Towards development of sustainable metallic superhydrophobic materials

Abstract

In the present study, an environment friendly, scalable, and cost-effective approach is proposed, combining thermo-mechanical and microwave-assisted hydrothermal processing techniques, resulting in the augmentation of nanoscale structures on metallic surfaces. The thermo-mechanical processing of the aluminium alloy performed at different strain rates resulted in significant grain refinement (∼ 1 µm for processed and ∼ 30 µm for unprocessed samples). After hydrothermal treatment, highly dense and networked nanostructured morphology was evoked by refined grains. Post silanization, samples exhibited high contact angle (θs > 155°) with a low tilt angle (θt < 10°) and CAH (< 5°). The low adhesion with water (∼ 16 µN) for the processed sample (∼ 50 μN for unprocessed) with utmost refined grains is attributed to the high interfacial energy of Cassie state (EC−B>1.0J) due to effective entrapment of air. The processed samples were highly de-wetting and mechanically resilient owing to the strong negative capillary pressure (PC > 1100 kPa) generated by highly dense networked nanostructures. As a result of thermo-mechanical processing, samples displayed higher resilience to abrasion, simulated rain, and long-term immersion tests with low tilt angles (θt < 10°) and CAH (< 5 °). This paper provides a practical approach to achieve anti-wetting surfaces in various industrial settings.