Search

[eng] The Cold Spray (CS) is a novelty technique for the production of coatings within the field of Thermal Spray. The use of low work temperatures (under the melting point of the material) is what makes it different from the other conventional spraying techniques. CS is an ideal technique to spray materials that are sensitive to temperature, such as nanostructured and amorphous materials, or sensitive to the oxygen, as could be titanium. These characteristics may be specially promising within the field of biomedical coatings. Compared to the conventional processes, it would allow to produce coatings in a more cost-effect and environmental friendly way. The research is mostly focused on the obtaining of highly rough Commercial Pure Titanium (CP-Ti) and Calcium Phosphate (CP) coatings by CS for joint prosthesis application. An exhaustive development of coating parameter optimization has been developed and the different deposition mechanisms for each feedstock powder were analyzed as well. The mechanical and biological properties of the optimal coatings were evaluated consequently. The mechanical testing (e.g. Tensile and shear strength test and Taber test), was performed on the optimized CP-Ti coating overcoming the ASTM standard specifications for joint, shoulder and knee prosthesis; CP-Ti coating showed good bonding between particles as well with the substrate. The used of coarse titanium particles provided high roughness (Ra=40±12 µm and Rz=235±44 µm) that shows an increase in cell viability, proliferation and differentiation as well as mineralization, in comparison with a low-roughness titanium surface obtained by Sand Blasted (SB).Afterwards, additional surface modification procedures were investigated to obtain nanotextured surfaces on the as-sprayed CS titanium coatings to evaluate their in-vitro response for comparison. The anodic oxidation treatment leads to a TiO2 Nanotube (NT) layer with a pore diameter between 50-100 nm and a roughness of Ra=36.8±4.6 nm, whereas the alkaline treatment leads to a nanosurface of Ra=1.2±0.2nm, composed by very fine porosity PS). To sum up, CS has shown to be suitable to produce metallic and ceramic coatings for joint applications, especially those dealing with materials that are sensitive to the temperature and oxygen. The non-microstructural changes from the feedstock powder to the coatings leads to a big advantage in CS to obtain customized coatings., [spa] La Proyección Fría o también conocida por el nombre de Cold Spray (CS), es una técnica muy novedosa para la obtención de recubrimientos en el ámbito de la proyección térmica. El uso de bajas temperaturas de trabajo (siempre por debajo del punto de fusión del material) es lo que la hace diferente respecto al resto de técnicas convencionales, ya que la hace ideal para depositar materiales sensibles a la temperatura (ej. Materiales nanoestructurados y amorfos) o reactivos al oxígeno (ej. Titanio). Además tiene un gran potencial a nivel económico y ambiental por ser un proceso eficiente y respetuoso con el medio ambiente. La investigación se basa principalmente en la obtención de recubrimientos de titanio rugoso y fosfato cálcico mediante proyección fría, donde se han estudiado los diferentes mecanismos de deposición de las materias primas y se ha elaborado un estudio a nivel mecánico y biológico. Además, se han realizado tratamientos adicionales sobre los recubrimientos de titanio para obtener superficies nanotexturizadas y poderlas comparar in vitro. El uso de partículas gruesas de titanio facilita la obtención de grandes rugosidades superficiales en los recubrimientos de titanio, mejorando así la viabilidad y proliferación celular, al igual que la diferenciación y mineralización celular, en comparación a superficies con bajas rugosidades (como las superficies de titanio granalladas). Aun así, los tratamientos de nanotexturización, tales como el anodizado (donde se obtuvieron nanotubos de TiO2 con un diámetro entre 50-100nm) y el tratamiento alcalino (en el cual se obtuvieron porosidades

Treballs Finals de Grau d'Enginyeria Química, Facultat de Química, Universitat de Barcelona, Curs: 2015-2016, Tutores: Irene Garcia Cano i Núria Cinca Luis, Commercial titanium alloys, which are used in automotive and aerospace applications, are characterized by a low specific weight, high strength and an excellent corrosion resistance at relatively low temperatures. In some applications, they are exposed to a combination of high temperatures and mechanical loading as well as wear damage. However, the oxidation and abrasive resistance of titanium at high temperatures are rather poor; alloys such as Ti6Al4V have applications which are limited to temperatures below 500ºC; therefore it is of interest to increase their application temperatures. Several methods have been employed to increase the oxidation resistance to 900ºC. Among them, the use of titanium aluminide coatings has been considered of interest, especially the titanium trialuminide, which possesses enough aluminium content to form protective alumina layers. Some approaches to this strategy have included the use of conventional thermal spray technologies. In the present work, we proposed the use of the Cold Gas Spray (CGS) process to first try to form γ-TiAl coatings on Ti6Al4V substrates. Due to some handicaps given by the low deformability of such powder alloy, γ-TiAl+Al composite coatings were produced and annealed afterwards to form the TiAl3. These coatings have been characterized from the microstructural point of view as well as their wear resistance and oxidation performance

Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2016, Tutors: Carlos M. Müller Jevenois i Núria Cinca Luis, Titanium is a metallic material that has been studied for decades because of its interesting chemical, physical and biological features. More specifically, there have been numerous efforts in studying how the formation of ordered titanium oxide (TiO2) structures on its surface affects its properties (optical, catalytic, electrical, biocompatibility...). These structures can be obtained by several techniques, such as from anodization. This electrochemical technique allows obtaining a controlled oxide layer with the desired thickness and structure, and if certain parameters are well defined (electrolyte, potential applied, time...), ordered nanostructures. This range of structures can be obtained using a power supply controlled by a computer and a simple experimental system. The aim of this project is the electrochemical production of titanium oxide nanotubes and its characterization, as well as creating a hierarchical structure (macromicronano) to see which impact has the roughness of the substrate in the bioactivity and biocompatibility of this material.