Navegando por Assunto "Propriedade mecânica"

Agora exibindo 1 - 11 de 11

Acesso aberto (Open Access)
Análise da influência dos solutos Zr e Ti sobre as propriedades mecânica, elétrica e de termorresistência de uma liga Al-Cu-Fe-Si destinada a Tx e a Dx de energia elétrica
(Universidade Federal do Pará, 2012-01-10) MACHADO, Paulo Cordeiro; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
The global energy context presents a steady increase in electricity consumption in the last century, thus requiring the search for new materials for use in wire and cable conductors of electricity. From these demands for new materials, was developed an analysis of the influence of solute titanium and zirconium in the modification of important characteristics of the Al-Cu-Fe-Si alloy, destined to be the middle conductor of electricity, aiming to get properties resistant to heat. For this study, the alloys were obtained by direct casting in Ushaped metal ingots, from the Al-EC, standing at the base levels of 0.05 wt% Cu, [0.24 to 0.28] wt% Fe and 0.7 wt% Si, and then inserting the contents of 0.26 wt% Zr and 0.26 wt% Ti. The experiments were, divided in two steps, STEP A and STEP B , respectively. In order to characterize mechanical, electrical and structure of alloys. The specimens after cold rolling (in diameters of 2.7, 3.0, 3.8 and 4.0 mm) were analyzed without heat treatment (STT) and with heat treatment (CTT): 230 °C for one hour, according to the protocol COPEL (Companhia Paranaense de Energia Elétrica), 310 °C and 390 °C for one hour, to evaluate the heat resistance at higher temperatures, thermal stability and analyze the microstructures developed in these heat treatments (TT). It was found that Ti has more capacity to refine the grain compared to Zr, which has less refined grains, but with better physical properties are presented and heat resistant.
Acesso aberto (Open Access)
Avaliação das propriedades mecânicas e elétricas da liga 6201 não refinada, modificada com os teores de cobre (0,05 e 0,3)% para transporte de energia elétrica
(Universidade Federal do Pará, 2009-03-27) VENTURA, Odila da Silva Passos; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
At the present work, experiments were made with the unrefined alloy Al – 0,6%Mg - 0,8%Si, with variations in copper content (0,05% e 0,3%), that aimed to evaluate two aspects of the alloy behavior. The first aspect concerns the affinity between it and the mold, which seeks to observe the effect of the solidification thermal variables of the structure of molten and the correlation with mechanical and electrical properties, the second aspect is related with the intrinsic behavior of the variation on the chemical composition subject at low speed and cooling rates. For evaluating the solidification thermal variables (liquidus isotherms velocities, cooling rates) was used a device for horizontal unidirectional solidification. The ingots produced from the solidification of the alloy rose by mechanical machining, laminating and steel drawing, examined in different positions and diameters, by testing the traction and electric conductivity. Fractures were analyzed in terms of micro cavities and different levels of copper and it was found that in the cold deformed material, the limit of tensile strength has a trend of growth for the alloys of higher concentration of copper. The measured values have also concluded that the electrical conductivity increases the greater the diameter of the micro cavities and lower the copper content. In order to evaluate only the intrinsic variation behavior of the alloy chemical composition, a second device was used for solidification, mold in "U", painted internally in solution of kaolin that attaches to such low rates of cooling. The results show that for both copper content there is a tendency of increase in the limit of tensile strength with increasing reduction suffered by the samples, the limit of tensile strength greater for the alloy with higher copper content. We attach this behavior to the higher content of solute which in turn showed better response to plastic deformation, compressing the material. However, the electrical characterization occurs in an opposite way, as seen in unidirectional solidification, where the lowest copper content was more efficient.
Acesso aberto (Open Access)
Caracterização microestrutural e de propriedades mecânicas de soldas do aço ASTM A 131 pelos processos FCAW convencional e com adição de arame frio
(Universidade Federal do Pará, 2011-09-23) RODRIGUES, Lino Alberto Soares; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500
The work presented here show comparatively mechanical properties and microstructure of weld metals employing two welding techniques, an already disseminated, FCAW (arc welding with cored wire) and the other is innovative, FCAW-AF (arc welding with Adding Tubular Wire with a cold wire is not energized) at three levels of speed 6, 8 and 10 m / min. In this process two diameters of the cold wire 0.8 and 1.0 mm were used. The base metal used was a naval steel ASTM 131 grade A (low carbon) in geometry of plates 150 mm x 300 mm x 9.5 mm, applied to V-groove (Bisel of 22.5°) with angle 45° summed, with mild opening of root of 2.4 mm. The weld used was top type with the application of two passes, one root pass and the pass of finish (or filling). In order to establish of weld conditions 5 types of destructive were carried out: face transverse bend, tension, impact test (Charpy notched type V), microhardness and metallographic test. In addition to the non-destructive analysis visual and penetrating liquid. In general, the results for the process FCAW-CW, show themselves compatibles, regarding the process FCAW conventional, but some results showed smaller values of mechanical property. This fact much probably happened due the presence of discontinuities in the welded joint FCAW-CW. The microstructural characterization presented similar results to FCAW-CW and FCAW conventional for all energy levels studied.
