Post‐plasma‐spraying heat treatment of the HA coating/Ti‐6Al‐4V implant system

The metal/ceramic interface that constitutes an important part of the plasma‐sprayed HA‐coated Ti‐6Al‐4V system may, in fact, represent the “weak link” in the implant design. A post‐plasma‐spray heat treatment to enhance chemical bonding at the metal/ceramic interface and, hence, improve the mechanical properties (interface fracture toughness and tensile coating adhesion strength) of the plasma‐sprayed implant system does show promise. In preliminary heat treatment studies, however, any improvements realized were lost due to the chemical instability of the coating in a moistureladen environment, with a concomitant loss in bonding properties. This deterioration in properties appears to be related to environmentally assisted crack growth as influenced by processing conditions. Still, an ability to improve HA/Ti‐6Al‐4V bonding through enhanced diffusion bonding was demonstrated, warranting further heat treatment studies involving atmosphere control during processing. © 1993 John Wiley & Sons, Inc.