Selective Laser Melting (SLM), a laser-based Additive Manufacturing technique has appealed to the bio-medical, automotive, and aerospace industries due to its ability to fabricate geometrically complex parts with tailored properties and high-precision end-use products. The SLM processing parameters highly influence the part quality, microstructure, and mechanical properties. The process-structure-property relationship of the SLM process is not well-understood. In the process-structure study, a quasi-2D model of Micro-Selective Laser Melting process using molecular dynamics is developed to investigate the localized melting and solidification of a randomly-distributed Aluminum nano-powder bed. The rapid solidification in the meltpool reveals the cooling rate dependent homogeneous nucleation of equiaxed grains at the center of the meltpool. Long columnar grains that spread across three layers, equiaxed grains, nano-pores, twin boundaries, and stacking faults are observed in the final solidified nanostructure obtained after ten passes of the laser beam on three layers of Aluminum nano-powder particles. In the structure-property study, the mechanical deformation behavior of the complex cellular structures observed in the SLM-fabricated 316L Stainless Steel is investigated by performing a series of molecular dynamics simulations of uniaxial tension tests. The effects of compositional segregation of alloying elements, distribution of austenite and ferrite phases in the microstructure, subgranular cell sizes, and pre-existing (grown in) nano-twins on the tensile characteristics of the cellular structures are investigated. The highest yield strength is observed when the Nickel concentration in the cell boundary drops very low to form a ferritic phase in the cell boundary. Additionally, the subgranular cell size has an inverse relationship with mechanical strength, and the nano-twinned cells exhibit higher strength in comparison with twin-free cells. / Master of Science / Additive Manufacturing's (AM) rise as a modern manufacturing paradigm has led to the proliferation in the number of materials that can be processed, reduction in the cost and time of manufacturing, and realization of complicated part geometries that were beyond the capabilities of conventional manufacturing. Selective Laser Melting (SLM) is a laser-based AM technique which can produce metallic parts from the fusion of a powder-bed. The SLM processing parameters greatly influence the part's quality, microstructure, and properties. The process-structure-property relationship of the SLM process is not well-understood. In-situ experimental investigation of the physical phenomena taking place during the SLM process is limited because of the very small length and time scales. Computational methods are cost-effective alternatives to the challenging experimental techniques. But, the continuum-based computational models are ineffective in modeling some of the important physical processes such as melting, nucleation and growth of grains during solidification, and the deformation mechanisms at the atomistic scale. Atomistic simulation is a powerful method that can offset the limitations of the continuum models in elucidating the underlying physics of the SLM process. In this work, the influence of the SLM process parameters on the microstructure of the Aluminum nano-powder particles undergoing μ-SLM processing and the mechanical deformation characteristics of the unique cellular structures observed in the SLM-fabricated 316L stainless steel are studied using molecular dynamics simulations. Ten passes of the laser beam on three layers of Aluminum nano-powder particles have unfolded the formation mechanisms of a complex microstructure associated with the SLM process. The study on the deformation mechanisms of 316L stainless steel has revealed the contribution of the cellular structures to its superior mechanical properties.

