Alterações microestruturais decorrentes dos sucessivos reparos de solda TIG aplicados ao longo da vida útil de uma estrutura aeronáutica crítica à segurança de vôo

The steel type AISI 4130 (ultra-high strength steel) is an alloy of low carbon and its main alloying elements are chromium and molybdenum, which improves the toughness of the weld metal. It has numerous applications, especially where the need for high mechanical strength. It is widely used in equipment used by the aviation industry, such as cradle-tomotor, and this is the motivation for this study. Cots are of fundamental importance, because the engine supports and maintains balance in the fixed landing gear. This equipment is subjected to intense loading cycles, whose fractures caused by fatigue are constantly observed. Will be determined the effects caused by re-welding the structure of aeronautical equipment, and will also study the microstructure of the metal without welding. The studies will be done on materials used in aircraft, which was given to study. The results provide knowledge of microstructure to evaluate any type of fracture that maybe caused by fatigue. Fatigue is a major cause of aircraft accidents and incidents occurred, which makes the study of the microstructure of the metal, weld and re-solder the knowledge essential to the life of the material. The prevention and control of the process of fatigue in aircraft are critical, since the components are subjected to greater responsibility cyclic loading

Mapeamento geológico, caracterização litoquímica e potencial econômico do corpo de cromitito de Cedrolina, Santa Terezinha de Goiás - GO

Studies of mafic-ultramafic bodies have been carried out through the years due to their great use on the interpretation of geochemical and geotectonic processes that took place in Earth's history. Amongst them, chromitites are notably recognized for being excellent indicators of their parental magma chemistry and of different geotectonic environments, as well for frequently containing associated noble metals mineralization. Thus the investigation of one of this ultramafic bodies that occurs inside the Pilar de Goiás Greenstone Belt was proposed, resulting in a detailed map of the chromitites and country rocks, as well as innumerous new data on the chemistry of chromite and associated matrix and accessory minerals. These studies were based upon geological field observations, optic and Scanning Electron Microscope (SEM), besides electron microprobe and cathodoluminescence analysis performed at the “Eugen F. Stumpfl Laboratory” of the Montanuniversität Institute of Resource Mineralogy, University of Leoben - Leoben, Austria. The chromitites are composed of 40-70% in volume of chromite (~50% on average), 14-55% of talc (~30% on average), 3-60% of chromium rich chlorite (~20% on average), traces to 4% of iron hydroxides and traces to 3% of rutile (1,5% on average). The chromite occurs as large spherical aggregates or as fine grained subhedral crystals disseminated in the matrix. This aggregates have diameters of 0.3-1.5 cm (1 cm on average) and are extremely well rounded, massive to intensively fractured, and commonly deformed to ellipsoids. When observed under the microscope, these aggregates show well rounded to slightly irregular borders, but on their interiors, these structures are represented by fine to medium grained euhedral to subhedral chromite crystals that have sharp contacts between themselves. The rock's matrix is basically made of chlorite and talc that define a metamorphic foliation (Sn), being the talc an alteration product ...

Desenvolvimento de aplicativo de análise técnica e econômica para adaptação de uma roda d’água acionada por cima para geração de energia elétrica no meio rural

The steel type AISI 4130 (ultra-high strength steel) is an alloy of low carbon and its main alloying elements are chromium and molybdenum, which improves the toughness of the weld metal. It has numerous applications, especially where the need for high mechanical strength. It is widely used in equipment used by the aviation industry, such as cradle-tomotor, and this is the motivation for this study. Cots are of fundamental importance, because the engine supports and maintains balance in the fixed landing gear. This equipment is subjected to intense loading cycles, whose fractures caused by fatigue are constantly observed. Will be determined the effects caused by re-welding the structure of aeronautical equipment, and will also study the microstructure of the metal without welding. The studies will be done on materials used in aircraft, which was given to study. The results provide knowledge of microstructure to evaluate any type of fracture that maybe caused by fatigue. Fatigue is a major cause of aircraft accidents and incidents occurred, which makes the study of the microstructure of the metal, weld and re-solder the knowledge essential to the life of the material. The prevention and control of the process of fatigue in aircraft are critical, since the components are subjected to greater responsibility cyclic loading

Potencial biotecnológico de rizóbios como bioemulsificante e biossorvente de cobre e cromo

Pós-graduação em Microbiologia Agropecuária - FCAV

Cádmio, chumbo, cromo, mercúrio e níquel nos rios do estado de São Paulo e em peixes do Rio Sorocaba (São Paulo, Brasil)

To verify the levels of concentration of some heavy metals in fishes from Sorocaba river (São Paulo, Brazil) and evaluate if this contamination offers health risks to the fishermen, 63 samples of fishes collected from four points along the river were studied for cadmium, lead, chromium, nickel and mercury, with emphasis in this last, since it is the most toxic and most probable as a fish contaminant. Analyzing muscle samples by cold vapor atomic absorption spectrometry it was shown that the fishes are not contaminated. None of the five metals studied were present in prohibitive level and the fishes could be judged secure for human consume. It was also analyzed data from four years of cadmium, lead, chromium, nickel and mercury monitoring made by CETESB, from 1997 to 2000, in water from the main rivers of the State of São Paulo. The study pointed out that the majority of the monitored rivers still present contamination by those metals in a level that requires an improvement of the pollution control actions.

