Superhydrophobic surface on MAO-processed AZ31B alloy with zinc phosphate nanoflower arrays for excellent corrosion resistance in salt and acidic environments

[Display omitted] •The nanoflower-shaped zinc phosphate is fixed on MAO-processed AZ31B alloy by glue.•The composite coating exhibits superhydrophobicity in salt and acidic solutions.•Excellent corrosion resistance in salt and acidic solutions are obtained.•The composite coating shows high stable superhydrophobicity in different environments. Corrosion caused by the active chemical properties of magnesium (Mg) alloys seriously restricts their applications in aerospace, transportation, biomedicine, and other fields. Although micro-arc oxidation (MAO) coatings can provide some corrosion protection for Mg alloys, their microporous structure is prone to localized corrosion. Herein, nanoflower-shaped zinc phosphate is prepared and hydrophobically modified. The commercial glue is used to bond the nanoflower-shaped zinc phosphate particle arrays to the MAO-coated AZ31B alloy substrate to produce a two-layer composite coating with superhydrophobic properties. The composite coating exhibits obvious repulsive effects in salt and acidic solutions as indicated by contact angles of 160° and 156°, respectively. The composite coating has improved electrochemical properties and immersion corrosion in both the salt and acidic solutions compared to the substrate and MAO-coated sample. Moreover, the composite coating retains the long-term superhydrophobic effects under different conditions such as immersion in salt and acidic solutions, water scouring, and sunlight exposure, which well indicates commercial applications.