Due to their enhanced tribological properties that contribute to an increased useful life of components, martensitic stainless steels are an excellent option for industrial applications such as hydroelectric, petroche...
Due to their enhanced tribological properties that contribute to an increased useful life of components, martensitic stainless steels are an excellent option for industrial applications such as hydroelectric, petrochemical, civil construction and mineral processing plants. In the present investigation, the erosive wear of AISI 410 martensitic stainless steel is evaluated after thermal treatment by quenching and tempering by mass loss, under erosive attack at 30° and 90° incidence angles, using a self-made jet slurry erosion equipment controlling parameters such as speed, volume of fluid, temperature and concentration of erosive particles of erodent. The characterization of the eroded samples was carried out in terms of the microstructure (SEM) and microhardness as well as the particle size distribution (LG) and morphology of the erodent. It was possible to establish the relationship between the slurry erosive wear and the physical properties inherent of stainless steel for this particular experimental configuration, concluding that the steel presents better resistance to jet slurry erosion wear when compared to austenitic steel commonly used in the industry.
Polyaramid fibers have excellent mechanical properties, such as high tensile strength-to-weight ratio and high thermal stability, but its applicability as reinforcement for composite materials is limited due to its hi...
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(纸本)9780997511789
Polyaramid fibers have excellent mechanical properties, such as high tensile strength-to-weight ratio and high thermal stability, but its applicability as reinforcement for composite materials is limited due to its high crystallinity and inert and smooth surface. In this work, an imidazolium-based ionic liquid (l-Butyl-3-methylimidazolium chloride) was used to treat Kevlar polyaramid fibers with the aim of improving Kevlar and epoxy resin interaction. The fibers were characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM). Tensile strength tests were carried out to verify loss of mechanical properties caused by the treatment. Contact angle measurements and pull-out tests verified an improvement of the wettability and adhesion between the fibers and epoxy resin. The interfacial shear strength (IFSS) was improved by 37% and the contact angle was decreased from 35° to 22.
Among the techniques for producing oxide catalysts, the solution combustion synthesis (SCS) has been widely used to produce high-quality nanostructured powders at low-cost. Through SCS, due to the high exothermic ener...
Among the techniques for producing oxide catalysts, the solution combustion synthesis (SCS) has been widely used to produce high-quality nanostructured powders at low-cost. Through SCS, due to the high exothermic energy liberated by the reaction between the transition metal nitrate and the fuel, it is possible to homogeneously incorporate dopant ions into the catalyst. Besides, SCS allows the production of nanopowders with sizes in the decimal scale, which is extremely important for powdered catalysts. The smaller the particle is, the larger the surface area is. Based on these possibilities, the aim of this work is to produce Fe-Mo/MgO nanopowders by SCS. The influence of concentration and composition of the fuels glycine and polyethylene glycol (PEG) on the final product were investigated. The morphology and the physicochemical properties were characterized by X-ray diffraction (XRD), electron microscopy (SEM), granulometry and surface area analysis. The results indicated high crystallinity for the samples produced with PEG and a wide variation on the nanoparticles sizes depending on the fuel properties.
Fingerprints are unique to each individual who contributes to human identification in forensic cases. In this sense, the present work aimed to synthesize 1H-pyrazol-1-yl-4-phenylthiazoles and apply them as powder agen...
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Fingerprints are unique to each individual who contributes to human identification in forensic cases. In this sense, the present work aimed to synthesize 1H-pyrazol-1-yl-4-phenylthiazoles and apply them as powder agents to reveal latent finger marks as an alternative and low cost related to powders found on the market. The compounds were characterized by infrared; fluorescence; 1H NMR; 13C NMR; laser diffractometer and SEM. In addition, cytotoxicity was also evaluated in oral keratinocytes showing high cell viability. The result of the hemolytic assay revealed that compound 2a does not present red cell cytotoxicity. The prepared powders were applied to fingermarks deposited on different surfaces providing quality visualization at level three so that human identification is possible.