Microchannel process technology (MPT) offers several advantages to the field of nanomanufacturing: 1) improved process control over very short time intervals owing to shorter diffusional distances; and 2) reduced reactor size due to high surface area to volume ratios and enhanced heat and mass transfer. The objective of this thesis was to consider how nanomaterials, produced in part using MPT, could be used to solve problems associated with the fabrication of MPT devices. Specifically, many MPT devices are produced using transient liquid-phase brazing involving an electroplated interlayer consisting of a brazing alloy designed for melting temperature suppression. Unfortunately, these alloys can form brittle secondary phases which significantly reduce bond strength. In contrast, prior efforts have shown that it is possible to leverage the size-dependent properties of nanomaterials to suppress brazing temperatures. In this prior work, thin films of off-the-shelf elemental nanoparticles were used as interlayers yielding joints with improved mechanical properties. In the present investigation, efforts have been made to characterize the synthesis and deposition of various elemental nanoparticle suspensions for use in the transient liquid-phase brazing of aluminum and stainless steel. Advances were used to demonstrate the nanoparticle-assisted diffusion brazing of a microchannel array. In the first section, a silver nanoparticle (AgNP) interlayer was produced for the diffusion brazing of heat exchanger aluminum. Efforts are made to examine the effect of braze filler particle size (~5 nm and ~50 nm) and processing parameters (heating rate: 5ºC/min and 25ºC/min; brazing temperature: 550ºC and 570ºC) on thin coupons of diffusion-brazed 3003 Al. A tensile strength of 69.7 MPa was achieved for a sample brazed at 570°C for 30 min under 1 MPa with an interlayer thickness of approximately 7 μm. Further suppression of the brazing temperature to 500ºC was achieved by sputtering a 1 µm thick layer of Cu before depositing a 5 nm thick film of AgNPs resulting in a lap shear strength of 45.3±0.2 MPa. In the middle section of this thesis, several techniques are investigated for the synthesis of sub 10 nm diameter nickel nanoparticles (NiNPs) to be used in the diffusion brazing of 316L stainless steel. The average NiNP size was varied from 9.2 nm to 3.9 nm based on the synthesis technique, solvent and reducing agent used. Conventional wet-chemical synthesis using NiCl₂.6H₂O in ethylene glycol (solvent) and N₂H₄.H₂O (reducing agent) resulted in the formation of 5.4 ± 0.9 nm NiNPs. Continuous flow synthesis using a microchannel T-mixer (barrel diameter of 521µm) and a 10 second residence time of reactants in a bath temperature of 130ºC resulted in a particle size of with 5.3 ± 1 nm. To make the synthesis safer and less energy intense, microwave heating was used along with less toxic Ni(CH₃CO₂)₂·4H₂O (nickel salt), propylene glycol (solvent) and NaPH₂O₂ (reducing agent) yielding 3.9 ± 0.8 nm diameter NiNPs. For the final section, nickel nanoparticles were synthesized using NiCl₂.6H₂O (nickel salt), de-ionized water (solvent), NaBH₄ (co-reducing agent), N₂H₄.H₂O (reducing agent) and polyvinylpyrolidone (capping agent) yielding 4.2 ± 0.6 nm NiNP. Several deposition techniques were investigated for controlling film thickness and uniformity in the diffusion brazing of 316L stainless steel (SS). Using in-house prepared NiNP and automated dispensing, a hermetic joint up to 70 psi (tested pressure) was obtained in 316L SS substrates under brazing conditions of 800ºC, 2 MPa and 30 min. Throughout the course of this thesis, techniques used for characterizing nanoparticles, films and joints included FT-IR, XRD, SEM, TEM, HRTEM, EDS, EPMA, DSC, mass spectrometry, and lap-shear testing. / Graduation date: 2012

Cette thèse est dédiée à l'étude du comportement des aciers inoxydables sous irradiation exposés en condition primaire des réacteurs à eau pressurisée (REP). Le potentiel électrochimique de l'acier inoxydable austénitique 316L et les paramètres environnementaux comme la teneur en hydrogène, ont été mesurés de façon continue à haute température (HT) et haute pression (HT) grâce à un dispositif expérimental unique, la cellule HTHP. Deux sources d'irradiation ont été utilisées: les protons et les électrons. Le comportement électrochimique du 316L s'est avéré similaire dans les deux cas: (i) une augmentation du potentiel sous irradiation de l'ordre de la dizaine de millivolts ("réponse oxydative"); (ii) l'augmentation de la teneur en hydrogène diminue cette augmentation du potentiel sous irradiation; (iii) une synergie est observée entre le vieillissement à 300 C et la fluence qui conduit également à limiter la réponse oxydative sous irradiation. Les observations du film passif d'oxydes mettent en évidence la présence de nickel métallique dans l'ensemble des oxydes (interne et externe) en présence d'hydrogène, sans irradiation. Après les irradiations les plus fortes, des cavités (piqûres) sont observées en surface du 316L. Ces défauts sont attribués à l'effet de la radiolyse de l'eau et de l'irradiation de la couche passive. La radiolyse influence également l'évolution de la chimie du milieu primaire qui devient plus acide et plus oxydante. Il en résulte une augmentation du relâchement des cations métalliques et la présence d'hématite ( a-Fe2O3) sur le film d'oxyde externe de l'acier inoxydable lorsque les cavités (piqûres) sont formées.

