Study On The Fabrication Of Carbon Nanotubes Grafted Carbon Fiber/Carbon Cloth And Their Composites

In this paper,carbon fibers were treated by electrochemical anodic oxidation to obtain activated surface and carbon nanotube(CNTs)were loaded on the surface of carbon fibers by chemical vapor deposition(CVD).Effects of pretreatment process on the loading of catalyst and mechanical properties of carbon fibers were investigated.Different CVD processes and their effects on CNTs/carbon fiber reinforcements were also clarified.Uniform growth of CNTs on the surface of carbon cloth was realized.SEM,Raman spectrometer,strength and extensibility tester,universal testing machine and thermal analyzer were employed as analysis methods and properties of carbon fibers,carbon cloth and composites were characterized.The surface of carbon fibers could be effectively activated by electrochemical anodic oxidation treatment.With the increase of current intensity,the oxidation etching degree of graphite microcrystals increased and the groove on carbon fibers became obvious.As the current intensity rose,the number and diameter of catalyst particles on carbon fibers also increased using ammonium dihydrogen phosphate as electrolyte.When the electrolytic current was 0.4 A,uniform catalyst nanoparticles were loaded on carbon fibers after electrolysis treatment,and CNTs with better morphology were grafted.With the increase of current intensity,the length of CNTs increased and the distribution of catalyst and CNTs became more uniform.The decrease of tensile strength of carbon fibers was slight,which indicated that the damage degree of carbon fibers brought by electrochemical anodic oxidation method was smaller than other methods.Through studying the reinforcement effect on CNTs/carbon fiber with different CVD process,we draw the following conclusions.Both Co and Ni could grow out uniform CNTs on carbon fibers,and the catalytic activity of Ni was higher compared with Co.After grafting CNTs,the tensile strength of carbon fibers was 6.98%higher compared with the untreated carbon fibers.The length and density of CNTs increased with the improve of CVD temperature.However,catalyst particles will seriously etching the surface of carbon fibers in the case of excessive temperature,then mechanical properties of carbon fiber were damaged.So the preparation temperature of CVD should not be too high.The highest tensile strength was obtained under 600?.Different CVD atmosphere also had significant effects on the morphology of CNTs.When C2H2:H2:N2 6:6:12,CNTs can be uniformly grown on the carbon fibers surface and the tensile strength of carbon fibers was up to 4.93GPa.The interlaminar shear strength(ILSS)and dielectric properties of composites were also improved.By studying the effects of experimental equipment and CVD process on the yield and morphology of CNTs on carbon cloth surface,uniform loading of CNTs on carbon cloth surface was realized.It was found that the catalytic activity of Fe catalyst was low and most of the products were carbon nanofibers without hollow structure,and the diameter distribution of carbon nanocrystals was uneven.When Co(0.05M)was used as catalyst,hollow CNTs with smaller diameter and narrower distribution were uniformly loaded on the surface of carbon cloth.The mixed products of CNTs and carbon nanofibers were obtained when Ni was used as catalyst.The catalytic activity of the three catalysts was in the order of Fe>Co>Ni.When the time of CVD was 5 minutes,the morphology of CNTs and the mechanical properties of the composites were also significantly affected.When the CVD time was 1 Omin,the yield and length of CNTs were further increased,and the tube diameter was also increased.The tensile strength of carbon cloth was positively correlated with the time of CVD.The tensile strength reached the highest value and the ILSS of carbon cloth reinforced composite was the highest when the CVD time was 10min.