HERCÍLIO GOMES DE MELO
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Resumo IPEN-doc 13321 Evolucao do processo corrosivo nas particulas intermetalicas e na matriz das ligas de aluminio 2024-T3 e 7050-T74512008 - FERRARI, J.V.; QUEIROZ, F.M.; COSTA, I.; MELO, H.G. deResumo IPEN-doc 12478 Investigation on the corrosion resistance of Nd-Fe-B magnets with phosphate conversion and silane coatings2007 - MARTINS, E.A.; COSTA, I.; MELO, H.G. deArtigo IPEN-doc 10908 The effect of aeration on the corrosion process of magnetized Nd-Fe-B magnets2004 - OLIVEIRA, M.C.L.; FARIA JUNIOR, R.N.; ANGELO, J.D.; COSTA, I.; MELO, H.G.The effects of aeration upon the corrosion process of magnetized Nd-Fe-B based sintered magnets have been studied. The tests were carried out in naturally aerated and in deaerated 3.5 (wt.%) sodium chloride solutions at various testing times by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods. In deaerated solution the magnets exhibit higher impedance values (one order of magnitude) than in aerated one. Bode phase angle diagrams obtained in the former solution presented a single broad time constant, indicating the existence of a single process in the investigated frequency range; moreover, the impedance behaviour was maintained fairly constant from 5 days of immersion throughout the rest of the testing period. On the other hand, the sample immersed in the aerated solution presented a constant and slow diminution of the impedance all long the immersion time. In this case, Bode phase angle diagrams presented a HF shoulder interpreted as the influence of the magnetic field on the transport of oxygen to the interface. Larger icorr values and more noble potentials were also obtained for the magnet in aerated solution. In the presence of oxygen, the corrosive attack penetrated deeply into the specimens and, consequently, the magnetic properties diminished with immersion time. The magnetic properties most influenced by corrosion were the remanence (Br) and the maximum energy product (BHmax).Artigo IPEN-doc 08473 Corrosion protection of sintered NdFeB magnets by phosphating2001 - SALIBA SILVA, A.M.; BAKER, M.A.; MELO, H.G.; COSTA, I.Artigo IPEN-doc 09492 Evaluation of self-assembled monolayer compared to chromatizing of aluminium alloy by electrochemical impedance spectroscopy2003 - REIS, F.M.; MELO, H.G.; COSTA, I.Artigo IPEN-doc 09491 Aplicacao de tecnicas eletroquimicas a caracterizacao de revestimento 'galvanneal'2003 - QUEIROZ, F.M.; MELO, H.G.; COSTA, I.Artigo IPEN-doc 08150 Characterization of sintered NdFeB magnets after phosphating in alkaline and acid environments2001 - SALIBA SILVA, A.M.; MELO, H.G.; BAKER, M.A.; BROWN, A.M.; COSTA, I.Artigo IPEN-doc 14480 Investigation of the corrosion behaviour of AA 2024-T3 in low concentrated chloride media2008 - QUEIROZ, F.M.; MAGNANI, M.; COSTA, I.; MELO, H.G. deArtigo IPEN-doc 09708 Characterization of sintered NdFeB magnets after phosphating in alkaline and acid environments2003 - SALIBA SILVA, A.M.; MELO, H.G.; BAKER, M.A.; BROWN, A.M.; COSTA, I.Artigo IPEN-doc 09651 Electroreductive polymerization of trans-[RuClsub(2)(vpy)sub(4)] on Nd-Fe-B magnets: electrochemical impedance spectroscopy interpretation, Raman spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy analysis2004 - BANDEIRA, M.C.E.; PROCHNOW, F.D.; NODA, L.K.; GONCALVES, N.S.; COSTA, I.; MELO, H.G.; CRAYSTON, J.A.; FRANCO, C.V.