Enhanced Corrosion Resistance and in Vitro Biocompatibility of Mg-Zn Alloys by Carbonate Apatite Coating

Dinh Ngoc Pham, Sachiko Hiromoto, Tomohiko Yamazaki, O. Minho, Equo Kobayashi

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


B-type carbonate apatite (CAp) coatings were formed on as-cast and T4-treated Mg-xZn (x = 1, 5, and 7 wt %) alloys containing various sized Zn-rich second phase to improve the corrosion resistance and biocompatibility. The CAp coating grew uniformly on the alloys with a thickness of 1.1-1.3 μm and did not show cracks or pores on 30 μm-sized second-phase particles. The CAp coating retarded corrosion of Mg-Zn substrates for the first 3-5 days in Hanks' solution. Polarization resistance of the CAp-coated alloys was 10-90 and 1-70 times higher than the uncoated and hydroxyapatite (HAp)-coated alloys, respectively. The corrosion rate of CAp-coated alloys was greatly affected by the substrate alloys once the coatings were partly broken. The CAp-coated alloys showed 40-60 and 25-45% lower 14-day average corrosion rates than the uncoated and HAp-coated alloys, respectively, in the immersion test. The CAp coating significantly enhanced the viability of osteoblastic MC3T3-E1 cells on the Mg-Zn alloys for 72 h compared to the uncoated and HAp-coated alloys. The cell densities on CAp-coated alloys were similar for 72 h regardless of substrate alloys. Therefore, the CAp coating can be a superior coating candidate for corrosion-control and biocompatibility improvement for biodegradable Mg alloys.

Original languageEnglish
Pages (from-to)6881-6892
Number of pages12
JournalACS Applied Bio Materials
Issue number9
Publication statusPublished - 2021 Sept 20


  • biodegradable
  • carbonate apatite
  • cell viability
  • corrosion
  • Mg-Zn alloys


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