Effect Of Electrolytes On Micro-arc Oxidation Coatings On AM60B Based On Formula Uniform Experimental Design

This paper takes AM60B magnesium alloy as the research object,adopts a formula uniformity test design scheme,and performs micro-arc oxidation in a silicate electrolyte composed of Na₂Si O₃,Na OH,and KF at a total concentration of 40 g/L.In order to explore the internal discipline between the electrolyte composition and the macro quality of the micro-arc oxidation,film thickness,micro structure and corrosion resistance.However,it also provides a new way to optimize the electrolyte formulation.Through the relationship between the electrolyte composition and the feasibility,film-forming of the micro-arc oxidation,Na OH has a greater influence on the feasibility and film-forming of the micro-arc oxidation,and Na2Si O3 and KF have less influence on it.The conductivity and p H value also have a certain effect on the feasibility and film-forming of the micro-arc oxidation.Combined with intuitive analysis,it is known that when the Na OH concentration is less than 10 g/L,the conductivity does not exceed 67.0 S/cm,and the p H value is not greater than 12.92,the feasibility and film-forming of the micro-arc oxidation are both available;when the Na OH concentration is greater than 10 g/L,the conductivity exceeds 67.0 S/cm,and the p H value is greater than 12.92,the micro-arc oxidation reaction is not feasible.According to the relationship between the electrolyte composition and the thickness of the film layer,it can be seen that the interaction between the electrolyte components has a greater impact on the thickness of the film layer,and the single factor has less effect on the thickness of the film layer.Nevertheless,KF has a greater influence on the film thickness,followed by Na OH and Na2Si O3 without considering the interaction.Simultaneously,the arc starting voltage,conductivity and p H have a certain effect on the film thickness,and within a certain range,as the conductivity and p H value increase,the arc starting voltage decreases and the film thickness increases accordingly.According to the relationship between the electrolyte composition and microstructure,corrosion resistance of the film layer,Na OH has a greater effect on the surface porosity,pore size distribution,microcracks.KF has a greater effect on the thickness of the film,and Na₂Si O₃ has a great influence on the smoothness and uniformity of the film.Simultaneously,it can be seen that the A4 film has the longest drip corrosion time,the smallest J_corrorr and the best corrosion resistance through nitric acid drip corrosion and electrochemical corrosion.Moreover,Na OH has the largest influence on the corrosion resistance of the coating,followed by KF,and Na2Si O3 has the least influence.However,when considering the interaction between the electrolyte components,the interaction has a greater impact on the corrosion resistance of the film layer,a single factor has a smaller effect,and Na₂Si O₃ has the smallest effect.In addition,A4 formula is the optimal formula on the basis of comprehensive consideration of film preparation,film thickness,microstructure and corrosion resistance combined with intuitive analysis,and its electrolyte composition is:Na₂Si O₃:19.24 g/L,Na OH:8.80 g/L,KF:11.96 g/L.