Preparation And Performance Research Of Superhydrophobic Coatings Fabricated On Aluminum Alloys With A Dipping Method

The natural oxide films of aluminum alloy have awful corrosion resistance and wear resistance and are easily corroded outdoors,which significantly restricts its service life and application areas.Therefore,it is of great economic value and practicality to improve the corrosion resistance of the aluminum alloy.Furthermore,due to the potential application of a superhydrophobic surface in corrosion resistance,the construction of a superhydrophobic surface on a metal substrate can significantly improve the corrosion resistance of the metal surface.However,many existing methods or techniques for preparing superhydrophobic surfaces have certain shortcomings,such as complex processes,expensive equipment,and not being suitable for large-scale fabrications,which restrict the large-scale preparation of the superhydrophobic surface and impedes its application in industry.As a result,it is of great practical significance to develop a method for superhydrophobic surface fabrication that is expected to achieve mass production.The 6063 aluminum alloys were selected as substrates in this paper.A superhydrophobic composite coating with the dense intermediate layer and porous hydrophobic layer by combining traditional fluorocarbon coating and superhydrophobic coating prepared by dipping technique broadened the application prospect of aluminum alloys.On the one hand,the method in the absence of expensive and complex equipment,and the whole synthesized process can be fully accomplished within hours.On the other hand,the process is simple,and the obtained coatings have superior binding force and corrosion resistance.In addition,the parameters were studied and optimized by the single factor experiment.The primary research work and experimental results of this essay are as follows:1)The superhydrophobic coating was fabricated via a facile one-step dipping method.First,the superhydrophobic coating with good corrosion resistance was successfully prepared on the surface of 6063 aluminum alloy by blending hydrophobic nanoparticles with commercially available fluorocarbon coatings.The fluorocarbon coating acts as a film-forming agent and reduces the chemical surface energy of the substrate without the need to introduce additional low surface energy substances.The coating's wettability and corrosion resistance were considered the main evaluation indications.In addition,the coating components and process parameters were systematically optimized,and their influence on the coating performance was explored.As a result,the superhydrophobic coating with the optimal comprehensive performance was fabricated by:50g/L SiO2,12mL/L KH560,8mL/L KH550,fluorocarbon paint 80g/L,anhydrous ethanol and distilled water as solvents,and the concentration was 20mL and 30mL,respectively.After dipping,the coating was heated at 120?for 90min.2)The superhydrophobic composite coating was fabricated via a two-step dipping method.The fluorocarbon coating was prepared as an intermediate layer by the first dipping method,and the superhydrophobic composite coating with good binding force was prepared by depositing a nano silica hydrophobic layer through the second dipping after the fluorocarbon coating was semi-cured.The process of the superhydrophobic composite coating was systematically investigated based on the coating's water contact angle,sliding angle,and binding force.The optimal condition of the composite coating was as follows:the first dipping was cured at 60? for 40min after dipping;the secondary dipping process was:70g/L SiO2,24mL/L KH560,10mL/L 1%ethanol FAS,10mL/L KH550,and cured at 120? for 90min after dipping.3)The hydrophobicity,adhesion to the substrate,corrosion resistance,surface morphology,and chemical compositions of the coatings obtained under the optimal parameters were characterized.The WCAs of the superhydrophobic and superhydrophobic composite coating were 151° and 152.1°,respectively.In addition,the binding force level of the superhydrophobic coating and the superhydrophobic composite coating was 2B and 5B,respectively.SEM observations showed that the coating surfaces had a hierarchically three-dimensional porous micro/nano rough structure.EDS and XPS test results showed that the superhydrophobic coating and the superhydrophobic composite coating are composed mainly of C,O,Ti,Si,F,and balanced Al.Compared with the blank sample,the icorr of the superhydrophobic coating is reduced by two orders of magnitude,the polarization resistance is increased by one order,and the corrosion inhibition rate reaches 91.554%;The icorr of the superhydrophobic composite coating is reduced by about 3 orders of magnitude,the polarization resistance is increased by 7 orders of magnitude,and the corrosion inhibition rate reaches 99.999%.