Materials Research

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List of Papers (Total 192)

Mechanical performance of concrete with incorporation of coarse waste from the marble industry

The waste resulting from marble extraction process is usually disposed of in landfills or dumps and its accumulation is causing serious environmental and landscaping problems. One way of reusing marble waste is to consider its incorporation in structural concrete as a non-primary aggregate. This research work attempts to alleviate the situation and provide information on the...

Study of oxo-biodegradable polyethylene degradation in simulated soil

This study aims to evaluate the influence of pro-oxidant additive and accelerated aging on the degradation of polyethylene (PE) samples in simulated soil, in accordance with ASTM G160-03. Films of polyethylene with and without pro-oxidant additive were studied, before and after 72 hours of accelerated aging. The films were initially characterized by analyses of Scanning Electron...

Effect of desulfurization of diesel and its blends with biodiesel on metallic contact

The current environmental scenario has required changes in fuel nature, in order to minimize the harmful effects caused by sulfur in diesel. However, reductions in sulfur content promote loss of its lubricity and consequently wear in the injection system of the diesel engine. This study aimed to investigate the influence of sulfur minimization on fuel lubricity and wear of...

Rheological and mechanical characterization of poly (methyl methacrylate)/silica (PMMA/SiO2) composites

The search for new materials with properties suitable for specific applications has increased the number of research studies to fill the market demands. The development of polymer composites by the addition of inorganic fillers to the poly(methyl methacrylate) (PMMA) increases the potential use of this polymer in various application fields. The main objective of this work was to...

Hydrodynamic Simulation of Gas - Particle Injection Into Molten Lead

A multiphase- hydrodynamic model was solved with the phase field method and the Cahn-Hilliard equation to simulate the behavior of particle injection with nitrogen as conveying gas through a submerged lance into a lead bath in two dimensions. The residence and mixing time were obtained for different operating parameters like gas flow rate, lance depth, and different kettle and...

Compressive strength, microstructure and hydration products of hybrid alkaline cements

Ordinary Portland cement (OPC) is the dominant binder in the construction industry with a global production that currently reaches a total of 3 Gt per year. As a consequence, the cement industry's contribution to the total worldwide CO2 emissions is of about 7% of the total emissions. Publications on the field of alkali-activated binders (also termed geopolymers), state that this...

Physical and mechanical properties of particleboard manufactured from wood, bamboo and rice husk

In this work, the physical-mechanical properties of particleboards manufactured with wood (Eucalyptus grandis), bamboo (Bambusa vulgaris) and/or rice husk (Oryza sativa) particles, combined or not, were assessed. They were produced in the following proportions: 100% wood; 100% bamboo; 100% rice; 50% wood and 50% bamboo; 50% wood and 50% rice husk. In order to characterize the...

Evaluation of a 7050-TAF aluminum alloy submitted to creep age forming

CAF process combines creep and precipitation hardening which are highly dependent on time and temperature. The aging cycle relax the stresses induced during the loading phase. At the end of the process stress relaxation induces shape changes in the part but significant spring back is observed (about 70%). Usually CAF cycles for 7XXX alloys use times around 20 h and temperatures...

Synthesis and application of natural polymeric plasticizer obtained through polyesterification of rice fatty acid

This study includes the synthesis of a new natural plasticizer obtained through esterification reaction of rice fatty acid and polyols, its physicochemical characterization and its preliminary application in polyvinyl chloride (PVC). Monopropylene glycol, octanol and diethylene glycol were used as polyols for esterification reaction. Catalyst Fascat® 4100, was also added...

Analysis of equal channel angular extrusion by upper bound method and rigid blocks model

In present paper the Equal Channel Angular Extrusion (ECAE) through a rectangular die was firstly physically simulated using plasticine and then theoretically analyzed by upper bound method. Physical simulation was used to identify the deformation zone and as a background for the following theoretical ECAE analysis by rigid block model. The plane strain deformation mode and ideal...

Influence of the oxidation step on the behaviour and the performances of an oxygen carrier in fixed bed reactor

Chemical Looping Combustion is a promising technology for clean power generation with integrated CO2 capture. In this process the oxygen required for combustion is provided by a metal oxide. This work deals with the development of an experimental procedure to study performances of an oxygen carrier during oxidation/reduction cycles and the influence of the oxidation step on its...

Consequences of enamel preparation with sodium hypochlorite, polyacrylic and phosphoric acids for the bonding of brackets with resin-modified glass ionomer cements

The aim of this study was to evaluate the effects of deproteinization with 5.25% sodium hypochlorite (NaOCl) prior to enamel conditioning with 10% polyacrylic acid (PAA) and 35% phosphoric acid (PA) on the bond strength (BS) of brackets bonded with resin-modified glass ionomer cement (RMGIC). One hundred human premolars extracted for orthodontic reasons were divided into 5 groups...

