In vitro fatigue behaviour of vacuum plasma and detonation gun sprayed hydroxyapatite coatings

The fatigue behaviour of vacuum plasma sprayed (VPS) and detonation gun sprayed (DGUN) hydroxyapatite coatings on titanium substrates has been compared in air and in buffered Ringerʹs solution. There was an increase in the surface microcracking and bulk porosity of both types of coating tested in air. After 1 million cycles in Ringerʹs solution the VPS coatings had completely delaminated from their substrates. In contrast the DGUN coatings retained their integrity when tested up to 10 million cycles but were beginning to show signs of delamination at the interface.