Study On Electrochemical Mechanism Of Pure Iron Prepared By Molten Salt Electrodeposition

Pure iron has good soft magnetic properties,corrosion resistance,electrical conductivity and thermal properties,which are widely used in many fields.Molten salt electrodeposition has the characteristics of high purification efficiency,low cost and easy industrial production.At the same time,it avoids the problems of difficult treatment of colloids in traditional aqueous solution electrolysis.The preparation of iron was studied.The primary crystallization temperature(T₀)and dissolution mechanism of Fe₃O₄in Na Cl-KCl-Na F and Na Cl-Ca Cl₂molten salt systems were studied.The results show that in Na Cl-KCl-Na F-Fe₃O₄system,when X_{Na Cl}:X_KCl:X_{Na F}=3:3:4,whenX_Fe3O4<30%,the higherX_{Fe3 O4},the lower the T₀;the higher X_{Na F},the higher the T₀.In Na Cl-Ca Cl₂-Fe₃O₄system,when XNa Cl:X_{Ca Cl2}=1:1,the T0 is the lowest and increases with the increase of A.Fe₃O₄did not dissolve chemically in the two systems and was verified by XRD.The electrochemical behavior of Fe₃O₄in Na Cl-Ca Cl₂molten salt system was studied by electrochemical method.The results show that Fe₃O₄is reduced to iron(Fe₃O₄?Fe O?Fe)by two steps on Ni and Pt electrodes,and both of them are quasi-reversible reactions controlled by diffusion.The reduction potential of Fe₃O₄on Ni/Pt electrode shifts negatively with increasing temperature and positively with increasing temperature.The diffusion coefficients of Fe³⁺and Fe²⁺at various temperatures and their relationship with temperature were obtained.ln D showed a good linear relationship with1/T.The activation energies of Fe³⁺and Fe²⁺on Ni/Pt were 62.38 k J/mol and 77.52k J/mol/127.79 k J/mol and 133.84 k J/mol,respectively.In the molten salt system of XNa Cl:X_{Ca Cl2}=1:1,the effects of nickel plate as cathode,high purity graphite plate as anode,deposition time,deposition temperature and molar fraction of iron oxide on the surface morphology of the deposited layer were studied.The results showed that the deposited time was 10 h,the deposition temperature was 1073 K and the molar fraction of iron oxide was 2%.The quality of the deposits is good.Figure51;Table16;Reference 86.