Plasma Sprayed Hydroxyapatite Bioceramic Coatings from Coprecipitation Synthesized Powder: Preparation, Characterization and in vitro Studies

Abstract

ABSTRACTPlasma spraying is the most recommended spraying methodology for coating of biomedical alloys by Food and Drug Administration and the process requires flowable powders. In the present study, plasma sprayable grade hydroxyapatite (HAp) powder has been prepared by a single step co-precipitation technique using mixture of precipitating agents and thereby avoiding agglomeration processes like spray drying. HAp coating has been deposited on Ti-6Al-4V substrate using atmospheric air plasma spraying system to get a coating thickness of ∼100 µm. The synthesized powder and plasma sprayed coating exhibit crystallinity of 12% and 56%, respectively. The powder possesses good flowability and shows an average agglomerated particle size of 87 µm. The coating consists of fully melted regions and unmelted/partially melted regions. Biocompatibility studies carried out under in vitro conditions using 3T3 fibroblast cells indicate the non-toxic nature of coatings and supports adherence and growth of the cells. Plasma sprayed HAp coating exhibits lower coefficient of friction than that of the substrate. A detailed electrochemical study of the plasma sprayed HAp coatings in Hanks’ medium has also been reported. The plasma sprayed HAp coating synthesized from solid state synthesized powder is porous and does not possess proper adhesion to the substrate.