Acesso aberto (Open Access)
Comportamento mecânico de material compósito de matriz poliéster reforçado por sistema híbrido fibras naturais e resíduos da indústria madeireira
(Universidade Federal do Pará, 2008-02-29) RODRIGUES, Jean da Silva; FUJIYAMA, Roberto Tetsuo; http://lattes.cnpq.br/3165747089941318
In this work, composite materials of polyester matrix reinforced by short sisal fiber, by residue of wood and by hybrid system for sisal / residue of wood, arranged randomly, were produced using the minimum stages of technology processing in the productive step, with views to produce a composite material easy technically to produce. The polyester matrix used was a pre-accelerated tereftálica with cobalt naftenato and cured at room temperature with methyl ethyl ketone peroxide (MEK) in different proportions in relation to the resin, 0.33%, 1.66%, 3.33% and 5.00% by volume in order to evaluate the influence on mechanical properties. The sisal fibers were manually cut in lengths of 5, 10 and 15 mm and used in the way purchased and surface untreated. The residue of wood powder was used of maçaranduba wood. The composites were produced by manual moulding, without pressure and room temperature. Specimen were manufactured for evaluated matrix, composites reinforced by sisal, ranging of the length of the fibres, composites reinforced by maçaranduba residue and strengthening of hybrid composites, sisal / wood residue, in different proportions of the constituents. Mechanical properties were evaluated by tests of traction and Charpy impact and the areas of fracture generated were evaluated by scanning electron microscopy in order to correlate aspects of fracture with the mechanical properties. It was determined the specific mass of each series of specimen of each manufactured, and the volume fraction of the composite material. The results showed that the increase in the length of the sisal fiber, tensile strength and impact of composites has been increased, reaching the composite of sisal fibre, 15 mm, the best performance with the specimen series tested. The heterogeneity of size maçaranduba residue was negative effect on the mechanical properties of composites. The hybrid composites materials sisal / wood residue with higher content of fibers elevated in 80% of the mechanical properties obtained for the composite material reinforced only by sisal fiber.
Acesso aberto (Open Access)
Comportamento mecânico e de flamabilidade de compósito de polipropileno reclicado com fibra de coco e hidróxido de alumínio
(Universidade Federal do Pará, 2006-05-02) SILVA, Vera Lúcia Dias da; DIAS, Carmen Gilda Barroso Tavares; http://lattes.cnpq.br/2113791118142177
The plastic recycling has been an interesting possibility to minimize the destiny problem of the plastic residues. The polypropylene (PP) is enters the types polymers of larger consumption, therefore the utilization of this material has been enabling the studies development of great scientific and social relevance. This polymer presents excellent cost-performance relation, besides can be easily conformed and to exibit mechanical properties that turns it useful in several applications. However, this material when being burnt generates products that act as combustible so that, for some uses, flame resistance good is necessary. This can be gotten by flame retardant addition, that has the intention to increase the resistance of this material to the ignition and, at the same time reducing the propagation speed of the flame. The aluminium hydroxide, or simply alumina hydrate, is the flame retardant agent used most in the market, therefore it also acts as smoke suppressant and it does not liberate toxic gases during the burning. However, for such properties, high alumina hydrate concentrations are necessary. This causes deterioration in the physical properties of the materials for not have reinforcing character. The natural fibres own good reinforcement capacity when combined adequately with polymers. Also presenting advantages as low cost, low density, biodegradability and in the combustion does not emanate toxic gases. In this work, mixtures contend alumina hydrate and coco fibres had been incorporated polypropylene with the objective of if finding an properties rocking adequate for use of this composite with characteristics flame resistance and mechanical performance. The composites were molded by hot compression and characterized by IV, DRX, MEV, mechanical and non-flammability tests. Increase in the elasticity modulus of the composites in general was observed, as well as increase in the tenacity resistance of the PP/coco fiber composite regarding pure PP. The results had indicated the efficiency of alumina hydrate as it flame retardant, in all the composites, except PP/F, classifying the materials as V-0 according to international norm UL 94V.
