Research On Metallization On Carbon Fibers And Wettability Between Fiber And Magnesium

In preparing carbon fiber reforced magnesium-based composite, the interface of the composite is always impact the quality of composite. The wettability between Cf and Mg is bad, in order to over come the problem, metalized surfaces were prepared in Cf by electroless plating in this paper. Ni-P, Cu, Ni-Cu-P coatings on Cf with good bonding strength were prepared. The interface of Cf/Mg were improved after metal-coating on the surface of Cf.In this paper, SEM was used to observe the surface of the coating in carbon fibers. EDS and XRD was adopted to qualitatively analyze the components of the plating. Through orthogonal experiment, the processing parameters of electroless Ni-P, Cu plating was optimized. Through single factor experiments, the effects of complexing agent concentration, temperature, and deposition time and pH value of solution on displacement rate have been discussed. Electroless Ni-Cu-P ternary alloy coating was prepared in Cf, the parameters were optimized through single factor experiments, the effects of CuSO4, reducing ,complexing agent concentration, pH of solution ,temperature and deposition time on displacement rate have been discussed.The research shows that colloid on Cf surface could be removed under 15min firing at 550℃, but Cf were hurts at high temperature; Extract Cf by acetone at 70℃for 4h could remove the colloid on carbon fiber.The optimal technology of electroless plating Ni-P on Cf were sodium citrate 25g/L, pH value-8.0, temperature 65℃, plating 3min. With an increase in deposition temperature or pH of the plating bath, or a decrease in stabilizer concentrations, the deposition rate increased but the stability of the bath became worse; there were obvious four stages in the deposition: initiation period, acceleration period, deceleration period, and stationary period. The tumor-like deposition shape formed in the surface of the plating, when the temperature or pH of plating bath and temperature were too high, the complexing agent concentration was too low, and the stability of solution also became worse. In the reaction of deposited Ni-P on Cf, the surface energy Ea= 140.378KJ/mol.The optimal technology of electroless plating Cu on Cf were EDTA·2Na 35 or 45g/L, pH value-13.5, temperature 55℃, plating 2min. With an increase in deposition temperature or pH of the plating bath, or a decrease in stabilizer concentrations, the deposition rate increased but the stability of the bath became worse. The deposition rate first increase then decrease by time. When the temperature or pH of plating bath and temperature were too high, the complexing agent concentration was too low; the stability of solution also became worse. In the reaction of deposited Cu on Cf, the surface energy Ea= 13.4KJ/mol.The optimal technology of electroless plating Ni-Cu-P on Cf were copper sulfate 2.0-2.5g/L, sodium citrate 55g/L,sodium hypophosphite 24-27g/L, pH value-8.5, temperature 80-85℃. With an increase in complexing agent and copper sulfate concentration, the deposition rate decrease. With an increase in deposition temperature or pH of the plating bath, or an increase in reducing agent concentration, the deposition rate increased. The deposition rate first increase then decrease by time. In the reaction of deposited Ni-Cu-P on Cf, the surface energy Ea= 416.7KJ/mol.Through theoretical calculation, the wetting angle between Cf and Mg is about 153°,the contact angle between Ni, Mg is 49.1°, between Cu and Mg is 39.6°. The bond between three kinds of coating and Cf were good enough through the thermal cycle tests. Contrast uncoated and coated fiber reinforced magnesium-based composites, found that the interface between coated fiber and magnesium is much better, Cu coated and Ni-Cu-P coated fiber united molten magnesium better than Ni-P coated fiber.