Temperature-regulated microstructure and corrosion resistance of Zn-Al LDH coatings on biomedical Zn

Purpose This study aims to regulate the degradation behavior of biomedical Zn by constructing Zn-Al layered double hydroxide (LDH) coatings through a hydrothermal process. Furthermore, the effect of reaction temperature on microstructures and corrosion resistance of LDH was clarified. Design/methodology/approach Zn-Al LDH coatings were in situ grown on the Zn surface via hydrothermal reaction at 60°C, 90°C and 120°C. The microstructures of LDH coatings were characterized using scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction, and the corrosion resistance of coatings was evaluated through electrochemical measurements. Findings At higher reaction temperatures, the coatings became thicker and denser. An extra Zn5(OH)8(NO3)2·2H2O phase appeared alongside LDH formation at 120°C. Besides, the corrosion resistance was initially enhanced and then diminished as the reaction temperature increased, and LDH coating grown at 90°C exhibited better corrosion resistance. Originality/value This work provided an effective surface modification strategy for controlling the degradation rate of Zn-based implants. The findings offered valuable insights for the clinical application and long-term performance optimization of biodegradable Zn alloy medical devices.