L'objectif de cette étude est d'aboutir à une meilleure compréhension de la fragilisation par les métaux liquides (FML) à travers l'étude des systèmes T91/Pb-Bi et 316L/Pb-Bi et notamment d'en établir les mécanismes mis en jeu lors du contact entre ces aciers sous tension et le métal liquide. Ce travail s'inscrit dans le cadre du projet MEGAPIE-TEST mis en place pour étudier la faisabilité d'une cible de spallation au plomb-bismuth liquide. L'effet de l'eutectique plomb-bismuth liquide sur le T91 et le 316L a été étudié en fonction de la température et de la vitesse de déformation, en utilisant des éprouvettes CCT adaptées à l'étude de propagation de fissures. La présence de Pb-Bi modifie le mécanisme de rupture du T91 au détriment de la germination, croissance et coalescence des cavités. La rupture procède alors par décohésion des bandes de cisaillement. L'effet fragilisant du Pb-Bi est très marqué aux très faibles vitesses de déformation. Une transition fragile-ductile se produit aux grandes vitesses de déformation (~10-5 m.s-1 à 160°C). Les propriétés mécaniques du 316L ne sont pas autant affectées par la présence de Pb-Bi, toutefois une transition réelle est observée sur les faciès de rupture, où là également il y a compétition entre l'effet fragilisant du métal liquide et la rupture ductile. Le mécanisme suggéré dans ce travail est fondé sur la localisation de la déformation en pointe de la fissure combinée au phénomène de réduction d'énergie de surface induite par adsorption de métal liquide (effet Rebinder) et ne fait intervenir aucun processus diffusionnel en particulier aux joints de grains.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-01-23T13:48:58Z No. of bitstreams: 1 AlessandraAgnaAraujoDosSantos_TESE.pdf: 10998370 bytes, checksum: 203c8ccdd2621cf59c7c9d2ff97b9c73 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-01-24T13:58:55Z (GMT) No. of bitstreams: 1 AlessandraAgnaAraujoDosSantos_TESE.pdf: 10998370 bytes, checksum: 203c8ccdd2621cf59c7c9d2ff97b9c73 (MD5) / Made available in DSpace on 2018-01-24T13:58:56Z (GMT). No. of bitstreams: 1 AlessandraAgnaAraujoDosSantos_TESE.pdf: 10998370 bytes, checksum: 203c8ccdd2621cf59c7c9d2ff97b9c73 (MD5) Previous issue date: 2017-10-11 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Metal duro do tipo WC-Co ? utilizado na usinagem, perfura??o e ou fabrica??o de ferramentas de corte. Atualmente, 70% das ferramentas de corte s?o carbetos do tipo WCligante. Em n?meros de produ??o, aproximadamente 40,000 MT de ferramentas ? base de WC foram produzidas mundialmente desde 2011. Hoje, mais de 90% da produ??o de todo o metal duro, do tipo WC-ligante, utiliza o cobalto como ligante principal. A superioridade do cobalto em rela??o a outros ligantes est? ligada a v?rios fatores, sendo o principal a largura da janela de carbono no diagrama de fase. As pesquisas por ligantes alternativos que possam vir a substituir ao menos de forma parcial o cobalto s?o de extrema import?ncia, devido: ? escassez e pre?o do cobalto e principalmente pelo sistema WC-Co ser carcinog?nico. O objetivo da referida tese de doutorado foi analisar a viabilidade do uso dos ligantes alternativos 316L e FeNi com adi??o de cromo no WC. Ambos os sistemas WC-316L (teores de ligante de 5, 7 e 20%) e WC-20%FeNi com adi??o de cromo (em 5, 10 e 20%) foram processados pela rota de metalurgia do p?, seguindo as etapas: prepara??o das misturas, moagem (1h, 24h), compacta??o uniaxial (200 MPa) e sinteriza??o a v?cuo (1400oC/1h). As caracteriza??es realizadas em todas as amostras sinterizadas foram: microsc?pia ?tica e eletr?nica, difra??o de raios x, satura??o magn?tica e coercitividade, dureza, ataque qu?mico eletrol?tico. Foi realizado c?lculos das sec??es verticais dos diagramas de fase para o sistema WC-FeNi com adi??o de cromo. Os resultados obtidos e discutidos demonstram que o ligante 316L n?o ? uma alternativa viav?l em metal duro devido conter elevado teor de cromo. O ligante alternativo 316L quando sinterizado com carbeto de tungst?nio sempre