| With the gradual exploitation of deep sea oil resources,the disadvantages of the marine drilling platform constructed with traditional steel were becoming increasingly prominent,such as easy corrosion,high construction and maintenance costs.Carbon fiber/epoxy resin(CF/EP)composites had become ideal structural materials due to their light weight,high strength,high modulus and corrosion resistance.Nano-silica and graphene oxide(GO)have high reinforcing efficiency for epoxy resin which little addition can greatly improve the mechanical strength and impact resistance of epoxy resin matrix.Therefore,carbon fiber/SiO2/GO/epoxy resin composites with good corrosion resistance,high strength and toughness were prepared by using GO and nano-SiO2 as modified fillers,which will have theoretical and practical significance.The PAN-based carbon fibers were treated by electrochemical oxidation method.Orthogonal experiments were designed to optimize the modification conditions considering the concentration of electrolyte,electrolytic temperature and electrolytic time.The modified products were characterized by modern testing techniques such as FTIR,TGA and SEM,and the effects of electrochemical modification of carbon fibers on the mechanical properties of CF/EP composites were investigated.The results showed that the optimum process parameters for electrochemical modification of carbon fibers were obtained as follows:electrolyte concentration was 0.25mol/L,electrolytic temperature was 35?,electrolytic time was 150s,and current was 150mA,The effect of electrochemical modification of carbon fibers was remarkable.The surface acidic functional group content of carbon fibers increased to 1.53×10-3mol/m.The tensile strength,flexural strength and impact strength of the composites made by the modified carbon fibers were 515.48MPa,462.40MPa and 56.91KJ/m2,respectively,which were 14.58%,6.09%and 13.28%higher than the composites made by untreated carbon fibers.Nano-SiO2 and GO were modified with silane coupling agent KH-550 and stearic acid,and the effects of nano-SiO2 and GO on the mechanical properties of epoxy resin matrix and CF/EP composites were investigated.The results showed that the optimum modification parameters of nano-SiO2 were as follows:the concentration of silane coupling agent was 6.25g/L,the concentration of stearic acid was 3.75g/L,the reaction temperature was 65?,and the reaction time was 2h.The optimum modification conditions of GO were as follows:the concentration of silane coupling agent was 6.25g/L,the concentration of stearic acid was 6.25g/L,the reaction temperature was 75?,and the reaction time was 2h.The modified nano-SiO2 and GO had excellent hydrophobic properties,and their contact angles were 117.61 degrees and 119.52 degrees,respectively.Their compatibility with epoxy resin and dispersibility were improved.When adding 1wt%SiO2,the tensile strength,flexural strength and impact strength of epoxy resin increased by 93.08%,41.99%and 312.68%respectively,and the tensile strength,flexural strength and impact strength of CF/EP composites increased by 14.27%,31.69%and 11.32%,respectively.When adding 0.1wt%GO,the tensile strength,flexural strength and impact strength of epoxy resin increased by 30.49%?14.46%and 196.80%respectively,and the tensile strength,flexural strength and impact strength of CF/EP composites increased by 40.74%?66.72%and 31.59%,respectively.The effects of compounding of nano-SiO2 and GO on the mechanical properties of CF/EP composites were investigated by preparing CF/SiO2/GO/EP composites,and the application properties of the CF/SiO2/GO/EP composites,such as seawater immersion resistance and salt spray aging resistance were investigated.The results showed that the mechanical properties of CF/EP composites were significantly improved by the combination of nano-SiO2 and GO.When the content of nano-SiO2was 1wt%and GO was 0.3wt%,the tensile strength,flexural strength and impact strength of the composites were 725.48MPa,770.93MPa and 74.89KJ/m2,respectively,which were 40.74%,66.72%and 31.59%higher than those of pure CF/EP composites.And the CF/SiO2/GO/EP composites had good seawater immersion resistance,salt spray aging resistance and heat-oxygen aging resistance,which can basically meet the performance requirements of structural materials for offshore drilling platforms. |
PDF Full Text Request