Acesso aberto (Open Access)
Compósito de argamassa de cimento reforçada por fibra de sisal com entalhe definidos: caracterização mecânica e mecanismo de falha
(Universidade Federal do Pará, 2010) PERES, Maria das Neves Pontes Barata; FUJIYAMA, Roberto Tetsuo; http://lattes.cnpq.br/3165747089941318
In this work, we developed a new composite material using as a matrix of cement mortar reinforced with sisal fibers to 1% by weight, which were manually cut into lengths of 15 mm and 25 mm used without surface treatment using the lowest possible level of technological processes in manufacturing steps. The research was conducted to study the mechanisms of failure of this new material. The composites were produced with manual molding using immersion vibrator for better densification. Specimens were fabricated of the pure base and with the composites with sisal fiber, with pre-defined slots of 1.7 mm, 3,0 mm and 5,0 mm. The mechanical properties were evaluated by a bending test at three points and correlated with the fractographic appearance made in the Scanning Electron Microscope. The results showed that the presence of sisal fibers, embedded in cement paste,plastic shrinkage caused restriction of fresh mixture, possibly due to high water absorption capacity of fibrous reinforcement, an increase in mechanical strength and increased toughness of the composite over the base between the series of notches, decreasing the tendency to sudden fracture.
Acesso aberto (Open Access)
Efeito da adição de lama vermelha como carga nas propriedades mecânicas de compósitos de poliéster insaturado reforçado com fibra natural de curauá (Ananas erectifolius)
(Universidade Federal do Pará, 2013-06-11) OLIVEIRA, Mauro Júnior Aires de; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
Nowadays, due to the increasing need for good mechanical performance and due to the environmental issues, researchers have tried to replace synthetic fibers used in composites (such as glass fiber) for natural fibers. A natural fiber that has already been used in the automobile industry is the curaua fiber (Ananas erectifolius) which shows excellent tensile strength. Expecting to enhance some properties of the composites and to minimize the usage of resin, and this way minimize costs, it has been researched the utilization of fillers incorporated to composites matrices. In recent papers, it has been studied the utilization of red mud (waste of the bauxite industry) as filler due to the great availability, low cost and for being potentially dangerous to the environment. The objective of this work was to evaluate effects of red mud addition on the mechanical properties of Curaua fiber (Ananas erectifolius) reinforced composites. The results showed that the using of red mud as filler in volume fractions equal or higher than 20% and Curaua fiber in volume fraction of 5% was improved significantly the reinforcing effect.
Acesso aberto (Open Access)
Estudo da influência de resíduos gerados pela indústria de mineração nas propriedades de compósitos de matriz poliéster reforçados com fibras naturais
(Universidade Federal do Pará, 2016-02-26) COSTA, Deibson Silva da; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
In this work, it was produced pure isophthalic unsaturated polyester matrix boards, composites with vegetable fibers (sisal, mauve and jute), composites with industrial waste (red mud, kaolin and ash) and hybrid composites with fibers and waste. The residues were used with a particle size less than 100 mesh and in fiber lengths of 15 mm arranged randomly within the matrix. The fibers were characterized considering their physical, mechanical and morphological properties. The composites were manufactured by a manual process called (hand lay-up) in the form of rectangular plates in metal and pressed mold. The proportions of the mass fractions of waste have varied by 10 % until saturation within the matrix, the mass fraction of fibers was fixed at 5 %. The composites were characterized physically (porosity, water absorption and bulk density), mechanically (tensile, bending and impact), thermally (thermogravimetry - TGA), mineralogically (diffraction of rays-X - DRX), flame retardance and morphologically (scanning electron microscopy - SEM). It was found with the insertion of waste and fibers in the composites, an increase of its physical, mechanical, thermal properties and flame resistance. The physical properties of porosity, water absorption and bulk density has increased significantly (6,7 % to 33 %) with the addition of constituents (residues and fibers). There was an increase (15 % to 95 %) in mechanical strength (tensile, bending and impact) of fiber composites and waste (10 %) composites with fibers. It was evident an improvement in thermal stability (10 % to 50 %) of composites with inclusion of waste. Only the red mud composites have presented a flame retardant ability, obtaining V-2 classification according to UL-94 standard. Morphological analysis of fracture surfaces was efficient in identifying the failure mechanisms and features present in the material. The composites manufactured in this study have resulted in materials with good properties, which makes them feasible candidates for certain types of applications such as panels, liners, partitions and internal doors, an inner lining of automobiles, residential rails and other applications of this nature, respecting the characteristics of these materials.
