Materials Science Forum Vols. 798-799

Abstract: Obtaining new raw materials for the production of ceramic coating is increasingly highlighted, however, it is desirable to maintain or improve the technological properties of the formed product. Thinking about it, and aiming at the environmental context, the aim of this work is to study the mixing recycled glass effect with syenite, an alternative melting often used in the production of ceramic tiles, in replacing to feldspar. The raw materials were characterized and subsequently the technological properties were determined for the standard formulation and the formulations with 5, 10, 15 and 20% mixing glass / syenite, in replacing to feldspar. The test bodies were prepared by wet, and sintered at different temperatures, with a rate of 30 °C /min and a level of 20 minutes. The results indicate that the mixing glass / syenite has the potential to be used as melting material in the composition of the ceramic mass.

Abstract: The mining industry generates large amounts of waste resulting in a very strong environmental impact. Its reuse in ceramic matrix composites are used as coating for floors that have high strength properties with low porosity due to the addition of a structuring polyester resin . This perspective, this work aims at the use of waste generated in the exploration and kaolin processing industries , and solid waste from the cutting of ornamental marble and granite , studying their properties in anticipation of production of coating plates . The residues were benefited by using the process of dry grinding in mill gauges and passed through sieve 0.074 mm ( No. 200 ABNT ) . Were performed on composites testing technology ( water absorption , apparent porosity , bulk density and flexural strength ) and microstructural ( Scanning Electron Microscopy - SEM) . The results showed that the composites showed water absorption ≤ 0.5 having no direct relationship with the porosity , which showed strength within the required standards ( ABNT 13,816 ) for coating plates . Variations in composition ( resin / residue ) showed that composites with higher strength and increased amount of waste resin showed less porous structure , a fact which can be attributed to a better adherence of these residues to the polymer resin and a process of mixing the components more efficient , showing the viability of its production having demonstrated satisfactory properties.

Abstract: Color is a very important characteristic in ceramic products. In ceramic coatings, the basis of ceramic is normally classified as red or white basis. Another relevant factor for color variation is the processing to which the material is submitted. In this sense, this work aims to analyze and quantify the color of ceramic pieces used as coatings, which were developed from a formulation of masses, using raw materials such as clay, feldspar, kaolin and quartz. Each raw material was analyzed separately and then a standard formulation was made, involving all of them, and these ones were submitted to different processing temperatures. All the samples were quantified regarding the color, by using the tridimensional colorimetric space by CIELAB method. Results point out that each raw material has an own value regarding color and the temperature has contributed directly to the color variation of the ceramic pieces.

Abstract: The development of organic materials with photovoltaic properties should enable the production of polymeric solar cells with high conversion efficiency. Due to low production cost and conversion efficiency above 10%, organic solar cells have great potential to compete with inorganic photovoltaic cells. This work proposes the development and integration of ETA (extremely thin absorber) photovoltaic cells, based on titanium oxide films and nanostructured conductive polymer in ceramic tiles, with the purpose of increasing the available area for sunlight capture, normally limited to roofs, expanding it onto the lateral sides of buildings. The nanostructured TiO₂ was obtained by sol-gel process from titanium isopropoxide, followed by supercritical CO₂ extraction in order to obtain a nanostructured aerogel. The conductive polymer used was the poly-3.4 (ethylenedioxythiophene)/polystyrene sulfonate (PEDOT:PSS) synthesized with iron III p-toluene sulfonate as an oxidizing agent. The materials were deposited layer by layer on a Cu electrode mounted on a ceramic tile piece, covered with glass containing a thin conductive layer of indium doped tin oxide (ITO). Transmission electron microscopy (TEM) revealed that the nanostructured titania aerogels exhibit particle sizes in the range of 2-5 nm. Preliminary studies have shown that the developed solar cell show a behavior typical of diodes (characteristic I×V curve) when subjected to different wavelength lamps (fluorescent and UV). Ceramic wall and roof tiles with photovoltaic properties, independently of the conversion efficiency, could serve as auxiliary energy sources to reduce expenses with conventional electricity.

