| There is great interest in developing anodic aluminum oxide（AAO）films for a wide range of applications,including anticorrosion,surface shading,catalytic reaction an biosensor,due to their controllable nanostructure.Recently,for lowing the fabricating cost and enhancing the corrosion resistance of AAO films,great effects have been spent on anodizing at wide-temperature and screening the formulation of effective sealing agents.In the present study,the effect of anodizing temperature and organic acid（citric acid+tartaric acid）addition on the structure and corrosion resistance of AAO films was firstly studied.This allows for a better understanding on the growth mechanism of AAO films at elevated temperatures and organic acid addition,which in turn serves to guide composition engineering of a novel additive to the electrolyte for performing the anodization process at wide temperature（25～40℃）,which is cerium nitrate+triethanolamine.In addition,several sealing processes of cerium ions on oxide film were studied,and the mechanism and corrosion resistance of cerium ions sealing under different process conditions were clarified.（1）In the case of common sulfuric acid anodizing,the pore structure of the porous layer of the prepared oxide film collapses under the condition of greater than 25°C,and the density of the barrier layer decreases.After adding the compound organic acid additive,the structure of the oxide film prepared at 30°C is intact.Since the organic matter participates in the formation of the oxide film,and the thickness and density of the oxide film barrier layer are increased.After the cerium salt compound additive not only improves the ionic current efficiency,but also reduces the erosion effect of oxygen bubbles on the film pores,the oxide film prepared at 35°C has a complete structure.Compared with adding composite organic acid,the porosity of the oxide film decreases after using the cerium salt composite additive,and the thickness and density of the barrier layer increase.（2）After adding the composite organic acid,the critical load of the oxide film prepared at 20℃is 14.23 N,which is lower than the critical load of 14.64 N of the oxide film prepared without addition;after adding the cerium salt composite additive,at 20℃The critical load of the oxide film prepared at the time is 14.74 N,and the critical load of the oxide film prepared at 25℃is the highest,at 15.71 N.The wear rate of the oxide film prepared at 20℃without additives is 0.095×10-3 mm3/Nm,and the wear rate of the oxide film prepared at 25℃using two kinds of additives are slightly lower than this value.The wear rate of the oxide film prepared by adding a composite organic acid at 30℃is 0.73×10-3 mm3/Nm,and the wear rate of the cerium salt composite additive under the same conditions is 0.6×10-3mm3/Nm.（3）The resistance of the porous layer of the oxide film prepared by sulfuric acid electrolyte at 20℃is 4.77×102Ω·cm2,and the resistance of the barrier layer is 3.304×105Ω·cm2.After the addition of the composite organic acid,the resistance of the porous layer rises slightly,and the resistance of the barrier Increased to 6.148×105Ω·cm2,the resistance value of the oxide film prepared by adding composite organic acid at 25℃is close to that of the oxide film prepared by sulfuric acid electrolyte.When the cerium salt composite organic acid additive was used,the resistance of the porous layer was 4.237×102Ω·cm2,and the resistance of the barrier layer was 5.498×105Ω·cm2.The resistance of the porous layer of the oxide film prepared at 30℃is 3.869×102Ω·cm2,and the resistance of the barrier layer is4.655×105Ω·cm2,the corrosion resistance is better than that of the addition of composite organic acids.（4）The polar oxide film is sealed in cerium ion solution by boiling brine,immersion,negative pressure sealing.Studies have shown that a relatively dense Ce O2 film is formed on the surface of the oxide film by negative pressure sealing,so the surface state is the best and the corrosion resistance is the best。The oxide film sealed by boiling salt water has a small amount of cerium ions,and also has boiling water sealing effect,but there are cracks on the surface,and the corrosion resistance is second only to negative pressure sealing,which is better than boiling water sealing.The Ce O2 film formed by immersing and sealing the oxide film is relatively loose and has the worst corrosion resistance.（5）The results of electrochemical AC impedance spectroscopy show that the addition of citric acid adjuvant improves the efficiency of cerium ions deposition.The temperature of the sealing fluid has an adverse effect on the sealing,when the temperature exceeds 30℃,the oxide film after sealing is resistant Corrosiveness is poor.The greater the sealing frequency of the double pulse power supply,the lower the deposition efficiency and the worse the corrosion resistance of the oxide film;the higher the negative duty ratio,the better the sealing effect on the oxide film and the better the corrosion resistance. |
