Epigallocatechin gallate (EGCG) induced chemical conversion coatings for corrosion protection of biomedical MgZnMn alloys

• A protective MgZnMn conversion coating was formed using polyphenol EGCG.
• The corrosion resistant ability of EGCG conversion coating was concentration dependent.
• The formation and content of EGCG–Mg complex was the main focus for anti-corrosion.

A protective chemical conversion coating based on epigallocatechin gallate (EGCG) was developed on MgZnMn alloy, where the formation of EGCG–metal complexes protected the corrosion of metal substrate from its environment. The coating was prepared via one-step immersion in the EGCG solution. The morphology, formation mechanism and corrosion resistance of the coating were found to be EGCG-concentration dependent. The EGCG conversion coating modified the MgZnMn showed substantially higher corrosion resistance as compared to bare MgZnMn according to the immersion and electrochemical tests. The present study suggests that the EGCG-coated MgZnMn alloy has a high potential for the application as implants due to the facility and effectiveness of the application.