Article scientifique

Calcium phosphate ceramics (CaP), particularly hydroxyapatite Ca₁₀(PO₄)₆(OH)₂ (HAP), are widely used as surface coatings on top of titanium and its alloys in biomedical applications thanks to their ability to form strong bonds with natural bone tissues. In this paper, the electrostatic spray deposition technique (ESD) by using an organic phosphorus(V) precursor is proposed as an alternative to the widely used plasma-spraying process. This approach enables the one-step fabrication of single-phase crystalline HAP coatings with unique morphologies. The microstructure and composition of the deposited CaP layers result from a delicate compromise between the physicochemical properties of the precursor solution (boiling point, the conductivity of the solution) and the ESD deposition conditions. An in-depth study of their structural, microstructural, compositional properties, and their reactivity with Ti₆Al₄V is undertaken. It shows that the Ca/P molar ratio and the nature of phases are strongly dependent on hydrolysis and evaporation of the P(V) precursor in the ESD process. Optimized deposition conditions are found, by using solvents of low-boiling point, for which the coatings deposited above 325 ºC correspond to a well crystalline, nanostructured, and single-phase HAP. Infrared heat treatment of a coating prepared from the one optimized precursor solution promotes the formation of nanostructured HAP.
https://doi.org/10.1016/j.apsusc.2020.148462