Influence of Yttria Stabilized Zirconia and Hydrothermal Treatment on Plasma Sprayed Hydroxyapatite Coatings

Abstract

A post-treatment of hydrothermal process was conducted to evaluate its effects on the material characteristics and mechanical properties of plasma-sprayed pure HA and HA/20% YSZ coatings. Surface morphology and microstructural changes, relative element contents as well as phase transformations were analyzed by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffractometry. Both microhardness and Young’s modulus were measured. CaCO₃ was found existing before and after the whole process of post-treatment. Peaks of impurity phases such as CaO, TCP, and TTCP of as-sprayed coatings were observed to disappear while HA peaks show a tendency of getting higher and wider over time. Surface morphology of SEM analysis presents a clear deposition behavior of ultrafine HA crystallized particles and cross-sectional analysis exhibits a dense and fine structure. Mechanical properties of HA/20%YSZ coatings are found to be significantly higher than those of pure HA coatings and both of which displayed an overall increase with the heating time, indicating enhanced performances.

Keywords

plasma spraying / hydroxyapaptite / hydrothermal treatment / composite coating