Browsing by Keyword "Titanium"
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Item Experimental Investigation of the Influence of Wire Arc Additive Manufacturing on the Machinability of Titanium Parts(2020-01) Alonso, Unai; Veiga, Fernando; Suárez, Alfredo; Artaza, Teresa; Tecnalia Research & Innovation; FABRIC_INTELThe manufacturing of titanium airframe parts involves significant machining and low buy-to-fly ratios. Production costs could be greatly reduced by the combination of an additive manufacturing (AM) process followed by a finishing machining operation. Among the different AM alternatives, wire arc additive manufacturing (WAAM) offers deposition rates of kg/h and could be the key for the production of parts of several meters economically. In this study, the influence of the manufacturing process of Ti6Al4V alloy on both its material properties and machinability is investigated. First, the mechanical properties of a workpiece obtained by WAAM were compared to those in a conventional laminated plate. Then, drilling tests were carried out in both materials. The results showed that WAAM leads to a higher hardness than laminated Ti6Al4V and satisfies the requirements of the standard in terms of mechanical properties. As a consequence, higher cutting forces, shorter chips, and lower burr height were observed for the workpieces produced by AM. Furthermore, a metallographic analysis of the chip cross-sectional area also showed that a serrated chip formation is also present during drilling of Ti6Al4V produced by WAAM. The gathered information can be used to improve the competitiveness of the manufacturing of aircraft structures in terms of production time and cost.Item Improved osseointegration in ion implantation-treated dental implants(2002-09) Braceras, I.; Alava, J.I.; Onate, J.I.; Brizuela, Marta; García-Luis, A.; Garagorri, N.; Viviente, J.L.; de Maeztu, M.A.; Oate, J. I.; INGENIERÍA DE SUPERFICIES; Tecnalia Research & Innovation; TECNOLOGÍAS DE HIDRÓGENO; TECNOLOGÍA DE MEMBRANAS E INTENSIFICACIÓN DE PROCESOSImplants for knee, hip and dental part replacement are becoming increasingly used in surgery. Unfortunately, their use is sometimes accompanied by failure due to infection, inflammation, integration problems with the surrounding tissues or bone, and implant failure due to mishandling. Surface treatment, such as ion implantation, has been identified as a good candidate to modify the surface properties of the implant to significantly improve its osseointegration. This work reports on the ion implantation of light ions in commercial Ti6Al4V dental implants and subsequent osseointegration tests. Various light ions were implanted (C, N, CO, Ne) with energy ranging from 45 to 100 keV and doses up to 5×10e17 ions/cm2. Both ion-implanted and control dental implants were inserted in the tibial plateau of adult rabbits, the epiphysis and diaphysis of the tibia for the evaluation of their degree of osseointegration. After 3 months the implants were extracted and several histological sections were prepared from whole bones for evaluation of their osseointegration in the tibia. In addition, the surface of the implant, and the interface between the bone and the implant were examined by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) techniques. Some ion implantation treatments did not significantly change the performance of the dental implants relative to the untreated implants, while tests showed that the ion implantation of CO remarkably improved the osseointegration properties, i.e. the percentage of bone and implant in contact.Item Nitriding of titanium by hollow cathode assisted active screen plasma and its electro-tribological properties(2021-04-15) Domínguez-Meister, Santiago; Ibáñez, Iñigo; Dianova, Anastasia; Brizuela, Marta; Braceras, Iñigo; Tecnalia Research & Innovation; INGENIERÍA DE SUPERFICIESTitanium presents good corrosion resistance, a high strength-to-weight ratio, but poor tribological properties. However, these can be enhanced by nitriding processes. Hollow cathode assisted active screen plasma has proved to be an effective and fast nitriding technique. In this work, the effect of process parameters (hollow cathode induced temperature and plasma intensity, electrical bias…) on the resulting surface microstructure (XRD, SEM/EDS), finishing and hardness of titanium (TiGr4) have been studied. Additionally, the electro-tribological properties have been evaluated on a ball on cylinder reciprocating configuration. The results show that hollow cathode assisted active screen plasma nitriding of titanium can produce titanium nitride surfaces with thicknesses far exceeding those typical in PVD coatings. Moreover, higher plasma processing intensities can generate same layer thicknesses at lower temperatures, minimizing the deleterious effect on grain size growth. Finally, monitoring of the electrical contact resistance can provide valuable information concerning the evolution of the status of the surfaces.