Preparation Of Superhydrophobic Coating On Aluminum Alloy Surface And Its Anticorrosion And Antifouling Properties

In this study,two kinds of superhydrophobic coatings were prepared on the surface of aluminum alloy with polyurethane as binder,different nano particles providing the rough structure needed for superhydrophobic,fluorosilane coupling agent as low surface energy modifier of nano particles,and silane coupling agent with hydrophilic group as dispersant of nano particles in solution,respectively.The wettability,mechanical stability,anti-corrosion and antifouling properties were studied.The main research work and results are as follows:(1)High fluorine content perfluorooctyltrimethoxysilane was used as nano ZnO low surface energy modifier,?-aminopropyltriethoxysilane(KH550)with amino group was used as dispersant.After reaction,it was mixed with polyurethane evenly and sprayed on aluminum alloy substrate.By controlling the mass ratio of polyurethane and nano ZnO,the superhydrophobic coating with better comprehensive properties can be found.The results show that when the mass ratio is 1:1,the average water contact angle of five random points on the coating surface is 165°,the rolling angle is 7.5°,the hardness test result is level 1,and the contact angle still has 144°when the pressure is 1000 PA and the friction is 10 m on 400#sandpaper.The SEM picture after the friction shows that the rough structure of the coating surface does not disappear,and the nano particles covered by polyurethane are re exposed on the surface,10 days salt spray After the test,the water contact angle of the sample surface is 135.6°and the corrosion potential is-0.42v.When the mass ratio of polyurethane to nano ZnO is 1:2,the corrosion potential can reach-0.21v due to the largest number of nano particles on the coating surface.However,considering all the properties,it is found that the superhydrophobic coating with mass ratio of 1:1 has better properties.(2)Nano TiO₂ Doped CNT was used to prepare double-layer superhydrophobic coating on the surface of aluminum alloy.The effects of different content of CNT on the surface morphology,wetting,mechanical stability,anti-corrosion and anti green algae adhesion of the coating were studied.The results show that when CNT content is 10wt%,the water contact angle of the sample surface is as high as 170.2°,rolling angle is only 2.93°,with excellent superhydrophobic performance,pressure of1000Pa,sandpaper specification of 320#,friction distance of 7m,coating contact angle of 165.4°,rolling angle of 13.5°,corrosion potential of the coating after 7 days of salt water immersion is-0.062v,corrosion current of 0.264×10-5a/cm2,corrosion rate of 0.264×10-5a/cm2 0.0288mm/a.The results of 40 days salt spray test show that the superhydrophobic coating with CNT content of 10wt%has no obvious salt particles on the surface,the coating around the scratch groove is intact,and the contact angle is still 151.4°.EIS test shows that the coating has a relatively large volume resistance.After 30 days salt spray test,the Nyquist diagram does not show a second time constant,and the corrosion resistance of the coating is very good.The static and dynamic green algae adhesion tests were carried out for 90 days respectively.The superhydrophobic coating had less green algae than the common aluminum sheet and polyurethane coating.There was no large green algae on the surface of the coating.The higher the content of CNT,the better the anti green algae adhesion performance of the coating.The coating shows good isolation effect on water,glycol,oil,sunflower seed oil and milk,and the surface self-cleaning effect is obvious.