Study on Superhydrophilic Surface Treatment Methods and Magnified Preparation for Stainless Steel

This study proposes an environmentally benign electrochemical method for fabricating superhydrophilic surfaces on stainless steel, enabling dual-functional modification through both anodic oxidation and cathodic reduction. By employing citric acid and ammonium chloride as noncorrosive electrolytes, milli-microscale porous morphologies were formed on anodically treated surfaces, while hydrophilic metallic coatings developed on cathodically treated surfaces, both achieving superhydrophilicity with water contact angles <10°. The critical role of initial current density in determining pore distribution density on anodic surfaces was systematically investigated, revealing that pore formation is governed by the "tip effect"─localized charge accumulation at pre-existing pore edges drives preferential reactions, independent of subsequent current adjustments. To address nonuniform pore distribution caused by edge-preferential reactions during scale-up, two strategies were validated: (1) groove pretexturing to enhance charge density in central regions, and (2) coaxial tube-rod configurations to homogenize electric fields, achieving uniform pore structures. The method's scalability, cost-effectiveness, and absence of hazardous chemicals underscore its potential for industrial applications.