| LY12 aluminum alloy is a typical hard aluminum alloy,and it is widely used in aviation and aerospace field for its excellent comprehensive performance.In order to improve its corrosion resistance,the usual method to improve the protective property is that the surface of alloy is treated by anticathode oxidation and then coated with paint film.The traditional anodizing methods include chromic acid oxidation,sulfuric acid oxidation and oxalic acid oxidation.On the basis of the traditional anodic oxidation of sulf’uric acid,the study focuss on the preparation of oxide film with better corrosion resistance,the sealing treatment of oxide film and formulation and technology of sealing process.Firstly,Zr02 sol was added to the traditional sulfuric acid anodizing solution.The optimum technology and formula to prepare the zirconium sol anodic oxide film were screened by electrochemical test.The process and formula were as follows:the addition of ZrO2 sol 50g/L,the anodizing temperature of 25,the anodizing time 20min,and the anode oxidation current density 0.6A/dm2.The film is smooth and and no defect with barrier layer impedance value of 5.822×108Ω ·cm2.The analysis of XRD and EDS atlas showed that the addition of ZrO2 sol did not affect the structure and composition of the film,and the added Zr02 sol was adsorbed on the pore wall of the porous layer of the oxide film during the anodic oxidation process.Secondly,the zirconium sol-sulfuric acid anodic oxide film was sealed with ammonium decanate solution,and the best process of sealing the ammonium sebacate was screened by electrochemical test.The process was:the concentration of ammonium sebacate was lOg/L,the sealing time was 20min and the closed temperature was 95 ℃.The corrosion resistance of the sealed oxide film is improved.During the sealing process,ammonium sebacate can react with Al2O3 and H2O to produce precipitate for sealing pore.Finally,the effect of ammonium sebacate sealing and several traditional sealing methods on the performance of the film was compared.The results showed that the corrosion resistance of the coating was the best after the sebacate closed. |
