Dritsite-like layered double hydroxides as anticorrosive material for AA2024 alloy: a preliminary study

Dritsite-like layered double hydroxides (LDHs) were synthesized by reacting gibbsite with LiCl, followed by anion exchange with sodium salts of molybdate, tungstate, and chromate using two distinct procedures, that varied concentration and exchange time, to optimize oxoanion intercalation while minimizing delithiation. The obtained materials were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopies and scanning electron microscopy (SEM). These characterization techniques confirmed the lamellar structure of the materials, with basal spacings consistent with those reported for dritsite-like LDHs, and evidenced the presence of characteristic chemical bonds associated with the constituent elements and intercalated oxoanions. In addition, ICP/OES analysis was used to quantify the release of intercalated species after 24 hours and 7 days of immersion in NaCl solutions, showing partial lithium leaching (≈1% of the total content) together with anion release (CrO 4 2- 2.5%, MoO 4 2- 0.2%, WO 4 2- 0.1%). Electrochemical impedance spectroscopy on AA2024 aluminum alloy demonstrated that the protective performance of each material can be correlated with the concentration of anion released and differences in inhibition efficiency of the intercalated anion. This is the first report describing a dual release from LDH-like structure combining Li + cations with well known oxoanions with different corrosion inhibition efficiency towards Al alloys. Furthermore, the present study shows that by proper controlling synthesis parameters it is possible to impart a joint release of ions from LDH structure, which can open new pathways for the preparation of novel LDH-like compositions. Schematic polyhedral representation of dritsite-like layered double hydroxide synthesis and protection mechanism on AA2024 alloys. • Dritsite, a layered Li–Al hydroxide, was synthesized and characterized • Controlled anion exchange was achieved within the layered structure • Structural stability was evaluated under different anion exchange conditions • Intercalated anions enabled stable protective film formation on AA2024 • Pristine dritsite also provided protection via Li + release during delithiation