Preparation Of Fe-Co-Ni Alloy Coating By Electrodeposition In Eutectic Solvent And Its Corrosion Resistance

The hardness and corrosion resistance of Fe-Co-Ni alloy coating are close to those of traditional chromium coating,and the pollution to the environment is much less than that of chromium.In the selection of electrodeposition fluid,aqueous electrolyte will lead to high power consumption.High temperature molten salt electrolyte has strong corrosivity.Low eutectic solvent has the advantages of high electrochemical window,low price and degradability.The electrodeposition process of low eutectic solvent is friendly to the environment.In this paper,the eutectic solvent system composed of choline chloride and levulinic acid was selected,and the electrodeposition effusion was configured according to the corresponding molar ratio.The conductivity of eutectic solvent and electrodeposition fluid at different temperatures were measured,and the cyclic voltammetry curve was measured,and the cyclic voltammetry curve was measured.In the electrodeposition experiment,Fe-Co-Ni alloy coating,Fe-Co-Ni-Cu alloy coating and Fe-Co-Ni-Cu-Sn alloy coat-ing were successfully prepared by constant current electrodeposition with brass Haste-lloy plate as cathode and graphite as anode.The hardness and The micro structure,composition,phase composition and corrosion resistance were analyzed.The results show that Fe-Co-Ni alloy coating can be obtained by using eutectic solvent as electrolyte.The conductivity of the eutectic solvent system increases with the increase of temperature.The surface of Fe-Co-Ni alloy coating prepared by electrodeposition at 50℃and current density of 3m A/cm~2for 10h is relatively flat and compact.The deposited layer is amorphous and has good corrosion resistance.With the increase of temperature,partial crystallization occurs.The surface hardness of the deposited layer at 70℃is 458hv0.025.During the co deposition of Fe,Co and Ni in eutectic solvent,With the increase of current density,the deposition rate of Ni ions increases and that of Co ions decreases.With the increase of current density,the grain size on the surface of the coating decreases and the gap between the grains increases.When the temperature is 70℃,the corrosion resistance of Fe-Co-Ni alloy coating obtained by electrodeposition at 10m A/cm~2for 0.5h is better than that of electrodeposition at 3m A/cm~2for 10h.In the process of preparing Fe-Co-Ni-Cu alloy coating,it is found that when the current density is greater than 5m A/cm~2,Fe,Co,Ni and Cu elements realize codep-osition,but the particles on the surface of the coating show large tumor shape and relatively dispersed.It is a solid solution phase with FCC structure.When the electro-deposition temperature is 70℃and the current density is 5m A/cm~2respectively,the corrosion resistance of Fe-Co-Ni Cu alloy coating is better.The deposition of Fe,Co,Ni,Cu and Sn can be realized in low eutectic solvent.The alloy coating is a solid solution phase with FCC structure.The particle size on the surface of the alloy coating is uniform and evenly distributed.When the current density is 10m A/cm~2and the temperature is 50℃,the Fe-Co-Ni-Cu-Sn coating with better corrosion resistance can be obtained.