Análise microestrutural de tubos API N80 soldados pelo processo HF/ERW para prospecção de petróleo e gás

On the grounds of the great advances achieved over recent years, the process HF/ERW (High-Frequency/Electric Resistance Welding)welded pipe have played an active role in the oil and gas industry for deep water applications, at high and extremely low temperatures, under high pressure and in highly corrosive environments, gradually replacing manufactured pipes by other processes. However, studies have shown that defects in the welded joints are a the leading causes of pipelines failures, which has required the determination of toughness values in this region, in compliance with the strict recommendations of the codes and standards with manufacturers and construction companies, on the oil and gas sector. As part of the validation process required toughness values, this research project focuses on a microstructural analysis in HF / ERW tubes microalloyed, steel grade API 5CT N80, designed to explore oil and gas in deep waters, the subject of strategic relevance to the country because of the recent discoveries in the Santos mega fields: Tupi and Libra (pre-salt). In this scientific work will be presented and discussed the results of mechanical tensile and Charpy, a few CTOD tests curves (showing the trend of toughness values to be obtained), and the microstructures of the base material obtained by optical microscopy, with special emphasis on the formation of non-metallic inclusions in the welded joint

Estudo da influência do agente nucleante )ALTi5%B1%) na microestrutura de chapas AA8011 obtidas por lingotamento contínuo

The aluminum includes several properties with excellent relation between weight and mechanical resistance. With technological advances, increasingly demand the development of new alloys and other production processes in order to reduce the cost of production and insert these new alloys in broader applications. The process of continuous caster (TRC promoted the unite of the aluminum smelting process with the first stage of rolling, making it most economical through the merger these two phases besides transform the continuous casting process. The AA8xxx series is one of the most versatile aluminum alloys and the most often used in continuous caster process provided a great potential application in the market. In order to further, optimize the process it is necessary to increase awareness of the aluminum solidification phenomena associated with the addition of grain refiner, and control of some aluminum production parameters in the process (production rate, metal temperature, etc.). In this study, AA8011 alloy samples were taken in the raw state obtained by the continuous casting process. The samples were laminated to a thickness of 7mm during the process itself and analyzed at three points along its width by microstructural analysis throughout its thickness, the variation rate of addition of the grain refiner in order to assess the influence of this addition with crystallographic formation and some formation of intermetallic precipitates during the solidification. Through this work, it was possible to improve the knowledge related to the addition of refiner with the monitoring of these production processes

Estudo da influência da adição de resíduos de óleo em concretos para aplicação em pavimentos

Pós-graduação em Engenharia Civil - FEIS

Moxonidine into the lateral parabrachial nucleus modifies postingestive signals involved in sodium intake control

The activation of a2-adrenoceptors with bilateral injections of moxonidine (a2-adrenoceptor and imidazoline receptor agonist) into the lateral parabrachial nucleus (LPBN) increases 1.8% NaCl intake induced by treatment with furosemide (FURO) + captopril (CAP) subcutaneously. In the present study, we analyzed licking microstructure during water and 1.8% NaCl intake to investigate the changes in orosensory and postingestive signals produced by moxonidine injected into the LPBN. Male Sprague–Dawley rats were treated with FURO + CAP combined with bilateral injections of vehicle or moxonidine (0.5 nmol/0.2 ll) into the LPBN. Bilateral injections of moxonidine into the LPBN increased FURO + CAP-induced 1.8% NaCl intake, without changing water intake. Microstructural analysis of licking behavior found that this increase in NaCl intake was a function of increased number of licking bursts from 15 to 75 min of the test (maximum of 49 ± 9 bursts/bin, vs. vehicle: 2 ± 2 bursts/bin). Analysis of the first 15 min of the test, when most of the licking behavior occurred, found no effect of moxonidine on the number of licks/burst for sodium intake (24 ± 5 licks/burst, vs. vehicle: 27 ± 8 licks/burst). This finding suggests that activation of a2-adrenoceptors in the LPBN affects postingestive signals that are important to inhibit and limit sodium intake by FURO + CAP-treated rats.

