O presente trabalho apresenta um breve apanhado do processo de forjamento, resultados da investigação experimental e da análise computacional acerca do teste de compressão do anel e ensaio do tubo cônico, ambos visando a determinação do coeficiente de atrito existente na região de contato entre as matrizes e os corpos-de-prova, para as ligas de alumínio AA6351 e de titânio Ti6Al4V. Foram realizadas curvas teóricas de calibração do coeficiente de atrito tanto para o alumínio quanto para o titânio com faixa de temperatura distinta para cada um dos materiais. Após a realização da calibração por meio das curvas foram realizados os ensaios práticos de compressão do anel e do tubo cônico, também foram realizadas as simulações computacionais dos ensaios do tubo. Estas simulações permitiram a verificação teórica do fluxo de material no interior dos corpos de prova comparando-as com o material obtido em ensaios práticos, comprovando a eficiência dos programas de simulação, visto que a geometria do tubo favorece a comparação entre a simulação e os testes experimentais. Os resultados obtidos tanto nos experimentos teóricos como os práticos, efetuou-se uma comparação com os dados das referências bibliográficas descritas neste trabalho. Em que os dois lubrificantes testados apresentaram desempenho satisfatório, devido à redução do contato interfacial da relação matriz/peça. E o ensaio do tubo cônico mostrou-se viável apenas para determinação a quente do coeficiente de atrito, neste caso o comportamento em ambos os ensaios é similar. / This paper presents a brief overview of the forging process and the results of experimental investigation and computational analysis of ring compression testing and conical tube-upsetting test, both aiming to determine the coefficient of friction in the region of contact between die and bodies-of-evidence for the AA6351 aluminum alloy and titanium Ti6Al4V. Theoretical calibration through curves were performed of the coefficient of friction were performed for both aluminum and titanium with different temperature range for each material. After completion of the calibration curves compression ring and the conical tube practical tests were performed, computer simulations of the tube-upsetting test were also performed. Continue) These simulations allowed to verify the theoretical flow of material within the samples and comparing them with the material obtained in practical tests, proving the efficiency of simulation programs, since the geometry of the tube facilitates the comparison between the simulation and testing experiments. The results in both theoretical and practical experiments, were a compared with the data from the references described herein. Two oils tested showed a satisfactory performance due to the reduced interfacial contact relationship die/workpiece. And the tube-upsetting test was feasible only to determine the hot coefficient of friction, in this case the behavior in both tests is similar.

O presente trabalho apresenta um breve apanhado do processo de forjamento, resultados da investigação experimental e da análise computacional acerca do teste de compressão do anel e ensaio do tubo cônico, ambos visando a determinação do coeficiente de atrito existente na região de contato entre as matrizes e os corpos-de-prova, para as ligas de alumínio AA6351 e de titânio Ti6Al4V. Foram realizadas curvas teóricas de calibração do coeficiente de atrito tanto para o alumínio quanto para o titânio com faixa de temperatura distinta para cada um dos materiais. Após a realização da calibração por meio das curvas foram realizados os ensaios práticos de compressão do anel e do tubo cônico, também foram realizadas as simulações computacionais dos ensaios do tubo. Estas simulações permitiram a verificação teórica do fluxo de material no interior dos corpos de prova comparando-as com o material obtido em ensaios práticos, comprovando a eficiência dos programas de simulação, visto que a geometria do tubo favorece a comparação entre a simulação e os testes experimentais. Os resultados obtidos tanto nos experimentos teóricos como os práticos, efetuou-se uma comparação com os dados das referências bibliográficas descritas neste trabalho. Em que os dois lubrificantes testados apresentaram desempenho satisfatório, devido à redução do contato interfacial da relação matriz/peça. E o ensaio do tubo cônico mostrou-se viável apenas para determinação a quente do coeficiente de atrito, neste caso o comportamento em ambos os ensaios é similar. / This paper presents a brief overview of the forging process and the results of experimental investigation and computational analysis of ring compression testing and conical tube-upsetting test, both aiming to determine the coefficient of friction in the region of contact between die and bodies-of-evidence for the AA6351 aluminum alloy and titanium Ti6Al4V. Theoretical calibration through curves were performed of the coefficient of friction were performed for both aluminum and titanium with different temperature range for each material. After completion of the calibration curves compression ring and the conical tube practical tests were performed, computer simulations of the tube-upsetting test were also performed. Continue) These simulations allowed to verify the theoretical flow of material within the samples and comparing them with the material obtained in practical tests, proving the efficiency of simulation programs, since the geometry of the tube facilitates the comparison between the simulation and testing experiments. The results in both theoretical and practical experiments, were a compared with the data from the references described herein. Two oils tested showed a satisfactory performance due to the reduced interfacial contact relationship die/workpiece. And the tube-upsetting test was feasible only to determine the hot coefficient of friction, in this case the behavior in both tests is similar.

