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GROSSO, MARCELLA ; LOPEZ, JUAN E.C. ; SILVA, VITOR M.A. ; SOARES, SERGIO D. ; REBELLO, JOÃO M.A. ; PEREIRA, GABRIELA R. (2016).
Resumo: We developed a computer simulation model using finite elements for the reproduction of physical phenomena found in active pulsed thermography of GFRP adhesive tubular joints. During the manufacture of the joint, defects such as the lack of adhesive were included in order to evaluate the ability of the active pulsed thermography technique to detect this type of material and joint configuration. The experimental results obtained with the thermographic camera were compared with a numerical approximation obtained through the simulation model developed in this study using the Comsol Multiphysics® software and, because of their similarity; it was possible to validate the computer simulation model. In both methods assessed in this study, it was only possible to detect the lack of adhesive when the thermographic test was performed from inside the joint, as, on the outer side of the joint, the defects' surfaces are at a depth greater than on the inner side.
Tavares, S.S. ; ROCHA, A.C. ; Silva, M. R. ; Oliveira, C.A.S ; Cunha, R.P.C. (2016).
Resumo: The demand for high strength materials with improved corrosion resistance boosted the development of supermartensitic steels from conventional martensitic stainless steels The first alloys were designed with 11-13%Cr, extra-low carbon and nickel addition. More recently, experimental alloys with higher Cr (15-17%) and other ferritizing elements (Mo, W, Nb,…) were developed with the aim of obtain higher corrosion resistance in high chloride environments. In this work, the microstructure features of a new 17%Cr stainless steel were investigated.
ALMEIDA, TATIANA DAS CHAGAS; GARCIA, ERIC MARSALHA ; DA SILVA, HUGO WALISSON ALVES ; MATENCIO, TULIO ; DE FREITAS CUNHA LINS, VANESSA. (2016).
Resumo: Electrochemical and surface analyses were carried out to study the leaching of chalcopyrite in acid media, aiming to increase copper extraction from low-grade chalcopyrite ores. Unpublished results include the use of electrochemical impedance spectroscopy (EIS) to characterize the dissolution resistance of chalcopyrite surfaces in 0.1 mol·L− 1 of hydrochloric, nitric or sulfuric acids. Potentiodynamic polarization, atomic absorption spectrometry and EIS analysis showed that hydrochloric acid solutions are more efficient leaching agents than nitric and sulfuric acids. The impedance results suggested that the chalcopyrite dissolution is a diffusion-controlled process in hydrochloric and sulfuric acids. The use of Raman spectroscopy and scanning electron microscopy with energy dispersive spectrometers (SEM/EDS) allowed the partial identification of lead and bismuth sulfides as impurities. Two products were identified on the surface of chalcopyrite after anodic polarization, i.e., sulfur in the sulfuric acid only and covellite in all three acids.
GARCIA, RODRIGO ; CALDAS, FELIPE ; MATTOS, OSCAR. (2016).
Resumo: This paper uses numerical analysis and experimental data to validate the use of strain gauges for load and crack propagation measurements in corrosion fatigue. It was shown that the measurement of crack length and load by strain gauges can be done following the requirements of ASTM E647-15. The results open the possibility for using strain gauges directly positioned on the samples, replacing both the classical load cells to measure load and direct current potential drop to determine fatigue crack growth rate, as neither are easily usable for high-pressure corrosion fatigue tests.
KYRYCHENKO, M. ; HILLMANN, S. ; F Macher ; SCHULZE, M. ; HEUER, H. ; CAMARINI, C. ; PEREIRA, G. (2016).
Resumo: This paper is focused on eddy current measurements of C/SiC samples in different status of the manufacturing process. The measurements are compared with results of X-Ray, Scanning Acoustic Microscope (SAM) and optical images and discussed.