Influência do tratamento superficial 3IP na vida em fadiga dos aços ABNT 4340 e 15-5PH para aplicação aeronáutica

Pós-graduação em Engenharia Mecânica - FEG

Avaliação dos mecanismos de endurecimentoda liga AISI 300M submetida a diferentes ciclos de transformações martensíticas

Pós-graduação em Engenharia Mecânica - FEG

Corrosion resistance of Ni-Cr alloys in different mouthwashes

Several alloys have been used for prosthodontics restorations in the last years. These alloys have a number of metals that include gold, palladium, silver, nickel, cobalt, chromium and titanium and they are used in oral cavity undergo several corrosion. Corrosion can lead to poor esthetics, compromise of physical properties, or increased biological irritation. The objective of this study was evaluated corrosion resistance of two alloys Ni-Cr and Ni-Cr-Ti in three types of mouthwashes with different active ingredients: 0.5g/l cetylpyridinium chloride + 0.05% sodium fluoride, 0.05% sodium fluoride + 0.03% triclosan (with fluor) and 0.12% chlorohexidine digluconate. The potentiodynamic curves were performed by means of an EG&G PAR 283 potentiostat/galvanostat. The counter electrode was a platinum wire and reference electrode was an Ag/AgCl, KCl saturated. Before each experiment, working electrodes were mechanically polished with 600 and 1200 grade papers, rinsed with distilled water and dried in air. All experiments were carried out at 37.0oC in conventional three-compartment double wall glass cell containing mouthwashes. The microstructures of two alloys were observed in optical microscopy. Analysis of curves showed that Ni-Cr alloy was less reactive in the presence of 0.12% chlorohexidine digluconate while Ni-Cr-Ti alloy was more sensitive for others two types of mouthwashes (0.5g/l cetylpyridinium chloride + 0.05% sodium fluoride  and 0.05% sodium fluoride + 0.03% triclosan). This occurred probably due presence of titanium in this alloy. Microstructural analysis reveals the presence of dendritic and eutectic microstructures for NiCr and Ni-Cr-Ti, respectively.

Structure, microstructure, and selected mechanical properties of Ti-Zr-Mo alloys for biomedical applications

New titanium alloys for biomedical applications have been developed primarily with the addition of Nb, Ta, Mo, and Zr, because those elements stabilize the β phase and they don’t cause cytotoxicity in the organism. The objective of this paper is to analyze the effect of molybdenum on the structure, microstructure, and selected mechanical properties of Ti-15Zr-xMo (x = 5, 10, 15, and 20 wt%) alloys. The samples were produced in an arc-melting furnace with inert argon atmosphere, and they were hot-rolled and homogenized. The samples were characterized using chemical, structural, and microstructural analysis. The mechanical analysis was made using Vickers microhardness and Young’s modulus measurements. The compositions of the alloys were sensitive to the molybdenum concentration, indicating the presence of α’+α”+β phases in the Ti-15Zr-5Mo alloy, α”+β in the Ti-15Zr-10Mo alloy, and β phase in the Ti-15Zr-15Mo and Ti-15Zr-20Mo alloys. The mechanical properties showed favorable values for biomedical application in the alloys presenting high hardness and low Young’s modulus compared with CP-Ti.

Análise da resposta dielétrica e varistora de compostos cerâmicos multifásicos à base de Ca2CU2Ti4-xSnxO12 (0,0 < x< 4,0)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Protocolo para sinterização de zircônia odontológica por energia de micro-ondas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Incorporação de nanopartículas de óxido de zinco a um cimento de ionômero de vidro por meio da calcinação: avaliação de propriedades mecânicas e físicas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Analisi del comportamento a caldo dell'acciaio AISI - H11 per la stima della vita utile di matrici per estrusione

The effect of process parameters on the creep-fatigue behavior of a hot-work tool steel for aluminum extrusion die was investigated through a technological test in which the specimen geometry resembled the mandrel of a hollow extrusion die. Tests were performed on a Gleeble thermomechanical simulator by heating the specimen using joule’s effect and by applying cyclic loading up to 6.30 h or till specimen failure. Displacements during the tests at 380, 490, 540 and 580°C and under the average stresses of 400, 600 and 800 MPa were determined. In the first set of test a dwell time of 3 min was introduced during each of the tests to understand the creep behavior. The results showed that the test could indeed physically simulate the cyclic loading on the hollow die during extrusion and reveal all the mechanisms of creep-fatigue interaction. In the second set a pure fatigue laod were induced and in the third set a static creep load were induced in the specimens. Furher type of tests, finite element and microstructural analysis were presented.

