[en] Ball clays are clays with a high amount of fine particles, high plasticity, and are fundamental for the ceramic technology. These clays have sedimentary origin, varied content of organic-matter content, and containing kaolinite as the predominant clay mineral. They have a significant influence on the plasticity and rheology of ceramic formulations and in the green strength of the produced bodies. Due to the importance of clays such as 'ball clay' for ceramic processing this paper aims to review the characteristics of clays classified as 'ball clay' and address properties of clays in the state of Paraíba. (author)

[en] The aim of this study is to evaluate the microstructure and the mechanical resistance of ceramic substrates of alumina and infiltrated with poly (methyl methacrylate) for possible applications in fixed dental prostheses. Initially the alumina samples were characterized as to particle size and mineralogical composition. Specimens were prepared and subjected to infiltration at low and high pressure for periods of 6 and 12 hs. The infiltrated specimens were analyzed with respect to porosity, bulk density and fracture surface morphology by scanning electron microscopy (SEM). The specimens were also subjected to mechanical tests of bending resistance. The infiltration of the polymer in the porous substrate with Alglass alumina sample for a period of 12 hs obtained the best results, with reduction of porosity close to 45.24%, density of 2.66 ± 0.03 g/cm³ and increased mechanical resistance close to 68% in relation to the Alcoa alumina sample infiltrated under the same conditions and to the Alglass alumina samples infiltrated by a period of 6h when compared with the alumina without polymer. It can be concluded that the infiltration of PMMA improves the properties of ceramic substrates, forming a promising material for use in dental infrastructure; however the alumina substrates used in this study with and without infiltration of PMMA presented flexural resistance below to the recommended values in ISO 6872 standard. (author)

[en] The Solution Blow Spinning (SBS) technique which use aerodynamic forces and has a high production rate, was created for production of nanofiber with versatile way, such as electrospinning. Therefore, the objective is to analyze the process parameters in order to optimize the production of mullite nanofiber using the SBS technique to determine the influence of air pressure, the concentration of the polymer and ejection rate in the diameter of the fibers. For this, it was used PVC as polymer in spinning, tetrahydrofuran as the solvent, HCl as acidifying, aluminum nitrate nonahydrate and tetraethylorthosilicate as precursors of mullite. The nanofibers obtained were heat treated at 1100°C. From of XRD and SEM results, it was proved the achievement of mullite nanofiber, and STATISTICA 7 software revealed that only ejection rate and the concentration influence in the average diameters of the fibers. (author)

No abstract available

[en] Recent surveys show a new method of obtaining nanofibers, spinning blow solution (SBS). In SBS technique, the advantage is given at low cost because the electrical forces used in electrospinning are replaced by aerodynamic forces. Possessing unique properties, the nanofibers have a high potential for applications in nanosensors, nanofiltration, among others. Thus, this work aims to produce and characterize nanofiber ferrite through the SBS technique. For execution of work, a solution was prepared from the alcohol solvents and DMF (dimethylformamide), with addition of iron-III nitrate, nickel and zinc, and hydrochloric acid to stabilize the solution. Spinning was performed at a rate of 7.2 ml / h, 50 psi pressure and room temperature, the sample obtained was characterized. The results showed the efficacy technique where obtaining ferrite nanofibers with an average diameter of approximately 400nm was possible.(author)

[en] This study aims to make a literature review on the state of art of antimicrobial activity of nanoscale cerium oxide. In order to do so, we have collected current works on the subject and discussed them concerning their structure, production methods, mechanism of action, combination with various materials (doping and composite), and factors that affect the antimicrobial activity of nanostructured cerium oxide. It was observed that there are basically two mechanisms to explain the antimicrobial activity of CeO₂, which were studied in several works in isolated and/or in combined form: oxidative stress and damage to the microorganism cell wall. It has also been verified that the antimicrobial activity can be influenced by external factors such as the synthesis method, and pH, being necessary to control them for the effectiveness of its action. Regarding antimicrobial properties, the main applications are in tissue engineering, water treatment and catalysts. (author)

[en] This work shows the successful production of alumina nanofibers after thermal treatment of solution blow spun hybrid fibers. These nanofibers were converted into γ-Al₂O₃ and α-Al₂O₃ after the thermal treatment in air between 500 to 1200 °C. The X-ray diffraction patterns presented all the characteristics of the γ and α phases of alumina. In addition, the scanning electron micrographs showed alumina nanofiber diameters varying between 200 and 270 nm for different temperatures. The results demonstrated that the solution blowing spinning method is efficient to produce alumina nanofibers. (author)

No abstract available

[en] The effect of adding two types of α-alumina on the mechanical strength of the base of geopolymers metakaolin was analyzed through the determination of the modulus of rupture and using X-ray diffraction and thermal analysis. Factorial design in two levels was used to evaluate the effects of the studied variables. It was used metakaolin and sodium hydroxide for production of geopolymeric bodies. The cure was performed for seven days, involving curing in oven at 60 deg C and cure at room temperature. Results showed that the grain size had a positive effect on the mechanical strength of the specimens, while the alumina content only had influence on the mechanical strength when adding fine alumina was added in the amount of 20%. It was not detected microstructural alterations in the analyzed bodies when the addition of alumina. (author)

[en] Currently over 80% of industrialized bentonite clay produced in Brazil in sodium form for use in various industrial applications come from the deposits in Boa Vista - PB. Recently they were discovered new bentonite deposits situated in the municipalities of Cubati - PB, Drawn Stone - PB, Sossego - PB, and last in olive groves - PB, requiring systematic studies to develop all its industrial potential. Therefore, this study aimed to evaluate chemical characterization several deposits of smectite clays from various regions of the state of Paraíba through the analysis of statistical variance. Chemical analysis form determined by fluorescence x-ray (EDX). Then analyzes were carried out of variance statistics and Tukey test using the statistical soft MINITAB® 17.0. The results showed that the chemical composition of bentonite clay of new deposits showed different amounts of silica, aluminum, magnesium and calcium in relation clays in Boa Vista, and clays imported. (author)