In order to improve corrosion resistance, biodegradability and inductivity of AZ91D used in bone-grafting therapies, composite coatings containing hydroxyapatite, chitosan and RuCl₃ are prepared by combination of pulsed electrochemical deposition and hydrothermal treatment.

A uniform and dense coating with a Ca/P ratio of 1.660 can be obtained and the coating could induce forming a new Ca-deficient apatite layer after immersion for 7 days in Hank's solution.

In new layer, with the increasing of RuCl₃ concentration, the absorption rate of Ru increases, and HA particles refined to 180 nm, with Ca/P ratio much closer to 1.67.

The corrosion resistance and inductivity have improved with RuCl₃ concentration increasing.

The results indicate composite coating is a suitable coating for AZ91D implants for orthopedic applications.