Estudo sobre o efeito dos parâmetros de processamento dos pós e sinterização do aço inox 316l reforçado com NbC

This masther dissertation presents a contribution to the study of 316L stainless steel sintering aiming to study their behavior in the milling process and the effect of isotherm temperature on the microstructure and mechanical properties. The 316L stainless steel is a widely used alloy for their high corrosion resistance property. However its application is limited by the low wear resistance consequence of its low hardness. In previous work we analyzed the effect of sintering additives as NbC and TaC. This study aims at deepening the understanding of sintering, analyzing the effect of grinding on particle size and microstructure and the effect of heating rate and soaking time on the sintered microstructure and on their microhardness. Were milled 316L powders with NbC at 1, 5 and 24 hours respectively. Particulates were characterized by SEM and . Cylindrical samples height and diameter of 5.0 mm were compacted at 700 MPa. The sintering conditions were: heating rate 5, 10 and 15◦C/min, temperature 1000, 1100, 1200, 1290 and 1300◦C, and soaking times of 30 and 60min. The cooling rate was maintained at 25◦C/min. All samples were sintered in a vacuum furnace. The sintered microstructure were characterized by optical and electron microscopy as well as density and microhardness. It was observed that the milling process has an influence on sintering, as well as temperature. The major effect was caused by firing temperature, followed by the grinding and heating rate. In this case, the highest rates correspond to higher sintering.

Construção, caracterização e aplicação de eletrodos para descarga por arco de cátodo oco

The system built to characterize electrodes and, consequently, deposited fine films are constituted by a hollow cathode that works to discharges and low pressures (approximately 10-3 to 5 mbar), a source DC (0 to 1200 V), a cylindrical camera of closed borossilicato for flanges of stainless steel with an association of vacuum bombs mechanical and spread. In the upper flange it is connected the system of hollow cathode, which possesses an entrance of gas and two entrances for its refrigeration, the same is electrically isolated of the rest of the equipment and it is polarized negatively. In front of the system of hollow cathode there is a movable sample in stainless steel with possibility of moving in the horizontal and vertical. In the vertical, the sample can vary its distance between 0 and 70 mm and, in the horizontal, can leave completely from the front of the hollow cathode. The sample and also the cathode hollow are equipped with cromel-alumel termopares with simultaneous reading of the temperatures during the time of treatment. In this work copper electrodes, bronze, titanium, iron, stainless steel, powder of titanium, powder of titanium and silício, glass and ceramic were used. The electrodes were investigated relating their geometry change and behavior of the plasma of the cavity of hollow cathode and channel of the gas. As the cavity of hollow cathode, the analyzed aspects were the diameter and depth. With the channel of the gas, we verified the diameter. In the two situations, we investigated parameters as flow of the gas, pressure, current and applied tension in the electrode, temperature, loss of mass of the electrode with relationship at the time of use. The flow of gas investigated in the electrodes it was fastened in a work strip from 15 to 6 sccm, the constant pressure of work was among 2.7 to 8 x 10-2 mbar. The applied current was among a strip of work from 0,8 to 0,4 A, and their respective tensions were in a strip from 400 to 220 V. Fixing the value of the current, it was possible to lift the curve of the behavior of the tension with the time of use. That curves esteem in that time of use of the electrode to its efficiency is maximum. The temperatures of the electrodes were in the dependence of that curves showing a maximum temperature when the tension was maximum, yet the measured temperatures in the samples showed to be sensitive the variation of the temperature in the electrodes. An accompaniment of the loss of mass of the electrode relating to its time of use showed that the electrodes that appeared the spherical cavities lost more mass in comparison with the electrodes in that didn't appear. That phenomenon is only seen for pressures of 10-2 mbar, in these conditions a plasma column is formed inside of the channel of the gas and in certain points it is concentrated in form of spheres. Those spherical cavities develop inside of the channel of the gas spreading during the whole extension of the channel of the gas. The used electrodes were cut after they could not be more used, however among those electrodes, films that were deposited in alternate times and the electrodes that were used to deposit films in same times, those films were deposited in the glass substrata, alumina, stainless steel 420, stainless steel 316, silício and steel M2. As the eletros used to deposit films in alternate time as the ones that they were used to deposit in same times, the behavior of the thickness of the film obeyed the curve of the tension with relationship the time of use of the electrode, that is, when the tension was maximum, the thickness of the film was also maximum and when the tension was minimum, the thickness was minimum and in the case where the value of the tension was constant, the thickness of the film tends to be constant. The fine films that were produced they had applications with nano stick, bio-compatibility, cellular growth, inhibition of bacterias, cut tool, metallic leagues, brasagem, pineapple fiber and ornamental. In those films it was investigated the thickness, the adherence and the uniformity characterized by sweeping electronic microscopy. Another technique developed to assist the production and characterization of the films produced in that work was the caloteste. It uses a sphere and abrasive to mark the sample with a cap impression, with that cap form it is possible to calculate the thickness of the film. Through the time of life of the cathode, it was possible to evaluate the rate of waste of its material for the different work conditions. Values of waste rate up to 3,2 x 10-6 g/s were verified. For a distance of the substratum of 11 mm, the deposited film was limited to a circular area of 22 mm diameter mm for high pressures and a circular area of 75 mm for pressure strip. The obtained films presented thickness around 2,1 µm, showing that the discharge of arch of hollow cathode in argon obeys a curve characteristic of the tension with the time of life of the eletrodo. The deposition rate obtained in this system it is of approximately 0,18 µm/min