precipitar? fase eta, fato que inviabiliza sua aplica??o como ligante alternativo em WC. Para o ligante FeNi com adi??o de cromo, os resultados demonstram que o m?ximo teor de cromo que pode estar contido em solu??o em WC, de forma que n?o haja precipita??o de carbeto de cromo ? de aproximadamente 4%. A adi??o de cromo acima de 4% em solu??o, leva ? precipita??o de carbetos complexos de cromo, e ainda reduz drasticamente a janela de carbono do comp?sito. / Hard metal WC-Co is used in the machining, drilling and or manufacturing of cutting tools. Currently, 70% of the cutting tools are WC-binder carbides. In production numbers, approximately 40,000 MT of WC-binder tools have been produced worldwide since 2011. Today, more than 90% of all WC-binder production uses cobalt as the main binder. The superiority of cobalt over other binders is linked to several factors, the main being the width of the carbon window in the phase diagram. The search for alternative binders that may at least partially replace cobalt is of extreme importance due to the scarcity and price of cobalt and especially the WC-Co system being carcinogenic. The goal of this doctoral thesis was to analyze the feasibility of using alternatives binders 316L stainless steel and FeNiCr alloy, in tungsten carbide. Both system WC-316L (5, 7 and 20% of binder contents) and WC-20%FeNi with addition of chromium (in 5, 10 and 20% in solution) were processed by powder metallurgy route following the steps: preparation of the mixtures, milling (1h, 24h), compaction uniaxial (200MPa) and vacuum sintering (1400oC/1h). The all samples were characterized by optical and electron microscopy, xray diffraction, magnetic saturation and coercivity, hardness and electrolytic etching. The calculation of vertical sections of the phase diagrams for the system WC-FeNiCr was made. The results obtained and discussed demonstrate that the binder 316L, is not a viable alternative in hard metal because it contains high chromium content. The binder 316L when sintered with tungsten carbide will always precipitate eta phase, which makes its application as an alternative binder in WC impossible. For the binder FeNiCr, the results demonstrate that the maximum content of chromium that may be contained in solution in tungsten carbide that there is no precipitation of chromium carbide is approximately 4%. The addition of chromium above 4% in solution leads to the precipitation of chromium complex carbides, and further drastically reduces the carbon window of the composite.

Spheroidal graphite cast iron is a material widely used in the industry for the manufacturing of all kind of covers and protective casings thanks to its good combination of mechanical properties, processability and cost. When cast iron components are put into service in corrosive environments the most common approach to protect the components is painting them. The protective painting has been found to flake off with time when aggressive washing procedures, such as the ones used in the Food & Beverage industry, are applied several times. In this project, the coating of cast iron with a corrosion resistant AISI 316L stainless steel by Laser Metal Powder Deposition has been studied as an alternative protection against corrosion. Several samples with different combinations of substrate preparation, number of layers and surface conditions were produced and analysed by optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, wash down tests and salt spray chamber corrosion tests. Main results show that the diffusion of carbon from the carbon-rich cast iron to the stainless steel coating, which would have a negative effect on the corrosion resistant properties, was significantly low as a result of the low penetration and dilution achieved during the laser metal powder deposition process. The deposited stainless steel coatings successfully protected the substrate during the corrosion tests and the integrity of the coatings is not expected to fail during the washing producers applied in the industry.