Kinematics of fibrous aggregates

This thesis reports on a research into the progressive development of fibrous aggregates, e.g. calcite, quartz and mica crystals in veins and strain fringes. The study is based on microstructural analysis of natural examples and on computer experiments. Investigation of fibrous looking elongate crystals in striped bedding-veins from the Orobic Alps, Italy indicate that these crystals do not track the opening trajectory of the veins but are oriented at an angle of up to 80° to the opening direction. Microstructural analysis of quartz, calcite and chlorite fibres in antitaxial strain fringes indicate that most strain fringes contain complex intergrowth of tracking (displacement-controlled) and non-tracking (face-controlled) fibres. To explain these growth features the computer program

A 300 million year-long history. The metamorphic evolution of the Northern Apennine Variscan basement

The Variscan basement of Northern Apennines (Northern Italy) is a polymetamorphic portion of continental crust. This thesis investigated the metamorphic history of this basement occurring in the Cerreto Pass, in the Pontremoli well, and in the Pisani Mountains. The study comprised fieldwork, petrography and microstructural analysis, determination of the bulk rock and mineral composition, thermodynamic modelling, conventional geothermobarometry, monazite chemical dating and Ar/Ar dating of muscovite. The reconstructed metamorphic evolution of the selected samples allowed to define a long-lasting metamorphic history straddling the Variscan and Alpine orogenesis. Some general petrological issues generally found in low- to medium-grade metapelites were also tackled: (i) With middle-grade micaschist it is possible to reconstruct a complete P-T-D path by combining microstructural analysis and thermodynamic modelling. Prekinematic white mica may preserve Mg-rich cores related to the pre-peak stage. Mn-poor garnet rim records the peak metamorphism. Na-rich mylonitic white mica, the XFe of chlorite and the late paragenesis may constrain the retrograde stage. (ii) Metapelites may contain coronitic microstructures of apatite + Th-silicate, allanite and epidote around unstable monazite grains. Chemistry and microstructure of Th-rich monazite relics surrounded by this coronitic microstructure may suggest that monazite mineral was inherited and underwent partial dissolution and fluid-aided replacement by REE-accessory minerals at 500-600°C and 5-7 kbar. (iii) Fish-shaped white mica is not always a (prekinematic) mica-fish. Observed at high-magnification BSE images it may consist of several white mica formed during a mylonitic stage. Hence, the asymmetric foliation boudin is a suitable microstructure to obtain geochronological information about the shearing stage. (iv) Thermodynamic modelling of a hematite-rich metasedimentary rock fails to reproduce the observed mineral compositions when the bulk Fe2O3 is neglected or determined through titration. The mismatch between observed and computed mineral compositions and assemblage is resolved by tuning the effective ferric iron content by P-XFe2O3 diagrams.

Microfabric memory of vein quartz for strain localization in detachment faults: A case study on the Simplon fault zone

This manuscript deals with the adaptation of quartz-microfabrics to changing physical deformation conditions, and discusses their preservation potential during subsequent retrograde deformation. Using microstructural analysis, a sequence of recrystallization processes in quartz, ranging from Grain-Boundary Migration Recrystallization (GBM) over Subgrain-Rotation Recrystallization (SGR) to Bulging Nucleation (BLG) is detected for the Simplon fault zone (SFZ) from the low strain rim towards the internal high strain part of the large-scale shear zone. Based on: (i) the retrograde cooling path; (ii) estimates of deformation temperatures; and (iii) spatial variation of dynamic recrystallization processes and different microstructural characteristics, continuous strain localization with decreasing temperature is inferred. In contrast to the recrystallization microstructures, crystallographic preferred orientations (CPO) have a longer memory. CPO patterns indicative of prism and rhomb glide systems in mylonitic quartz veins, overprinted at low temperatures (�400 �C), suggest inheritance of a high-temperature deformation. In this way, microstructural, textural and geochemical analyses provide information for several million years of the deformation history. The reasons for such incomplete resetting of the rock texture is that strain localization is caused by change in effective viscosity contrasts related to temporal large- and small-scale temperature changes during the evolution of such a long-lived shear zone. The spatially resolved, quantitative investigation of quartz microfabrics and associated recrystallization processes therefore provide great potential for an improved understanding of the geodynamics of large-scale shear zones.