Biomass is a renewable resource which importance has attracted much attention face to the concerns involving the environmental and the oil crisis. The aim of this work is to convert lignin into coal by carbonization h...
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Biomass is a renewable resource which importance has attracted much attention face to the concerns involving the environmental and the oil crisis. The aim of this work is to convert lignin into coal by carbonization heat treatment of this biomass up to 1000 °C, under inert atmosphere, at different heating rates. The resulted coal samples were characterized by X-Ray diffraction, Raman spectroscopy and surface area analyzes. Raman spectroscopy and X-ray diffraction results show that longer heat treatment resulted in coals more ordered structurally. On the order hand, longer heat treatments favored the coal production with smaller surface area.
This paper purposes the development of an isolated battery charger. In energy storage systems, these devices are essential, performing batteries charging in the way to maintain their lifecycle and safety since they ar...
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This paper purposes the development of an isolated battery charger. In energy storage systems, these devices are essential, performing batteries charging in the way to maintain their lifecycle and safety since they are main responsible for the costs associated with these systems. In many works theses circuits are implemented through bidirectional Full-Bridge converters. These converters require auxiliary circuits to reduce their switching losses. However, circuits such as snubbers or voltage clampers are not adequately addressed in these works since their use is undesirable for bidirectional operation. To eliminate these circuits in isolated converters, this work presents a switching technique applied in a Full-Bridge converter with the objective to reduce overvoltage in semiconductors and make it suitable for use in bidirectional converters, as in the charge of battery banks.
The main goal of this work is to verify the possibility of the improving the process variables in CO 2 capture process using ionic liquids as sorbent, by changing the anions and/or cation type of the Ionic liquids. AN...
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The main goal of this work is to verify the possibility of the improving the process variables in CO 2 capture process using ionic liquids as sorbent, by changing the anions and/or cation type of the Ionic liquids. ANOVA models a PCA were performed for CO 2 capture capacity, viscosity, melting degradation temperature and chemical information of the ionic liquids. The results shows that tunning of ionic liquids are statistically significant and the resultants insights could be used to predict new sorbents.
COVID-19 has led to the enormous rise of medical wastes throughout the world, and these have mainly been generated from hospitals, clinics, and other healthcare establishments. This creates an additional challenge in ...
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COVID-19 has led to the enormous rise of medical wastes throughout the world, and these have mainly been generated from hospitals, clinics, and other healthcare establishments. This creates an additional challenge in medical waste management, particularly in developing countries. Improper managing of medical waste may have serious public health issues and a significant impact on the environment. There are currently three disinfection technologies, namely incineration, chemical and physical processes, that are available to treat COVID-19 medical waste (CMW). This study focuses on thermochemical process, particularly pyrolysis process to treat the medical waste. Pyrolysis is a process that utilizes the thermal instability of organic components in medical waste to convert them into valuable products. Besides, the technique is environmentally friendly, more efficient and cost-effective, requires less landfill capacity, and causes lower pollution. The current pandemic situation generates a large amount of plastic medical wastes, which mainly consists of polyethylene, polypropylene, polystyrene, polyethylene terephthalate, and nylon. These plastic wastes can be converted into valuable energy products like oil, gas and char through pyrolysis process. This review provides detailed information about CMW handling, treatment, valuable product generation, and proper discharge into the open environment.
Nowadays ionic liquids (IL) are target of massive research in CO 2 captures technologies, due to its thermic degradation resistance, low vapour pressure and low requirement of power for regeneration. All these propert...
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Nowadays ionic liquids (IL) are target of massive research in CO 2 captures technologies, due to its thermic degradation resistance, low vapour pressure and low requirement of power for regeneration. All these properties, including solubility capacity, are known to vary with the nature of the IL cation and anion. The main goal of this study was calculate electronic indicators for ILs that have thermodynamic data available and verify the existence of correlation between then, providing a possible new way to get information of these processes.
Carbon fiber reinforced plastics (CFRP) have been used for manufacturing curved structures, which are applied in several equipment due to its high specific stiffness and strength. Recently, improvements in pultrusion ...
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