Encontrados 11 documentos, a visualizar página 1 de 2
Optical and electrical diagnostics of microdischarges at moderate to high press...
Sismanoglu,B.N.; Cunha,C.L.A.; Gomes,M.P.; Caetano,R.; Grigorov,K.G.Microdischarges at moderate to high pressure in argon were investigated. A hole opening diameter of 500 µm direct current (dc) microhollow cathode discharges (MHCD) were characterized by electrical measurements and optical emission spectroscopy (OES) for pressures ranging between 90 and 800 Torr and current from 5 to 20 mA. Current-voltage characteristic curves were obtained as a function of the pressure for th...
Tribological behaviour of multilayered textile composites : the effect of recip...
Mathew, M. T.; Padaki, N. V.; Alagirusamy, R.; Deopura, B. L.; Fangueiro, Raúl; Rocha, L. A.; Gomes, J. R.Textile composites have been used for various applications because of their enhanced strength/weight ratio and versatile properties compared to other materials such asmetals. Many studies have investigated the tribological behaviour of textilecomposites, but none have focused onthe tribological characterization of 3D multilayeredwoven reinforced textile composites. Five types of 3-plywoven interlocked structure...
Influência da incorporação de partículas de SiC na microestrutura e no comporta...
Vieira, A. C.; Rocha, L. A.; Gomes, J. R.Devido à boa relação entre densidade e resistência mecânica apresentada pelos compósitos de matriz de alumínio, estes materiais têm-se destacado em algumas aplicações industriais. Com efeito, a adição de reforços cerâmicos às ligas de alumínio, nomeadamente partículas de SiC, resulta na melhoria das suas propriedades mecânicas com particular impacto no aumento da resistência ao desgaste, ampliando o seu campo d...
Tribological properties of the directionally oriented warp knit GFRP composites
Mathew, M. T.; Padaki, N. V.; Rocha, L. A.; Gomes, J. R.; Alagirusamy, R.; Deopura, B. L.; Fangueiro, RaúlRecently, directionally oriented warp knit structures have gained prominence as reinforcements in composite materials due to their superior isotropic behaviour compared to other types of textile reinforcements. In the present study, composites prepared from four types of directionally oriented warp knit glass preforms with three different thermoset resins have been considered for the tribological characterisati...
Wetting in Al composites reinforced with SiC particles
Vieira, A. C.; Rocha, L. A.; Gomes, J. R.Aluminium matrix composites have been wide used essentially due to the good relation between weight and mechanical resistance. To develop a ceramic particle/matrix interface with good characteristics, it is essential to control the interface reactivity, avoiding the formation of undesirable reaction products such as Al4C3. Essentially, there are three methods to prevent the Al4C3 formation: Si addition to Al m...
Effect of silicon carbide particles on the microstructure and tribological beha...
Vieira, A. C.; Rocha, L. A.; Gomes, J. R.Aluminium matrix composites have been wide used essentially due to the good relation between weight and mechanical resistance. Also, the additions of ceramic reinforcement, mainly SiC particles, improve some properties of these composites, particularly wear resistance. Additionally, when functional gradients of properties are promoted in this type of composites, a wide range of properties are improved. This typ...
Estudos de molhabilidade em compósitos de Al reforçados com partículas de SiC
Vieira, A. C.; Rocha, L. A.; Gomes, J. R.Os compósitos de matriz de alumínio têm-se mostrado extremamente atractivos principalmente devido a uma relação peso/resistência muito favorável. Também, a incorporação de reforços cerâmicos, nomeadamente partículas de SiC, nestes compósitos conduziu à melhoria significativa na resistência ao desgaste, propiciando possibilidades de novas aplicações. Para melhorar as características da interface partícula/matriz...
Tunable L-band erbium-doped fibre ring laser by means of induced cavity loss us...
M. Melo; O. Frazão; A. L. J. Teixeira; L. A. Gomes; J.R. Ferreira da Rocha; H. M. SalgadoIn this paper, we present a continuous-wave tunable fibre ring laser operating in the L-band. A bi-directional pumped L-band erbium-doped fibre amplifier provides gain to the loop. Tunability is achieved by bending a single-mode fibre taper using a micrometer drive, controlling in this way the spectral cavity losses. Laser emission is achieved between 1587 and 1606 nm, and low variation of the output laser powe...
Microstructure and mechanical properties of nanocomposite (Ti,Si,Al)N coatings
Carvalho, S.; Rebouta, L.; Cavaleiro, A.; Rocha, L. A.; Gomes, J.; Alves, E.In this work (Ti,Si,Al)N films were deposited using only rf or a combination of rf and d.c. reactive magnetron sputtering. Chemical composition, thickness, film structure and mechanical properties of the films were investigated by means of Rutherford backscattering (RBS), electron microprobe analysis (EPMA), ball-cratering, X-ray diffraction (XRD) and ultramicroindentation, respectively. All samples showed high...
Microstructure and mechanical properties of nanocomposites (Ti,Si,Al)N coatings
Carvalho, S.; Rebouta, L.; Cavaleiro, A.; Rocha, L. A.; Gomes, J.; Alves, E.In this work (Ti,Si,Al)N films were deposited using only rf or a combination of rf and d.c. reactive magnetron sputtering. Chemical composition, thickness, film structure and mechanical properties of the films were investigated by means of Rutherford backscattering (RBS), electron microprobe analysis (EPMA), ball-cratering, X-ray diffraction (XRD) and ultramicroindentation, respectively. All samples showed high...
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