Navegando por Assunto "Aluminum"

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Acesso aberto (Open Access)
Efeito de adições de Ni e Mg sobre o comportamento térmico, mecânico e elétrico de ligas Al-Cu-Fe solidificadas unidirecionalmente
(Universidade Federal do Pará, 2013) SOUZA, Pedro Henrique Lamarão; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
This work studied the influence of Mg and Ni solute content on the modification of the thermal, electrical and mechanical properties of an Al-Cu-Fe alloy for application as an electrical conductor. To realize the present study, the alloys were obtained by unidirectional horizontal casting, starting from the commercial pure aluminum with the addition of 0.05wt% Cu and [0.24 to 0.28]wt% Fe content. This basis was modified on a first stage with 0.45, 0.60 and 0.80wt% of Mg content. The alloys obtained with these contents had its properties studied for the selection of a Mg content for further Ni addition at the alloy. The study of these properties on the first stage passed through the analysis of the thermal properties: growth rate (VL) and cooling rate (Ṫ). The electrical characterization studied the electrical conductivity property (φ) and the following mechanical properties were determined: ultimate tensile strength (σ) and Vickers microhardness (HV). The alloy which has Ni additions passed through ageing heat treatments of 1, 4 and 8 hours. These samples were analyzed in a scanning electron microscope – SEM by the electrons backscattered – EBS and energy dispersive spectroscopy – EDS signals. As a result of the research, it was found that Mg additions had significantly influenced the alloys viscosity, increasing its growth rates at the final moments of the solidification. The microhardness tests for the aged samples showed that they suffered a significant gain of hardness at the fourth hour of ageing, also, the EDS analysis showed that Ni content increased at the same treating conditions.
Acesso aberto (Open Access)
Eletrodeposição pulsada e caracterização de revestimentos de cobre/nanotubos de carbono em ligas de alumínio 3003 e 1350
(Universidade Federal do Pará, 2025-06-25) SILVA, Alberto Solary da; SOUSA, Mário Edson Santos de; http://lattes.cnpq.br/4761512397509247; HTTPS://ORCID.ORG/0000-0002-7605-2371; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637; https://orcid.org/0000-0003-2226-2653
The demand for more efficient and sustainable electrical systems has driven research toward innovative materials that enhance the properties of electrical conductors. Aluminum (Al) and its alloys are widely used in power transmission and distribution due to their low density and good electrical conductivity. The pursuit of improved electrical properties has led to the development of coatings that increase conductivity without compromising the lightweight nature of the material. This study presents an investigation into the anodization of Al substrates as a preparation step for nanostructured coatings, combined with pulsed current electrodeposition of a copper (Cu) and multi-walled carbon nanotube (MWCNT)-based nanocomposite, focusing on the correlation between electrical properties and microstructure. Experiments were conducted on Al 3003 alloy sheets, and on wires and cables made from Al 1350 alloy. Optimized anodization parameters were established using 100% H₂SO₄, direct current of 3 A, and 10 V applied for 2 hours. For the pulsed current electrodeposition, a concentration of 1 mg/mL of MWCNTs, an 80% duty cycle, 2 A, and 10 V were applied for 1 hour. Field Emission Gun Scanning Electron Microscopy (FEG-SEM) micrographs confirmed the formation of a uniform and porous aluminum oxide (Al₂O₃) layer, essential for coating adhesion, and revealed the homogeneous and effective distribution of the nanocomposite over the anodized surface. Energy Dispersive Spectroscopy (EDS) verified the presence of Cu and carbon (C) elements distributed throughout the coating layer. Raman spectroscopy identified characteristic vibrational modes of MWCNTs: D, G, and G′ bands, showing variations in intensity and bandwidth due to structural modifications induced by electrodeposition. X-ray Diffraction (XRD) analysis revealed the crystalline phases present in the coating and structural changes resulting from the surface treatment, confirming the integration of the nanocomposite into the metallic substrate. Electrical conductivity tests using the four-point Kelvin probe method, before and after coating, demonstrated a significant increase in electrical conductivity (σ), indicating improved charge transport efficiency due to the synergy between Cu and MWCNTs. Among the results, a ∼ 52.33% increase in surface electrical conductivity (σₛ) of the Al sheets and an increase in IACS from 67.76% to ∼ 73.5% in the coated wires stood out. Similarly, the average resistance of the coated cable decreased from 4.88×10⁻⁴ Ω to 1.934×10⁻⁴ Ω, a reduction of ∼ 60.37% compared to the uncoated cable. Statistical analyses supported these findings and confirmed their significance. Joule heat dissipation and ampacity calculations confirmed the superior performance of the coated material and its potential for application in power transmission and distribution systems. Therefore, the Cu-MWCNT nanocomposite coating obtained via pulsed current electrodeposition on anodized surfaces represents a promising approach for improving the electrical properties of Al-based conductors.
Acesso aberto (Open Access)
Estudo eletroquímico de ligas metálicas alumínio-silício em meio ácido
(Universidade Federal do Pará, 2012-03-30) SANTOS, Luana Santana dos; CARDOSO FILHO, José Carlos; http://lattes.cnpq.br/7033790503322903
The alloys based on aluminum-silicon have low specific weight, good mechanical strength and corrosion resistance, have been widely used as substitutes for some ferrous alloys in manufacturing parts for various industries. In this research we studied the electrochemical behavior of aluminum and aluminum-silicon alloys 0.3 and 0.7% by mass in electrolytes sulfuric acid and hydrochloric acid, both at 0.1 mol/L. The results of electrochemical techniques showed that the Si caused a shift to more positive values corrosion potential was observed a region of passivity anodic curves of the electrodes in sulfuric acid, this phenomenon was not observed in hydrochloric acid. The Nyquist diagrams show two arcs, a capacitive region of high frequencies related to the formation of the layer oxidizes and an inductive at low frequencies attributed to adsorption of anions on the metal surface, the similarities in the diagrams show that the electrochemical phenomena are identical and independent addition of Si. The impedance diagrams also showed low polarization resistance of the alloys Al-Si. Considering only the electrochemical studies it can be stated that the electrodes did not show significant differences between themselves and susceptibility to corrosion in these acidic solutions does not imply a negative feature to your application.
Acesso aberto (Open Access)
Transporte pneumático fluidizado: estudos de casos aplicados à indústria do alumínio primário
(Universidade Federal do Pará, 2011-08) VASCONCELOS, Paulo Douglas Santos; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
This work is a contribution to science and applied technology developed to fluidized bed and fluidized motion conveying used in the powder handling of the industrial processes. In the case of fluidized bed it is proposed an empirical equation to predict the minimum fluidization velocity for the fluoride alumina, crust powder and others powders used in the industrial processes with good results compared with the experiments and the equations available in the literature. It was also studied the constitutive equations to predict the behavior of the angle of repose and interparticles friction as a function of the superficial velocity of fluidization. In a second step it is proposed an equation to predict the capacity of the Air Pneumatic Fluidized Conveyor with good results compared with the experiments for fluoride alumina. The Air Fluidized Conveyor is a contribution to applied technology reducing the consumption of energy, it operates even in upward direction, and so, decreasing the rate kWh/ton in the powder handling of the industrial processes.