Formulação de pastas cimentícias com adição de suspensões de quitosana para cimentação de poços de petróleo

Primary cementing is one of the main operations in well drilling responsible for the mechanical stability and zonal isolation during the production of oil. However, the cement sheath is constantly under mechanical stresses and temperature variations caused by the recovery of heavy oil. In order to minimize fracture and wear of the cement sheath, new admixtures are developed to improve the properties of Portland cement slurries and avoid environmental contamination caused by leaking gas and oil. Polymers with the ability to form polymeric films are candidates to improve the properties of hardened cement slurries, especially their fracture energy. The present study aimed at evaluating the effect of the addition of a chitosan suspension on cement slurries in order to improve the properties of the cement and increase its performance on heavy oil recovery. Chitosan was dissolved in acetic ac id (0.25 M and 2 M) and added to the formulation of the slurries in different concentrations. SEM analyses confirmed the formation of polymeric films in the cementitious matrix. Strength tests showed higher fracture energy compared to slurries without the addition of chitosan. The formation of the polymeric films also reduced the permeability of the slurry. Therefore, chitosan suspensions can be potentially used as cementing admixtures for heavy oil well applications

Estudo da molhabilidade de ligas de adição à base de prata sobre insertos cerâmicos para aplicação em brocas perfuração de poços de petróleo

Metal-ceramic interfaces are present in tricone drill bits with hard ceramic inserts for oil well drilling operations. The combination of actions of cutting, crushing and breaking up of rocks results in the degradation of tricone drill bits by wear, total or partial rupture of the drill bit body or the ceramic inserts, thermal shock and corrosion. Also the improper pressfitting of the ceramic inserts on the bit body may cause its total detachment, and promote serious damages to the drill bit. The improvement on the production process of metal-ceramic interfaces can eliminate or minimize some of above-mentioned failures presented in tricone drill bits, optimizing their lifetime and so reducing drilling metric cost. Brazing is a widely established technique to join metal-ceramic materials, and may be an excellent alternative to the common mechanical press fitting process of hard ceramic inserts on the steel bit body for tricone drill bit. Wetting phenomena plays an essential role in the production of metal/ceramic interfaces when a liquid phase is present in the process. In this work, 72Silver-28Copper eutectic based brazing alloys were melted onto zirconia, silicon nitride and tungsten carbide/Co substrates under high vacuum. Contact angle evolution was measured and graphically plotted, and the interfaces produced were analysed by SEM-EDX. The AgCu eutectic alloy did not wet any ceramic substrates, showing high contact angles, and so without chemical interaction between the materials. Better results were found for the systemns containing 3%wt of titanium in the AgCu alloy. The presence os titanium as a solute in the alloy produces wettable cand termodinamically stable compounds, increasing the ceramics wetting beahviour

Nitretação em plasma com gaiola catódica: caracterização e avaliação do desempenho da camada nitretada em facas de corte

Nowadays, in the plastic industry are used mills that accomplish the recycling of residues generated in the production of its components. These mills contain cut sheets that suffer accelerated wear, once they are submitted constantly to the tribologic efforts, decreasing its useful life. To reduce this problem, it s used noble steels or takes place superficial treatments. The ionic nitriding process presents some limitations related to the uniformity of the layer in pieces with complex geometry, committing its application in pieces as knives, head offices, engagements, etc. However, the new technique of nitriding in cathodic cage eliminates some problems, as the restrictions rings, inherent to the conventional ionic nitriding. In present work, was studied the use viabilization of steels less noble, as SAE 1020, SAE 4320 and SAE 4340, nitreded by two different techniques, to substitute the AISI 01 steels, usually used in the cut knifes fabrication, seeking to reduce the costs and at the sane time to increase the useful life of these knifes. The steel most viable was the SAE 4340, nitrided in cathodic cage, because it presented uniformity in thickness and in the hardness of the layer, besides of increased 58% in the average its useful life

