Enhanced Corrosion and Wear Resistance of LA43M Magnesium-Lithium Alloy with Magnesium-Aluminum Layered Double Hydroxide Coating

An Mg-Al layered double hydroxide (LDH) coating was prepared directly on the surface of an LA43M Mg-Li alloy substrate by in situ hydrothermal treatment at 90 °C with different reaction times. The effects of the hydrothermal reaction time on the microstructure, corrosion resistance, and wear resistance of LDH coatings were systematically investigated. After the hydrothermal reaction, LDH nanoflake microstructures formed on the surface of the alloy. With an increase in the reaction time, the size and quantity of these microstructures increased, and their distribution became denser. Immersion tests and hydrogen evolution tests showed that the corrosion resistance of LDH coatings varied with the reaction time as follows: LDH-30 h > LDH-24 h > LDH-18 h > LDH-12 h > LA43M substrate. The film coated with a reaction time of 30 h exhibited excellent corrosion resistance in 3.5 wt.% NaCl solution, and its corrosion current density was three orders of magnitude higher than that of the LA43M substrate. Friction and wear tests showed that the LDH coatings displayed markedly improved wear resistance in comparison with LA43M alloy, and wear marks were shallow and narrow. Anticorrosion and anti-wear mechanisms of the LDH coatings were also analyzed and are discussed.