This diploma thesis is focused on dental materials used in prosthetic medicine. In the introduction, the most important characteristic of dental materials is summarised, which is biocompatibility. Further it contains distribution of nowadays used dental materials, which are oxidic ceramics and titanium alloys. It describes pitfalls of machining of those materials. Final part is devoted to process of the production of the new dental crown, from the first arrival of the patient to the machining of final product. The thesis also compares the economics of dental crown production using milling and 3D printing.

Machining technology is a multi disciplinary field, and together with the economy are playing always more important role in the success of the enterprise market products and services. Recent studies show that it requires very close link between technology, management and information technology such as the integration process and production planning, simulation of manufacturing systems, production flexibility, virtual machines, control algorithms, etc. The key changes are based on the requirements for miniaturization of products, higher production accuracy, closer tolerances, better surface quality, part of weight reduction, reduction of lot size and reducing production costs. The report is focused on machining titanium alloys. In the theoretical part are presented the properties and the distribution of titanium alloys. In the practical part is then carried out an experiment aimed to influence the composition of workpiece material on tool wear. Experiment results and recommendations are listed at the end of this report.

No description available.

The usage of titanium alloys in many industries has increased significantly over the years due to their superior properties. However, they are extremely difficult to machine because of their distinctive characteristics such as their high temperature strength, low thermal conductivity, and high chemical affinity for tool materials. Hence, despite their increased usage, they are still expensive to machine when compared to other metals. The current research aims to address the machinability issues of titanium alloys by developing novel compositions of a new generation of self-adaptive Physical Vapor Deposition (PVD) coatings that function by forming beneficial tribo-films through their interaction with the environment. These tribo-films form during cutting and provide enhanced lubricity, hardness, strength, and thermal barrier characteristics to the cutting tool. It was found that during Ti6Al4V machining, significant BUE and crater wear formation occurs; however, one is dominant over the other depending on the cutting conditions. Therefore, the coatings investigated were designed by taking into consideration the dominant tool wear mechanisms and the complex tribological phenomena that occur in the cutting zone. The current research investigated monolayer TiB2 and CrN self-adaptive PVD coatings for the rough (cutting speed - 45 m/min, feed -0.15 mm/rev, and depth of cut – 2 mm) and finish (cutting speed - 150 m/min, feed -0.1225 mm/rev, and depth of cut – 0.25 mm) turning of Ti6Al4V alloy. Detailed experimental studies were performed to study the effectiveness of the coatings during machining. Micro-mechanical characteristics of the coatings were also studied to understand how coating properties affect the coatings performance in machining and tribo-film formation. The results obtained show that both the TiB2 and CrN coatings significantly improve tool performance during the rough turning of Ti6Al4V alloy compared to the current industrial standard, which is due to certain micro-mechanical coating properties and the beneficial tribo-films formed. A coating of CrN coating was found to increase tool life during finish turning. It was also established that for machining applications where intensive adhesive interaction occurs at the tool-chip interface, coatings with lower hardness values perform significantly better than harder ones. / Thesis / Doctor of Philosophy (PhD) / Titanium alloys are increasingly becoming the material of choice for many industrial applications due to their superior properties. However, they are very difficult to machine since they have high chemical affinity towards tool materials, low thermal conductivity, and high temperature strength. These properties cause rapid failure of the tool. The objective of the current research is to address machinability issues during Ti6Al4V machining and improve tool performance. One effective strategy to minimize tool wear is to apply self-adaptive PVD tool coatings that can form beneficial tribo-films through their interaction with the environment and provide enhanced lubricity, hardness, strength, and thermal barrier characteristics to the cutting tool. In the current research, two self-adaptive PVD coatings were developed that offset the dominant tool wear mechanisms prevalent during the rough and finish turning of Ti6Al4V alloy and reduced the tool wear rate by more than 60% compared to the current industrial standard.

No description available.