A moldagem de pós por injeção (MPI) foi empregada neste trabalho para a fabricação de micro componentes de uma pinça de biópsia, através do desenvolvimento de misturas injetáveis. Utilizou-se a liga de aço inoxidável AISI 316L, liga reconhecidamente biocompatível, para obtenção dos micro componentes. Determinando a quantidade de 39% em volume para fração orgânica das quatro formulações de misturas injetáveis produzidas neste trabalho. Os polímeros estruturais empregados foram o PP, o PEBDL, o PEAD e o PMMA. Como material auxiliar de fluxo foi utilizada a parafina e para agente surfactante, o ácido esteárico. O desenvolvimento do sistema de extração química do polímero auxiliar de fluxo com solvente e posterior extração térmica do ligante em forno convencional e em um reator a plasma foram testados, ainda se empregou estes para testes em sinterização a temperaturas 1200°C, 1250°C e 1300°C. A extração química foi realizada com hexano atingindo 2,41% em massa de material extraído das amostras, após seis horas em um sistema aquecido entre 60°C e 70°C e uma atmosfera de vácuo. As amostras foram testadas química, física, mecânica e eletroquimicamente. Obteve-se os melhores resultados em termos de densificação de 7,05 g/cm³ para as amostras extraídas a plasma e sinterizadas a 1300 °C à vácuo em forno tubular. Isso significa uma densificação de 88,96% comparada a densidade do material comercial cuja a densidade é 7,93 g/cm³. As microdurezas encontradas nas amostras sinterizadas a 1300 °C em um forno convencional obtiveram valores de 208HV se mostrando maiores do que os 165HV obtido de um material maciço fabricado pelo extrusão e comercialmente vendido. Encontrou-se a dureza de 55HRB nas amostras processadas a 1300 °C, devido a presença de poros em componentes sinterizados. Nos componentes maciços foram medidos a dureza de 88HRB que foi maior que os resultados das amostras sinterizadas. As análises metalográficas mostraram um tamanho de grão variando entre, 30 e 50μm, se comparado ao tamanho de partícula médio do D90 de foi de 8,59 μm, se estima que este aumento foi entorno de três vezes e meia. Os testes químicos revelaram que a extração térmica em reatores a plasma melhoram significativamente os níveis de C, N, H e S quando comparados ao processo de extração térmica em forno convencional. A redução dos níveis de carbono residual, resultaram em diminuição do carboneto de cromo nas amostras, provocando uma menor corrosão. As amostras sinterizadas a 1200 °C a plasma apresentaram os melhores resultados de corrosão. / The powders injection molding (PIM) was used in this research, with objective to manufacture micro component, for application in biopsy forceps being developed injectable mixtures . It was used the powder stainless steel AISI 316L alloy, material biocompatible, to obtain the micro components. Through tests was determining the amount optimal volume in 39 % for the organic fraction of the four formulations of injectable mixtures produced in this research. The structural polymers used were PP , LLDPE , HDPE and PMMA . The paraffin was used as auxiliary material flow, the surfactant agent employed that was stearic acid . The development of chemical debiding and the thermal extraction for binder system, was used the conventional furnace and in a plasma reactor were tested also be employed for these tests sintering temperature 1200 ° C , 1250 °C and 1300 °C. Chemical extraction was performed with hexane achieving 2.41 % by extracted mass of sample material, after six hours in a heated system between 60 °C and 70 °C and a vacuum atmosphere. The samples were tested analysis by chemical , physical , mechanical and electrochemical.If it obtained the best results in terms of densification of 7.05g/cm ³ for plasma samples extracted and sintering at 1300 °C in vacuum tube furnace . This means densification of 88.96 % compared to the density of commercial material whose density is 7.93 g/cm ³ . The microhardness found in the samples sintered at 1300°C in a conventional furnace obtained 208HV microhardness showing larger than the commercial 165HV. Found that the HRB hardness of 55 in the samples processed at 1300 °C, due to the presence of pores in sintered parts. In the extruded components were measured hardness of 88HRB which was higher than the results of the sintered samples. The metallographic analysis showing a grain size ranging between 30 and 50μm , compared to the average particle size D90 was 8,59 microns is estimated that this increase was around three and half times . The chemical tests revealed that the thermal plasma extraction reactor significantly improve the levels of C, N , H and S compared to the process heat extraction in a conventional furnace . The residual carbon levels significantly improved, which helps to avoid the formation of chromium carbides , which aumnetou corrosion resistance . The best results in terms of corrosion were found for the samples sintered at 1200 ° C the plasma.

