Matéria (Rio de Janeiro)

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List of Papers (Total 65)

Influencia de la deficiencia de itrio en la sinterización de cerámicos YBaCuO (123)

In this work the densification of YBa2Cu3O7-x (or 123) ceramic starting from compacts with two compositions having lower Y-contents relative to the superconducting cationic Y:Ba:Cu ratios equal to 1.0:2.0:3.0 were analyzed. Thermal evolution of the powders was monitored by DTA-TG, under O2-flow, up to the peritectic decomposition temperature, Tp»1050ºC. The sintering...

Análise por difração de raio-x de uma hidroxiapatita carbonatada usando o método de Rietveld

The crystal structure of hydroxyapatite (HAP) is known to permit a great variety of substitutions anionic and cationic. Among these substitutions, the insertion of CO32- group is emphasized for its importance in biomaterial applications. In this work, a synthetic sample of nanostructure carbonated hydroxyapatite (CHA) was submitted to thermal treatment at 500ºC for 6 h. Later the...

Análise micromecânica dos compósitos com fibras curtas e partículas

The present work presents the investigation of the mechanical behavior of the composite materials, strengthened with short fibers and particles.  A simple model is presented, with purpose for prediction of the breaking stress of this class of composite material.  The model consists in the modification of the Rule of Mixture, with the introduction of a term, referring to the...

In vitro bioactivity of PMMA-based composite in simulated plasma with albumin

A new composite of poly(methyl methacrylate) - co -(ethyl-hexyl-acrylate) filled with glass of composition (wt.%) 61,33% 3CaO.P2O5 - 23,03% SiO2 - 15,64% MgO was developed. The formation of CaP (calcium phosphate) layers on implants is crucial for their integration in bone. Simulated biological fluids to study in vitro formation of those layers do not usually contain important...

Desenvolvimento de protótipo de células a combustível do tipo óxido sólido com reforma direta

Catalyst based on nickel and cobalt, supported on zirconia stabilized with ytria (YSZ) was developed, characterized and used for the hydrogen production from ethanol. The catalyst had metal contents of c.a. 35% in weight and presented high activity above 400ºC. This catalyst was tested in ethanol steam reform at very low water concentration, condition similar to that of SOFC...

Estudo da produção de suspensões aquosas para serigrafia de anodos para PaCOS e introdução de modificadores de superfície

The present work has the objective of presenting the preliminary results of the development of aqueous ceramic suspensions for SOFC anodes. These suspensions had been used for the generation of electrodes on flat electrolytes of 8%mol yttria stabilized zirconia (YSZ) using procedures compatible with the screen-printing technique, since it results in low cost processing and good...

Prototipagem rápida de pilhas a combustível de óxido sólido

Rapid prototyping (RP) technologies can automatically manufacture near-net shape parts with complicated geometry from Computer-Aided Design (CAD) data. The three dimensional part is built up by powder consolidation in layers ("additive" or "generative" process). For this reason, these techniques are often referred to as solid freeform fabrication or layered manufacturing. In...

Argamassa geopolimérica: estudo da degradação por sulfato de sódio e ácido sulfúrico

This work aims to evaluate the durability of a geopolymer mortar in contact with highly aggressive environments by sodium sulfate and sulfuric acid, in solutions with 10wt% and 5wt% of concentration, respectively. The mortar was made with metakaolin, Portland cement, potassium hydroxide and alkaline sodium silicate. The evaluated properties were: axial compressive strength and...

Utilização de finos de brita em cerâmica argilosa

This work has as its objective to evaluate the incorporation of stone fines in the microstructure and fired properties of a clayey ceramic. The evaluated properties were: linear shrinkage, water absorption and flexural strength. Compositions were prepared with 0 and 25 wt.% of stone fines to obtain specimens by extrusion that were fired at temperatures varying from 800 to 1200ºC...

Simulação do ensaio de indentação em filmes finos com o uso de modelos de trinca difusa

The aim of the present study was simulate the cycle of indentation test with spherical indenters in a system composed of thin surface coating deposited on a metallic substrate through PVD process by finite element models. Recent studies suggest that the indentation technique could be used as a tool to evaluate mechanical properties of thin films, as well as to determinate the...

Desenvolvimento de biocerâmicas porosas de hidroxiapatita para utilização como scaffolds para regeneração óssea

Porous bioceramics have important biomedical applications such as bone defect fillers and tissue engineering scaffolds. The hydroxyapatite (HA, Ca10 (Po4)6(OH)2) shows resemblance to the mineral phase of bone and teeth, it is biocompatible and osteoconductive, and has excellent chemical and biological affinity to bone tissue. The aim of this work is to develop HA porous...

Characterization and exploitation of piston ring chips in the rectification process a new recycling proposal

The rough grind machine operation in metallic material produce a sub product with the followings components such as: metallic residue, small parts come from the resin grinds, diatomaceous earth material (filter material) and soluble oil in water for tools cooling. According [HU1UH] from ABNT, this sub product is toxic, not inert material, aggress the environment with pollution in...

Tensile behavior of lignocellulosic fiber reinforced polymer composites: Part I piassava/epoxy

The fibers extracted from the piassava palm tree, scientifically known as Attalea funifera, are among the stiffest lignocellulosic fibers being considered for polymer composite reinforcement. Characterization of piassava composites have been carried out for different polymeric matrices and mechanical tests. In this work the tensile properties of DGEBA/TETA epoxy matrix composites...

Charpy impact resistance of alkali treated curaua reinforced polyester composites

Natural fibers obtained from cellulose-based plants are being used as reinforcement of polymer composite owing to both environmental and technical advantages. One important technical characteristic of most lignocellulosic fibers is the bend flexibility, which allows them to resist impact forces. As a consequence, there is an increasing application of these lignocellulosic fibers...

Thermal behavior of buriti biofoam

A natural biofoam extracted from the petiole of the buriti palm tree has shown values of density and mechanical strength with potential for uses in engineering applications such as automobile interior parts and floating components. Moreover, foams can also be used as insulating materials in packing and building panels. In this case some thermal properties are required. Therefore...

Incorporação de resíduos de borracha em compósitos de matriz polimérica termorrígida

The difficulty of degradation and storage of rejected tyres has led to increasing environmental problems, beyond the proliferation of insects which may transmit diseases becoming a harmful residue to the public health. This work investigates the physical and mechanical properties of polymeric composites based on tyre rubber wastes in order to achieve a sustainable material which...

Evaluation of the cytotoxicity of polyurethane and non-latex orthodontic chain elastics

Allergy caused by latex proteins has been well documented. Thus, the study of non-latex materials, is necessary. The aim of this study is to evaluate the cytotoxicity of silver-coloured orthodontic chain elastics, of polyurethane and latex-free. Nine chain elastics from different manufactures (3 latex-free and 6 polyurethane) were divided into 9 groups of 10 elastics each: Group...

Avaliação do comportamento em fadiga de juntas estruturais de ligas de Al2024T3 coladas com adesivo epóxi

Aluminum alloys are widely used in aeronautical parts due to their good mechanical properties and low densities. These parts must be joined together to form larger assemblies. A structural joint is defined as a segment of structure that provides a means of transferring load from one structural member to another. The majority of aircraft joints are mechanically fastened with...