**4. Conclusions**

The influence of the combined addition of Mg and Zn on the microstructure and corrosion resistance of AlSi-based coatings for steel sheets was investigated using a range of analytical and experimental techniques. In particular, the corrosion resistance was also evaluated after ED coating on the metallic coated steel sheets. The major findings can be summarized as follows:


and Mg-Al LDH, stabilized by Mg(OH)2, is the major mechanistic reason for the higher corrosion resistance of AlSiZnMg-MC.

4. In contrast to the corrosion resistance of metallic coatings, ED-coated AlSiZnMg-MC exhibited more severe surface degradation after the accelerated corrosion tests. The non-uniform formation of Mg-based oxide over the AlSiZnMg-MC can weaken the adhesion between the inner metallic coating/outer ED coating. Hence, the corrosive species are more able to permeate through the ED coating on AlSiZnMg-MC, and the electrochemical corrosion reactions occurred rapidly. Therefore, further optimization of the alloy contents in AlSi-based coatings needs to be investigated.

**Author Contributions:** Conceptualization, W.S.Y. and S.J.K.; methodology, S.O.K., W.S.Y., and S.J.K.; investigation, S.O.K., W.S.Y., and S.J.K.; data curation, S.O.K., W.S.Y., and S.J.K., writing—original draft preparation, S.O.K. and S.J.K. All authors have agreed to the published version of the manuscript.

**Funding:** This research was supported in part by the National Research Foundation of Korea (NRF) gran<sup>t</sup> funded by the Korea governmen<sup>t</sup> (MSIT), gran<sup>t</sup> number No. 2019R1C1C1005007. In addition, this work was partly funded and conducted under the Competency Development Program for Industry Specialists of the Korean Ministry of Trade, Industry and Energy (MOTIE), operated by the Korea Institute for Advancement of Technology (KIAT) (No. P0002019, HRD Program for High Value-Added Metallic Materials Expert).

**Conflicts of Interest:** The authors declare no conflict of interest.
