Evaluation of Credibility of Plasma Spray Biocompatible HAp Coatings by Electrochemical Impedance Technique

INTRUDUCTION It is well known that hydroxy apatite (HAp, Ca10(PO4)6(OH)2) is a biocompatible implant material because the main inorganic composition of bones or teeth is HAp. Since its mechanical properties are poor just as other ceramic materials, HAp has been widely applied as a surface coating on metallic materials to improve their biocompatibility instead of being used as a bulk biocompatible material. The development of biocompatible plasma spray HAp coating on metallic substrates has been conducted for years in our research lab. In this study, the credibility of HAp/Ti combined coatings and the effect of heat treatment were assessed by electrochemical impedance monitoring in physiological saline. Conditions during postal heat treatment such as cooling or heating rate were also investigated. The adhesion of HAp/Ti combined coating on SUS316L was evaluated by three-point bending test. The effect of Zn addition on the credibility of HAp coating was also investigated.