Study Of Whole Coloring And Surface Dyeing Of Micro Arc Oxidation Ceramic Layers On Aluminium Alloy

Aluminum alloy micro-arc oxidation ceramic layers have good hardness,wear resistance,corrosion resistance,and adhesion.As its porous structure of surface,micro-arc oxidation ceramic layer has strong adsorption ability.The color of ceramic layers produced in silicate electrolyte were white or gray.In this article,the ceramic layer was mainly dealt with micro-arc oxidation coloring and surface dyeing.Studied the effect of various concentration ammonium metavanadate,potassium chromate,potassium permanganate on the process of micro-arc oxidation,composition,structure and mechanical properties of ceramic layers.Through contrastive analysis,studying the influence of different coloring additives on micro-arc oxidation coloring,and discussing the coloring mechanism of micro-arc oxidation.At the same time,studying the effect of color and thickness of micro arc oxidation ceramic layer on dyeing,and analyzing the mechanical properties of ceramic layer after dyeing.The surface morphology,chemical composition,phase composition and color of micro-arc oxidation ceramic layers were investigated by SEM,EDS,XRD,color measurement instrument respectively.The ultraviolet-visible spectrophotometer was used to study the optical performance of micro-arc oxidation ceramic layer.The corrosion resistance of micro-arc oxidation ceramic layers was studied by electrochemical method.The results indicate that with the increasing of ammonium metavanadate concentration,the color of ceramic layers deepen gradually until to black and its reflectance decreases gradually,and the content of V in the ceramic layer first increases and decreases then,the maximum value is 23.93 at.%.and the structure of ceramic layers change crystal structure into amorphous structure which can promote the ceramic layer change into amorphous structure.When the concentration of ammonium metavanadate is 6 g/L,its lightness value is minimum.With theincreasing of potassium chromate concentration,the color of ceramic layers deepen gradually until to black,the content of Cr in the ceramic increases gradually,the maximum value is 18.61 at.%,the ceramic layers mainly consist of ?-Al2O3 but also contain ?-Al2O3,and other elements are existed in amorphous structure.When the concentration of potassium chromate is 8 g/L,its lightness value is minimum.With the increasing of potassium permanganate concentration,the color of ceramic layers deepens gradually until to brown,the content of Mn is around 35 at.%.When potassium permanganate are added into basic electrolyte,which can strengthen the amorphous strcture of cemamic layers.When the concentration of potassium permanganate is 2g/L,its lightness value is minimum.The electrochemical experiment shows that when the concentration of ammonium metavanadate,potassium chromate and potassium permanganate is6 g/L,8 g/L and 0.5 g/L respectively,the ceramic layers have the most good corrosion resistance.the potential of which is-0.3405 V,-0.1085 V,-0.3405 V respectively,At the same time,adding different coloring additives into electrolyte can improve the corrosion resistance of ceramic layers in varying degrees.The study of dyeing on micro-arc oxidation ceramic layer surface shows: to micro arc oxidation ceramic layer,the color is more grayer,the thickness is more greater,the dyeing effect is better.As surface porous structure and strong adsorption ability of micro-arc oxidation ceramic layer,which can make the dye adsorb on the surface of the ceramic layer and happen chemical reaction,eventually make ceramic layer with colors.After surface dyeing,the potential of micro-arc oxidation ceramic layer increases 0.4 V,the corrosion current density reduces 3 orders of magnitude,the corrosion resistance is improved,at the same time,the reflectivity of ceramic layer increases almost 20%.