Materials Science Forum Vols. 727-728

Abstract: The development of technology for the application of enamels on pieces of red pottery, in the handicraft sector, is an alternative to improve the quality of the ceramic body forming a waterproof layer that serves as a protection when used for foods and also to add a decorative effect and increase commercial value. This work develops an enameling technique in the production conditions of the artisans in the village of Icoaraci-PA/Brazil. The characterization of raw materials was performed by X-ray fluorescence, X-ray diffraction, particle size analysis, Thermogravimetric and Differential Thermal Analysis. Steps for enamel preparation using commercial transparent frit and bottle glass, and the technique for applying the glaze and firing are presented. The results for the test pieces were very good with the application of transparent frit fired at 900 ° C for 3 hours.

Abstract: A LZSA (Li₂O-ZrO₂-SiO₂-Al₂O₃) glass-ceramic porous media produced by the replication method has been studied for relatively low temperature applications. Different suspensions have been tested, and appropriated parameters to obtain good impregnation and green strength were determined. The structures after the sintering process (975 °C for 120 min) were evaluated by scanning electron microscopy and showed a good reproducibility for the best tested suspensions (70.0 wt.% LZSA, 3.5 wt.% bentonite as binder and 1.5 wt.% Darvan 821A as dispersant) Strut and geometric densities were determined so that glass-ceramic foams with porosity of about 91% were obtained.

Abstract: Many studies have been reported in the literature related to YSZ films deposited on dense substrate or applied directly on the SOFC anode. However, there are not a lot of studies about the YSZ deposition on the cathode. The present work aims to obtain yttria-stabilized zirconia (YSZ), using the spray pyrolysis technique, for their application as electrolyte in solid oxide fuel cells (SOFC). The films were obtained from a precursor solution containing zirconium and yttrium salts, dissolved in ethanol and propylene glycol (1:1), this solution was sprayed onto a heated LSM porous substrate. The substrate temperature was varied in order to obtain dense and homogeneous films. After deposition, the films were heat treated, aiming to crystallize and stabilize the zirconia cubic phase. The films were characterized by Scanning Electron Microscopy (SEM), thermal analysis, X-ray diffraction and Fourier transform Infrared Spectroscopy (FT-IR).

Abstract: The use of kaolin in any industrial segment requires previous physical and chemical treatment to minimize the amounts of impurities to or below standard levels established according to the desired application. Wastes from kaolin processing from the Amazon region were characterized by DTA-TGA and XRD. This paper shows the thermal transformations of the rejects studied at temperatures of 600°C, 700°C, 800°C, 900 °C, 1000°C, 1300°C, 1400°C and 1500°C, tests with pyrometric cones and ceramic properties of the sintered materials aiming their use in refractory materials.

Abstract: Large quantities of rock dust are daily discarded by dimension stone industries. These wastes can be reduced if they are selected according to their composition and used as base in other products. Two kinds of wastes (BS and OI) were mixed at different proportions with kaolinitic clay traditionally used as raw material in ceramic industry. BS has high contents of plagioclase, quartz, microcline and low biotitic; and OI has high quantities of microcline and plagioclase, besides quartz, biotitic, enstatite and edenite. At the same firing temperature, water absorption of samples with 50% BS, or less, didnt show significant differences in relation to samples with pure clay, but firing shrinkage and flexural strength decreased. On the other hand, mixtures with OI content up to 50% showed reduction of water absorption and firing shrinkage, while flexural strength was increased.

Abstract: The present work was performed in São Fidélis/BR, technologically characterizing four types of soil. Aiming to use them in artistic ceramic, some of their properties were determined, such as the analysis of color after burn. In order to do so, essays regarding their granulometry (sifting and sedimentation), specific gravity, chemical analysis of xray fluorescence, mineralogical identification through x-ray diffraction (DRX), differential thermal analysis (ATD), thermal gravimetric analysis (TG) and scanning electron microscopy (MEV) were carried out in the Laboratories of Universidade Estadual do Norte Fluminense (UENF).The soils were analyzed before drying at 110°C and after burn under temperatures of 750°C and 1,050°C. The analyses of results returned their physical, chemical and mineralogical compositions. Many variations of color could be observed after burn.

Abstract: Operation in an integrated steel making plant, such as the processing of iron ore by blast furnace result in several wastes that need to be conveniently disposed to avoid environmental pollution. In the case of sludge wastes, a feasible solution is their addition to clayey ceramics. The objective of this work was then to characterize a steel making plant waste was subjected to mineralogical, chemical and physical tests. The combustion gases: CO, CO₂, NO and SO₂ from thermal emission were analyzed. It was found that the blast furnace sludge has a high content of both iron and carbon. Its combustion generates enough heat to sensibly contribute to the firing of the ceramic, which is an energetical advantage associated with the sludge waste addition. The gas emission was monitored and, for relatively small addition of waste, no harm is apparently caused to the environment.

Abstract: In the ceramic industry, the firing is one of the main stages of the production process. There are two heating rates prevailing at this stage: low heating rate (long residence time) and high heating rate (fast residence time), the low rate is more used in traditional ceramics. This study aims to evaluate the influence of firing conditions on technological properties of three compositions of clay, used in the manufacture of red ceramic products. Initially, the mixtures were characterized subsequently were extruded, dried and submitted to firing at temperatures at 900 and 1000 °C with heating rates of 1, 2, 5, 15, 20 and 30 °C/min. The crystalline evolution of the different samples was analyzed using X-ray diffraction and the technological properties were determined. For the mechanical resistance, it was not observed significant change with the increase of the temperature and heat rate

Abstract: This work involves the processing of bovine bone for use as biofilter collector of heavy metals in water. Before processing, it was necessary to clean the bone selected for removing the organic material adhered thereto. Drying was done in weathered during 18 days. Then the bones were calcined at a constant temperature of 750°C for 6 hour. The bone grinding was performed by means of an analytical mill in order to obtain a finer grain size. Once processed, the bovine bone powder was characterized by X-ray diffraction and fluorescence analyses. The results showed that the powder phase is less crystalline hydroxyapatite, when compared to highly crystalline synthetic hydroxyapatite, which favors the sorption capacity of lead by bovine bone.

Abstract: In the present work we have carried out production and characterization of a new complex cubic perovskite ceramic Ca₂MgWO₆ to evaluate its application viability as inert material for petroleum industry. Ca₂MgWO₆ was produced by thermo-mechanical processing and calcinations at 1.200°C, using stoichiometric amounts of constituent chemicals CaCO₃, MgO and WO₃. The calcined material was examined by x-ray diffraction, which identified the phase formation Ca₂MgWO₆. Calcined material was powdered in a ball mill, compacted as circular discs and subjected to sintering at temperatures of 1.250, 1.300 and 1.350°C. The powders, both those employed in the calcined pellets as those produced by the mill, were characterized by size distribution. The sintered discs were characterized by SEM. The results showed that the ceramics sintered at 1.250°C presented better results in terms of microstructural features and mechanical properties for their possible application as inert material for petroleum industry.