OLANDIR VERCINO CORREA

OLANDIR VERCINO CORREA

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Influence of the tungsten content on surface properties of electroless Ni-W-P coatings
2018 - OLIVEIRA, MARA C.L. de; CORREA, OLANDIR V.; ETT, BARDIA; SAYEG, ISAAC J.; LIMA, NELSON B. de; ANTUNES, RENATO A.
Ternary Ni-W-P films were produced by electroless deposition using baths with different tungsten concentrations. After deposition, the coated surfaces were annealed at 400°C for 1h. Surface morphology and film composition in the as-plated condition were assessed by SEM and EDS analyses, respectively. The crystalline phases after annealing were investigated by X-ray diffraction (XRD). Nanoindentation tests were performed to assess the mechanical properties of the deposited films. Surface roughness was determined by confocal laser scanning microscopy (CLSM). Friction coefficient was evaluated by reciprocating were tests in a nanotribometer. The corrosion behavior was evaluated by potentiodynamic polarization curves. The results showed that the surface morphology, crystallization behavior and corrosion resistance were affected by the tungsten content in the film. The best corrosion performance was obtained for the ternary films after annealing. Hardness, surface roughness and friction coefficient were dependent of the tungsten concentration in the film.
High temperature erosion-oxidation resistance of thermally sprayed nanostructured Cr3C2-25(Ni-20Cr) coatings
2017 - 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.
High temperature oxidation behavior of yttrium dioxide coated Fe-20Cr alloy
2016 - PILLIS, MARINA F.; CORREA, OLANDIR V.; RAMANATHAN, LALGUDI V.
Effect of processing on microstructure and corrosion mitigating properties of hydrotalcite coatings on AA 6061 alloy
2015 - FERNANDES, STELA M. de C.; CORREA, OLANDIR V.; SOUZA, JOSE A.B. de; ANTUNES, RENATO A.; LIMA, NELSON B. de; RAMANATHAN, LALGUDI V.
The corrosion resistance of materials used for the manufacture of ear piercing studs
2003 - CORREA, O.V.; SAIKI, M.; ROGERO, S.O.; COSTA, I.
Corrosion performance of anodized AZ91D magnesium alloy: effect of the anozizing potential on the film structure and corrosion behavior
2014 - OLIVEIRA, MARA C.L. de; PEREIRA, VIVIAM S.M.; CORREA, OLANDIR V.; ANTUNES, RENATO A.
Influence of processing parameters on the microstructure and oxidation behavior of hot pressed Ni-20Cr + WC metal matrix composites
2003 - KUNIOSHI, C.T.; CORREA, O.V.; BELLINATI, C.E.; RAMANATHAN, L.V.
Ni20Cr+WC composites with a gradient in the volume fraction of hard WC particles are ideal materials for applications where high temperature oxidation and erosion resistance are desired properties. The WC particles impart erosion resistant and the Cr content of the alloy, oxidation resistance. This paper presents the influence of WC particle content and consequently the extent of densification, on the oxidation behavior of hot pressed Ni20Cr+WC composites. Oxidation measurements in the range 700-1000°C revealed overall parabolic behavior. The increase in oxidation rate with WC content has been attributed to formation of islands of WO3 globules protruding through the Cr2O3.
Characterization of ear piercing studs and their corrosion products by neutron activation analysis
2001 - SAIKI, M.; ROGERO, S.O.; COSTA, I.; CORREA, O.V.; HIGA, O.Z.
Corrosion resistance of powder injection moulded AISI 316L and 17-4PH stainless steels in acid rain environments
2003 - SOBRAL, A.V.C.; FRANCO, C.V.; CORREA, O.V.; COSTA, I.
Corrosion and cytotoxicity evaluation of AISI 316L stainless steel produced by powder injection molding (PIM) technology
2005 - COSTA, I.; ROGERO, S.O.; CORREA, O.V.; KUNIOSHI, C.T.; SAIKI, M.
This study investigates the in vitro corrosion and cytotoxicity response of AISI 316L stainless steel produced by powder injection molding (PIM) technology in a solution that simulates physiological fluids (MEM) by electrochemical techniques and neutral red uptake cytotoxicity assay. The results were compared with those of AISI 316L produced by conventional metallurgy. Both steels showed high corrosion resistance and no toxic effect in the cytotoxicity test. The corrosion products were analyzed by instrumental neutron activation analysis (INAA). The surfaces of the alloys were evaluated before and after corrosion test by scanning electron microscopy and a passive behaviour was indicated supporting the results from other techniques.