Selective laser melting (SLM) of metallic powders is an additive manufacturing technique that is widely employed to produce 3D components, and is fast becoming an important method for manufacturing near-net shape and complex metallic parts. In this thesis, a comprehensive investigation on the effect of SLM on the mechanical and corrosion properties of the Al-12Si (AS), 316L stainless steel (SS), and 18(Ni)-300 grade managing steel (MS) is investigated, with particular emphasis on the developing (micro- as well as mesa-)structure -property correlations. Detailed microstructural characterization combined with quasi-static tensile, fracture toughness, fatigue crack growth, and unmatched fatigue tests were conducted. The effect of post-SLM heat treatment as well as the scanning strategy (linear vs. checker board hatch style) was examined and the results are compared with those of conventionally manufactured (CM) counterparts. The SLM alloys exhibit a mesostructured, in addition to the fine cellular structure along the boundaries. In a case of SLM-AS, the fine cellular structure imparts higher strength at the cost of ductility, while the mesostructured, which arises due to the laser track hatching, causes the crack path to be tortuous, and in turn leads to substantial increase in fracture toughness. This imparts significant anisotropy to the toughness while tensile properties are nearly-isotropic. The experimental results of SLM-SS also show that higher tensile strengths properties with a marked reduction ductility. In spite of these, the fracture toughness, which ranges between 63 and 87 MPa.m0.5, of the SLM-SS is good, which is a result of the mesostructured induced crack tortuousity.Both tensile and toughness properties of SLM-SS were found to be anisotropic in nature. Upon aging SLM-MS, nanoscale precipitation of intermetallic compounds occurs within the cells that, in turn, lead in marked improvements in tensile strengths properties, but substantial reductions in ductility and fracture toughness. Overall, the mechanical performance, except ductility, of the SLM-MS after aging is found to be similar to that of CM-MS. Importantly, the lack of ductility does not lead to a reduction in toughness. Although the SLM-MS alloy possesses a mesostructured, no significant anisotropy in the mechanical behaviour is observed. The unnoticed studies on SLM-AS, -SS, and -MS reveal that the tensile residual stresses, gas-pores, and unmelted powder particles, can degrade the unmatched highest fatigue properties considerably and hence need be eliminated for high fatigue strength. Room temperature, electrochemical corrosion resistances (CRs) of SLM-AS, -SS and -MS in 0.1M NaCl solution were also evaluated and compared with those CM counterparts. While SLM improves CRs of AS and SS, it degrades that of MS. The results are discussed in terms of microstructural refinement and porosity that are common in SLM alloys.

