title: Influence of experimental parameters on spatial phase distribution in as-sprayed and incubated hydroxyapatite coatings.
abstract: In the present study, the behavior and properties of plasma-sprayed hydroxyapatite coatings [Ca(10)(PO(4))(6)(OH)(2), HAp] were investigated in relation to the spraying process. The experiments were focused on the influence of type of feedstock and spray power on the phase composition and distribution within the coatings. Depth profiles of the coatings were investigated before and after incubation in revised simulated body fluid (SBF) by X-ray diffraction and infrared spectroscopy. Besides HAp, the coatings contain oxyapatite (OAp) and carbonate apatite (CAp). Additionally, tricalcium phosphate (TCP), tetracalcium phosphate (TTCP), CaO, and an amorphous phase were detected in the coatings. The HAp content directly depends on the used spray powder and spray power, where the influence of spray powder is much higher than the influence of the spray power. The grain size range of the spray powder strongly influences the HAp content in the coating and the formation of CaO. The in vitro behavior of the coatings in simulated body fluid mainly depends on the contents of CaO and amorphous calcium phosphate, respectively. The formation of portlandite due to the reaction of the coating with the SBF is strongly influenced by the porosity of the coatings and can be used as an indicator for the depth of interaction between fluid and coating.
authors.affiliation: Institute of Mineralogy, TU Bergakademie Freiberg, Brennhausgasse 14, 09596 Freiberg, Germany. hesse@geol.uni-erlangen.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Hesse
authors.forename: Margitta
authors.initials: M
authors.lastname: Hengst
authors.forename: Reinhard
authors.initials: R
authors.lastname: Kleeberg
authors.forename: Jens
authors.initials: J
authors.lastname: Götze
mesh_terms: D002130:Calcium Phosphates / Q000737:chemistry; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry*; D006358:Hot Temperature; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D011208:Powders; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D011208:Powders; C519480:amorphous calcium phosphate; C485830:tetracalcium phosphate; D017886:Durapatite; C018392:tricalcium phosphate