The Fabrication Of Al-based Superhydrophobic Coatings And Study Of Their Corrosion Resistance Property

With the development of metallurgy industry and material science,the application of metals and alloys bring about increasingly importance in scientific research and industrial production.Especially,the utilization of aluminum and its alloy involve in oceanography,ship manufacture,construction material,machine building and space technology.However,the metal material is so easily be corroded that causes severe economic loss and safety problem.Consequently,increasing number of corrosion resistance methods was invented for this problem because the prevention of metal corrosion becomes an urgent problem in its utilization process,these methods include electroplate,anodic oxidation,vapor deposition and heat spraying.But some of these methods are high cost,complicated and environmentally unfriendly.Therefore,cheap and convenient methods were utilized in this thesis to construct superhydrophobic coating on aluminum substrate with excellent corrosion resistance.The main investigation content was listed as follows:(1)The various stearate particles were sprayed onto aluminum substrate by one step spraying method in order to fabricate colorful superhydrophobic coatings.As the existence of the micro-scale roughness and low surface energy material on the surface,all of these coatings have the contact angle more than 160°.Subsequently,the anti-corrosion capability of coatings was tested by the electrochemical method of dynamic polarization and electrochemical impedance spectroscopy after immersion in 3.5 wt % NaCl solution for a certain period.In the polarization curves,the corrosive potential of superhydrophobic coating is larger than bare Al substrate while its corrosive current is lower than bare Al substrate and its impedance magnitude is lower than bare Al substrate even for 2 orders.Furthermore,the superhydrophobic coating can still maintain the stability and endurance of corrosion resistance even immersed in 3.5 wt % NaCl solution for 30 days.(2)The mixed solution of PVDF and stearic acid was made into nono-scale fibers and collected onto gathering equipment by one electrospinning method in order to fabricate SA/PVDF superhydrophobic membrane.The property of SA/PVDF membrane for corrosion resistance,oil/water separation and water in oil emulsion separation was tested subsequently.By using the polarization plot and electrochemical impedance spectroscopy test,it was found that the SA/PVDF membrane performs better corrosion resistance ability than bare Al substrate and pristine PVDF membrane.Furthermore,the SA/PVDF electrospinning membrane could also be utilized in oil/water mixture separation and water in oil emulsion separation with significant separation efficiency.(3)Superhydrophobic diatomaceous particles were prepared by a liquid-phase reaction of modifying hydrophilic diatomaceous particles with trimethoxyoctadecylsilane.The superhydrophobic particles was dispersed in ethanol and sprayed onto bare Al substrate in order to fabricate superhydrophobic coating.The corrosion resistance test was achieved by electrochemical method after immersed in 3.5 wt % NaCl solution for a certain period,it was found that the superhydrophobic diatomaceous coating performs better anti-corrosion ability than bare Al substrate and maintains endurance of corrosion resistance after long period immersion.