Formation of Conversion Coatings on Magnesium Alloy AZ31 in Solutions Containing Nicotinic Acid

The coating of nicotinic acid (NA), sodium fluoride (SF) and sodium fluoric - nicotinic acid (SF-NA) deposited from a sodium fluoric solution with subsequent treatment in nicotinic acid on magnesium alloy AZ31 has been investigated. The corrosion resistance of coated AZ31 in a simulated body fluid (SBF) solution was studied using potentiodynamic polarization tests. A comparison polarization tests results of conversion coatings have shown a sharp reduction in corrosion current density from SF to NA, respectively 70.1 ′ 10–6 A/cm2 to 20.4 ′ 10–6 A/cm2. The morphology of the coatings was studied by a scanning electron microscope (SEM). The results revealed that there are cracks in the NA coatings. Despite the presence of cracks, the NA coatings better protect the AZ31 magnesium alloy against corrosion than as SF coatings. The cytotoxicity tests showed that AZ31 magnesium alloy with NA conversion coatings have no any toxic effect on the normal adult stem cells and this means that the magnesium AZ31 alloy with NA is distinguished for its good biocompatibility in a cell culture in vitro. DOI: http://dx.doi.org/10.5755/j01.ms.18.2.1912