Development of carbon-based nanomaterials indicators using the analytical tools and data provided by the web of science database

The recent rise of nanotechnology and nanomaterial research is marked by the huge amount of publications indexed in electronic databases, which can be evaluated using bibliometric indicators in order to help researchers find hidden trends, gain novel insights and support new scientific developments. Although in-depth analyses require specialized software and advanced...

Nondestructive evaluation of wood decayed by xylophagous organisms

The aim of this study was to investigate the effects of attack by xylophagous organisms on the physicomechanical properties of Araucaria angustifolia wood from the floor of a historic house in Pelotas, Southern Brazil using two nondestructive methods. To achieve this, samples were collected from the floor for visual assessment by photography in metric scale. All the images were...

Strength and stiffness of thermally rectified eucalyptus wood under compression

The aim of this work was the evaluation of the thermal-rectification process of reforestation wood Corymbia citriodora Hook by measuring of mechanical properties under compression parallel to the grain and also determining of chemical composition. The tested samples were thermally treated in a furnace with nitrogen-atmosphere at heating rate of 0.033 ºC.min-1, at temperatures of...

Study of aluminum nitride precipitation in Fe- 3%Si steel

For good performance of electrical steels it is necessary a high magnetic induction and a low power loss when submitted to cyclic magnetization. A fine dispersion of precipitates is a key requirement in the manufacturing process of Fe- 3%Si grain oriented electrical steel. In the production of high permeability grain oriented steel precipitate particles of copper and manganese...

Structural and magnetic properties of YBa2Cu3O7/BaZrO3 composites

We reported a study of the structural and magnetic properties of BaZrO3 (BZO) as possible substrate material for the production of YBa2Cu3O7-δ (YBCO) superconducting films. Rietveld analyses of the X-ray diffraction pattern show that BZO crystalizes as a cubic perovskite, space group Pm3m (#221). Chemical stability and crystallographic coupling between BZO and YBCO were examined...

Does crystallinity of extracted bone mineral increase over storage time?

It was recently shown that the crystallinity of extracted bone mineral samples from the fin bones of zebrafish could increase over storage time. This would have implications in many studies in which the samples need to be stored until analysis. The aim of this study was to further evaluate if the crystallinity of extracted bone mineral increases over storage time. The extracted...

In situ polymerized wood polymer composite: effect of additives and nanoclay on the thermal, mechanical properties

This study concerns the preparation and characterization of wood polymer nanocomposites based on impregnation of styrene acrylonitrile co-polymer-nanoclay intercalating system in presence of glycidyl methacrylate (GMA), a cross linking agent, and vinyl trichloro silane (VTCS) as additives into Simul (Bombex ceiba, L.), a soft wood. The effect of nanoclay and VTCS on the...

Study of indium nitride and indium oxynitride band gaps

This work shows the study of the optical band gap of indium oxynitride (InNO) and indium nitride (InN) deposited by magnetron reactive sputtering. InNO shows multi-functionality in electrical and photonic applications, transparency in visible range, wide band gap, high resistivity and low leakage current. The deposition processes were performed in a magnetron sputtering system...

FTIR study of the relation, between extra-framework aluminum species and the adsorbed molecular water, and its effect on the acidity in ZSM-5 steamed zeolite

The infrared spectroscopy study of zeolite samples, obtained by steam treatment at 560‑960 °C of the ZSM‑5 catalyst (framework Si/Al ratio of 13), suggests an association between adsorbed molecular water and extra‑framework aluminum hydroxyls generated after treatment. Moreover, infrared spectroscopy of adsorbed pyridine shows the reduction of the densities of Brönsted and Lewis...

Simultaneous incorporation of magnesium and carbonate in apatite: effect on physico-chemical properties

Synthetic apatites are widely used both in the dental and the orthopaedic fields due to their similarity in composition with the inorganic phase of hard tissues. Biologic apatites are not pure hydroxyapatite (HA), but are calcium-deficient apatites with magnesium and carbonate as minor but important substituents. The aim of the present study was to produce a more soluble...

Microhardness and EBSD microstructure mapping in partially-pressed al and cu through 90º ECAP die

Equal-channel angular pressing (ECAP) is widely recognized as an effective method for processing ultrafine-grained and even nanostructured materials. Important details on processes occurring in the die intersections can be obtained by mapping the microhardness and EBSD microstructures in partially-pressed aluminum and copper through the 90º die of ECAP. Precise measurements were...

Crystallization of II-VI semiconductor compounds forming long microcrystalline linear assemblies

In this work we report the formation of long microcrystalline linear self-assemblies observed during the thin film growth of several II-VI compounds. Polycrystalline CdTe, CdS, CdCO3, and nanocrystalline CdTe:Al thin films were prepared on glass substrates by different deposition techniques. In order to observe these crystalline formations in the polycrystalline materials, the...

Preparation and characterization of stainless steel 316L/HA biocomposite

The austenitic stainless steel 316L is the most used metallic biomaterials in orthopedics applications, especially in the manufacture of articulated prostheses and as structural elements in fracture fixation, since it has high mechanical strength. However, because it is biologically inactive, it does not form chemical bond with bone tissue, it is fixed only by morphology. The...