Study On Preparation Method And Mechanism Of Copper-nickel Composite Coating On Carbon Fibers By Thermal Reduction

Carbon fiber reinforced metal matrix composite material has many advantages of fiber and metal, but the poor wettability and prone to biochemistry reaction between carbon fiber and metal substrate in a composite reduces its application. Surface metallization is an effective means to solve the Poor compatibility between carbon fiber and metal substrate. Surface metallization make the contact between carbon fiber and metal into metal and metal, which reduces damages to the carbon fiber when manufacturing composite materials and give full play to the good performance of carbon fiber.The Subject adopts the way of thermal reduction plating to surface metallization on carbon fiber. Thermal reduction plating take the advantage of the strong reducibility characteristics of hydrogen at high temperature, which is a new method of plating that put carbon fiber with metal salt back into metal coating carbon fiber. The process of the new method is relatively simple, the plating is more homogeneous and the adhesion strength between plating and carbon fiber is relatively better compare with the traditional methods(electroplating, Electroless plating).The following conclusions in the study.(1)The experiment put the carbon fiber in the muffle furnace to degum the carbon fiber, the experimental results show that the effect of degumming is ideal when the fiber is calcined at 400 degrees Celsius for 30 minutes. Put the degumming carbon fiber in concentrated nitric acid to coarsen at room temperature, the effect is better when the coarsening time is 70 min. The surface pretreatment on carbon fiber have no damage to the microstructure of carbon fiber by XRD analysis. As the coarsening time prolonged, the amount of the pre plating solution on carbon fiber surface are also more.(2)The plating mechanism of two different kinds of main salt(copper sulphate, copper nitrate) are studied in this paper. Based on the different mechanisms, two different plating processes are formulated. On the basis of the plating processes, we get the coating carbon fiber with better performance.(3)Making use of the orthogonal experiment to design Preliminary solution of Copper sulfate. We found the quality of pre-coating carbon fiber is better as the formula is: the solubility of copper sulfate was 800 g/L, the dosage of polyvinyl alcohol was 0.5%, the dosage of dodecyl benzene sulfonic acid sodium was 0.3%, the dosage of glycerin was 4%. Use orthogonal experiment to design of copper coated carbon fiber, we found that the optimal level of factors was: the soak interval was 80-10?, the heat preservation temperature is 650?,the heat preservation time is 0.5 hours. The coating mainly exists in the form of particles, and the coverage rate of coating is high, the elemental composition of coating is elemental copper.(4)In order to improve the performance of coating carbon fiber, we add borax in the Preliminary solution. And through the orthogonal experimental to study the influence of borax, heat preservation temperature and heat preservation time on the coating, we find the optimal level of the three factors is: borax is 8%, heat preservation temperature is 750?and heat preservation time is 90 min. By comparing the morphology of copper layer on carbon fiber that add and not add borax, we found that the coating can be flat because of the presence of borax.(5)Owing to the high solubility of copper nitrate, when we put copper nitrate as the main salt to manufacturing coating carbon fiber, the experiment got the coating of good coverage on carbon. But due to the limit of reduction process when the main salt was copper nitrate, we got the coating Consists of particles in the form of mutual accumulation, the coating exists in the form of relatively loose and small particles and the coating is easy to fall off.(6)Using the same method to plating a layer of nickel on the surface of copper coating carbon fiber, surface scan was carried out to analysis the surface element distribution on carbon fiber. We found that if copper can plating up, nickel can also plating up, if there is no copper on the surface of carbon fiber, there is no nickel. This shows that preparation of the good performance of copper and nickel Composite coating carbon fiber by thermal reduction, solving the problem of copper plating is the key. On the surface of copper, nickel is easier to plating up.