Improvement in Ca and P incorporation in the coating on Ti by gas-assisted electrical discharge coating

Abstract

Electrical discharge coating (EDC) has been applied to prepare a Ca and P-containing layer on Ti as implant applications. This study aimed to enhance Ca and P incorporation in the coating by absorbing HA on gas using gas-assisted perforated electrodes. The effects of gas flow rate and electrode rotational speed on the coating composition and coating thickness were investigated. Using the gas-assisted perforated electrodes at an appropriate gas flow rate (0.02 L/min) enhanced the Ca and P amount in the coating. In addition, an increase in the rotational speed of the electrode decreased the Ca and P amount in the coating. The coating thickness decreased with increasing electrode rotational speed. The EDC-treated Ti exhibits higher surface hardness and corrosion resistance than Ti. After hydrothermal treatment, the needle and prism HA crystals precipitated on the coating surface, exhibiting hydrophilic property. Furthermore, the hydrothermal treatment slightly improves the corrosion resistance of the EDC-treated Ti.