Study On The Construction And Properties Of Superhydrophobic Aluminium Coating

Superhydrophobic surface has important application value in the field of corrosion protection of metal and alloy,but the problem of poor durability seriously limits its practical application.According to this,this paper studied a method for 6061 aluminum alloy to prepare superhydrophobic coating which has excellent corrosion resistance and good mechanical durability.Firstly,combination of anodic oxidation and magnetron sputtering method in the construction of micro/nano composite aluminum alloy surface rough binary structure,as a super hydrophobic on the surface of the water meter"structural basis";and then by vacuum-pressure-recycling immersion method to modify the surface with low surface energy,as the super hydrophobic on the surface of the water meter"component based".The influence of the key technological parameters of anodic oxidation and magnetron sputtering on the microstructure and composition of the film was studied emphatically,and the corrosion resistance and mechanical durability of the film were evaluated by electrochemical test and linear wear test.Main anodization parameters,such as the type of electrolyte,electrolyte concentration,oxidation temperature,and secondary oxidation,and their influence on the morphology,thickness,and hardness of the anodized aluminum oxide film(AAO)are explored respectively.According to the requirements of subsequent modification steps,the optimal process combination selected in this paper is:oxalic acid electrolyte with mass fraction of 5%,under oxidation temperature of 5? for 40min without secondary oxidation.And a hexagonal cellular porous AAO film with a pore size of about 150-160nm and a hole wall thickness of about 20-25nm could be formed.The thickness of the film layer was about 50-60nm,with a hardness of up to 400HV,which was 4-5 times the hardness of the aluminum alloy matrix.On this basis,SiO₂ nanoparticles were sputtered on the porous AAO structure by magnetron sputtering.The sputtering power mainly affects the particle deposition structure by influencing the deposition speed.Under 50W power,particle size less than 10nm is uniformly deposited on the AAO hole wall,while under 100W power,the deposition is much more unordered,even some AAO hole structures are covered.Sputtering time affects the grain coarsening,from 10nm at 15min to 50-60nm at 45min by affecting the substrate temperature.Three magnetron sputtering samples with different morphology were modified with low surface energy PFDS to obtain superhydrophobic coating.The wettability test showed that all of 3 samples achieved superhydrophobic performance,and when the sputtering power 50W and sputtering time15min,the sample has the highest contact angle,up to 163.4°.The electrochemical test results showed that the self-corrosion potential of the samples increased successively and the self-corrosion current density decreased successively for sputtering power 100W and sputtering time15min?sputtering power 50W and sputtering time 45min?sputtering power 50W and sputtering time 15min,which means their corrosion resistance improved successively.Mechanical durability tests showed that only sputtering power 50W and sputtering time 15min sample maintained superhydrophobic properties after linear wear.The results of SEM observation and EDS characterization of its cross section show that the presence of nanoparticles and PFDS on the surface after abrasion is the reason why this sample can maintain its superhydrophobic property.