Fabrication And Properties Of Ni Matrix Composite Brush Plating Superhydrophobic Surface

Superhydrophobic surfaces have wide application prospect in many fields due totheir excellent performance, such as Waterproof, self-cleaning, anti-icing,anti-corrosion, etc. So far, there are many methods to fabricate superhydrophobicsurfaces on metal substrate. But all of them have some deficiencies more or less, suchas tedious fabrication, high requirements for the equipment, limits to large-scaleproduction, low mechanical strength, which block their practical application. Theelectro-brush plating technology is very flexible and efficient, which can depositdifferent kinds of coatings and prepare large-area coating, the binding force betweencoating and substrate is strong and the required equipment is portable. So, based onthe fractal characterization of lotus leaf surface, this paper analyzes the hydrophobicmechanism of lotus leaf, fabricates lotus-leaf-like superhydrophobic surface onE355DD carbon steel substrate via two-layer nano-composite electro-brush platingand subsequent surface modification with low free energy materials, studies theinfluence of brush plating process and nano particle concentration on hydrophobicproperties of coatings, and tests the hardness, tribological properties, anti-corrosionability, self-cleaning ability and anti-icing ability of the as-prepared superhydrophobiccoatings.The fractal model of lotus leaf surface micro structure has been established.Researches on fractal structure and hydrophobic mechanism of lotus leaf show that:the fractal dimension of lotus leaf surface is2.19; the theory contact angle of lotusleaf surface calculated using the fractal dimension is153°, which is smaller thanactual contact angle; if the lotus leaf surface profile is considered as a Koch curves, ofwhich the n is4, the theory contact angle of lotus leaf surface is161°, which is closeto the actual contact angle value.Brush plating process of lotus-leaf-like surface has been studied and the surfacemorphology has been analyzed. Result shows that: the lotus-leaf-likesuperhydrophobic coating can be successfully prepared by plating nano-C/Ni andnano-Cu/Ni two-layer coating on carbon steel substrate and subsequent modificatingwith low free energy materials; the contact angle of superhydrophobic coating is up to155.5°, the sliding angle is less than5°; brush plating process and nano particleconcentration have influence on the surface morphology and thus affect thehydrophobic properties of coating. Researches on the surface morphology, fractal structure and hydrophobicmechanism of superhydrophobic coating show that: the micro/nano scale roughness ofas-prepared superhydrophobic coating surface is similar to that of lotus leaf; thefractal dimension of superhydrophobic coating is2.15; the hydrophobic mechanism ofsuperhydrophobic coating is Cassie-Baxte model, and it is the same with that of lotusleaf.The results of hardness test show that: the hardness of hydrophobic coating firstincreases and then decreases when the Cu nano particle content increases; thehardness of superhydrophobic coating is lower than that of Ni coating, but still higherthan that of E355DD carbon steel substrate.The results of electrochemical experiments show that the superhydrophobiccoating has good anti-corrosion performance in comparison with Ni coating andE355DD carbon steel substrate.The results of tribology experiment show that: from the angle of frictioncoefficient, the abrasion resistance of superhydrophobic coating (Cu particleconcentration is5g/L) is poor in comparison with that of Ni coating and equivalent tothat of E355DD carbon steel substrate; the abrasion resistance of hydrophobic coating(Cu particle concentration is3g/L) is the best; compared with that of other coatings,the lubrication of deionized water and oil to superhydrophobic coating is small.Results of self-cleaning test and anti-icing test show that the as-preparedsuperhydrophobic coating has good self-cleaning performance and obvious anti-icingperformance.In summary, based on the fractal characterization of lotus leaf surface microstructure, this paper has fabricated lotus-leaf-like two-layer nano-compositesuperhydrophobic coating on E355DD carbon steel substrate successfully. Theas-prepared superhydrophobic coating has good abrasion resistance, excellentanti-corrosion performance, self-cleaning performance and obvious anti-icingperformance. This paper has provided the theoretical and practical value for theapplication of superhydrophobic materials.