Matéria (Rio de Janeiro)

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List of Papers (Total 195)

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...

Novos processos de reciclagem de chumbo

The conventional pirometallurgical process for the production of metallic lead is compared with two innovative clean processes: electrohydrometallurgical and alkaline smelting. The electrohydrometallurgical process consists on reducing the particle size of the lead compounds and leaching them with an acidic solution of ferric fluoroborate. In this step, lead is dissolved with the...

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...

Cinzas volantes álcali-ativadas com solução combinada de NaOH e Ca(OH)2

The main objective of this work was to evaluate over time the development of the compressive strength of alkali-activated fly ash mortars.  A combined solution of NaOH and Ca(OH)2 was used as alkaline activator. The curing of the samples was carried out in two distinct ways. In the first one, samples were kept at 70°C during the first 12 hours after mixing and at 22°C afterwards...

Efeito da utilização de laterita nas propriedades físicas e mecânicas de cerâmica vermelha

This work has for objective to evaluate the incorporation of laterite up to 40 wt.% into a clay aiming at the fabrication of red ceramic. Initially, the laterite was submitted to mineralogical, chemical and physical characterization tests. Specimens were then prepared by uniaxial pressing at 20 MPa before firing at 700, 900 and 1100ºC in a laboratory furnace. The evaluated...

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...

Estudo da degradação "in vivo

The peripherical nervous regeneration can help the axonal regeneration and fiber reorganization, performing in nerve injury after trauma. In the present study the regeneration of sciatic nerve was observed inside the poly(L-lactide acid-co-D,L-lactide acid) tubes made with membranes obtained by solvent evaporation The tubes were implanted around the sectioned sciatic nerves of 20...

Utilização do resíduo do beneficiamento do caulim na produção de blocos e telhas cerâmicos

The miner and processing industries of kaolin are an important economic sector in the state of Paraíba, however, they generate a large amount of wastes, which are source of contamination and pollution of environment. This work has as aim the characterization of the kaolin processing waste and the evaluation of its suitability as an alternative ceramic raw material for the...

Estudo da interação células Vero/PLGA após a modificação da superfície por plasma de oxigênio

The application of bioreabsorbable polymers as support for cells culture is an alternative method to treat lesions and loss of tissues. The surface modifications of these polymers by plasma is an effective and economical technique to make it more hydrophilic. The aim of this work was to study the interactions between Vero cells and PLGA supports previously treated by oxygen...

Comparative study of hydroxyapatite coatings obtained by Sol-Gel and electrophoresis on titanium sheets

A comparative study of two coating methods on titanium (Ti) substrates, sol-gel and electrophoresis processes, was performed. Before coating, two different surface treatments were employed. The hydroxyapatite (HA) powder were characterized by infrared spectroscopy (FTIR) and X-ray diffraction (XRD) while coated samples were examined by using scanning electron microscopy (SEM...

Preliminary results of osteoblast adhesion on titanium anodic films

Osteoblast adhesion on metallic titanium coated with anodic films was evaluated. The anodic oxidation treatment was carried out on commercially pure-titanium (cp-Ti) substrate under the following conditions: 1.0M H2SO4/150V and 1.0M Na2SO4/100V. Osteoblast cells were cultured onto the samples for 4 hours. The morphologies of both Ti anodic films and cells were observed by...

Avaliação das propriedades mecânicas de espumas híbridas de vidro bioativo/álcool polivinílico para aplicação em engenharia de tecidos

Bioactive glass/ polymer hybrids are materials of high interest for biomedicals applications because their assets, they combine the bioactivity of ceramics, with the flexibility of the polymers. In bone regenerations, mechanicals properties of the scaffold are criticisms and they must be similar to the bone properties. In previous works, hybrid foams with 80% bioactive glass and...

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...

Experimental determination of the effect of some straight biological oils on cutting force during cylindrical turning

Cutting fluids of various types are usually employed to control the heat generated in machining. The continued application of conventional petroleum based metal working fluids is being challenged by the need to reduce overall volume of fluids, minimize health risks and bio-contamination. Bio-oils assisted machining is an environmental bio-compatible technology for desirable...

Recobrimentos poliméricos hidrofóbicos sobre isoladores elétricos de porcelana

Polymeric coatings of acrylic, polyester, polyurethane and silicone were applied on porcelain substrates used as electrical insulators. The coatings were applied as a liquid resin by spraying or as a powder by surface deposition. Contact angle measurements between the surfaces and a water drop were taken with a goniometer in order to characterize the coating hydrophobic behavior...

Avaliação das propriedades físicas e mecânicas de papéis reciclados artesanais com resíduos de bananeira ou palha de arroz

The cultures of bananas and rice are predominant in the Northeast of Santa Catarina State and in the case of banana the, reach 200 ton/year of waste, including pseudo-stem, stalks and leaves, which are usually incorporated into the soil. Thus, this work analyzed the physical-mechanics properties of handmade papers produced with recycled fibers with local agro-industry resources...

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...

Influência de colorantes na degradação termo-oxidativa do policarbonato

Dyes and pigments are additives used in polymer systems to change the original coloration of the material. However, the thermal and photochemical stability of the polymer is frequently affected with the incorporation of these additives. The aim of this work was to study the influence of different colorant types (bismuth vanadate pigment, condensation diazo pigment, Cu...

Impacto do co-monômero hidroxivalerato na cinética de degradação térmica dos poli(3-hidroxialcanoatos)

The aim of this work was to evaluate the impact that the content of the co-3-hydroxyvalerate monomer has on thermal degradation kinetics of P3(HB-x%HV) copolymers. Films of the copolymers with different contents of 3-hydroxyvalerate were obtained by controlled evaporation of solvent from chloroform solution (1% m/m). Thermogravimetry study was carried out in helium atmosphere...

Influencia de la temperatura de curado: hidratación y resistencia de pastas de cemento con escoria

Nowadays it is well known that using blast furnace slag as partial replacements for Portland cement adds technological, economic and environmental benefits. Those are some of the reasons why cements containing several additions (blast furnace slag, fly ash, calcareous material, etc) are commonly used. In recent years, blended cements started to increase amounts of additions as...