructure of C/C composites was studied.After the introduction of GO,the matrix texture of C/C composites did not appear multi-layered structure.The extinction Angle measured by PLM was about 21±2°,and the structure was high textured pyrolysis carbon.When the size of GO increases within a certain range,compared with the pure C/C composites,the matrix microstructure of C/C composites is improved by the introduction of GO,which makes the matrix obviously refined and induces the formation of a large number of growth cones and grain boundaries.With the further increase of GO size,the graft content of GO in the prefabricated body decreased,the active sites decreased,and the induction effect on the matrix was small.Compared with the graft condition of p H=1.5±0.5,the graphitization degree of the GO-C/C composite matrix in the GO-C/C rich region is greater than that in the graft condition of p H=3.5±0.5,with smaller(002)crystal plane spacing d₀₀₂value and larger stacking height LC value,the I_D/I_Gratio decreases,the graphene plane size L_aincreases,and the order degree of the GO-C/C composite material is improved.The introduction of the research GO interface mechanical properties of C/C composites:for bending performance:the size of the GO within a certain range increased when improve the bending performance of C/C composites,the highest rate of about 29%and 51%,and continue to increase the size of the GO will results in the decrease of C/C composites apparent density,open porosity increased,lower the C/C composite bending performance.The introduction of GO interface increases the bending fracture brittleness of C/C composites,which is related to the high brittleness of carbon during the pyrolysis of high texture.In terms of interlaminar shear performance,the interlaminar shear strength of C/C composites is improved by the introduction of GO interface,and the maximum increase ranges are 55%and 72%.The interlaminar shear strength of C/C composites and the cohesion force of matrix are improved by the introduction of GO interface,so that the destructive cracks can be deflected.The compressive strength of C/C composites is improved by 27%and 35%only when the GO size is 8-15?m.Compared with the grafted GO-C/C composites at p H=1.5±0.5,the grafted GO-C/C composites at p H=3.5±0.5 can improve the mechanical properties of C/C composites more,only when the size of GO increases within a certain range.At lower p H value,the surface protonization of carbon fiber is serious,which leads to incomplete grafting and low improvement of matrix structure.The effect of GO interface introduction on the oxidation resistance of C/C composites was studied.The introduction of GO interface can improve the properties of C/C composites with weak fiber/matrix interface bonding and more defects in matrix microstructure,thus improving the oxidation resistance of C/C composites.The oxidation loss rate of GO_8-15?mC/C composites is 45%and 51%higher than that of pure C/C composites.In terms of thermal shock performance,the thermal shock resistance of GO-C/C composites is 42%and38%higher than that of pure C/C composites,and the thermal shock resistance of GO-C/C composites is higher than that of grafted GO-C/C composites under p H=1.5±0.5 grafted environment.The matrix defects of C/C composites increase,the apparent density decreases significantly,the opening rate increases,and the closed pores increase.