Acesso aberto (Open Access)
Estudo da técnica de infusão de resina aplicada à fabricação de compósitos de matriz poliéster reforçados por fibras naturais da Amazônia
(Universidade Federal do Pará, 2014-03-26) RODRIGUES, Jean da Silva; FUJIYAMA, Roberto Tetsuo; http://lattes.cnpq.br/3165747089941318; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
In this work were produced unsaturated polyester composites reinforced by fibers of curaua, jute and raffia, arranged in the form of fabric in plan style and aligned fibers. The composites were manufactured by resin infusion process, studying the main parameters that govern the manufacturing method, such as permeability and porosity of the reinforcement and architecture of infusion. Natural fibers were characterized according to their physical, morphological and mechanical properties. The curaua fiber reinforced composites were made using fibers in nature and treated by an alkaline NaOH solution at different concentrations. The composites were characterized in tests of tensile and impact strength, beyond of the determination of their physical properties such as density, porosity and volume fractions of the constituents. The results showed that the composites obtained better performance in tensile and impact were those reinforced with aligned curaua fibers manufactured under vacuum of 101.3 kPa. The evaluation of the cross section of the specimens showed that composites can provide partial saturation of wires or fiber reinforcement due to the vacuum level used mainly in reinforcements in the form of fabric with relatively larger diameter wires. The infusion process proved to be a good method of making composites reinforced with natural fibers, because in addition to being more environmentally friendly because it is a closed mold process, enabled the manufacture of products with high fiber content and good mechanical properties.
Acesso aberto (Open Access)
Influência do uso de resíduo do processo bayer nas propriedades térmicas e mecânicas de compósitos de base polimérica reforçados com fibra de curauá (Ananas lucidus. Mill)
(Universidade Federal do Pará, 2015-05-15) CUNHA, Edinaldo José de Sousa; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
In this work it was produced composite isophthalic polyester, using red mud (RM) and fibers of carded curaua (FCC) randomly oriented and aligned with and without red mud. The composites were made by hand lay-up process and compression molding. Isophthalic polyester plates were produced composites with polyester matrix and composites with RM and RM and FCC. Physical, thermal and mechanical properties of the composites were evaluated. It was found that the increase in RM in 30% (v/v) improves the mechanical, thermal and physical properties of the composites. The addition of 25% (v/v) FCC and RM 5% (v/v) recovering at 84% the modulus of elasticity compared to composite with 10% (v/v) and 5% FCC RM. In composites with 5% FCC randomly oriented and 30% (v/v) RM has 29% recovery of the modulus of elasticity. In composites with 25% (v/v) shows RM to be effective flame retardancy. LV is the influence of the thermal conductivity of the composite isophthalic polyester with increased (92% to 0 ° C) (71% at 25 ° C) (69% at 50 °C) composites with 30% LV compared with the matrix. The red mud and curaua fiber may be important inputs in composite isophthalic polyester, for the production of panels, walls, doors and internal partitions for construction.
Acesso aberto (Open Access)
Reforço superficial em alumínio fundido por nanotubos de carbono via tratamento de solubilização
(Universidade Federal do Pará, 2021-10-14) BRITO, Paulo Roberto de Oliveira; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637
Carbon nanotubes (CNTs) are noteworthy, as they reinforce the metallic matrix, due to mechanical properties, such as the ~ 1.0 TPa Young module. To improve the maintenance of the commercially pure aluminum surface, multi-walled carbon nanotubes (MWCNTs) were incorporated into the aluminum surface with heat treatment by solid solubilization, in order to improve the surface properties of aluminum. The aluminum samples were subjected to chemically attacked with the Keller reagent, for a period of 30, 60 and 120 seconds, and soon after the roughness assessment was carried out, and then they were placed in a container containing NTCs, being subjected to a 640°C for one hour. Afterwards, the morphology was evaluated in the scanning electron microscope, where an aggregate of NTCs was observed, the DRX was performed to evaluate the addition of the NTCs in the matrix, and the Raman Spectrum that evaluated the charge transfer to the matrix. Microhardness was performed to evaluate the result of the incorporation of the NTCs in the matrix. The results obtained show that the incorporation of CNTs in the aluminum matrix increases the hardness in approximately 20% of the surface, in comparison with the control sample. The process of incorporating CNTs into the aluminum matrix by solubilization is a promising, simple and inexpensive alternative to improve the durability of the aluminum surface.