Study on the Preparation and Properties of Micro-Nano Structure on the Surface of 304 Stainless Steel by One-Step Anodizing

Abstract

The micro-nanostructures were prepared on the surface of 304 stainless steel by one-step anodizing with perchloric acid-ethylene glycol electrolyte. The morphologys, phase behaviour and microstructures of the prepared micro-nanostructures were characterized by SEM, XRD and metallographic examinations. The corrosion resistance and hydrophobic properties of 304 stainless steel after anodizing at different times were studied by Tafel test and contact angle test. The results show that when the anodization voltage is 30V, the electrolyte is 5vol% perchloric acid-ethylene glycol, the reaction temperature is 0 ± 5 ° C，and the anodization time is 15min, a honeycomb micro-nanostructure having an average pore diameter of 143 nm, an average pore spacing of 124 nm and a uniform distribution can be prepared on the surface of 304 stainless steel. The prepared nanostructure has a contact angle with water of 128° and a hydrophobicity of 86.3%, which corrosion resistance is 21 times higher than that of ordinary 304 stainless steel in 3.5 wt% NaCl solution. Metallographic microscopic observation and XRD indicate that the anodic oxidation begins along the grain boundary of the austenite, and then the micro-nano holes grow on the austenite and fill the entire austenite phase. Finally, Fe2O3 structure with uniformly distributed micro-nano pores is formed on the surface of the stainless steel.