Abstract: The ceramics industry has been conducting numerous research studies with the objective of reducing and reusing waste to improve the quality and efficiency of the porcelain polishing process. Large amounts of residue are generated during the porcelain polishing process. Recycling this residue during the process itself reduces production costs. In this work, the residue of porcelain was characterised by thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray fluorescence (XRF), linear retraction, water absorption, apparent density, apparent porosity and optical microscopy. Mixtures with different proportions of waste were obtained to evaluate at what proportion no loss of visual quality and structural material could be attained. Little structural or visual change was observed for samples that contained up to 2.0% porcelain residue by weight.

Abstract: Studies have been performed to improve the oxidation resistance of ferritic stainless steels at high temperatures because these materials have been proposed for the manufacture of interconnectors for solid oxide fuel cell (SOFCs) and solid oxide electrolysis cells (SOECs) operating at intermediate temperatures (IT-SOFCs). Among the coatings employed, ceramic spinel-type oxides have been the most frequently applied. In this context, Mn-Co-based coatings were deposited on ferritic stainless steel (AISI 430) in this study using a dip-coating technique. The obtained coatings were characterized with respect to their morphology by SEM, their elementary composition by EDS and their structure by XRD. It was possible to produce continuous and adherent Mn-Co-based coatings on the surface of the metallic substrates.

Abstract: Ferritic stainless steels exhibit properties, such as good electrical conductivity, good corrosion resistance and low cost, that are beneficial for their application as interconnects in intermediate temperature solid oxide fuel cells (ITSOFC) that function at temperatures between 600°C and 800°C. However, the stainless steel corrosion resistance is attributed to the amount of Cr, which is an element that forms a chromium oxide (Cr₂O₃) layer, acts as an oxidation protective barrier at high temperatures, and reduces the interconnector performance due to its low electrical conductivity. In this context, the objective of this work was to obtain spinel coatings from the Fe and Ni metallic alloy thermal conversion on AISI stainless steel 430 substrate produced by electrodeposition. The morphology and microstructure of the spinel films deposited on stainless steel were characterized by SEM, EDS, XRD and adherence analysis. The results obtained showed that the films were adherent, dense and continuous along the AISI stainless steel 430 substrate surface. In addition, the heat treatment procedure effectively produced crystalline spinels ((NiFe)₃O₄).

Abstract: This work was carried out in a tile ceramic company that works with the wet milling process. The main objective was to evaluate the variations in the characteristics of the spray-dried powder transported vertically using compressed air. The particle size distribution, moisture and fluidity of the spray-dried powder were evaluated. The granule morphology was evaluated by scanning electron microscope. The main concern was the spray-dried powder fluidity, which in turn can impair the loading of the press, causing compaction fluctuations and thereby geometrical and size variations in the pressed samples. The results show that the vertical transportation by compressed air significantly impairs the fluidity of the spray-dried powder, reduces the moisture content and change the sphericity of the granules.

Abstract: Soil-cement blocks are worldwide used in civil construction competing with ceramic blocks like the red clay ceramic bricks. In the southeast of Brazil, particularly in the states of Espirito Santo and Rio de Janeiro, clay ceramic blocks predominate owing to lower processing costs. The incorporation of inexpensive raw materials into soil-cement blocks could improve their margin of competition. Therefore the present work investigated the processing and properties of soil-cement blocks incorporated with a relatively high amount, 81 wt%, of natural grit in substitution for the conventionally used gravel and sand. The grit had a convenient particle size. The results of compression and water absorption tests indicated that the grit incorporated soil-cement blocks attend the norms for civil construction.

Abstract: The civil construction sector is considered among one of the most polluting to the environment because of the huge amount of wastes generated in its processes. Lighter and more rational structures not only reduces the amount of waste but also decrease the final price of the buildings and thus become more accessible to lower income population. One possible solution for reducing the weight of building structures is the application of light materials to the concrete, which represents a relatively larger part of the construction cost. Therefore, this study aimed to assess the compressive resistance of a concrete using expanded polystyrene (EPS), as an addition, by replacing the sand. This addition was found to provide lightness as well as economy and flexibility to structures. However, the highest strength obtained was 8.86 MPa. According to the results, it is recommended that the use of EPS should be restricted to non-structural concretes, for which the required strength is below 20 MPa, following the standards prescribed by the regulations.