OLANDIR VERCINO CORREA

OLANDIR VERCINO CORREA

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Preparation and characterization of hydrotalcite coatings to protect aluminium alloys
2016 - FERNANDES, S.M.C.; CORREA, O.V.; SOUZA, J.A.; ANTUNES, R.A.; LIMA, N.B. de; RAMANATHAN, L.V.
Pitting corrosion of the aluminium alloy cladding of spent research reactor fuels during wet storage is the main form of degradation. To prevent this, hydrotalcite (HTC) based coatings were proposed. This paper presents the effect of chemical bath parameters on the microstructure of HTC coatings and the corrosion behavior of HTC coated AA 6061 specimens. The HTC coating formed at 98 °C from nitrate baths and referred to as HT-HTC was homogeneous and consisted of intersecting blade-like crystallites. Electrochemical tests revealed that HT-HTC coated specimens that were treated in a cerium salt solution were the most resistant to corrosion. Field tests in which un-coated and HTC coated AA 6061 alloy coupons as well as full-size plates were exposed to the IEA-R1 reactor’s spent fuel basin for 23 months corroborated the high corrosion resistance imparted by the HT-HTC + Ce coating. The mechanism by which the HTC coating and cerium protect the Al alloy is discussed.
Coatings to protect spent aluminium-clad research reactor fuel during wet storage
2015 - FERNANDES, S.M.C.; CORREA, O.V.; SOUZA, J.A. de; RAMANATHAN, L.V.; ANTUNES, R.A.; OLIVIERA, M.C.L. de
Corrosion behavior of hydrotalcite coated AA 6061 alloy
2014 - FERNANDES, STELA M.; CORREA, OLANDIR V.; SOUZA, JOSE A.; RAMANATHAN, LALGUDI V.; ANTUNES, RENATO A.; OLIVEIRA, MARA C. de
Pitting corrosion of the aluminium cladding of spent research reactor (RR) fuel during wet storage is the main form of degradation and this could eventually lead to release of fissile material and contamination of storage facilities. Hence, the use of conversion coatings to protect spent Al-clad RR fuel during long term storage was proposed. Preliminary laboratory and field investigations carried out at IPEN in São Paulo, Brazil, revealed that cerium hydroxide coatings increased the corrosion resistance of Al alloys. These investigations were extended to include boehmite, hydrotalcite (HTC), cerium modified boehmite and cerium modified HTC coatings on Al alloy surfaces. This paper presents: (a) the preparation of hydrotalcite coatings from different baths followed by post-coating treatments; (b) the results of x-ray diffraction analysis and scanning electron microscopic studies of the HTC coatings; (c) the effect of HTC coating process variables such as temperature, duration of treatment and the duration of cerium modification on HTC morphology and electrochemical polarization behavior of HTC coated AA 6061 alloy in NaCl; (d) results of field tests in which uncoated and HTC coated AA 6061 coupons were exposed to the IEA-R1 reactor spent fuel basin for up to 5 months. The laboratory test specimens as well as the field test coupons coated with HTC from a high temperature bath followed by cerium modification were the most resistant to pitting.
Effect of nanocrystalline mixed rare earth oxide coatings on the high temperature oxidation behavior of Fe20Cr5Al alloy
2014 - FERNANDES, STELA M.C.; CORREA, OLANDIR V.; RAMANATHAN, LALGUDI V.
Rare earths (RE) have been used to improve high temperature oxidation resistance of chromium dioxide and alumina forming alloys. The RE can be added to the alloy as elements or as oxide to form dispersions. It can also be applied as a RE oxide coating to the surface of the alloy. In this investigation the sol-gel technique was used to prepare sols of the RE oxides as it produces nanocrystalline oxide particles. In an effort to increase further the oxidation resistance of high temperature alloys, optimization of RE oxide additions to the alloy surface has been attempted. This paper presents the effect of nanocrystalline oxide gel coatings of CeO2, Nd2O3, Pr2O3, CeO2 + Nd2O3, CeO2 + Pr2O3 and Pr2O3 + Nd2O3 on the oxidation behavior of Fe20Cr5Al alloys at 1100 °C. The individual oxides decreased oxidation rate. However, the CeO2 + Nd2O3 mixture did not increase oxidation resistance of the alloy further, compared to those with either one of these two rare earth oxides. The Pr2O3 + CeO2 mixture increased oxidation resistance of the alloy markedly where as the mixture Nd2O3 to Pr2O3 had no significant effect. The differences in the influence of a specific rare earth oxide or a mixture are attributable to differences in the ionic radii of the RE and the morphology as well as the crystallite sizes of the RE oxides.
Nanocrystalline rare earth oxide coatings for increased protection of iron-chromium alloys at high temperatures
2014 - FERNANDES, STELA M.C.; CORREA, OLANDIR V.; RAMANATHAN, LALGUDI V.
Protective coatings for long term wet storage of spent aluminium-clad research reactor fuel
2014 - FERNANDES, S.M.; CORREA, O.V.; SOUZA, J.A.; RAMANATHAN, L.V.; ANTUNES, R.A.; OLIVEIRA, M.C.L de
Effect of sol-gel preparation technique of mixed nanocrystalline rare earth oxide coatings on high temperature oxidation behavior of Fesup(2)0Cr5al alloy
2014 - FERNANDES, S.M.C.; CORREA, O.V.; RAMANATHAN, L.V.
Conversion coatings to protect spent nuclear fuel during extended wet storage
2012 - FERNANDES, S.M.C.; CORREA, O.V.; SOUZA, J.A. de; RAMANATHAN, L.V.
Nanostructured coatings to protect metallic materials at high temperatures
2013 - FERNANDES, S.M.C.; PILLIS, M.F.; CUNHA, C.A.; CORREA, O.V.; RAMANATHAN, L.V.
Effect of temperature and erodent velocity on erosion-oxidation behaviouir of steels AISI 1020, 410, 304 and 310
2008 - FERNANDES, S.M.C.; CORREA, O.V.; RAMANATHAN, L.V.