HYDROXIAPATITE COATING METHOD ON STAINLESS STEEL FOR ORTHOPEDIC IMPLANTS

Abstract

This invention relates to a method of electrochemical deposition of hydroxyapatite (HAp) on the surface of 316L stainless steel or SS 316L using AC–DC voltage superposition. This method begins with the preparation of the SS 316L substrate through a cleaning and activation process, followed by the preparation of an electrolyte solution containing calcium and phosphate ions with a controlled pH. The deposition process is carried out at a low temperature (<100 °C) by applying an electrical signal in the form of a combination of sinusoidal AC and low-voltage positive-offset DC (<5 V). Variations in the ratio of AC to DC voltage and frequency settings are used to control ion distribution, reduce the formation of hydrogen bubbles (Hâ‚‚), and increase the homogeneity of the coating. The product resulting from this invention is a thick, uniform HAp layer, having a Ca / P ratio close to stoichiometric HAp, and showing better corrosion resistance than the coating resulting from the DC or pulsed DC method.The HA layer according to this invention has great potential for use in orthopedic implants because it is able to increase biocompatibility and support the bone osseointegration process.