Electrodeposition Of Rare Earth Magnesium Alloy Coatings In Low Eutectic Solvent

With advantages of hydrogen storage,high temperature resistance,corrosion resistance and creep resistance,Rare earth magnesium alloy coatings have been widely used in aircraft,automotive parts and electronic communications.There are many ways to obtain alloy coatings,among which the electrodeposition method is simple and easy to operate.At present,deposition bath system consists aqueous solution,pure organic solvent and ionic liquid.In this article,therefore,choline chloride-urea eutectic solvent?new ionic liquid?is a system of ontology,copper deposit as the preparation of rare earth magnesium alloy plating,the electrochemical behavior of metal ions in the ontology is studied and mechanism of the alloy coating,the preparation conditions,the morphology and corrosion resistance,has carried on the preliminary inquiry for alloy coating used in the production and living provides a new way of thinking.Cyclic voltammetry was used to test the electrochemical behavior of Co²⁺,Ni²⁺,Mg²⁺,Ce³⁺,Sm³⁺and Ho³⁺in the ontology system.The nucleation mechanism of Co²⁺and Ni²⁺and the deposited rare earth magnesium alloy coatings of Co-Mg,Ni-Mg,Co-Mg-Ce,Co-Mg-Sm,Co-Mg-Ho,Co-Ni-Mg-Ce,Co-Ni-Mg-Sm and Co-Ni-Mg-Ho were studied by constant potential technique.The deposit conditions were determined by cyclic voltammetry and orthogonal experiment.The morphology of the coating was analyzed by SEM and elemental distribution.Finally,the corrosion resistance of the coating was studied by tafel curve.The conclusions are as follows:1.The electrochemical behaviors of Mg²⁺,Ce³⁺,Sm³⁺and Ho³⁺in bulk plating solution were analyzed.The CV curve and electrodeposition experiments showed that none of the above four ions could electrodeposit on copper substrate alone.The one-step irreversible reduction reactions of 0.04 mol/L Co²⁺and 0.04 mol/L Ni²⁺occurred in main plating bath.Through cyclic voltammetry and electrodeposition experiments,it is found that Mg²⁺,Ce³⁺,Sm³⁺and Ho³⁺can be induced by Co²⁺and Ni²⁺.2.When the concentration ratio is 4/3,the deposition time is 20 min,the deposition potential is-1.05 V,and the temperature is 353 K,the appearance appearance of the Co-Mg alloy coating is grayish-black,the coating is uniform,the magnesium content reaches 8.6 wt%,and the microstructure of coating is the best.The best condition for Ni-Mg binary alloy coating is 25 min,4/3,-1.10 V,353 K.The nucleation mechanism of binary coating still conforms to three-dimensional continuous nucleation.3.With the condition of deposition time for 20 min,sedimentation potential 1.05 V,Co²⁺is 0.04 mol/L,0.03 mol/L Mg²⁺,0.02 mol/L Ce³⁺,the morphology of Co-Mg-Ce coating is best,and Mg,Ce content is higher.Adhere to the substrate of the alloy coating for high temperature crystallization,It is found that the coating could not be separated from the substrate at 873 K,indicating that the adhesion of the coating is good.The optimum deposition condition for Co-Mg-Sm coating is 25 min,-1.2 V,Mg/Sm:3/4,358 K.Co-Mg-Ho coatings are 20 min,-1.2 V,Mg/Ho:3/4,353 K.4.The results show that the rare earth content of Co-Ni-Mg-Ce quaternary alloy coating is more than that of Co-Ni-Mg-Ce quaternary alloy coating when the deposition time is 20 min,the deposition potential is-1.10 V,the deposition temperature is 353 K,and the deposition concentration is 0.02 mol/L Ni²⁺.The best deposition conditions of Co-Ni-Mg-Sm coating are 20 min,358 K,-1.15 V,0.03mol/L Ni²⁺;the optimal deposition conditions of Co-Ni-Mg-Ho coating are 353 K,25min,0.03 mol/L Ni²⁺,-1.15 V.5.Taking the rare earth Sm as an example,comparing the corrosion resistance of binary,ternary and quaternary alloy coatings under strong alkali conditions,it is found that the surface of the coating formed a bluish white film after the full immersion corrosion experiment,the immersion time has little effect on the coating quality,the reduction of the binary coating quality is greater than the ternary and quaternary alloy coating,the longer the time is,the more serious the material erosion in the coating.