Preparation Of Porous Anodic Aluminum Oxide Template And Study On Wetting Performance

Due to non-magnetic,no low temperature brittleness,good reaction performance,thermal conductivity,plasticity and formability,etc.,aluminum and its alloy become the largest use of non-ferrous metals,and its application is also the most extensive.Although the aluminum in the natural environment can generate a layer of natural oxide film,but in the ocean,acid,alkali and other corrosive environment,the protection performance of the layer can not meet the application requirements.Therefore,it is necessary to protect the aluminum and its alloy from corrosion to improve its corrosion resistance,to ensure the safety of aluminum products,and expand its application.In this paper,high purity aluminum was used as the research object.Anodized aluminum oxide films with rough porous nanohole structure were prepared and was modified by the low surface energy to achieve the superhydrophobic aluminum surface.The corrosion resistance after modification was evaluated.The main work and achievements are as follows:(1)The influence of 10 typical chemical polishing processes on the macroscopic morphology and microstructure of AAO film was studied,and the optimal polishing process is:A,500ml/L;B,400ml/L;C,100ml/L;t=80℃,polishing for 10min.(2)The effects of oxalic acid complex electrolytes and citric acid complex electrolytes on the microstructure of AAO films and surface wetting after modification were studied.The results showed that the AAO films with the"hole-in-hole"cage structure were obtained with P,tartaric acid,lactic acid or citric acid added in oxalic acid mother liquor.The dense AAO films ere obtained in citric acid complex with sodium pyrophosphate,ethylene glycol,boric acid and phytic acid.With citric acid alone and its complex with phosphoric acid,D as the working medium,the AAO film with cell size 310-770nm can be obtained.After surface modification,the film has superhydrophobic properties.(3)The effects of the concentration of D and citric acid on the microstructure of AAO film and surface wetting after modification were studied in citric acid/D complex medium.It was found that the AAO film with pore diameter of 90-160nm and pore distance of 280-380nm could be prepared in the complex medium of citric acid and D;The pore diameter is an important factor affecting the wettability of porous alumina film.The hydrophobicity of the oxide film is better when the pore diameter is about 130nm-160nm;The AAO film prepared in 30g/L citric acid+10g/L D has a surface contact angle of 151.4°,showing superhydrophobic properties.(4)The influence of current density on the microstructure of AAO film and surface wetting after modification were studied.It was found that the pore diameter,inter-pore distance and porosity of AAO films increased with the increase of current density,and the surface contact angle of the modified AAO film increases first and then decreases.When the current density is10mA/cm~2,the modified AAO film preparaed in 30g/L citric acid+10g/L D shows superhydrophobic properties with the surface contact angle of 151.4°and sliding angle of 3°.(5)Study on Corrosion Resistance of Typical Samples.The results show that the anodic oxidation itself and superhydrophobic surface modification based on anodic oxidation both can improve the corrosion resistance of metallic aluminum.And in different corrosive media,the sort of corrosion resistance from high to low is:superhydrophobic anodic oxidation sample>anodized oxidation sample>blank sample.