Biomimetic superhydrophobic matrix constructed on a buffer aluminum layer: A compositing coating for Mg-Li alloy corrosion inhibition

Abstract

The magnesium-lithium (Mg-Li) alloy, highly valued for its low density and high strength, has been hampered by its susceptibility to corrosion caused by the presence of active Mg and Li elements. In order to enhance the corrosion inhibition performance of Mg-Li alloy, a double-layer coating is fabricated on its surface in this report. Initially, a sealing aluminum layer is deposited onto the alloy using the magnetron sputtering (MS) technique. Subsequently, an alkyl-ketone dimer (AKD) layer is coated onto aluminum by spray method, resulting in a facile formation of superhydrophobic surface (SHS) at room temperature. In-depth characterization of the microstructure, chemical composition, topology and wettability is conducted using scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle measurement. The resulting aluminum/AKD composite coating exhibits superhydrophobic properties, displaying a static contact angle of 156.3° and a rolling angle of approximately 1°. The low frequency impedance (|Z|0.01 Hz) of the aluminum /AKD coating is ca. 7.85 × 103 Ω cm2, which is around 100 times of magnitude larger than that of bare Mg-Li alloy. Additionally, immersion of the SHS in a 3.5 wt% NaCl solution for 72 h reveals no visible corrosion pitting, confirming the enhanced corrosion resistance of this superhydrophobic coating.