Evaluation of corrosion resistance of biocompatible coatings on magnesium

  • M. Cabrini
  • P. Colombi
  • S. Lorenzi
  • T. Pastore


The work deals with the study of innovative biocompatible coatings for magnesium resorbable osteosynthesis
devices. Conversion layers based on magnesium fl uoride and “diamond like carbon” coatings (DLC) obtained
by chemical vapor deposition were considered in order to reduce the corrosion rate of magnesium to levels
compatible with the time needed for fracture healing. DLC coating was applied on both pure magnesium
and on magnesium after conversion treatment in hydrofl uoric acid. Weight loss tests and potentiodynamic
polarization tests in aerated Hank’s solution at room temperature were performed. The corrosion rate was
about 100 mg/cm2day for the commercially pure magnesium (99.9 %) in the fi rst 24 hours of exposure. Both
the coatings reduced the short-term corrosion rate but the protective layers did not grant long-term stability
and corrosion rate rapidly increases approaching the values of uncoated magnesium.