Avaliação do efeito de particulados sólidos na eficiência de um inibidor de corrosão recomendado para meios salinos com CO2

The main problem on the exploration activity on petroleum industry is the formation water resulted on the fields producing. The aggravating of this problem is correlated with the advancing technologies used on the petroleum extractions and on its secondary approach objecting the reobtainment of this oil. Among the main contaminants of the water formation are corrosives gases such as: O2, CO2 and H2S, some solids in suspension and dissolved salts. Concerning to those gases the CO2 is the one that produce significant damage for carbon steel on corrosion process of the petroleum and gas industries. Corrosion inhibitors for carbon steel in formation water is one of the most used agents in control of those damages. In this context, the poor investigations of carbon steel corrosion proceeding from solids in suspension is an opened field for studies. On this work the inhibitor effect of the commercial CORRTREAT 703 was evaluated on some specific solids in suspension at saline medium containing 10.000 ppm of de-aerated chloride using CO2 until non oxygen atmosphere been present. For that, quartz, calcium carbonate, magnetite and iron sulphide were subjected to this investigation as the selected solids. The effect of this inhibitor on corrosion process correlated with those specific solids, was measured using electrochemical (resistance of linear polarization and galvanic pair) and gravimetrical techniques. During all the experimental work important parameters were monitored such as: pH, dissolved oxygen, temperature, instantaneous corrosion rate and galvanic current. According to the obtained results it was proved that the suspension solids calcium carbonate and iron sulphide decrease the corrosion process in higher pH medium. Meanwhile the quartz and magnetite been hardness increase corrosion by broking of the passive layer for erosion. In the other hand, the tested inhibitor in concentration of 50 ppm, showed to be effective (91%) in this corrosion process

Influência da lubrirrefrigeração na qualidade superficial de metais retificados

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

Risco ocupacional no contexto hospitalar

O presente estudo tem como objetivo conhecer as representações sociais sobre o risco ocupacional construídas por trabalhadores da saúde no contexto hospitalar. Trata-se de um estudo exploratório fundamentado no referencial teórico da Teoria das Representações Sociais realizado com duzentos e vinte trabalhadores da saúde pertencentes ao quadro permanente de um hospital público na cidade do Natal- RN. Os dados foram coletados através da Entrevista semi-estruturada e da Técnica da Associação Livre de Palavras. Na análise das informações utilizou-se o software Evoc 2000 e o Alceste. Os resultados indicam condições de trabalho desfavoráveis com desgaste físico e mental ao trabalhador da saúde, e, patologias pouco reconhecidas como ocupacionais em sua origem. Pode-se observar que as representações sociais construídas pelos trabalhadores da saúde, revelam o nível de conscientização desses trabalhadores referentes às consequências do ambiente de trabalho para sua saúde, referindo-se ao processo de trabalho hospitalar, como múltiplo e complexo pela dimensão tecnológica e pelos aspectos físicos, psíquicos e cognitivos

Representações sociais de enfermeiros brasileiros e portugueses sobre o estresse em serviço de urgência

This study aimed to analyze the social representations of Brazilian and Portuguese nurses on stress in the emergency service. A semi-structured interview and the free word association test, with "stress" as the inductive stimulus, were used as research instruments. Data were collected from 120 nurses, being 60 from an emergency hospital in the city of Natal, Brazil and 60 from an urgency hospital in the city of Aveiro, Portugal. Data from the word association test were analyzed with the EVOC 2002 program, after thematic categorical content analysis, enabling construction of a data bank. Data gathered from the interview were analyzed by ALCESTE 4.8 software. Nurse represent the stress in the urgency department as a generation of physical and mental detrition where adaptation is unsatisfactorily, resulting in the onset of fatigne, irritability, lack of concentration, lack of motivation, pessimism, impaired interpersonal relationship and low productivity. The solution is part of a complex whole, which demands an integrated way of acting that has demanded increasingly professional attitudes based on multidisciplinarity

Desenpenho funcional, carga alostática e biomarcadores do estresse em idosos residentes na comunidade

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Aspectos socioeconômicos e demográficos relacionados ao estresse e a síndrome de Burnout em fisioterapeutas no Brasil

