RESIDUAL-STRESS MEASUREMENT IN THERMAL SPRAYED HYDROXYAPATITE COATINGS

Hydroxyapatite coatings have been used for many years on dental and prosthetic implants to provide a biocompatible surface for long-term fixation of the implant to bone. In this study two thermal spraying processes, air plasma spraying (APS) and a high velocity oxy fuel process (CDS) have been employed to produce hydroxyapatite coatings. An X-ray diffraction technique (XRD) has been applied to measure the residual stresses in thermal sprayed hydroxyapatite coatings. It has been shown that such stresses are sensitive to spraying parameters and that the newer high velocity oxy fuel spraying process results in lower residual stresses than the conventional air plasma spraying process. Heat treatment of the coating has been shown to significantly reduce the residual stress in the coating.