Preparation of durable underwater superoleophobic Ti6Al4V surfaces by electrochemical etching

Underwater superoleophobic Ti6Al4V surfaces were fabricated successfully via electrochemical etching. The morphologies, chemical compositions and crystal structures of the prepared titanium alloy surfaces were characterised by scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction, respectively. The relationship between the etching time and oil wettability in water was investigated and the formation mechanism of hierarchical micro/ nano rough structures on titanium alloy surfaces was also carefully analysed. Further, a series of exposure, immersion and abrasion tests were conducted to evaluate durability, corrosion resistance and abrasion resistance of the fabricated titanium alloy surfaces under harsh conditions. The results show that the prepared surfaces exhibit good underwater superoleophobicity, whose oil contact angle for dichloromethane in water is 158.9 degrees +/- 1.7 degrees and corresponding sliding angle is 6.4 degrees +/- 1.4 degrees. Our approach is simple, efficient and may broaden the potential applications of superoleophobic titanium alloy surfaces in underwater self-cleaning and anti-oil pollution fields.