Interface Regulation And Mechanical Properties Of C/C And C/SiC Composites Prepared By Slurry Brushing

C/C and C/SiC composite materials have excellent properties such as low density,high specific modulus,high specific strength,high temperature resistance and ablation resistance.They are ideal thermal structural system materials for aerospace,metallurgy and chemical industries.The interface structure is the core issue of strengthening and toughening of composite materials.In order to further improve the strength and toughness of C/C and C/SiC composites,this paper aims to investigate the interface structure between each structural unit in C/C and C/SiC composites.The control and optimization are used to enhance and toughen the material,and the correlation between the number of CVD interfacial phase layers and the fracture behavior and fracture mechanism of the material is discussed.In this paper,the composite material preform is prepared by slurry brushing and needle punching process,and C/C and C/SiC composite materials are prepared by chemical vapor infiltration（CVI）process.By adjusting the volume fraction of slurry resin in the process,curing pressure,slurry solid content,study their effects on the interface structure and mechanical properties of C/C and C/SiC composites.Explore the process parameters to optimize the interface state and mechanical properties of the composites,and provide the C/C and C/SiC composites with the best mechanical properties.The 0.25μm×2（Py C/SiC）₁ and 0.25μm×4（Py C/SiC）₂ multilayer interface phases prepared by CVD process were introduced into the C/SiC composites,respectively,and interface phase layers were analyzed and discussed.Effects on the strength and toughness of composite materials.The main research contents and conclusions are as follows:（1）When the volume fraction of resin is 10%,the mechanical properties of C/C and C/SiC composites are the best,the material matrix is evenly distributed,and the interface bonding strength between matrix phase and reinforcement phase is high.At this point,the strength and toughness of C/C composites are 367.80 MPa and 11.33 MPa·m^1/2,respectively.The strength and toughness of C/SiC composites are 517.06MPa and 11.96 MPa m^1/2,respectively.（2）The C/C and C/SiC composites prepared at curing pressure of20 MPa have better interface bonding state between matrix and fiber,and the interface bonding strength between fiber layers is high,showing better strength and toughness.（3）When the solid content（volume ratio）of slurry is 10%,the matrix density of C/C composite material is higher,the pore defects in the material are less,the matrix modulus and fiber modulus are the best match,and the strength and toughness of the material are the best.（4）The interfacial phase and matrix,interfacial phase and interfiber bond state of（Py C/SiC）₁ type interfacial composite are poor,and the strength and toughness of C/C composite are low,which are 287.22 MPa and 9.30 MPa·m^1/2,respectively.The interfacial phase of（Py C/SiC）₂interfacial composite is well bonded to matrix and fiber,and the strength and toughness are 420.69 MPa and 12.39 MPa·m^1/2,respectively.（5）The（Py C/SiC）₁ interfacial C/SiC composites prepared in this paper have a large number of fiber bundle inner holes and poor mechanical properties;On the contrary,（Py C/SiC）₂ interfacial C/SiC composites are very compact,with strength and toughness of 545.17 MPa and 15.67 MPa·m^1/2,respectively.There are 54 graghs,18 tables,87 references.