Research On Surface Wettability And Corrosion Characteristics Of Bionic Hierarchical Structure On Stainless Steel Substrate

The micro-nano scale structure of biological surface has far-reaching influence on its surface wettability.Inspired of the study on the microstructure of lotus leaf,taro leaf and other biological surfaces,combine sandblasting technology with electro-brush plating technology or chemical etching technology respectively to construct two bionic micro-nano hierarchical structures on 304 stainless steel surface.By observing the surface morphology characteristics,it was found that the surface of the sample constructed by combining twice sandblasting with electro-brush plating has incomplete "cauliflower-like" mastoid hierarchical structure.And the surface of the sample constructed by combining sandblasting with chemical etching has loose irregular hierarchical structure.The surface wettability of the hierarchical structures of the above two surfaces was measured,it was found that the maximum water contact angle of the above two surfaces are tend to 149.4° and 158.6° respectively.It can be analysed that a layer of air film formed while the droplets contact the micro-nano hierarchical structures.This air film can reduce the contact area between the surface of the hierarchical structure and water droplets,which realize the transition from hydrophilicity of polished substrate surface to hydrophobicity of hierarchical structure surface.Tafel curve was measured in 3.5 wt.% NaCl solution,it was found that the corrosion current density of the above two surfaces decreased by 2 and 1 orders of magnitude respectively compared with polished substrate surfaces,which shows excellent corrosion resistance.In addition,the result of the dilute hydrochloric acid immersion test shows the hydrochloric acid corrosion resistance of the sample constructed by combining twice sandblasting with electro-brush plating is far superior to polished substrate surfaces.All the results show that the hierarchical surface fabricated by the two methods in this paper has good hydrophobicity and corrosion resistance properties.This achievement will make stainless steel surface have broad application prospects and considerable economic benefits in production and life.