In-situ fabricated hierarchical nanostructure on titanium alloy as highly stable and durable super-lubricated surface for anti-biofouling in marine engineering

Titanium alloys, with superior corrosion resistance, have been widely used in marine engineering. However, they are biocompatible and attractive to biofouling organisms. In this work, based on the micro-arc oxidation and hydrothermal treatment, a Slippery Liquid-Infused Porous and Prickly Surface (SLIPPS) was in-situ fabricated on titanium alloy (TA2) via a cost-efficient and facile process. The hierarchical nanostructure consisting of micro/nano-pores and nano-prickles was infused by lubricant to form a super-lubricated surface. The micro/nano-pores can offer sufficient space to store the lubricant, and the tiny prickles on/inside the pores can provide the firm mechanical interlock with the lubricant. These unique features can ensure the long-lasting storage and conservation of the lubricant, which endows the excellent stability and durability. The SLIPPS remains well lubricated after a series of tests with extreme conditions, such as the high-rate centrifugation, scouring test and long-time immersion. As an inert barrier, this stable and durable lubricant layer also significantly improves the corrosion resistance. Compared with pristine TA2 and super-hydrophobic samples, the SLIPPS possesses an impressive anti-biofouling performance. After being immersed for 31 days with two typical biofouling organisms (Chlorella and Phaeodactylum tricornutum), the coverage percentages are only 0.03% and 0.06% on SLIPPS, respectively, while for the pristine TA2, the corresponding values are 53.3% and 23.2%, respectively. Therefore, this in-situ fabricated, low-cost and super-lubricated coating on the titanium alloy surface can effectively, stably and durably prevent from biofouling and corrosion in seawater, which may pave the way for the large-scale applications of titanium alloys in marine engineering.