Fabrication And Property Investigation Of The Superhydrophobic Surface By Electrodeposition Method

Metal materials have important applications in the field of aerospace,automotive industry,petrochemical engineering,high and new technology,etc.However,the problem of corrosion are always comlicating us in production and daily life.Corrosion and rusting may shorten service life,cause environmental pollution and enormous resources.Sometimes,security incidents may even occur.In recent years,superhydrophobic coatings have been applied in various engineering metal surfaces,to realize the protection purpose for metals.Nevertheless,most of these methods usually require special devices,high costs,comlicated conditions,small substrate size and simple shape,limiting their widespread industrial applications enormously.Electrodeposition has become a hotspot of research to construst large area superhydrophobic surfaces taking advantage of its simplicity,easy control,non-toxic non-polluting,low-cost and suitability for practical applications.In the present dissertation,preparation of superhydrophobic coatings with excellent corrosion and wear resistance is the research object,surface and boundary is the fundamental research questions.Hierarchical nano-micro structure can be realized through regulation of the composition and structure.After modification with low surface energy materials,the superhydrophobic coatings with excellent corrosion resistance and wear resistance can be fabricated.The main contents can be summarized as the following:(1)Inspired by the adhesive proteins secreted by mussels,researchers find dopamine has the same structure and surface properties,which can generate adhesive polydopamine during the process of self-polymerzation on solid surfaces and can stick firmly to solid surface.In the experimental design,a novel electrodeposition route has been developed to create multifunctional zinc/polydopamine/n-dodecyl mercaptan(Zn/pDop/NDM)composite coatings,where oxidative polymerization of dopamine was simultaneously integrated during electrodeposition process.In the meantime,the processes of self-polymerization and electrodeposition can realize mutual promotion due to the oxidation and deoxidization of Zn2+ and dopamine,achieving the rapid and efficient conduction of electrodeposition process.Hierarchical cauliflower-like structure was obtained on the electrodeposited Zn/pDop coatings.After modification with NDM,the prepared Zn/pDop/NDM coatings obtained excellent superhydrophobicity.The results of wettability under different electrodeposited conditions revealed that the optimal electrodeposition voltage and time for fabricating superhydrophobic surfaces was 1.5 V and 30 min,in which exhibiting the best superhydrophobicity of the coating.(2)In order to evaluate the practicability and application prospect of the Zn/pDop/NDM coating,the coating was fabricated on the different surface of steel,aluminum and copper plates.The study found that the Zn/pDop/NDM coatings under different substrates all exhibited excellent superhydrophobicity.The Zn/pDop/NDM coated surface was immersed into the muddy water and maintained its clean surface without any contaminants even after 30 testing cycles.Meanwhile,the dopamine greatly improved the bonding strength and mechanical abrasion resistance of the prepared superhydrophobic coatings.The surface of the Zn/pDop/NDM coating can maintain superhydrophobicity after 500 mm abrasion(Load: 2.8 kPa),while the Zn/NDM coating was severe damaged after 100 mm abrasion and its contact angle decreased sharply.Moreover,these coatings demonstrated superior superhydrophobic stability and corrosion resistance,which shows stable superhydrophobicity under the solution with pH=1-14.(3)Inspired by the superior anti-corrosive and mechanical properties of stainless steel,designing special nickel-chromium(Ni-Cr)alloy coatings on the carbon steel substrate according to the composition and content of stainless steel.The composition and content was adjusted by investigation the parameters during electrodeposition.And then the Ni coating,Cr coating and Ni-Cr alloy coating were prepared.Additionally,the wettability,cleaning property and wear resistance of coatings were investigated.The electrochemical corrosion performance were conducted to evaluate the corrosion resistance of coatings.The results of electrochemical testing indicated that Ni-Cr alloy coating obtained the lowest corrosion current and the highest corrosion potential.The corrosion resistance enhanced about 3 orders of magnitude compared with bare steel substrate.