Comparison of Physical-chemical and Mechanical Properties of Chlorapatite and Hydroxyapatite Plasma Sprayed Coatings

Chlorapatite can be considered a potential biomaterial for orthopaedic applications. Its use as plasma-sprayed coating could be of interest considering its thermal properties and particularly its ability to melt without decomposition unlike hydroxyapatite. Chlorapatite (ClA) was synthesized by a high-temperature ion exchange reaction starting from commercial stoichiometric hydroxyapatites (HA). The ClA powder showed similar characteristics as the original industrial HA powder, and was obtained in the monoclinic form. The HA and ClA powders were plasma-sprayed using a low-energy plasma spraying system with identical processing parameters. The coatings were characterized by physical-chemical methods, i.e. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, including distribution mapping of the main phases detected such as amorphous calcium phosphate (ACP), oxyapatite (OA), and HA or ClA. The unexpected formation of oxyapatite in ClA coatings was assigned to a side reaction with contaminating oxygenated species (O2, H2O). ClA coatings exhibited characteristics different from HA, showing a lower content of oxyapatite and amorphous phase. Although their adhesion strength was found to be lower than that of HA coatings, their application could be an interesting alternative, offering, in particular, a larger range of spraying conditions without formation of massive impurities.This study was carried out under a MNT ERA-Net Project named NANOMED. The authors gratefully thank the Midi-Pyrénées region (MNT ERA Net Midi-Pyrénées Région, NANOMED2 project) and the Institute National Polytechnique de Toulouse (BQR INPT 2011, BIOREVE project) for supporting this research work, especially the financial support for research carried out in the CIRIMAT and the LGP laboratories (France), and the Basque government and Tratamientos Superficiales Iontech, S.A. for their financial and technical support under the IG-2007/0000381 grant for the development of the LEPS device and deposition of the coatings carried out in Inasmet-Tecnalia. The French industrial collaborators (TEKNIMED SA and 2PS SA) were financed by the OSEO programs

The Temperature Dependence of the Properties of Electrolyte Solutions. III. Conductance of Various Salts at High Concentrations in Propylene Carbonate at Temperatures from − 45°C to + 25°C

Specific conductances of Et4NPF6, Pr4NPF6, Bu4NPF6, LiPF6, KPF6, LiClO4, and KSCN in propylene carbonate were studied at high concentrations in the temperature range from +25°C to -45°C. Data are fitted by a least-squares method to a four-parametric empirical equation, yielding the maximum specific conductance κmax and the corresponding concentration μ. Within the frame-work of a hydro-dynamic model the Stokes-radii of the ions and the solvent viscosity are found to be the most important conductance-determining parameters, affecting both κmax and μ Ionic association in solutions with propylene carbonate as the solvent is not of significant importance. Kinetic treatment of conductance yields temperature-dependent activation energies, but at any one temperature equal for all salts at concentration μ. Die spezifische Leitfähigkeit konzentrierter Lösungen von Et4NPF6, Pr4NPF6, Bu4NPF6, LiPF6, KPF6, LiClO4 und KSCN in Propylencarbonat wurde im Temperaturbereich zwischen +25°C und -45°C untersucht. Die Datenanalyse mittels eines Ausgleichs nach einer vier-parametrigen empirischen Gleichung liefert für jede Temperatur die maximale spezifische Leitfähigkeit kmax mit zugehörigem Konzentrationswert μ. Die Stokes-Radien der Ionen und die Viskosität des Lösungsimittels erweisen sich für ein hydrodynamisches Modell als die wichtigsten leitfähigkeitsbestimmenden Parameter zur Diskussion von κmax und μ. Ionenassoziation spielt in Propylencarbonat als Lösungsmittel keine hervorragende Rolle. Die Behandlung des Transportprozesses im Rahmen eines kinetischen Modells führt zu temperaturabhängigen Aktivierungsenergien, die aber bei jeder Temperatur für alle Salze bei der Konzentration μ gleich sind