MICROSTRUCTURAL AND IN-VITRO CHEMICAL INVESTIGATIONS INTO PLASMA-SPRAYED BIOCERAMIC COATINGS

Hydroxyapatite (HA) coatings plasma sprayed without and with bond coat s (titania, zirconia) onto titanium alloy (Ti6A14V) substrates under b oth atmospheric and low pressure plasma spray conditions were investig ated in terms of their microstructure and their resorption resistance during immersion in simulated body fluid (Hank's balanced salt solutio n), The microstructures of test samples were characterized using SEM o n as-sprayed and leached surfaces and on the corresponding cross secti ons. Selected coating systems were studied by 2-dimensional secondary ion mass spectroscopy imaging to obtain information on plasma spray in duced diffusional processes at the coating interfaces, as well as the spatial distribution of minor and trace elements. Coatings consisting of thin (10-15 mu m) titania/zirconia (eutectic ratio) and titania bon d coats, combined with a 150- to 180-mu m thick HA top coat, yielded p eel strengths in excess of 32 N/m, as web as sufficient resorption res istance. (C) 1998 John Wiley & Sons, Inc.