Effect Of Oxidized Nanoparticles On The Properties Of Anodized Aluminum Alloy Films

Over the years,safety accidents and economic losses caused by material failure brought great loss to both people and society.Based on the optimization of basic electrolyte of aluminum alloy anodic oxidation,this paper hopes to improve the protection of aluminum alloy by anodic oxidation film,prolong the life and safety of aluminum workpiece or equipment,and reduce the risk of accident by improving the performance of anodic oxidation film.Based on the traditional sulfuric acid(SAA)and boron-sulfuric acid(BSA)anodic oxidation electrolyte system,the malic acid-sulfuric acid(MSA)electrolyte system was introduced,and the electrolyte system was optimized by changing the addition amount of malic acid.The results show that in the first three electrolytic liquid systems,the highest hardness of the sample is 245.16 HV and the lowest friction coefficient is0.24 when the addition of malic acid in MSA is 75 g/L(MSA-75 g/L).It also has the lowest corrosion current density of 1.94×10^-8 A/cm² and corrosion rate of 2.00×10^-4 mm/a,the highest polarization resistance of1.35×10⁶?·cm^-2 and impedance modulus of 1.13×10⁷?·cm² in the electrochemical test.It also performs well in film continuity,alkalinity resistance and copper accelerated acetate spray corrosion test(CASS).This indicates that MSA-75 g/L is the optimal electrolyte parameter for the three electrolyte systems.Based on the optimized electrolyte,different kinds and concentrations of oxidized nanoparticles(TiO₂,ZrO₂ and CeO₂)were added into the electrolyte to study the effects of different oxidized nanoparticles on the film properties.It was found that the addition of nanoparticles did not change the growth law of the anodized film,and the surface morphology and structure did not change significantly.However,it reduced the solution-generation ratio and increased the hardness and thickness of the anodized film.Nanoparticles only exist on the surface of the sample film due to the adsorption of the oxide film,and no nanoparticles have been detected to enter the micropores or film of the anodic oxidation film.The analysis by energy spectrometer shows that the oxide film is composed of Al,O and S elements.Friction tests show that nanoparticles can reduce the friction coefficient of the film,and the degree of reduction is ZrO₂>CeO₂>TiO₂.When the addition amount of ZrO₂ particles is 4 g/L,the friction coefficient reaches the lowest 0.06.In the electrochemical test,the three kinds of nanoparticles can all improve the corrosion resistance of the film,and the improvement range is CeO₂>ZrO₂>TiO₂.The sample CeO₂-3 g/L has the lowest corrosion current density of 4.07×10^-10 A·cm^-2,the corrosion rate of 4.21×10^-6 mm/a,the highest polarization resistance of 6.41×10⁷?·cm^-2 and the highest impedance modulus.It also has excellent performance in the film continuity,alkali resistance and CASS tests.In conclusion,when the appropriate dosage is selected,the three kinds of nano-particle additives can improve the friction and corrosion properties of anodic oxide film,among which ZrO₂ has a higher improvement in the friction property and CeO₂ has a higher improvement in the corrosion property.