Fluoroalkyl silane cross-linked Mg(HCOO)0·4(OH)1.6 superhydrophobic coating on magnesium alloys with a high corrosion-resistance

The low corrosion resistance of magnesium alloys directly limits their applications in natural environments. In this work, a superhydrophobic and corrosion-resistant coating was prepared on AZ31 magnesium alloys using a combination of a sodium formate hydrothermal reaction and fluoroalkyl silane cross-linking. The hydrothermal treatment successfully generates a corrosion-resistant Mg(HCOO) 0·4 (OH) 1.6 coating on the magnesium alloy surface, which exhibits a multi-scale microstructure, such as nanoscale stacking and microscale nanoflowers. The low surface energy modification of this micro-nano rough surface with fluoroalkyl silane imparted superhydrophobic properties. The coating has a corrosion inhibition efficiency of 99.999 % based on the lowest corrosion current density, i.e.,1.23 × 10 −9 Acm −2 . Furthermore, the superhydrophobic coating maintains good corrosion resistance even after 30-day immersion in simulated seawater. The low frequency impedance remains 10 5 Ωcm 2 during the growth cycle of A. niger . The static contact angle of the coating is 151.4°, attributed to the high-density –CF 2 - and –CF 3 groups on the surface. This work provides new insights into the preparation of superhydrophobic coatings on AZ31 magnesium alloys to significantly enhance their corrosion resistance.