Plasma-spraying methods for applications in the production of quality biomaterials for modern medicine and dentistry
B. GUEORGUIEV; I. IORDANOVA; C. M. SPRECHER
Journal of Optoelectronics and Advanced Materials
Abstract
Bioceramic hydroxylapatite (HA) coatings have been shown to be promising bioactive properties in load-bearing implant applications. Biocompatible heterostructure HA/TiO2 deposits, consisting of a TiO2 transition layer (100μm) and a HA top layer (20 and 40μm) were applied on Ti-6Al-4V (TAV) substrates, using atmospheric plasma-spraying (APS). The microstructure parameters were analysed by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The bond strength was evaluated with a tensile test for thermally sprayed coatings (ASTM C633-79). The results revealed that all deposits have a relatively dense and homogeneous, predominantly polycrystalline, microstructure. In addition, a negligible amount of an amorphous-like HA phase, formed mainly in the near-surface regions, and an insignificant amount of partially molten spherical grains are also presented. A not well pronounced crystallographic texture was detected. Compressive residual stresses in the range 7-10GPa, acting parallel to the top surface and decreasing during the growth, were registered. The HA/TiO2 interface, about 15μm wide, was diffuse in nature and enabled a smooth transition between the two layers. The evaluated tensile bond strength was sufficiently high, and varied between 49 and 53MPa.
keywords:Thin films and coatings, Crystallographic structure, Interface, XRD, SEM
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