Superhydrophobicity on AISI 304 stainless steel through surface sensitization process and etching

Abstract

In this research, the surface sensitization process of austenitic stainless steel (304) was used to create the superhydrophobicity through a facile etching method with a significantly lower etching time. In order to utilize the surface sensitization process for the purpose of forming island-like chromium carbide on surface, oxyacetylene flame heat-treatment was performed at 650 °C for one min. After HF etching at ambient temperature, treatment in nitric acid, and the reduction of surface energy by stearic acid modification, a water contact angle (WCA) of 167°, water sliding angle (WSA) of 3°, and water contact angle hysteresis (WCAH) of 7° have been achieved. The sensitization process makes the sample susceptible to intergranular corrosion and uniform micro- and nano-sized pores entirely cover the surface after boiling in nitric acid. This phenomenon is the main reason for creating the hierarchical microstructure on the surface of stainless steel in a shorter time.