One-step electrodeposition of cerium stearate on AAO to improve the corrosion resistance

To enhance the corrosion resistance of anodic aluminum oxide (AAO) films, this study employed a one-step electrodeposition strategy to seal and hydrophobically modify the AAO pores with cerium stearate, achieving a hydrophobic composite coating. The influence of key deposition parameters on the coating’s morphology, composition, and corrosion resistance was systematically examined using scanning electron microscopy, water contact angle (WCA) analysis, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electrochemical characterization. The results confirm the formation of a dense cerium stearate coating comprising an outer Ce(CH3(CH2)16COO)3 layer and an inner Ce(CH3(CH2)16COO)4 layer, which completely seals the surface pores and markedly improves the substrate’s corrosion resistance. Single-factor experiments identified the optimal processing conditions as: 50 V deposition voltage, 10 min deposition time, and 25°C deposition temperature. The coating prepared under these conditions displays a dense micro-nano structure, outstanding hydrophobicity (WCA ≈ 145°), and superior anticorrosion properties. In 3.5 wt.% NaCl solution, the optimal coating exhibits a remarkably low corrosion current density of 1.95 × 10−10 A·cm−2 – two orders of magnitude lower than unsealed AAO – while its charge transfer resistance reaches 3.36 × 108 Ω·cm2, an enhancement of approximately three orders of magnitude. With a protection efficiency of 99.79%, the coating demonstrates exceptional corrosion protection performance.