Fabrication of durable hydrophobic micropatterns on stainless steel using a hybrid irradiation process

• Published in: Surface & coatings technology 2016-09, Vol.302, p.535-542
• Main Authors: Kim, Jisoo, Sim, Sun Oh, Park, Hyung Wook
• Format: Article
• Language: English
• Subjects: Austenitic stainless steels; Contact angle; Corrosion resistance; Discharge machining; Durability; Electric discharge machining; Electron beam irradiation; Grooves; Hydrophobicity; Irradiation; Micropatterning; Stainless steels; Steel; Surface energy
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2016.06.051

Patterns were fabricated on AISI 304 stainless steel combining the wire electric-discharge machining (WEDM) with large pulsed electron beam (LPEB) irradiation to improve the surface hydrophobicity and corrosion resistance of the alloy. The WEDM-fabricated patterns showed a Wenzel-to-Cassie transition with contact angle (CA) of 140° at a groove depth of 250μm, which indicated hydrophobic surface. LPEB irradiation of the WEDM-fabricated patterns increased the CA (166.7°) to the Cassie state at a lower groove depth of 200μm. The LPEB-irradiated patterns had smooth surfaces that decreased the critical angle for Wenzel-to-Cassie transition. Attenuated total reflection-infrared spectroscopy revealed that hydrophilic functional groups on the surface were absent following LPEB irradiation. LPEB irradiation modified the surface corrosion resistance of a WEDM-fabricated pattern, likely because of a lower surface energy and formation of a passive resolidified layer following irradiation. •LPEB irradiation of the WEDM-fabricated patterns increases the CA (166.7°) at a lower groove depth of 200μm.•Roughness reduction by electron beam irradiation contributes to prevent hemi-wicking.•Hydrophilic functional groups are removed by electron beam irradiation.•Electron beam treatment also improves corrosion resistance of super-hydrophobic patterns.