Study On Preparation And Performance Of Carbon/glass Fiber Three-dimensional Fabric And Its Antioxidant Coating

In recent years,carbon fiber has been widely used in the fields of aviation,aerospace,chemical industry,machinery,and sports equipment.It has the advantages of high strength,high modulus,low density,low expansion coefficient,and high temperature resistance.Glass fiber is an inorganic metal material that can replace metals and has excellent performance.It has high strength,high modulus,heat resistance and compressibility,good chemical stability,non-flammability,and corrosion resistance.The price is lower than carbon fiber.It has high cost performance and has been widely used in many fields.The continuous development of three-dimensional braiding technology makes three-dimensional braiding reinforcement materials no longer limited to carbon fiber.The combination of carbon/glass fibers can both excel in mechanical properties,and its economic value is more cost-effective.However,carbon fiber has the disadvantage of poor oxidation resistance.Research shows that this will directly reduce the mechanical properties of the three-dimensional braid by 30%-40%,so it is particularly important to effectively improve the oxidation resistance of carbon fiber.By using carbon fiber and glass fiber as raw materials,five different hybrid methods of three-dimensional through orthogonal structure weave fabrics are designed.The five hybrid methods are non-hybrid carbon fiber;non-hybrid glass fiber;warp yarn is glass fiber,Z-direction yarn and weft yarn are Carbon fiber;warp yarn and Z-direction yarn are glass fiber,weft yarn is carbon fiber;warp and weft yarn is carbon fiber,Z-direction yarn is glass fiber.The mechanical properties of 5 kinds of preforms,such as tensile strength and elongation at break,were tested respectively.The results showed that the warp and weft yarns are carbon fibers,and the Z-direction yarns are glass fibers,which can better reflect the advantages of mechanical properties.In order to give full play to the structural advantages of carbon fiber materials,a carbon/glass fiber three-dimensional fabric with oxidation resistance is obtained.The carbon/glass fiber three-dimensional fabric is used as a preform,and vinyl triethoxysilane（VTES）and ethyl orthosilicate（TEOS）is the precursor.The precursor sol is prepared by the sol-gel method.The precursor sol is coated on the surface of the carbon/glass fiber by the dipping method,dried at room temperature and gelled on the surface of the fiber,and then placed in argon Inorganicization in the tracheal furnace,and finally a SiC-SiO₂ coating is formed on the surface of the carbon/glass fiber.Use SEM to observe the microscopic morphology and changes of the coating on the fiber surface,test the molecular configuration of the coating composition by FTIR,and detect the crystal structure of the coating by XRD.Use a rotating rheometer to study the pH value,H₂O/TEOS mass ratio,Et OH/TEOS mass ratio,aging time,reaction temperature influence on the stability of the sol.Experiments show that the sol developed by the sol-gel method is successfully prepared after inorganicization of the SiC-SiO₂ coating/carbon/glass fiber three-dimensional fabric sample,and the pH of the sol is determined to be 1.5,and the mass ratio of H₂O,TEOS,VTES,and Et OH is7:7:0.5:11,the reaction temperature is 50°C.The SiC-SiO₂ coating/carbon/glass fiber three-dimensional fabric was subjected to thermal weight loss and anti-oxidation experiments.The oxidation process of the coating/carbon/glass fiber three-dimensional fabric was analyzed through gradual oxidation and constant temperature oxidation tests.The fiber surface of the three-dimensional fabric was observed before and after oxidation.Microscopic configuration,detecting the crystal configuration of the fiber surface coating after oxidation,and studying the mechanical properties of the three-dimensional fabric samples before and after oxidation.Experiments show that the quality loss of the coating/carbon/glass fiber three-dimensional fabric is significantly lower than that of the initial carbon/glass fiber three-dimensional fabric;the two oxidation reaction mechanisms are analyzed,and the coating/carbon/glass fiber three-dimensional fabric is better than the original carbon/glass fiber three-dimensional fabric.The activation energy（Ea）of the three-dimensional fiber fabric is increased by about 13%;when the ratio of water to TEOS solution is 7:7,the viscosity of the sol ranges from 3.17 to 4.2m Pa·s,and the immersion time is about 35 min,the coating/carbon/glass The three-dimensional fiber fabric has better oxidation resistance;compared with the initial fabric,the strength of the 5 groups of coated fabric samples is slightly weaker and the thickness is increased,but the strength after oxidation is increased.The warp and weft yarns are carbon fibers,and the Z-direction yarns are glass fibers.The coated fabric has the highest strength after oxidation;the SiC-SiO₂ coating gives the fabric surface hydrophobic properties.