Engenharia de Materiais
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/17
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5 resultados
Resultados da Pesquisa
- Fracture toughness of the eutectic alloy Al3Nb-Nb2Al(2003-08-05) TRIVENO RIOS, C.; FERRANDINI, P.; CARAM, R.Presenting high fracture toughness is a decisive condition to any structural material, and when considering brittle alloys, the Vickers indentation method to determine fracture toughness is an interesting alternative. Like many other intermetallics, the Al3Nb-Nb2Al eutectic alloy shows high strength at high temperatures and low fracture toughness at room temperature. Al3Nb-Nb2Al samples, both in the as-solidified condition and in the directionally solidified condition, had their hardness and fracture toughness determined by the Vickers indentation method. Lower values of hardness were found when higher loads were used, and fracture toughness was found to be about 2.0 MPa m1/2. The as-solidified condition is harder and less tough, and when fracture occurs, cracks always develop by cleavage. © 2003 Elsevier Science B.V. All rights reserved.
- Reusing Ionomer Scraps as Impact Modifier in Polyamide 6(2020) ALMEIDA, L. J. DE; Adriana Souza© 2020, Springer Science+Business Media, LLC, part of Springer Nature.Blends of PA6 and ionomer scraps, with compositions ranging from 5 to 30 wt% ionomer without incorporation of compatibilizer, and blends with 10 and 20 wt% ionomer compatibilized with 2 wt% maleic anhydride grafted polyethylene copolymer (PEgMA) were obtained by extrusion. Their morphology (SEM), mechanical (tensile, flexural and impact tests) and thermal properties (HDT, DSC and TGA tests) were analyzed. The incorporation of ionomer in PA6 promoted an increase in strain at break and impact strength. PEgMA acted positively on these properties, increasing the interaction between the ionomer and PA6 phases. Tensile and flexural strength, tensile and flexural modulus decreased with increasing ionomer concentration. The compatibilizer acted significantly, reducing these properties. The crystallinity and melting temperature of PA6 were not influenced by the incorporation of ionomer and compatibilizer in the blends.
- Influence of mixing protocol on the morphology and mechanical properties of PP/SEBS/MMT and PP/SEBS/PPgMA/MMT blends(2018) Torrecillas H.V.; Costa L.C.; Souza A.M.C.© 2018 Elsevier LtdPP/SEBS blends containing MMT and MMT/PPgMA were obtained by extrusion using different mixing protocols. Specimens were subjected to mechanical testing (tensile, flexural and impact tests) and blend morphologies were characterized by SEM, TEM and XRD. MMT and PPgMA incorporation and the mixing protocol were shown to affect morphology (droplet size), whereas MMT location resulted in variations in nanocomposite mechanical properties. The presence of PPgMA attracted the organoclay towards the matrix phase due to the interaction between the functional groups at the MMT surface layers and the maleic anhydride groups. Nanocomposites with or without PPgMA obtained in one step presented higher stiffness, while nanocomposites obtained in two steps presented higher impact strength.
- An investigation on recycled PET/PP and recycled PET/PP-EP compatibilized blends: Rheological, morphological, and mechanical properties(2015) De Souza A.M.C.; Caldeira C.B.© 2015 Wiley Periodicals, Inc.The effectiveness of P(E-co-MA-co-GMA) as a compatibilizer for recycled PET/PP and recycled PET/PP-EP (polypropylene (ethylene-propylene) heterophase copolymer) blends was investigated by means of morphological (scanning electron microscopy), rheological (small amplitude oscillatory shear), mechanical (tensile, flexural and impact tests), and thermal (differential scanning calorimetry) properties. Compatibilizer concentration ranged from 1 to 5 wt % with respect to the whole blend. All blends were obtained in a 90/10 composition using a twin screw extruder. Compatibilization effects for PETr/PP-EP were more pronounced due to ethylene segments present in both PP-EP and P(E-co-EA-co-GMA). PETr/PP-EP has shown greater dispersed phase size reduction, a more solid-like complex viscosity behavior and larger storage modulus at low frequencies in relation to PETr/PP blend. For both investigated blends, mechanical properties indicated an improvement in both elongation at break and impact strength with increasing compatibilizer content. PETr/PP-EP blends showed improved performance for the same level of compatibilizer content.
- Toughness of Two HSLA Steel Sheets(2003) Magnabosco R.; Rossetto L.C.This paper presents a study concerning the toughness anisotropic behavior of two high-strength low-alloy steel sheets having ferrite-martensite (dual-phase) and ferrite-perlite grain-refined structures. The anisotropic behavior quantification was possible through tension and Charpy impact tests. It has been concluded that mechanical resistance has higher values in the longitudinal direction for both steels, and the inverse occurs for ductility. This could be explained with the microstructure preferential orientation with rolling direction. The higher tensile strength found in dual-phase steel is related to the presence of martensite islands, and the higher yield strength found in ferrite-perlite grain-refined steel is related to the fine structure observed. The higher toughness is a ferrite-perlite grain-refined steel characteristic, and this could be explained with the presence of only globular-oxide type inclusions, which reduces fracture nucleation sites, and does not promote fracture easy-propagation. Sulfide type inclusions found in dual-phase steel, associated with globular-oxide ones, give to this material a more brittle behavior. Toughness anisotropy is clearly noted, and in both cases the highest values are found inthe longitudinal direction, related to the preferential inclusion alignment achieved in rolling. The low ductile-to-brittle transition temperature found in both steels, however, could be related to the very fine structures found.