Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Manufacturing highly porous Ti alloys by molten salt sintering
Submission Author:
Sérgio Noal Alves , RS
Co-Authors:
Sérgio Noal Alves, Maria José Silva Carvalho, Fernanda Signor, Paulo Mareze, Natalia Daudt
Presenter: Sérgio Noal Alves
doi://10.26678/ABCM.COBEM2023.COB2023-1537
Abstract
Titanium alloys are materials widely used in different areas, like medicine, mechanics and aerospace industries due to their unique combination of high strength and corrosion resistance. Some titanium alloys like Ti-Nb and Ti-Ni alloys can present superelasticity. The addition of porosity in those alloys reduces their Young modulus, which makes it close to the human bone avoiding stress shield in the case of bone implant application. Furthermore, pore addition can increase the vibration dampen capacity. Powder metallurgy is a suitable technology for manufacturing less ductile metals as titanium alloys, it enables a good control over the porosity, composition and mechanical properties. However, sintering of titanium alloys is a critical step due to titanium´s high oxygen affinity. In general, high vacuum furnace is required to avoid titanium oxidation. Recently, a new sintering route using molten a protective atmosphere was proposed for sintering titanium alloys. The molten salt avoided the contact of the sample with oxygen without the need of a vacuum furnace. In this study, we applied the molten salt approach for sintering porous Ti, Ti-10Nb and Ti-50Ni parts. For that, green parts were produced by warm compaction of metal injection molding (MIM) feedstocks with addition of space holder. As space holder, was added 30% in volume of KCl in order to increase final porosity. The green samples were placed in closed tube filled with KCl and sintered in a tube furnace, at 1200ºC for 180 min. Microstructure and porosity of sintered parts were analyzed scanning electron microscopy, X-Ray Diffraction, apparent porosity using the Archimedes principle, Hardness and Young Modulus were evaluated by Vickers microhardness and vibroacoustic test respectively. The data were then compared with the non-porous alloys obtained by the same process, as expected the introduction of porosity decreased strength and Young modulus. Highly-porous titanium alloys produced from MIM feedstock using molten salt sintering are attractive for biomedical implants due to its low Young Modulus and open porosity, which can contribute to bone ingrowth and implant fixation.
Keywords
Titanium alloys, Powder metallurgy., Mechanical Properties, Microstructure, Microhardness, Porous Titanium Alloys
