Study On Preparation And Performance Of SiO₂or Composite Coating On Aluminum Alloy Surface

To improve the corrosion resistance performance of aluminum alloy anodicoxidation film, this paper adopts electrophoretic deposition (EPD) and air pressurespraying (APS) method preparation of coatings on aluminum alloy anodic oxidationfilm, then the coating through high temperature sintering densification as heat treatment.Through single factor experiment, orthogonal experiment, through test thickness, aciddrop time, micro-hardness, alkali resistance, polarization curve and ac impedanceNyquist diagram of the coating films, using scanning electron microscope (SEM),Fourier infrared spectrometer (IR), and other characterization methods, studied theinfluence of electrophoresis voltage, electrophoresis time, electrophoresis times tosilicon electrophoresis coatings, silane film, modified silica coating performance. Themain conclusions of the experiments are as follows:Optimum parameters of electrophoresis S silica-sol for electrophoresis voltage is10V, electrophoresis time is2min, electrophoresis for1times; Optimum parameters ofelectrophoresis S silica-sol for electrophoresis voltage is12V, electrophoresis time is2min, electrophoresis for2times. Film forming in natural air, at80℃baking, mufflefurnace sintering temperature is240℃for45min to get the best silicon oxide coatings.The thickness of coating is about20μm.The optimized condition of electrophoresis of silane film determined throughorthogonal experiment was as follows: electrophoresis optimum parameters of the G7silane-sol for electrophoresis voltage is16V, electrophoresis time is2min,electrophoresis for2times; electrophoresis optimum parameters of GB silane-sol forelectrophoresis voltage is14V, electrophoresis time is2min, electrophoresis for2times;electrophoresis Optimum parameters of ZH2silane-sol for electrophoresis voltage is12V, electrophoresis time is2min, electrophoresis for1times. Film forming in natural air, baking at80℃, muffle furnace sintering temperature is200℃for45min to get the best silicon oxide coatings. By scanning electronmicroscopy (SEM), silane-sol film on the anodic oxide film of uniform deposition.Through testing the thickness gauge, the thickness of the film is about22μm.The optimized condition of electrophoresis of silane film determined throughorthogonal experiment was as follows: to modified silica-sol, pH=10, SG dosage is0.3g, corrosion inhibitor dosage of0.5mL, adding carboxymethyl cellulose for1.5mg,adding ZH3for0.4g, stiring use magnetic stirrer for1.5h under45℃, using ammoniaand HAc to adjust pH. By air pressure spraying method, sealed the aluminum alloyanodic oxidation films. Film forming in natural air after spraying for3times, baking at80℃, muffle furnace sintering temperature is200℃for45min to get the bestmodified silicon-sol oxide coatings. The morphology of coating is observed by scanelectron microscope (SEM). Through the thickness meter, coating thickness is about22μm.