In this paper

surface engineering technique of two-step anodization was used to solve the problems of corrosion and fouling in the geothermal water. TiO2 nanotube layers were prepared on the substrates of pure titanium and its alloy (Ti-6Al-4V)

and factors affecting layer structure were explored. Hydrophobization was further applied on the surface of TiO2 coatings by immersion method. Microstructures of TiO2 nanotubes were characterized by SEM. Static contact angle was obtained on the coatings via optical contact angle measuring device

and surface free energy was calculated. Roughness of the coatings was measured. Fouling property of coatings was investigated by static immersion experiments in CaCO3 fouling solution. Corrosion property of coatings in geothermal water was investigated by potentiodynamic polarization curve. Well-aligned array of TiO2 nanotubes and micro- and nano-scale coatings with low surface free energy were obtained on substrates of pure titanium and its alloy under optimal conditions of two-step anodization and immersion techniques. The TiO2 coatings showed anticorrosion ability in geothermal water and antifouling property in saturated solution of CaCO3. Compared with pure titanium and its alloy

fouling deposition rate decreased by 15% on the coatings. Meanwhile

the coatings displayed good mechanical durability through maintaining hydrophobicity after many times of tape-peeling and abrasion tests.