Evaluation of nanostructured carbonated hydroxyapatite coatings formed by a hybrid process of plasma spraying and hydrothermal synthesis
Résumé
Carbonated hydroxyapatite (CHA) coatings on a titanium alloy were prepared by hydrothermal synthesis of precursors plasma‐sprayed with brushite as a raw powder. The structures, residual stresses, and bond strengths of the precursors and CHA coatings were investigated. The results showed that the sprayed precursors consisted of β‐Ca2P2O7, α‐Ca3(PO4)2, and CaHPO4, whereas the CHA coatings exhibited a unique phase construction, nanostructured and needlelike crystals, and a fairly low tensile residual stress. The bond strength of a CHA coating 200 μm thick was 15 MPa, equivalent to that of a plasma‐sprayed hydroxyapatite (HA) coating. The evaluation of the CHA coatings was performed together with that of plasma‐sprayed HA coatings immersed in distilled water. The dissolution and bond‐strength degradation of the CHA coatings were much lower than those of the plasma‐sprayed HA coatings.