A Controllable Fabrication Strategy of Anodization Film with Dense, Nano-Porous, and Open-Top Morphology on 304 Stainless Steel in Fluoride-Based Electrolyte

Abstract

A facile anodizing strategy without using perchloric acid is reported to controllably produce three different types of self-organized structure anodization film with dense, nano-porous, and open-top ordered porous arrays structure morphology on 304 austenitic stainless steel (SS) substrate in fluoride-based ethylene glycol electrolyte by simply regulating the H2O concentration in electrolyte and anodizing voltages. It is found that the above anodizing parameters have a great influence on the morphologies for anodization film rather than its chemical composition. The anodization film is mainly composed from the metal oxides of α-Fe2O3 and Cr2O3 or (FexCr1-x)2O3 composite oxides. Moreover, the higher (70 V), middle (50 V), and lower voltages (30 V) are suitable for the preparation of the dense, nano-porous, and open-top morphology structure anodization films due to the different anodized film deposition rates, respectively. Finally, this work creatively proposes a plausible deposition-dissolution mechanism during the anodization process based considering the dissolution effect derived from H2O and provides the parameters selected principle for the formation of corresponding anodization layer with different morphologies onto the SS substrate. The controllable fabrication strategy for the various anodization film may greatly broaden the application of the SS substrate in anti-corrosion and decoration fields.

Keywords: Anodization film, Various morphologies, 304 stainless steel, Anodizing parameters, Formation mechanism