Dos problemas de saúde existentes no ambiente de trabalho, 18% afetam o aparelho psíquico, a exemplo do estresse, atingindo cerca de 30% dos trabalhadores em geral. A persistência e intensidade do estresse, associada às sucessivas tentativas de lidar com os mesmos, tornam os indivíduos vulneráveis ao surgimento da Síndrome deBurnout. O objetivo deste trabalho foi identificar a relação dos aspectos socioeconômicos e demográficos com o estresse e a Síndrome de Burnout em fisioterapeutas do Brasil. Para isso, este estudo teve uma abordagem do tipo transversal, com 1040 fisioterapeutas do Brasil, através de uma amostragem do tipo snowbolle não probabilística. Utilizou-se um questionário socioeconômico, demográfico e profissional, a Escala de Estresse no Trabalho (EET) e a adaptação do Cuestionario para la Evaluación del Síndrome de Quemarse por el Trabajo (CESQT). Na análise dos dados, foram utilizadas a estatística descritiva e inferencial. Dentre os principais resultados obtidos, percebeu-se uma maior representatividade da região Nordeste (48,7%), com idade média de 31anos, sexo feminino (75,7%), carga horária semanal de 35,4 horas, com 3-5 anos de atuação profissional. Observou-se que 37,0% apresentavam estresse relacionado estatisticamente com a idade (p=0,008),atividade física (p=0,039) e satisfação com a saúde (r=-0,322; p<0,001). Não foi observado nenhum caso de Burnout, porém houve uma média elevada nas dimensões, desgaste psíquico, indolência e culpa, totalizando 49,0% comtendência ao desenvolvimento da síndrome. Portanto, as variáveis, idade, prática da atividade física e satisfação com a saúde obtiveramrelação com o estresse. Para o Burnout, destacaram-se a região de moradia (centro-oeste), satisfação com a saúde, local de trabalho (clínicas e hospitais), além do maior número de locais de trabalho. Diante desse contexto, os estudos sobre o estresse e a Síndrome de Burnout se apresentam como elementos derelevância dentro do contexto da prevenção dos riscos laborais e da análise das condições de trabalho

Análise de depoimentos de mulheres mastectomizadas sobre o câncer de mama

The breast cancer is the most incident neoplasia in Brazilian women, configure as important cause of female death in Brazil. Its magnitude is go to be consider as a disease that go out the biological and numerical, extending of the subjective dimension and interrelationships of society and socials experiences, to into in knowledge and practices. Linking of the growing older process, the breast cancer extend as social, economical and cultural dimensions, madding in plot of socials relationships, through that acquire mean. In the context of the high expectative of live and the high number of older age persons, consider that that the high number of years had lived correspond the exposition of this individuals to corporate of the ambientals aggressions and own processes of human constitution of natural wear, like as chronicle-degenerate disease, the example is cancer. In the perspective, we collected narratives of mastectomies women with 60 age or so, about the breast cancer, the body and the growing older process, had has as objectives to reflexes about relatives questions, the comprehension about cancer, like experience, had lived and mean in the context of action and interaction of mastectomies older women, and to comprehend like women interrelationships and respond the changes that grow up of the disease and the growing older process in the everyday of their lives. Through of the narratives. We know that the disease is an initial information that take a form through successives approximation between women with their reality, since the family from hospital institution. The breast cancer to be continue a disease who cause a lot of apprehension and fear, getting and changing the ill s live as marked form. Have dad the body and the growing older process genteels and redimensions by disease, women need to define news and multiples functions due to the contingency that the disease impose

O princípio constitucional da redução das desigualdades regionais e o transporte de gás natural

In a country of continental dimensions as Brazil, one of the top challenges to its economic growth is the logistic related to energetical demand supply. We live now in the era of environmental protection and, in this new context of priorizations, it passes trough the search for alternative energies for the energetic matrix, due the petroleum elevated costs in the global market (and its finitude), but also due its pollution over the environment. This attempt of substitution needs solutions related to the national reality, into a national long term developing plan and based at a juridical-economic analysis of its realization. This study will look for, also based in an economical analysis, the juridical legitimity of choosing natural gas as the new protagonist of national economic growth (as a substitute of petroleum) and the necessary boost that must be done by law, based on an economic policy focused strictly for that fact, as a modifying agent of this reality. This study, therefore, will always be turned to a constitutional aspect, respecting the principles of economic order and the goal of reducing regional inequalities, which must influence the making off of a developing plan. At the end, it will try to demonstrate the juridical viability of such undertaking, tuned in jus-economical criteria. Another goal is related to the analysis of the natural gas industry, due the regulation of its transport has a major importance for national energetic integration, not only because this activity be characterized as a net industry, still under control of a natural monopoly, but also because the competitive or cooperative profile that should be priorized at the beginning of the economic planning for this activity (such as investment policies and its own rules that will submit private agents)

