Fabrication of Nanostructured TiO₂ Fibers on TiO₂ Coatings Produced from a Nanostructured Feedstock

Titania (TiO₂) coatings were produced using the high velocity oxy-fuel (HVOF) technique on Ti-6Al-4V substrates. The titania feedstock powder exhibited nanostructured morphology, formed by the agglomeration of individual nanostructured titania particles (spray-drying) smaller than 100 nm. The resulting coatings were dense (porosity <1%) and exhibited rutile and anatase as phases with percentages of ~75% and ~25%, respectively. These coatings were heat-treated in a H₂/N₂ environment at 700oC for 8 h. During the heat-treatment, nanostructured titania fibers were formed on specific surface regions of the coatings. The nanofibers formed by this “chemical or reaction-based texturing” exhibited diameters of 50-400 nm and lengths in the order to 1-5 µm. It is thought that engineering these surfaces at nano and microscales may lead to interesting applications of titania coatings related to cell attachment/growth (for biomedical applications).