Stearic Acid Treatment Enhancing Corrosion Resistance of Biomimetic-Deposited Calcium Phosphate Dihydrate Coating on Medical Degradable Magnesium Alloy

Magnesium (Mg) alloys, a degradable material, have beenstudied for medical applications due to their excellent mechanicaland chemical properties. However, their applications are limited byrapid corrosion. In this work, stearic acid and sodiumstearate were used to treat the silane-induced calcium phosphate dihydratecoating to improve its protection for the Mg alloy further withoutchanging the bone-like structure of calcium phosphate. The differenteffects of stearic acid treatment and sodium stearate treatment werecompared. Electrochemical test and immersion test results confirmedthat the corrosion resistance of the stearic acid-treated compositecoating was greatly enhanced with a reduced corrosion current densityby 3 orders of magnitude and hydrogen evolution reduced to 1/25 after14 days. The stearic acid-treated coating also exhibited improved in vitro biocompatibility corroborated by promoted cellviability and better cell morphology.