Browsing by Author "Rey, C."
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Item A comparative physico-chemical study of chlorapatite and hydroxyapatite: From powders to plasma sprayed thin coatings(2012-10) Demnati, I.; Grossin, D.; Combes, C.; Parco, M.; Braceras, I.; Rey, C.; EXTREMAT; INGENIERÍA DE SUPERFICIESDue to their bioactivity and osteoconductivity, hydroxyapatite (HA) plasma sprayed coatings have been widely developed for orthopedic uses. However, the thermodynamic instability of HA leads frequently to a mixture of phases which limit the functional durability of the coating. This study investigates the plasma spraying of chlorapatite (ClA) powder, known to melt without decomposition, onto pure titanium substrates using a low energy plasma spray system (LEPS). Pure ClA powder was prepared by a solid gas reaction at 950°C and thermogravimetric analysis showed the good thermal stability of ClA powder in the range 30-1400°C compared to that of the HA powder. Characterization of ClA coating showed that ClA had a very high crystalline ratio and no other crystalline phase was detected in the coating. HA and ClA coatings composition, microstructure and in vitro bioactivity potential were studied, compared and discussed. In vitro SBF test on HA and ClA coatings revealed the formation of a poorly crystalline apatite on the coating surface suggesting that we could expect a good osteoconductivity especially for the ClA coating prepared by the LEPS system.Item Hydroxyapatite coating on titanium by a low energy plasma spraying mini-gun(2012-01-15) Demnati, I.; Parco, M.; Grossin, D.; Fagoaga, I.; Drouet, C.; Barykin, G.; Combes, C.; Braceras, I.; Goncalves, S.; Rey, C.; EXTREMAT; INGENIERÍA DE SUPERFICIESPlasma-sprayed hydroxyapatite (HA) coatings are used on metallic implants to improve osseointegration and bone growth. The purpose of this work was to determine the microstructure and composition of HA coatings obtained with a newly developed low energy plasma spray mini-gun employing an HA feedstock powder with smaller granulometry than that commonly used. The microstructure and the phase composition of the coatings obtained by varying the number of mini-gun runs were examined using scanning electron microscopy, X-ray diffraction and Fourier transform infrared and micro-Raman spectroscopy. In all cases, the results indicate the presence of an amorphous phase and oxyapatite in the coatings due to hydroxyl group removal. No other foreign crystalline phases were detected. The absence of foreign phases was attributed to the fast cooling rate of the small particles used in the experiments and the low amount of energy employed with the mini-gun. Decomposition in the υ1PO4 region of the Raman spectra allowed a semi-quantitative evaluation of the phase contents as a function of the number of runs. Micro-Raman spectroscopy appears to be a powerful technique providing comprehensive and localised information concerning calcium phosphate phases in coatings.