A moldagem de pós por injeção (MPI) foi empregada neste trabalho para a fabricação de micro componentes de uma pinça de biópsia, através do desenvolvimento de misturas injetáveis. Utilizou-se a liga de aço inoxidável AISI 316L, liga reconhecidamente biocompatível, para obtenção dos micro componentes. Determinando a quantidade de 39% em volume para fração orgânica das quatro formulações de misturas injetáveis produzidas neste trabalho. Os polímeros estruturais empregados foram o PP, o PEBDL, o PEAD e o PMMA. Como material auxiliar de fluxo foi utilizada a parafina e para agente surfactante, o ácido esteárico. O desenvolvimento do sistema de extração química do polímero auxiliar de fluxo com solvente e posterior extração térmica do ligante em forno convencional e em um reator a plasma foram testados, ainda se empregou estes para testes em sinterização a temperaturas 1200°C, 1250°C e 1300°C. A extração química foi realizada com hexano atingindo 2,41% em massa de material extraído das amostras, após seis horas em um sistema aquecido entre 60°C e 70°C e uma atmosfera de vácuo. As amostras foram testadas química, física, mecânica e eletroquimicamente. Obteve-se os melhores resultados em termos de densificação de 7,05 g/cm³ para as amostras extraídas a plasma e sinterizadas a 1300 °C à vácuo em forno tubular. Isso significa uma densificação de 88,96% comparada a densidade do material comercial cuja a densidade é 7,93 g/cm³. As microdurezas encontradas nas amostras sinterizadas a 1300 °C em um forno convencional obtiveram valores de 208HV se mostrando maiores do que os 165HV obtido de um material maciço fabricado pelo extrusão e comercialmente vendido. Encontrou-se a dureza de 55HRB nas amostras processadas a 1300 °C, devido a presença de poros em componentes sinterizados. Nos componentes maciços foram medidos a dureza de 88HRB que foi maior que os resultados das amostras sinterizadas. As análises metalográficas mostraram um tamanho de grão variando entre, 30 e 50μm, se comparado ao tamanho de partícula médio do D90 de foi de 8,59 μm, se estima que este aumento foi entorno de três vezes e meia. Os testes químicos revelaram que a extração térmica em reatores a plasma melhoram significativamente os níveis de C, N, H e S quando comparados ao processo de extração térmica em forno convencional. A redução dos níveis de carbono residual, resultaram em diminuição do carboneto de cromo nas amostras, provocando uma menor corrosão. As amostras sinterizadas a 1200 °C a plasma apresentaram os melhores resultados de corrosão. / The powders injection molding (PIM) was used in this research, with objective to manufacture micro component, for application in biopsy forceps being developed injectable mixtures . It was used the powder stainless steel AISI 316L alloy, material biocompatible, to obtain the micro components. Through tests was determining the amount optimal volume in 39 % for the organic fraction of the four formulations of injectable mixtures produced in this research. The structural polymers used were PP , LLDPE , HDPE and PMMA . The paraffin was used as auxiliary material flow, the surfactant agent employed that was stearic acid . The development of chemical debiding and the thermal extraction for binder system, was used the conventional furnace and in a plasma reactor were tested also be employed for these tests sintering temperature 1200 ° C , 1250 °C and 1300 °C. Chemical extraction was performed with hexane achieving 2.41 % by extracted mass of sample material, after six hours in a heated system between 60 °C and 70 °C and a vacuum atmosphere. The samples were tested analysis by chemical , physical , mechanical and electrochemical.If it obtained the best results in terms of densification of 7.05g/cm ³ for plasma samples extracted and sintering at 1300 °C in vacuum tube furnace . This means densification of 88.96 % compared to the density of commercial material whose density is 7.93 g/cm ³ . The microhardness found in the samples sintered at 1300°C in a conventional furnace obtained 208HV microhardness showing larger than the commercial 165HV. Found that the HRB hardness of 55 in the samples processed at 1300 °C, due to the presence of pores in sintered parts. In the extruded components were measured hardness of 88HRB which was higher than the results of the sintered samples. The metallographic analysis showing a grain size ranging between 30 and 50μm , compared to the average particle size D90 was 8,59 microns is estimated that this increase was around three and half times . The chemical tests revealed that the thermal plasma extraction reactor significantly improve the levels of C, N , H and S compared to the process heat extraction in a conventional furnace . The residual carbon levels significantly improved, which helps to avoid the formation of chromium carbides , which aumnetou corrosion resistance . The best results in terms of corrosion were found for the samples sintered at 1200 ° C the plasma.