Análise estrutural e morfológica de ferrita NiFe2O4 dopada com cromo

This paper reports on the effect of the substitution of Fe3+ for Cr3+ ions in the spinel lattice of the powders was investigated. Nickel ferrite powders with a NiFe2-xCrxO4 nominal composition (x = 0.0; 0.5; 1.0 and 1.5 mol of the chromium) were synthesized by combustion reaction using urea as fuel. The powders resulting were characterized by XRD, nitrogen adsorption by BET, SEM and Mössbauer spectroscopy (57Fe Mössbauer spectra). The results show that the substitution of the Fe3+ for Cr3+ions increased the crystalline degree of the phase, reduced the superficial area and consequently increased the particle size. The Mössbauer spectra of the samples also confirm the distribution of the particles size by the magnetic properties. Analyze of the spectra Mössbauer gives an estimate of the superparamagnetic and ferromagnetic particles behavior in each sample for several chromium concentrations.

Effect of Er,Cr:YSGG laser application in the treatment of experimental periodontitis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Treatment of periodontal disease with an Er,Cr:YSGG laser in rats exposed to cigarette smoke inhalation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aplicação do laser Er,Cr:YSGG em periodontia e implantodontia: revisão de literatura

Lasers are widely used tools in many therapeutic modalities in medical lasers and can be divided into low and high intensity. For the treatment of periodontal disease, lowintensity lasers are related to reduce the number of bacteria and to induce inflammatory and analgesic properties. The high intensity lasers can be used in surgical procedures, improving hemostasis, promoting more accurate cuts, removal of dental calculus as well as thermomechanical and photochemical interactions with tissue. The high-intensity laser Erbium impregnated with chromium: YSGG laser has shown satisfactory results when applied in endodontic, restorative denstistry, surgical procedures and non-surgical periodontal treatment. The purpose of this review is to evaluate the studies that investigated the effects of Er, Cr: YSGG laser on the morphology and biocompatibility of titanium and root surfaces irradiated with these lasers, even beyond the effect on the treatment of periodontitis and periimplantitis.

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

Descontaminação do resíduo industrial de couro, uma proposta para o desenvolvimento sustentável nos curtumes

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Load-application devices: a comparative strain gauge analysis

In view of the low loading values commonly employed in dentistry, a load-application device (LAD) was developed as option to the universal testing machine (UTM), using strain gauge analysis. The aim of this study was to develop a load-application device (LAD) and compare the LAD with the UTM apparatus under axial and non-axial loads. An external hexagonal implant was inserted into a polyurethane block and one EsthetiCone abutment was connected to the implant. A plastic prosthetic cylinder was screwed onto the abutment and a conical pattern crown was fabricated using acrylic resin. An impression was made and ten identical standard acrylic resin patterns were obtained from the crown impression, which were cast in nickel-chromium alloy (n=10). Four strain gauges were bonded diametrically around the implant. The specimens were subjected to central (C) and lateral (L) axial loads of 30 kgf, on both devices: G1: LAD/C; G2: LAD/L; G3: UTM/C; G4: UTM/L. The data (με) were statistically analyzed by repeated measures ANOVA and Tukey's test (p<0.05). No statistically significant difference was found between the UTM and LAD devices, regardless of the type of load. It was concluded that the LAD is a reliable alternative, which induces microstrains to implants similar to those obtained with the UTM.

Fecal collection methods for the determination of protein digestibility in bullfrogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Axial loads on implant-supported partial fixed prostheses for external and internal hex connections and machined and plastic copings: strain gauge analysis

The aim of this in vitro study was to use strain gauge (SG) analysis to compare the effects of the implant-abutment joint, the coping, and the location of load on strain distribution in the bone around implants supporting 3-unit fixed partial prostheses. Three external hexagon (EH) implants and 3 internal hexagon (IH) implants were inserted into 2 polyurethane blocks. Microunit abutments were screwed onto their respective implant groups. Machined cobalt-chromium copings and plastic copings were screwed onto the abutments, which received standard wax patterns. The wax patterns were cast in a cobalt-chromium alloy (n = 5): group 1 = EH/machined. group 2 = EH/plastic, group 3 = IH/machined, and group 4 = IH/plastic. Four SGs were bonded onto the surface of the block tangentially to the implants. Each metallic structure was screwed onto the abutments and an axial load of 30 kg was applied at 5 predetermined points. The magnitude of microstrain on each SG was recorded in units of microstrain (mu epsilon). The data were analyzed using 3-factor repeated measures analysis of variance and a Tukey test (alpha = 0.05). The results showed statistically significant differences for the type of implant-abutment joint, loading point, and interaction at the implant-abutment joint/loading point. The IH connection showed higher microstrain values than the EH connection. It was concluded that the type of coping did not interfere in the magnitude of microstrain, but the implant/abutment joint and axial loading location influenced this magnitude.

A critical comparison of different approaches to sediment-quality assessments in the Santos estuarine system in Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)