Study On The Structure And Performance Of Short Fiber Reinforced C/C-SiC Composites Prepared By Molding-infiltration Method

In order to further improve the load-bearing and tribological properties of C/C-SiC composites and expand its application in the field of braking,short fiber reinforced C/C-SiC composites were designed and prepared in this paper.Microstructure,mechanical properties and tribological properties of SiC composites were systematically studied,the structural evolution law during the material forming process was clarified,and the mechanical failure and friction/wear behavior of C/C-SiC composites were discussed.The results are as below:(1)A method for designing and controlling the porosity of porous C/C composites was established,and the controllable formation of the porosity of the infiltration carrier was realized.The pore size distribution of porous C/C composites exhibit bimodal distribution characteristics.The addition of aramid fiber can reduce the pore tortuosity and improve the absolute permeability of the network pore structure,which have obvious pore structure regulation effect.(2)High-density short fiber reinforced C/C-SiC composites were prepared by reactive melt infiltration using porous C/C composites as carriers.The ceramic phase matrix of the composites has the characteristics of continuous network skeletons,which forms strong interfacial bonding and pinning structure with the fiber bundles.The addition of aramid fiber can improve the transport capacity of liquid Siof interconnected pores,and has significant effect on improving the distribution uniformity of the ceramic phase matrix and reducing the Sicontent.(3)The flexural,compressive and interlaminar shear strengths of the short fiber reinforced C/C-SiC composites are 75～96 MPa,226～274 MPa and 7.7～10.1 MPa,and exhibit pseudoplastic flexural fracture,brittle compression fracture and brittle shear fracture.The high density,high fiber content and the formation of SiC network skeletons endow the C/CSiC composites with excellent load-bearing properties.The high content of SiC/C interface and strong interfacial pinning structure endow CRF-C/C-SiC with excellent strength and toughness properties.(4)The difference among the structures of short fiber reinforced C/C-SiC composites doesn’t show obvious effect on thermophysical properties.Taking the resin matrix composites as the counterpart,the friction coefficients of the C/C-SiC composite are between 0.2 and 0.3,with excellent friction stability.The uniformly distributed ceramic phase skeletons enable the C/C-SiC composites to have low wear rates.