Correlation between anti-corrosion performance and optical reflectance of nano fluoride film on biodegradable Mg-Zn-Zr alloy: A non-destructive evaluation approach

Magnesium alloy is promising new biomaterial due to its satisfactory mechanical performance, biocompatibility and degradation of non-toxic substances. However, the dual problems of corrosion and hydrogen evolution require overcoming in order to reach a practical application level. For anti-corrosion modification, fluoride conversion treatment was chosen to provide varied MgF₂ coatings on the microstructure-modified Mg-Zn-Zr alloy The aim of the present study was to investigate the influence of coating structures and their corresponding corrosion resistance. The fluoride coatings were constructed with nano-crystalline composites, which demonstrated that Mg-Zn precipitates participate in the coating-growth mechanism. In addition, the improved corrosion resistance was also systematically investigated. Compared with the pristine substrate, the F24h and F48h specimens significantly improved the anti-corrosion performance. Moreover, this report is the first report to propose a non-destructive evaluation method through simultaneous evaluation of the corrosion behavior and the establishment of a correspondence surface reflectance for fluoride conversion coatings on Mg-Zn-Zr alloy.