Study on Electrodeposition Preparation and Corrosion Resistance of Ni-Co-Ce Composite Coatings
Ni-Co alloy coatings have good corrosion resistance and are mostly used for metal corrosion pro-tection.The addition of Ce to the alloy coatings can refine the crystal grains and improve the microstruc-ture densification and corrosion resistance of the alloy coatings.Using marine steel EH40 as the substrate,Ni-Co-Ce alloy coatings were prepared on its surface by composite electrodeposition process.The corrosion resistance of the alloy coatings prepared under different process conditions was tested through tests of po-tentiodynamic polarization curve and electrochemical impedance spectroscopy in a 3.5％NaCl solution.The surface morphology and phase composition of the coatings were investigated by scanning electron micro-scope and X-ray diffractometer.The results show that the optimal electrodeposition conditions of the coat-ings are a cerous sulfate concentration of 0.6 g/L,a current density of 0.04 A/cm2,and an electrodeposi-tion temperature of 50 ℃.Under these conditions,the prepared coating possesses smooth surface,with the lowest self-corrosion current and self-corrosion potential(absolute value)of 3.694 5 × 10-6 A/cm2 and-0.534 V,respectively.In addition,the above coating exhibits the maximum charge transfer impedance of 889.81 Ω·cm2,having the best corrosion resistance.
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