Chemical and morphological properties of electrosprayed calcium phosphate coatings
Résumé
Introduction: Replacement of missing or diseased hard tissues has become a common procedure in medicine and
dentistry. In this field, coatings are frequently applied onto the surface of metallic implants, such as titanium and titanium
alloys, to improve their biological performance. Bioactive calcium phosphate (CaP) ceramics have been widely studied as
a synthetic material for this purpose due to their osteoconductive properties [1]. In addition, one of the major constituents
of bone and hard tissues in mammals is a CaP whose structure closely resembles hydroxyapatite (HAP), Ca10(PO4
)
6
(OH)2
. This biological apatite is poorly crystallized, non-stoichiometric with multiple cationic and anionic substitutions [2].
Electrostatic spray deposition (ESD) is a versatile and low-cost technique enabling deposition of CaP coatings with a
wide variety of controlled morphologies and crystallinity degree. As a result, phenomena such as coating dissolution rate
and apatite precipitation layers might be controlled by tailoring the coating properties. Therefore, the objective of this
study is to obtain ESD-prepared pure HAP coatings with optimized and original microstructures.
Experimental methods: Solutions containing calcium nitrate and triethyl phosphate were sprayed on polished and clean
titanium alloy surfaces by means of an electro-spraying deposition device. In order to investigate the influence of
processing condition on the characteristics of the coatings, several ESD parameters were considered -e.g. relative and
absolute precursor solution concentrations, the temperature of deposition, solvents, etc.
The microstructure and composition of the obtained coatings were characterized by scanning electron microscopy (SEM)
associated with energy-dispersive X-ray spectroscopy (EDX). Their structural properties were determined using X-ray
diffraction (XRD), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR).