Hydroxyapatite, (HA), is a calcium phosphate bioceramic material which has an almost identical chemical composition to that of bone. It has excellent biocompatibility and is osteoconductive, allowing bone cells to grow on its surface. It has therefore been recognised as an attractive material for the repair and replacement of body parts. One such application is as a coating on implants such as hip prostheses. The HA coating encourages the growth of bone into the coating, providing fixation for the implant.

Plasma spraying is the most commonly used method for the application of HA coatings. The process is a complex one, influenced by at least 50 process parameters. In order to produce higher quality HA coatings a clearly understanding of the structure-property-process relationship is necessary. This study uses the design of experiment technique to investigate the effect of various spray parameters on the final coating. The effect of post spray treatment methods is also examined.