Por su elevada biocompatibilidad, resistencia a la corrosión y resistencia específica, entre otras, el titanio es ampliamente utilizado en el campo de la biomedicina. No obstante, su rigidez resulta elevada en comparación con la del hueso cortical humano, lo que genera problemas por debilitamiento óseo. Por otra parte, pese a que se considera un material bioinerte, es necesario generar rugosidad superficial, con una porosidad y tamaño de poro adecuado para permitir el desarrollo óseo y reducir así el tiempo de recuperación del paciente. Además, la elevada reactividad del titanio dificulta su procesado, pues la reacción con elementos intersticiales deteriora en gran medida sus propiedades. En la presente investigación se han desarrollado piezas porosas de la aleación Ti6Al4V, con una rigidez similar a la del hueso cortical humano y resistencia suficiente para permitir su uso como implante. Para ello se han empleado dos técnicas pulvimetalúrgicas distintas, como son la sinterización de microesferas y el método de espaciadores. El estudio previo de reactividad realizado reveló una interacción máxima sobre gres y alúmina, y una reacción mínima sobre itria, lo que condujo a la obtención de las mejores propiedades mecánicas y menor fragilización. Las piezas porosas de Ti6Al4V desarrolladas por sinterización de microesferas presentan una porosidad abierta e interconectada, con un tamaño de poro proporcional al tamaño de las microesferas. Presentan una rigidez inferior al 40% de la del material sólido, con unas propiedades mecánicas que aumentan con la temperatura y tiempo y evolucionan de forma inversa con el tamaño de la microesfera, siendo éste el parámetro de mayor influencia. Por el contrario, las piezas obtenidas por el método de espaciadores presentan una porosidad cerrada y aislada. La rigidez de éstas oscila entre un 20 y 65% en relación a la del material sólido y, al igual que el resto de propiedades mecánicas, depende principalmente del contenido en bicarbonato. / Reig Cerdá, L. (2010). Desarrollo de piezas porosas de Ti6Al4V mediante técnicas pulvimetalúrgicas [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/7284

Tato diplomová práce se zabývá problematikou plazmového nanášení bioaktivních keramických povlaků hydroxylapatitu s využitím technologie radio-frekvenčně buzeného indukčně vázaného plazmatu. Cílem bylo optimalizovat proces a nanést kompaktní hydroxylapatitové povlaky na substráty z titanové slitiny Ti6Al4V. Nanesené vzorky byly následně podrobeny analýzám povrchové drsnosti, mikrostruktury a fázového složení. Ze získaných výsledků byly vyvozeny závěry, které byly srovnány s dalšími odbornými pracemi zabývajícími se příbuznou problematikou.

>Magister Scientiae - MSc / Hydrogen has high energy density and it is regarded as the future energy carrier. Hydrogen can be stored as a gas in high-pressure cylinders, as a liquid in cryogenic tanks and as a solid in metal hydrides. The storage of hydrogen in gas and liquid form has many limitations. Light metal hydrides show high energy density and are a promising and more practical mode of hydrogen storage. In particular, titanium and its alloys are promising metal hydrides for hydrogen storage due to their high affinity to hydrogen. The aim of this study is to investigate the effect of thermal annealing on hydrogen storage capacity of Ti-Pd multilayer systems. Ti-Pd multilayer films were prepared on CP-Ti (commercial pure Ti) and Ti6Al4V substrates using an electron beam evaporator equipped with a thickness monitor. The sequential deposition of layers Pd(50nm)/Ti(25nm)/Pd(50nm) was done at a constant deposition rate of 0.6 Å/s. The first batch of samples were thermally annealed at 550 °C in vacuum for two hours, the second batch of samples were annealed at 550 oC under H2(15%)/Ar(85%) gas mixture for two hours and the third series of samples was annealed under pure H2 gas at 550 oC for one hour. SEM showed relatively homogeneous and smooth topography of surfaces in as-deposited samples, while a rough textured surface was observed in both samples annealed under vacuum and under H2/Ar gas mixture. The samples annealed under pure H2 gas did not show any sign of crystallites grow but instead a relatively smooth surface with sign of etching. XRD revealed structural transformation as evidenced by the presence of PdTi2 phase in samples annealed under vacuum; in samples annealed under the gas mixture Pd2Ti was noted in addition to TiH2 and TiO2. While the TiH2 phase is an indication of hydrogen absorption, the TiPd2 phase suggests intermixing of the deposited layers and the presence of TiO2 is evidence of oxidation. The samples annealed under pure H2 gas showed only TiH2 with no trace of structural transformation. RBS confirmed the intermixing of layers in the samples annealed under vacuum and H2(15%)/Ar(85%) gas mixture, while samples annealed under pure H2 gas did not show any intermixing of layers. ERDA revealed an average H content of ~ 3.5 at.% in CP-Ti and ~6.2 at.% in Ti6Al4V for samples annealed under H2(15%)/Ar(85%) gas mixture. We recorded an hydrogen content of ~19.5 at.% in CP-Ti annealed under pure H2 while ~25.5 at.% was found in Ti6Al4V annealed under the same conditions. When the thickness of the Pd catalyst layers was increased to 100 nm (i.e. Pd (100 nm)/Ti (25 nm)/Pd (100 nm)), only ~ 12.5 at.% and 11.2 at. % hydrogen content was recorded in samples prepared on CP-Ti and Ti6Al4V alloy respectively, both annealed under pure hydrogen for one hour as above.