In vitro electrochemical evaluation and phase purity of natural hydroxyapatite coating on medical grade 316L stainless steel

Abstract

AbstractNatural hydroxyapatite (HA) has been electrophoretically deposited on the surface of medical grade 316L stainless steel (SS). Deposition was performed at various applied voltages of 30, 60, and 90 V for 3 min. After deposition the samples were dried at room temperature and sintered in a vacuum furnace (10−4–10−5 Torr) at 800 °C for 1 h. In vitro electrochemical studies were performed in the Hank's solution. The results showed that corrosion potential and breakdown potential of the coated samples shifted toward nobler potential compared with the uncoated 316L SS. Electrochemical impedance spectroscopy investigations revealed a higher polarization resistance, total impedance, and lower capacitance values for the coated samples compared to the bare one which indicated the improvement of corrosion resistance of the coated samples. The surface morphology of the samples was studied by a scanning electron microscope, and also phase purity and crystallinity of the coating material were investigated by X‐ray diffraction. Deposition at 60 V for 3 min was found to be an optimum coating condition which led to the uniform, continuous, and crack‐free coatings. The crystallinity of the coating materials was measured to be high, and quantitative analysis of the coatings after sintering showed some partial decomposition of natural HA to tricalcium phosphate.