CECÍLIO ALVARES DA CUNHA
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Artigo IPEN-doc 23482 High temperature erosion-oxidation resistance of thermally sprayed nanostructured Cr3C2-25(Ni-20Cr) coatings2017 - CUNHA, CECILIO A. da; CORREA, OLANDIR V.; SAYEG, ISAAC J.; RAMANATHAN, LALGUDI V.This study reports the high temperature erosion-oxidation (E-O) behavior of conventional and nanostructured Cr3C2-25(Ni-20Cr) coatings prepared by high velocity oxygen fuel (HVOF) spraying. As-received and nanostructured Cr3C2-25(Ni-20Cr) powders with mean crystallite sizes of 145 nm and 50 nm respectively, were used to prepare 120 - 200 μm thick coatings on AISI 310 samples. The E-O behavior of the coatings prepared with the as-received (AR) and nanostructured (NS) powders was determined as weight change in a custom designed rig at room temperature, 450, 700 and 800 ºC. The Vickers microhardness, Young’s Modulus and fracture toughness of the AR and NS coatings were determined, and the NS coatings exhibited higher values compared with the AR coatings. The E-O resistance of the NS coating was higher than that of AR coating at all temperatures, and particularly at 800 ºC. The increase in E-O resistance of the NS coatings is due to its superior mechanical properties as well as to the presence of some heterogeneities in the AR coatings. The E-O mechanisms of both types of the coatings are discussed, with special attention to that at high temperatures. The results suggest that at 800 ºC the E-O process is controlled by erosion of the oxide.Artigo IPEN-doc 23968 Structural and thermodynamic properties of nanocrystalline Cr3C2-25(Ni20Cr) composite powders produced by high-energy ball milling2016 - CUNHA, CECILIO A.; CORREA, OLANDIR V.; SAYEG, ISSAC J.; LIMA, NELSON B.; RAMANATHAN, LALGUDI V.Nanostructured coatings have been used to protect components exposed to severe service conditions. High energy milling is widely used to produce nanocrystalline feedstock of coating materials such as chromium carbide and tungsten carbide. This paper presents the structural and thermodynamic properties of Cr3C2-25(Ni20Cr) powders that were high energy milled for different times. During the high energy milling of Cr3C2-25(Ni20Cr) powder, severe plastic deformation takes place. A small part of the energy spent in this process is stored in the crystal lattice as deformation energy. The crystallite size and microstrain in nanocrystalline Cr3C2-25(Ni20Cr) powders milled for different times were determined by X-ray diffraction measurements. Differential scanning calorimetric (DSC) studies of the milled powders revealed a broad transformation, characteristic of a large exothermic reaction in the nanostructured powder. The enthalpy variation measured by DSC permitted determination of the deformation energy stored in the Cr3C2-25(Ni20Cr) powders milled for different times. These measurements also enabled calculation of the specific heat variation of the milled powders.Resumo IPEN-doc 17963 Effect of high energy milling parameters on WC-Co powder features, composition and thermal stability2011 - PADIAL, A.G.; CUNHA, C.A.; CORREA, O.V.; LIMA, N.B.; RAMANATHAN, L.V.Resumo IPEN-doc 19754 Nanostructured coatings to protect metallic materials at high temperatures2013 - FERNANDES, S.M.C.; PILLIS, M.F.; CUNHA, C.A.; CORREA, O.V.; RAMANATHAN, L.V.Artigo IPEN-doc 15882 Thermal stability and erosin-oxidation behaviour of nanostructured Crsub(3)Csub(2)-Ni20Cr coatings2010 - PADIAL, A.; CUNHA, C.A.; CORREA, O.V.; RAMANATHAN, L.V.Artigo IPEN-doc 18563 Mechanical properties and erosion-oxidation resistance of thermally sprayed nanostructured Crsub(3)Csub(2)-25(Ni-20Cr) coatings2012 - CUNHA, C.A.; CORREA, O.V.; SAYEG, I.J.; LIMA, N.B. de; RAMANATHAN, L.V.Artigo IPEN-doc 18559 Structural and thermodynamic properties of Crsub(3)Csub(2)-25(Ni20Cr) powders produced by high energy milling2012 - CUNHA, C.A.; CORREA, O.V.; SAYEG, I.J.; LIMA, N.B. de; RAMANATHAN, L.V.Artigo IPEN-doc 18565 Preparation and properties of nanostructured WC-Co composite powders and coatings2012 - PADIAL, A.G.; CUNHA, C.A. da; CORREA, O.V.; LIMA, N.B.; RAMANATHAN, L.V.Artigo IPEN-doc 18564 Mechanical and structural properties of thermal sprayed Crsub(3)Crsub(2)-25(Ni20Cr) nanocomposite coatings2012 - CUNHA, CECILIO A. da; CORREA, OLANDIR V.; SAYEG, ISSAC J.; LIMA, NELSON B. de; RAMANATHAN, LALGUDI V.Artigo IPEN-doc 14778 Structure and properties of thermal sprayed nanostructured Crsub(3)Csub(2)-25(Ni20Cr) coatings2009 - PADIAL, A.; CUNHA, C.A.; LIMA, N.B.; MARTINELLI, J.R.; CORREA, O.V.; RAMANATHAN, L.V.