Encontrados 13 documentos, a visualizar página 1 de 2
Miniaturised cylinder head production by rapid prototyping
Melo, Rodrigo; Monteiro, A. Caetano; Martins, Jorge; Coene, Stijn; Puga, Hélder; Barbosa, J.This work shows the development of the design and manufacturing of a very small engine, namely its head. The engine works under the 4-stroke cycle, therefore having a very complex cylinder head, housing the camshaft, valves and its auxiliaries (seats, guides, springs), spark plug, inlet and exhaust passages and a coolant chamber. The geometries, both inner and outer are highly intricate which makes the producti...
Uso da prototipagem rápida no projecto e produção de motores de combustão interna
Monteiro, A. Caetano; Martins, JorgeOs motores de combustão interna são constituídos por peças de elevada complexidade, tal como a cabeça do motor. Nesta peça existem várias condutas (admissão, escape, arrefecimento), vários postiços (sedes e guias das válvulas de admissão e escape) e vários acessórios estão a ela ligada ou fazem dela parte, tal como a vela e todo o sistema de distribuição constituído por árvore de cames, balanceiros, válvulas e ...
Influence of superheating on casting of gamma-TiAl
Barbosa, J.; Ribeiro, Carlos Silva; Monteiro, A. CaetanoIn this work, a Tie48Al alloy was induction melted and allowed to cool and solidify in a ZrO2 based crucible with an inner layer of Y2O3, and the effect of superheating parameters (time and temperature) on the metalecrucible interface, alloy chemical composition, microstructure and microhardness is evaluated. Microhardness variation and segregation profiles of residual elements, namely yttrium and oxygen, from ...
Characterization of the metal/mould interface on the investment casting of gamm...
Barbosa, J.; Puga, Hélder; Ribeiro, Carlos Silva; Teodoro, O. M. N. D.; Monteiro, A. CaetanoThis paper describes the evaluation of different refractory compounds – SiO2, ZrO2 and Y2O3 – as face coats of investment casting shells for c-TiAl. The effect of the different refractories on the metal–mould interaction is studied in different aspects. Experimental results include characterisation of the constituents present at the metal/ mould interface, the segregation profiles of residual elements, namely o...
Evaluation of Y2O3 as front layer of ceramic crucibles for vaccum induction mel...
Barbosa, J.; Ribeiro, Carlos Silva; Teodoro, O. M. N. D.; Monteiro, A. CaetanoDuring the last decades titanium alloys were found to be valuable engineering materials for many different applications. Formerly used in critical applications like aerospace, aeronautic and military equipment, where the factor cost is not relevant, titanium alloys are finding now new and different markets. However, the development of such new markets will depend on an effective cost reduction of titanium part...
Engine design using rapid prototyping techniques
Martins, Jorge; Monteiro, A. Caetano; Barbosa, J.An internal combustion engine was designed in ProEngineer. The aim of this project was to develop a proposefull tool enabling the rapid design/development of the required engine. The first non-working model was built using a rapid prototyping machine. A visual analysis of the engine head model shown various fields where improvements could be made on the engine design. Therefore, the head was re-designed taking ...
Microstructure, mechanical properties and cutting performance of superhard (Ti,...
Carvalho, S.; Ribeiro, E.; Rebouta, L.; Tavares, C.; Mendonça, J. P.; Monteiro, A. Caetano; Carvalho, N. J. M.; Hosson, J. Th. M. De; Cavaleiro, A.This paper reports on the optimization of coating properties to improve the performance of tools in severe cutting conditions. Tungsten carbide tools coated with (Ti,Si,Al)N films deposited by d.c. reactive magnetron sputtering have been investigated. The structure and the hardness of the coated samples were analyzed by X-ray diffraction (XRD) and depth-sensing indentation, respectively. XRD results revealed a ...
Characterization of TiAl alloys by secondary Ion mass spectrometry
Barbosa, J.; Teodoro, O. M. N. D.; Ribeiro, Carlos Silva; Moutinho, A. M. C.; Monteiro, A. CaetanoTitanium aluminides are arising as a valuable alternative to superalloys in applications where the ratio resistance/density is important. Together with excellent mechanical and corrosion properties at high temperatures, such characteristics are very attractive for applications in the aeronautical, aerospace and automotive industries. However, the current high selling price, due to high costs of production and r...
Processing of gammaTiAl, by ceramic crucible induction melting, and pouring in ...
Barbosa, J.; Ribeiro, Carlos Silva; Monteiro, A. CaetanoThe production of high quality titanium and titanium alloys castings is a difficult and expensive task. The main reasons for that are: the high melting point; the extremely high reactivity of titanium alloys against a large amount of elements (solid, liquids and gaseous) at high temperatures, with particular emphasis to oxygen. For this reason, traditional casting techniques and materials cannot be used, both f...
The production of TiAl by foundry processes
Barbosa, J.; Ribeiro, Carlos Silva; Monteiro, A. CaetanoThis paper describes a foundry technique that enables the production of TiAl employing an adapted melting procedure that uses an induction furnace with suitable refractory crucibles, inside a controlled atmosphere chamber. The developed technique allows the production of samples with a low and controlled amount of residual elements, with a thin superficial hard skin – known as “alpha-case” – and allows the use ...
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