Influence of synergistic effect of phosphate on corrosion resistance of self-assembled superhydrophobic composite film on 6061 aluminum alloy surfaces.

[Display omitted] • HEDP/LA/rGO composite film was successfully prepared using HEDP and LA and rGO. • HEDP/LA/rGO composite film has super-hydrophobicity and self-cleaning properties. • The film has a high fitting impedance and corrosion inhibition efficiency. • Quantum chemical calculations discuss the mechanisms and synergistic effects. Aluminum (Al) alloys are used in a wide range of applications due to their advantages. However, the existing corrosion protection methods have insufficient protection ability and cannot achieve long-term protection. In this paper, reactive protective film on the surface of aluminum alloys using 1-hydroxyethyl-1,1-diphosphonic acid (HEDP) molecules. Then, Lauric acid/Graphene (LA/rGO) film is used to prepared on the surface of HEDP film. SEM, XRD, EDS, Raman, XPS and WCA were conducted to analyze physical and chemical features of coatings. The total resistance of the film reaches 1.0 × 10²⁰ Ω·cm², in a salt spray test using 5wt% NaCl as the corrosion medium, corrosion spots appeared on day 28 with a corrosion inhibition efficiency of 99.99%. Theoretical studies with quantum chemical calculations have shown that HEDP/LA/rGO composite films can be adsorbed on Al alloy surfaces through P-O-Al and P-O-C chemical bonding. The influence of phosphate synergistic effect on the corrosion resistance of the self-assembled superhydrophobic composite film on the surface of 6061 aluminum alloy is discussed. This study presents a scientific and innovative design concept to develop coatings with excellent corrosion protection for aluminum alloy, and then extend their application to certain areas. [ABSTRACT FROM AUTHOR]