Synthesis and evaluation of MgF₂coatings by chemical conversion on magnesium alloys for producing biodegradable orthopedic implants of temporary use

Effect of Fluoride Conversion Coating on the Corrosion Resistance and Adhesion of E-painted AZ31 Magnesium Alloy

“…1. Fluoride conversion coatings were formed a function of treatment time, acid concentration, and substrate pre-treatment [7][8][9]. Coating properties such as thickness and porosity can change significantly depending on these parameters [10].…”

“…In the case studies of [7,9] it was shown that the fluoride conversion coating on Mg alloys can contain considerable amount of hydroxide and oxides. Generally, lower acid concentrations lead to greater amount of hydroxides/oxides formed on the metal surface.…”

“…The rate of each process will depend on the HF concentration. According to the studies in literature, the quantity of hydroxides in the coating has considerable negative effect on the protective properties of MgF 2 layer [9]. Mg(OH) 2 is not stable in the acidic solution.…”

“…Fluoride conversion coating is presently limited for improving the corrosion resistance of Mg alloys in body fluids [2,[4][5][6][7][8][9][10] and no studies have been reported on the E-painting of AZ31 Mg alloy with FCC. Two main methods have been reported to produce MgF 2 protective coating on pure Mg and Mg alloy substrates so far [7].…”

Fluoride Coatings on Magnesium Alloy Implants

“…Furthermore, the crystalline phase on the alloy surface is also an essential factor affecting the formation of fluorinated magnesium coatings. Casanova et al [ 58 ] analyzed the morphology of fluoride conversion coatings synthesized on Elektron 21 and AZ91D alloys. In a hydrofluoric acid (HF) solution, AZ91D and Elektron 21 alloys form MgF2 coatings, which provide good corrosion protection, where the presence and nature of different intermetallic phases play a pivotal role in its growth.…”