RENE RAMOS DE OLIVEIRA
4 resultados
Resultados de Busca
Agora exibindo 1 - 4 de 4
Resumo IPEN-doc 29188 Phases identification and quantification of AISI 316L produced by laser powder bed fusion2022 - RIBEIRO, GLEICY de L.X.; CASTRO, RENATO S. de; PORTO, JOAQUIM F.B.; SILVA, LEANDRO S. da; GABRIEL, ANDRE H.G.; SANTOS, LUIS U. dos; TERADA, MAYSA; OLIVEIRA, RENE; COUTO, ANTONIO A.The additive manufacturing process by powder bed fusion (L-PBF) consists of the incidence of a high power laser on the material that promotes the fusion and later the solidification layer by layer creating the 3D from a computational model. The main advantage of this process is the fabrication of objects with complex geometries. AISI 316L steel is widely used in the additive manufacturing process because it has good weldability. Due to good corrosion resistance, it is used as a biomaterial for the manufacture of implants. The high temperatures achieved in the L-PBF process can cause phase transformation, in which part of the austenitic phase (FCC) is transformed into the martensitic phase (CCC), affecting its corrosion resistance. The purpose of this work is the crystallographic characterization by X-ray diffraction of AISI 316L in powder form and after additive manufacturing by L-PBF. The powder used in the process was gas atomized, with an average particle diameter of 50 micrometers. The parts were manufactured using the Yb laser (wavelength 1060 nm) with a scan speed of 1200 mm/s and power of 147 W, 184 W and 211 W. The powder was characterized by SEM for morphological analysis and by X-ray diffraction for phase identification and quantification. The manufactured samples were characterized by SEM and MO, to observe the microstructure, and by X-ray diffraction to identify and quantify the phases present. After the additive manufacturing process, with the increase in laser power, it was possible to observe, in addition to the austenite, the presence of the ferritic phase.Artigo IPEN-doc 25833 The effect of plasma nitriding on the fatigue behavior of the Ti-6Al-4V alloy2019 - CASTRO, MICHELE C.B. de; COUTO, ANTONIO A.; ALMEIDA, GISELE F.C.; MASSI, MARCOS; LIMA, NELSON B. de; SILVA SOBRINHO, ARGEMIRO da; CASTAGNET, MARIANO; XAVIER, GLEICY L.; OLIVEIRA, RENE R.The Ti-6Al-4V alloy is widely used in the manufacture of components that must have low density and high corrosion resistance and fatigue strength. The fatigue strength can be improved by surface modification. The aim of this study was to determine the influence of plasma nitriding on the fatigue behavior of a Ti-6Al-4V alloy with a lamellar microstructure (Widmanstätten type). Nitriding was executed at 720 C for 4 h in an atmosphere with N2, Ar, and H2. Microstructure characterization of the samples was carried out by X-ray diffraction analysis, optical microscopy, and scanning electron microscopy. The average roughness of the specimens was determined, and fatigue tests were executed in a bending–rotating machine with reverse tension cycles (R = 1). X-ray diffraction analysis of the nitrided alloy revealed the following matrix phases: , , "-Ti2N, and -TiN. A nitrogen diffusion layer was formed between the substrate and the titanium nitrides. Plasma nitriding resulted in an increase in low-cycle fatigue strength, whereas at high cycles of 200 MPa, both conditions exhibited similar behaviors. The fracture surface of the fatigue-tested specimens clearly revealed the lamellar microstructure. The fracture mechanism in the non-nitrided specimens appears to be due to cracking at the interface of the and phases of the lamellar microstructure.Resumo IPEN-doc 25494 Evaluation of 3YTZP films deposited by electrophoretic deposition on titanium and irradiated with Nd:YAG laser2018 - XAVIER, G.L.; USSUI, V.; OLIVEIRA, R.R.; ROSSI, W. de; LIMA, N.B.; CASTRO, M.C.B. deTitanium is widely used in chemical, power generation, aerospace and biomedical industries because of its good mechanical properties, corrosion resistance and good biocompatibility. However, when is used, for example, in steam turbines is necessary increase the corrosion resistance at high temperature, or when is used in dentistry, when the metallic gray color compromise the aesthetics rehab, it becomes interesting to coat the titanium with a ceramic layers, and 3YTZP (Yttria-stabilized tetragonal zirconia) is suitable for this application, because it has good mechanical properties, good resistance to thermal cycles and good biocompatibility. The electrophoretic deposition is a suitable technique to obtain theses coatings. After deposition, is necessary achieve out the sintering of coating, but the sintering temperature of zirconia is about 1500 °C, and submit metal/ceramic joint to this temperature, cam bring on the degradation of metal. The solution to these problems is performing the sintering using a laser radiation. In this work it was studied the laser irradiation of zirconia ceramic coating deposited on titanium by electrophoretic deposition. Three series of irradiation tests were carried out using Nd:YAG (wavelength 1.06 μm) pulsed laser, energy of 0.5 J, pulse duration of 10 ms and rate of 10 Hz. During the tests, it was studied the influence of fluency, scanning speed and repetition of laser incidence. The repetition covered a range of 1 to 27 times. Prepared samples were characterized by optical and scanning electron microscopy, X-ray diffraction and scratch microindentation. The Xray results showed presence of tetragonal and monoclinic phases in the irradiated coatings. The optical and SEM results showed that densification increases with the increasing of number of laser incidence repetition and the scratch results showed that the irradiated samples presented more scratch resistance than non-irradiated samples.Artigo IPEN-doc 25258 Effect of plasma nitriding on fatigue behavior of Ti-6Al-4V alloy2018 - CASTRO, MICHELE C.B. de; COUTO, ANTONIO A.; ALMEIDA, GISELE F.C.; MASSI, MARCOS; LIMA, NELSON B. de; SILVA SOBRINHO, ARGEMIRO da; CASTAGNET, MARIANO; XAVIER, GLEICY L.; OLIVEIRA, RENE R.The Ti-6Al-4V alloy is widely used in the manufacture of components that should have low density, high corrosion resistance, and fatigue strength. The fatigue strength can be improved by surface modification. The aim of this study was to determine the influence of plasma nitriding on the fatigue behavior of Ti-6Al-4V alloy with a lamellar microstructure (Widmanstätten type). Nitriding was executed at 720 °C for 4 hours in an atmosphere with N2, Ar and H2. Samples microstructure characterization was carried out by X-ray diffraction analysis, optical microscopy and scanning electron microscopy. The average roughness of the specimens was determined, and fatigue tests were executed in a bending-rotating machine with reverse tension cycles (R= -1). X-ray diffraction analysis revealed the matrix phases α and β, and the phases Ɛ-Ti2N and δ-TiN in the nitrided alloy. A nitrogen diffusion layer was formed between the substrate and the titanium nitrides. Plasma nitriding resulted in an increase in low cycle fatigue strength, whereas at high cycles, both conditions exhibit similar behavior. The fracture surface of the fatigue tested specimens clearly revealed the lamellar microstructure. The fracture mechanism appears to be due to cracking at the interface of α and β phases of the lamellar microstructure.