Multipurpose surface functionalization on AZ31 magnesium alloy by atomic layer deposition: tailoring the corrosion resistant and electrical performance
An environmentally friendly atomic layer deposition (ALD) method with excellent atomic scale roughness controllability is developed to fabricate a highly conformal, corrosion preventive and conducting Al doped ZnO (AZO) film on the plasma electrolytic oxidation (PEO) layers coated AZ31 magnesium alloy. Compared with the insulated PEO coated magnesium alloy, the electrical conductivity of the composite coating jumps to 25 S/m, in the meantime the anticorrosion performance of the PEO/AZO coating is greatly improved from the bare Mg alloy. The enhanced electrical property of the composite coating is due to the abundant oxygen deficiency in AZO film generated during ALD process. The improvement of the corrosion resistant is attributed to the changes in the bond angle and distance between the surface molecule of coating and adsorbent H2O molecule, as a result, the hydrophilic surface of PEO changes to the hydrophobic surface of AZO, providing a novel process to protect the surface of magnesium alloy. It is believed that this technique may open a novel and controllable strategy to expand the practical applications of the magnesium alloys.