Investigating the influence of pore-widening time control in electrochemical anodization for the formation of hybrid titanium nanostructures with enhanced superhydrophobicity for improved corrosion resistance efficiency

Titanium (Ti) alloys possess remarkable strength, high-temperature stability, and processability, making them indispensable in biomaterials, aircraft engines, fuselage manufacturing, and ship propulsion shafts. However, when exposed to potential differences or minor defects in contact with other alloys, the thin natural oxide film on their surface is vulnerable to damage, leading to accelerated corrosion or diminished stability. This study investigated the morphology of the final oxide film formed with varying pore-widening (PW) process time (10–60 min with 10-minute intervals) after the anodization of Ti-Grade 4 material. The oxide films formed from the anodization and the PW process for 10 to 40 minutes exhibited a porous structure, while a hybrid pillar and pore structure were observed after a PW process of 50 minutes. As the PW time increases, the pore diameter expands, forming hybrid pillar and pore nanostructures, and superhydrophilicity is observed. After FDTS (1H, 1H, 2H, 2H-Perfluorooctyltrichlorosilane) coating, the phenomenon elucidates the transition from hydrophobicity to superhydrophobicity and the enhancement of water droplet mobility, with the lowest contact angle hysteresis measured at PW of 60 minutes and demonstrating improved corrosion resistance, achieving a corrosion inhibition efficiency of over 99% compared to the untreated titanium alloy surface. Notably, the structure encompassing pillar and pore features exhibits exceptional suitability for applications on material surfaces and interfacial phenomena, such as cell adhesion. Furthermore, surfaces characterized by excellent superhydrophobicity because of coating can find multifunctional applications encompassing anti-corrosion, anti-fouling, anti-icing, and self-cleaning capabilities.