A moldagem de pós por injeção (MPI) foi empregada neste trabalho para a fabricação de micro componentes de uma pinça de biópsia, através do desenvolvimento de misturas injetáveis. Utilizou-se a liga de aço inoxidável AISI 316L, liga reconhecidamente biocompatível, para obtenção dos micro componentes. Determinando a quantidade de 39% em volume para fração orgânica das quatro formulações de misturas injetáveis produzidas neste trabalho. Os polímeros estruturais empregados foram o PP, o PEBDL, o PEAD e o PMMA. Como material auxiliar de fluxo foi utilizada a parafina e para agente surfactante, o ácido esteárico. O desenvolvimento do sistema de extração química do polímero auxiliar de fluxo com solvente e posterior extração térmica do ligante em forno convencional e em um reator a plasma foram testados, ainda se empregou estes para testes em sinterização a temperaturas 1200°C, 1250°C e 1300°C. A extração química foi realizada com hexano atingindo 2,41% em massa de material extraído das amostras, após seis horas em um sistema aquecido entre 60°C e 70°C e uma atmosfera de vácuo. As amostras foram testadas química, física, mecânica e eletroquimicamente. Obteve-se os melhores resultados em termos de densificação de 7,05 g/cm³ para as amostras extraídas a plasma e sinterizadas a 1300 °C à vácuo em forno tubular. Isso significa uma densificação de 88,96% comparada a densidade do material comercial cuja a densidade é 7,93 g/cm³. As microdurezas encontradas nas amostras sinterizadas a 1300 °C em um forno convencional obtiveram valores de 208HV se mostrando maiores do que os 165HV obtido de um material maciço fabricado pelo extrusão e comercialmente vendido. Encontrou-se a dureza de 55HRB nas amostras processadas a 1300 °C, devido a presença de poros em componentes sinterizados. Nos componentes maciços foram medidos a dureza de 88HRB que foi maior que os resultados das amostras sinterizadas. As análises metalográficas mostraram um tamanho de grão variando entre, 30 e 50μm, se comparado ao tamanho de partícula médio do D90 de foi de 8,59 μm, se estima que este aumento foi entorno de três vezes e meia. Os testes químicos revelaram que a extração térmica em reatores a plasma melhoram significativamente os níveis de C, N, H e S quando comparados ao processo de extração térmica em forno convencional. A redução dos níveis de carbono residual, resultaram em diminuição do carboneto de cromo nas amostras, provocando uma menor corrosão. As amostras sinterizadas a 1200 °C a plasma apresentaram os melhores resultados de corrosão. / The powders injection molding (PIM) was used in this research, with objective to manufacture micro component, for application in biopsy forceps being developed injectable mixtures . It was used the powder stainless steel AISI 316L alloy, material biocompatible, to obtain the micro components. Through tests was determining the amount optimal volume in 39 % for the organic fraction of the four formulations of injectable mixtures produced in this research. The structural polymers used were PP , LLDPE , HDPE and PMMA . The paraffin was used as auxiliary material flow, the surfactant agent employed that was stearic acid . The development of chemical debiding and the thermal extraction for binder system, was used the conventional furnace and in a plasma reactor were tested also be employed for these tests sintering temperature 1200 ° C , 1250 °C and 1300 °C. Chemical extraction was performed with hexane achieving 2.41 % by extracted mass of sample material, after six hours in a heated system between 60 °C and 70 °C and a vacuum atmosphere. The samples were tested analysis by chemical , physical , mechanical and electrochemical.If it obtained the best results in terms of densification of 7.05g/cm ³ for plasma samples extracted and sintering at 1300 °C in vacuum tube furnace . This means densification of 88.96 % compared to the density of commercial material whose density is 7.93 g/cm ³ . The microhardness found in the samples sintered at 1300°C in a conventional furnace obtained 208HV microhardness showing larger than the commercial 165HV. Found that the HRB hardness of 55 in the samples processed at 1300 °C, due to the presence of pores in sintered parts. In the extruded components were measured hardness of 88HRB which was higher than the results of the sintered samples. The metallographic analysis showing a grain size ranging between 30 and 50μm , compared to the average particle size D90 was 8,59 microns is estimated that this increase was around three and half times . The chemical tests revealed that the thermal plasma extraction reactor significantly improve the levels of C, N , H and S compared to the process heat extraction in a conventional furnace . The residual carbon levels significantly improved, which helps to avoid the formation of chromium carbides , which aumnetou corrosion resistance . The best results in terms of corrosion were found for the samples sintered at 1200 ° C the plasma.