Characterisation of Microstructure and Residual Stresses in Hydroxyapatite Coatings on Titanium Prostheses

Abstract

Hydroxyapatite (HA) is one of the most used biomaterials in modern orthopaedics. It allows good chemical bonding to human bones, as it is one of its constituents. HA coatings on prostheses of different nature are currently used to improve their functional performances. Substrates of Titanium and Ti6Al4V Titanium alloy are largely used as they have good mechanical properties. However, they do not induce any osteointegration. Good mechanical properties and good osteointegration processes are achieved when Titanium base prostheses are coated with HA via plasma spray deposition. This work aims to characterise the mechanism of adhesion at the coating–substrate interface in orthopaedic prostheses. Microstructural information is obtained by using optical microscopy, electron microscopy and X-ray diffraction techniques. The residual strain and residual stress gradients close to the interface are investigated by using synchrotron radiation.