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1924 |
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Characterization of biocompatible HA/TiO2 coatings obtained by thermal spray |
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Sergi Dosta / Thermal Spray Centre (CPT) - Universitat de Barcelona, SPAIN Fernandez Javier / Thermal Spray Centre (CPT), Spain I. Canno/ Thermal Spray Centre (CPT), Spain A. Ferrer/ Thermal Spray Centre (CPT), Spain J. Guilemany/ Thermal Spray Centre, Spain |
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As it is well known that the hydroxyapatite (HA: Ca10(PO4)6OH2), is a biocompatible and bioactive ceramic material. Its application as a coating on metallic substrates has been widely studied in orthopedic and dental prosthesis. Nevertheless, the bond strength of the coating is one of the main important properties for medical application. This adherence is quite low in case of thermal sprayed coatings because the thermal coefficients of HA and metallic substrate, are particularly different. The aim of this work is to increase the bond strength of the coating by means of TiO2 incorporation to HA powder. A mixture of HA and TiO2 (60/40 wt%) has been sprayed on Ti6Al4V substrate using both atmospheric plasma spray and HVOF. The microstructure of coatings was characterized by SEM and XRD. Adherence strength was calculated following the standard ASTM F1147-99. Bioactivity results were considered by immersion of the coatings in SBF fluid evaluating the apatite surface deposition. A higher crystalline degree was observed in the coatings obtained by HVOF compared to plasma, where crystalline HA, TiO2 rutile and small amount of amorphous phase (ACP) were found in case of HVOF. This higher crystallinity plays an important role improving the strength of adhesion to substrate. The bond strength of the as-sprayed coatings reach values from 44.33±1.76 to 54.08±6.32 MPa for HVOF coatings while the APS values were lower than HVOF ones. These values are considerable higher than those obtained for conventional HA coatings. |