Ultrathin film coating of hydroxyapatite (HA) on a magnesium–calcium alloy using RF magnetron sputtering for bioimplant applications

A thin film of hydroxyapatite (HA) was coated on a magnesium–calcium (Mg–Ca) alloy using radio frequency (RF) magnetron sputtering. The thickness of the HA coating was in the range of 550–750 nm. In vitro degradation behaviour of the HA coated alloy was evaluated in simulated body fluid (SBF) using electrochemical methods. The ultrathin film coating has significantly improved the degradation resistant of the alloy. The polarisation resistance (Rp) of the coated alloy was more than two-order of magnitude higher and the corrosion current density (icorr) reduced by ~98% as compared to the base alloy