The influence of alkali pretreatments of AZ31 magnesium alloys on bonding of bioglass–ceramic coatings and corrosion resistance for biomedical applications

Coating defects and poor interface bonding between substrates and coatings derived through sol–gel technique are common problems, which are detrimental to protective effects of coatings. Alkali pretreatment was adopted to prepare 45S5 bioglass–ceramic coatings on AZ31 magnesium alloy. After pretreatment, the 45S5 coating was uniform, dense, crack-free and close bonding to substrates. Electrochemical tests in simulated body fluid (SBF) revealed that 45S5 coatings after pretreatment could obviously improve the pitting corrosion potential and polarization resistance of AZ31 substrate, and lessen corrosion current density, suggesting effective protection. The results showed that alkali pretreatment could be a potential process for development of other coatings on magnesium alloy.