Nanostructured titania/hydroxyapatite composite coatings deposited by high velocity oxy-fuel (HVOF) spraying

Abstract

Nanostructured titania/hydroxyapatite composite coatings deposited by high velocity oxy-fuel (HVOF) spraying Gaona, M.; Lima, R. S.; Marple, B. R.Contact us / Contactez nous: nparc.cisti@nrc-cnrc.gc.ca. AbstractPure nanostructured titania (TiO 2 ) and blends with 10 and 20 wt% hydroxyapatite (HA) powders were sprayed onto Ti-6Al-4V substrates using a high velocity oxy-fuel (HVOF) system. The feedstock powders employed in this work were engineered to exhibit similar particle size distributions in order to generate similar values of particle temperature and velocity in the spray jet. By achieving these characteristics it was assumed that the differences in coating properties and microstructures produced in this study were mainly related to the nature and composition of the feedstock powders, rather than to the spraying parameters or in-flight particle characteristics. The microstructure, porosity, roughness, Vickers hardness and bond strength (ASTM C633) of these coatings were analyzed and evaluated. X-ray diffraction (XRD) patterns showed that no detectable chemical reaction occurred between the nanostructured TiO 2 and HA phases during the spray process. Due to the poor mechanical performance of HA, its addition decreased the bond strength and hardness values of the coatings, especially when the content of HA was 20 wt%; however, the bond strength values were still much superior to those of HA thermally sprayed coatings. The addition of HA to nanostructured titania for producing HVOF-sprayed coatings could be very interesting for biomedical applications due to the combination of the good mechanical performance and chemical stability of nanostructured titania and a bioactive phase (HA) that can enhance the bio-performance of the coating. Crown

Calcium orthophosphate-based biocomposites and hybrid biomaterials

“…For example, HA was combined with Bioglass Ò (Novabone Products, Alachua, FL) [748,749] and with other glasses [750] to form glassceramics biocomposites. Other reinforcement materials for calcium orthophosphates are differentiated by either shape of the fillers, namely, particles [751,752], platelets [753,754], whiskers [484,755,756], fibers [757][758][759], or their chemical composition: zirconia and/or PSZ [250, 743-746, 755, 760-793], alumina [250,751,754,[793][794][795][796][797][798][799][800][801][802], titania [307,747,752,[803][804][805][806][807][808][809][810][811][812][813][814][815][816][817], other oxides [818-821], silica and/or glasses …”

Plasma Sprayed Bioceramic Coatings on Ti-Based Substrates: Methods for Investigation of Their Crystallographic Structures and Mechanical Properties

“…Therefore, the bioceramic coatings and calcium orthophosphates in particular, applied on Ti-based substrates, having a useful combination of biocompatibility, mechanical properties and relative stability in bodily environment, are subjects of an increasing interest for biomedical applications in modern orthopaedics and dentistry (Gaona et al, 2007;Salman et al, 2008;Soares et al, 2008;Thomas, 1994).…”

“…not initiating a response or interaction in contact with biological tissues. However, it was recently indicated that the titania surface bioactivity can be activated by different chemical treatments (Gaona et al, 2007;Zhao et al, 2007). This could provoke reconsideration of the titania coatings role, making them superior to other biomedical coatings, as so far TiO 2 is mostly recognized with its excellent corrosion resistance and high adhesion strength to different substrates (Liu et al, 2006).…”

Caracterización de nuevos recubrimientos biocompatibles de hidroxiapatita-TiO₂ obtenidos mediante Proyección Térmica de Alta Velocidad

“…Resalta por tanto el papel positivo que ha tenido la adición de óxido de titanio, con mejores propiedades mecánicas que la hidroxiapatita, en el aumento de la adherencia de los recubrimientos. Son pocos los grupos que hacen recubrimientos lo suficientemente similares como para ser comparados con éstos, pero el fenómeno citado es especialmente palpable en estudios como el de Lima, Marple y Gaona (12), que consiguen llegar a valores alrededor de 60-70MPa con HVOF, pero siempre con porcentajes elevados de titania (80-90%). Si se recurre a los estudios realizados por el propio grupo (13), se puede observar que las adherencias pre-inmersión son similares a las obtenidas, a pesar de aumentar el contenido relativo de hidroxiapatita en la mezcla.…”

“…Por ello, se escoge el óxido de titanio como complemento de la hidroxiapatita, para provechar sus propiedades mecánicas y anticorrosivas. Estudios previos de recubrimientos con elevadas proporciones de TiO 2 constatan fuertes aumentos de propiedades como la adherencia (12). Asimismo, no se teme una reacción biológica adversa, ya que históricamente se sabe que el óxido de titanio es bioinerte o biocompatible.…”