Preparation of MAO-LDH hydrophobic coating on ZK60 magnesium alloy surface by one-step hydrothermal method and its corrosion resistance
Mg-Al layered double hydroxide(LDH)composite coatings modified with myristic acid(MA)were prepared on the surface of micro-arc oxidation(MAO)film of ZK60 magnesium alloy by one-step hydrothermal method.Microstructure,phase composition and structure of the coatings were analyzed by means of field emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD)and Fourier infrared spectroscopy(FTIR),and the wettability and corrosion resistance of the coatings were analyzed using a contact angle tester and an electrochemical workstation.The results show that the micro-pores on the surface of the MAO film are successfully sealed by MA/LDH coatings.When the hydrothermal temperature is 120 ℃,the LDH layer on the surface of the MA/LDH/MAO composite coatings is relatively complete and uniform,and the contact angle is the largest,which is 143.42°.The corrosion resistance of the ZK60,MAO film and MA/LDH/MAO composite coatings prepared at different hydrothermal temperatures in descending order is MA/LDH/MAO-120＞MA/LDH/MAO-110＞MA/LDH/MAO-130＞MAO＞ZK60.This is attributed to the uniform and complete LDH structure of the MA/LDH/MAO-120 composite coatings and the effect of MA intercalation/surface modification of LDH,which can effectively improve the corrosion resistance of the ZK60 magnesium alloy.
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