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

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.CaCO3was 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.