Preparation Of Nanocrystalline Iron Electroplating Nickel Chromium Alloy Foil And Mechanism Research

Fe-Ni-Cr foil is widely used in electromagnetic shielding field because of their excellent electrical conductivity and corrosion resistance, but few about electrodeposition Fe-Ni-Cr alloy foil were reported in the literature. Fe-Ni-Cr alloy foil containing high iron low nickel and chrome had been electrodeposited in this, which had good hardness, corrosion resistance and electrical conductivity. This work includes three aspects:(1)Fe-Ni-Cr alloy foils were electrodeposited by direct current (DC) from the trivalent chromium bath containing glycine as complexing agent. The optimal process conditions are followed as that:50g·1-1CrCl3·6H2O, with15A·dm-2DC density, at60℃temperature in the solution of pH1.5. About20μm Fe-Ni-Cr alloy foil was obtained with a smooth and uniform appearance after45min electroplating, which contains4-6wt%Cr;(2)Fe-Ni-Cr alloy foils were electrodeposited by pulse current (PC) from the trivalent chromium bath containing glycine as complexing agent. The optimal process conditions are followed as that:90g·1-1CrCl3·6H2O, with17A·dm-2average density, at60℃temperature in the solution of pH1.5. About20-30μm Fe-Ni-Cr alloy foil was obtained with a smooth and uniform appearance after45min electroplating, which contains5-8wt%Cr;(3) The electrochemical deposition mechanism of Fe-Ni-Cr alloy foil were studied by infrared spectrum(IR) cathode polarization curve, circulate voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). The result indicated Cr3+was easily reduction on the cathode because the stable structure of [Cr(H2O)6]3+was changed instale structure after adding glycine and citric acid in solution; complexing agent changed the deposite potential of Cr, Fe, Ni respectively, and make the co-deposition possible; the reduction control steps were electron transfer control; the i0of gly-Cr system was the smallest because the deposition resistance was increased when Cr3+was added in gly-Fe-Ni system; composition distribution difference of alloy foil in cross-section was caused by large volume and small diffusion and reduction velocity of tri-chromium ions; EIS results indicated the electrochemical reaction and adsorption resistance of gly-Cr system is maximum, that’s one of the reason chromium was difficult to deposited.