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

The PAN-based CF precursor was prepared from polyacrylonitrile fiber by series processof oxidation and carbonization, its carbon content is above90percent. CFs have been widelyused for many specific fields due to their better performance (high specific strength,toughness, low density, high thermal resistance, corrosion resistance, high tenacity, electricalconductivity, thermal conductivity and small coefficient expansion,etc)than other traditionalfiber (e.g, kevlar and glass fibers),such as industrial、aerospace、biotechnology, etc. Carbonfiber was an outstanding material of advanced materials, which can bring immeasurablesociety and economic benefits.In this paper， the author studied mainly on how to improve the wettability(interfacial energy with metallic surfaces)between a common reinforced composite-carbonfiber and metal substrate. CFs have a poor wetting characteristics and high reactivity withmolten metals. These drawbacks cause difficulties in fabricating metal matrix compositesreinforced with CFs, and deteriorate their physical and mechanical properties. One solutionfor these difficulties is to apply surface modification of a metal layer on the CFs surface. Inthis experiment we used Cu as the metal layer. In this paper, thermal reduction was applied tometallized the CFs, and provided a new way for the development of metal matrix composites.Results are as follows：(1) To find an effective pretreatment method for removed the epoxy from CFs surfaceby combination with the burning and nitric acid soaking. These methods cause nodamage to the fibers structure;(2) The thermal reduction process is more convenient and reduce costs though omittedsensitize and activation, its without use precious metal solution (AgNO3, PdCl2);Formula of pre-coating was optimized by orthogonal test. And the optimal dosagesare saturated solution of dosages are saturated solution of CuSO4, PVA0.3%~0.4%,surface-active agents0.4%,glycerol6%;(3) The thermal reduction process was determined by the analysis to performance ofcarbon fiber and composition of the Cu layer. The hydrogen as reduction gas, thenitrogen as protective gas, heat treatment at1000~1050℃for1~1.5hour anddetermined the flow of gas, and it achieved good results of the Cu layer though theprocess;(4) The experiment shows that heat treatment providing energy to promote atomicdisplacement, transformed the way of combination to a thermal way. Withincreasing the treatment temperature, the coating quality and adhesive strength ofthe films increased. The mechanical and surface characteristics of CFs were observed and analyzed by XRD,SEM and wetting measurements. Based on orthogonal test, the pre-plating and thermalreduction parameters were gained. The experimental copper coating with excellent propertieswas obtained in the laboratory.