A5001653458- Intermetallics and Advanced Alloy Properties
- Aluminum Alloy Microstructure Properties
- Metallurgical and Alloy Processes
- Advanced materials and composites
- Metallurgical Processes and Thermodynamics
- Metal Alloys Wear and Properties
- Microstructure and Mechanical Properties of Steels
- Semiconductor Quantum Structures and Devices
- Metallurgy and Material Forming
- Magnetic Properties of Alloys
- Advanced ceramic materials synthesis
- Aluminum Alloys Composites Properties
- Semiconductor Lasers and Optical Devices
- Rare-earth and actinide compounds
- Fatigue and fracture mechanics
- Advanced Semiconductor Detectors and Materials
- MXene and MAX Phase Materials
- Solid State Laser Technologies
- Titanium Alloys Microstructure and Properties
- High-Temperature Coating Behaviors
- Photonic and Optical Devices
- Laser Design and Applications
- Advanced Materials Characterization Techniques
- Inorganic Chemistry and Materials
- Bauxite Residue and Utilization
Universidade do Porto
1999-2022
Institute of Mechanical Engineering and Industrial Mangement
2008-2022
Universidade Federal Fluminense
2021
Universidade Tecnológica Federal do Paraná
2018
Coral Reef Research Foundation
2009-2010
Universidade Estadual de Campinas (UNICAMP)
1980-2001
AbstractAbstractThis paper describes the evaluation of different refractory compounds – SiO2, ZrO2 and Y2O3 as face coats investment casting shells for γ-TiAl.The effect refractories on metal–mould interaction is studied in aspects. Experimental results include characterisation constituents present at metal/mould interface, segregation profiles residual elements, namely oxygen, from interface to inner part samples, extension microhardness samples external hard case surface...
AbstractThis paper describes the processing results of TiAl alloys melted in a controlled atmosphere induction furnace, using crucibles made graphite, calcia and zirconia stabilized with yttria, magnesia. Samples were poured into graphite permanent moulds or solidified cooled inside crucible, order to simulate worst case scenario metal/refractory reaction this process. This presents segregation profiles residual elements their influence on micro hardness different phases extent...
The effect of preconditioning treatments on the control and improvement spheroidal graphite iron (SGI) microstructure was evaluated. In melt, 0.15% Zr-(Ca, Al) FeSi preconditioner added into different conditions. Four samples were produced for this investigation: (1) in first there no addition a comparative purposes; (2) second at cold charge; (3) third before last (4) fourth tapping from furnace. Microstructural characterization conducted to understand treatment SGI. Optical microscopy...
During the last years a very significant effort to develop melting crucible for induction of Ti based alloys at competitive cost has been carried out by many researchers, where authors are included. Results obtained so far have shown that no material accomplishes crucibles two main demands: inertness facing titanium and suitable/enough thermal-shock resistance. Until now, yttrium calcium oxides were those materials performed best on what concerns thermodynamic stability. However, in both...
The production of high quality titanium and alloys castings is a difficult expensive task. main reasons for that are: the melting point; extremely reactivity against large amount elements (solid, liquids gaseous) at temperatures, with particular emphasis to oxygen. For this reason, traditional casting techniques materials cannot be used, both moulding operations, pouring have performed under vacuum or inert gas. However, such demands are important factors cost castings, one possible way...
Abstract Iron carbonyl sorption in PTFE, followed by situ oxidation, gives the composite material, iron oxide–PTFE. Oxide particle size determination was performed electron microscopy. The particles were found to be nearly spherical and very small, having diameters 30–40 Å range on average. Optical absorption spectra obtained photoacoustic spectroscopy, their intensities show a complex dependence oxide concentration samples.
Directional solidification experiments were employed on Fe–Pr alloys at several low cooling rates in order to observe the sequence displayed along length of samples. Measurements transition temperatures around eutectic temperature this system also performed using a Calvet-type calorimeter. The results show precipitation Fe2Pr phase and its peritectic formation, described as Fe17Pr2+L→Fe2Pr. calorimetric measurements give reaction being 669 °C. presents only one 664 °C, L→Fe2Pr+Pr, with...
Melting TiAl based alloys in ceramic crucibles often leads to chemical contamination, alloy heterogeneity and non-metallic inclusions. The severity of such phenomena usually depends on the nature crucible materials, melting stock composition parameters, namely superheating time temperature pressure. Among referred drawbacks, Al loss during is a critical aspect, as its concentration has very strong effect their mechanical properties. Although few studies factors affecting evaporation...
This paper describes the work carried out in order to use thermal analysis, not only forecast carbon and silicon compositions, but also anticipate some significant structural features, such us graphite nodularity, perlite count others, make it available swiftly at foundry floor.A procedure relating influence of melting charge, melt processing inoculation potential over analysis inflexions, critical points arrests is being developed with aim study techniques as a swift tool microstructure...
This paper describes the processing results of TiAl alloys melted under argon atmosphere by induction melting, using crucibles made calcia and stabilized zirconia.Castings were allowed to solidify inside crucible, in order simulate worst situation this processing.Segregation profiles residual elements microhardness different phases evaluated, as well its relation with "alpha-case" extension.Two alloys, 1 at.% zirconium free, produced heat treated aiming replace their as-cast structure a...
It is theoretically demonstrated that the FM light output of a semiconductor laser can be detected through FM-AM conversion using an optical fiber. The analysis made in case narrow-band and for fundamental mode step-index monomode shown 10 GHz modulation frequency, fiber length necessary to achieve maximum demodulation lies range km.