Clinical and radiographic evaluation of a polyester prosthesis in dogs with cranial cruciate ligament rupture

Os achados clínicos e radiográficos após reparo intra-articular do ligamento cruzado cranial com prótese de poliéster, utilizando a técnica over-the-top modificada, foram avaliada em seis cães. Sete cirurgias foram realizadas devido ao acometimento bilateral em um dos animais. A avaliação clínica foi realizada ao 3º, 10º e 40º dias de pós-operatório, e a avaliação radiográfica realizada ao 5º e 24º meses após a cirurgia em cinco cães, por meio da qual se confirmou a progressão da doença articular degenerativa. A resolução dos sinais clínicos foi observada entre o 25º e 68º dias após a cirurgia, segundo avaliação realizada pelos proprietários. A função do membro operado foi considerada boa. Dois cães apresentaram desgaste e ruptura da prótese após a cirurgia. Concluiu-se que a prótese de poliéster, da forma como foi implantada neste estudo, não pode ser considerada como substituto satisfatório, uma vez que resultados superiores podem ser obtidos com ténicas menos invasivas e mais simples.

Os direitos humanos e a jurisdição constitucional brasileira no estado democrático de direito: a legitimidade contramajoritária no contexto do constitucionalismo pluralista

Os Direitos Humanos, compreendidos como o conjunto de direitos indispensáveis à efetivação da dignidade humana, encontram-se, atualmente, no centro das discussões e relações jurídicas internacionais e nacionais. Seu amplo reconhecimento em nível mundial e a universalização de seus preceitos centrais alçaram o Direito Internacional a um nível de evolução e de relacionamento com o Direito Constitucional que se mostram impassíveis de serem ignorados pelas jurisdições nacionais. Encontrando-se tais direitos na base do constitucionalismo moderno, o que os mantém em estreito relacionamento com o pluralismo e a democracia, faz-se imperioso recordar-se que as noções jurídicas que os animam serviram de base histórica e genética ao reconhecimento e à positivação, em nível constitucional, dos assim chamados direitos fundamentais. Em sintonia com a especial deferência que se tem ofertado aos direitos humanos na sociedade contemporânea global, nossa Constituição positivou entre os princípios regentes de suas relações internacionais ordem expressa de prevalente respeito aos tratados internacionais estabelecedores desses direitos, além de ter possibilitado a recepção desses pactos em nosso ordenamento jurídico, inclusive a título de preceitos constitucionais, conforme Emenda Constitucional n. 45/2004. Esse tratamento especial, além do processo democrático que conduziu o Brasil a uma progressiva aceitação dos tratados, pactos e convenções humanitários, torna possível a conclusão de que os Direitos Humanos apresentam elementos de diferencial carga legitimadora, podendo contribuir, significativamente para, a legitimação democrática de nossa Jurisdição Constitucional. Também é possível perceber-se que, ocorrente em esferas de poder e de legitimação diversos, em particular a nível internacional, a importância conferida aos Direitos Humanos não resta esvaziada pela ampla proteção constitucional conferida aos direitos fundamentais. Particularmente questionada em sua perspectiva democrática, mormente ante o cumprimento da nominada regra contramajoritária e em face da crescente ampliação de seu poder político, nossa Jurisdição Constitucional não pode mais permanecer alheia aos condicionantes determinados pelas amplas imbricações que se desenvolveram no estreitamento de relações entre o Direito Constitucional e o Direito Internacional dos Direitos Humanos. Também a crise dogmática ditada pelo distanciamento havido entre o direito posto e a realidade nacional tem implicado em inegável desgaste público da atividade jurisdicional, principalmente da jurisdição voltada à proteção constitucional. O papel da Jurisdição Constitucional atual há, portanto, de ser cumprido em sintonia com as normas internacionais de Direitos Humanos, principalmente em respeito às normas constitucionais pátrias que ordenam a prevalência desses direitos nas relações internacionais. Nesse sentido, pode e necessita nossa Jurisdição Constitucional valer-se do particular potencial legitimador das normas definidoras de Direitos Humanos, reconhecendo e efetivando tais normas e adequando-se às tendências modernas que a elas conferem especial proteção, num processo dialético de inolvidável natureza democrática