| LA103Z magnesium-lithium alloy is a high-lithium alloy.Because of its higher lithium content and lower density;The activity of magnesium itself is high.Because the addition of lithium is an uneven material structure,the corrosion resistance become worse.In this paper,a micro-arc oxidation process is used to prepare the MAO(short for "Micro Arc Oxidation")film layer on LA103Z magnesium-lithium alloy,to investigate the effects of voltage,frequency and time on the growth characteristics of MAO films during the initial micro-arc oxidation process,and prepare Mg-Al-LDH and Mg-Al-Co LDH for the micro-arc oxidation films,respectively,the morphology,composition,and insulation of the MAO/LDH composite film were analyzed,and the polarization resistance test and AC impedance test were performed on the corrosion resistance of the composite film.Through micro-arc oxidation of LA103Z magnesium-lithium alloy for 10s-90s,It shows that the micro-arc oxidation process is anodic oxidation at the beginning,and gradually changes to micro-arc oxidation with arc light over time.The effect of different micro-arc oxidation parameters on the growth of the micro-arc oxidation layer of the LA103Z magnesium-lithium alloy was investigated by performing micro-arc oxidation on the LA103Z magnesium-lithium alloy with different voltages,frequencies and times.The results show that,similar to most magnesium alloys,voltage and time contribute to the film thickness.The maximum film thickness can reach 26 ?m,and the frequency does not significantly change the growth of the MAO film.In order to further improve the corrosion resistance of the alloy,the LDH sealing treatment was performed on the micro-arc oxidation samples.The results showed that the micro-arc oxidation film layer obtained in the single-component electrolyte had larger micropores.After the preparation of Mg-Al LDH,the cross-section of the MAO/LDH composite film layer could not be clearly observed,and only a small number of through-holes were observed.After testing by the electrochemical workstation,compared with the matrix The corrosion resistance of the subsequent alloys has been improved.The maximum resistance value of the composite film is 7000 ohm·cm2,which is much larger than the 70 ohm·cm2 of the substrate and 1000 ohm·cm2 after micro-arc oxidation.In order to improve the sealing effect of LDH,the cross-section morphology of the composite film layer can be clearly observed.Mg-Al LDH was prepared from the micro-arc oxidation samples obtained from the electrolyte with complex composition.The results show that the micro-arc oxide film with a small aperture is beneficial to the growth of LDH.After the test of the electrochemical workstation,the corrosion resistance of the sample with the composite film layer is further improved.The maximum resistance value of the composite film layer is 65000 ohm·cm2,which is greater than composite film layer obtained under small pore size.In order to explore the sealing effect of other sealing processes,Mg-Al-Co LDH was prepared on the micro-arc oxidation samples.The results show that the film formation of the composite film is good,and the analysis of the composition shows that LDH is formed.Insulation and corrosion resistance indicate that the sealing effect of Mg-Al-Co LDH is relatively poorer than that of Mg-Al LDH in the same temperature and time range.The maximum resistance value of the composite film is 35000 ohm·cm2,and the corrosion resistance is worse than that of the Mg-Al LDH composite film,but it is still far better than the substrate. |
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