The use of firewood ash waste for the production of electric porcelain can represent an important technological and environmental alternative for the final disposal of this abundant solid waste material. This work aims to study the effect of replacing of sodium feldspar (albite) for firewood ash waste in electrical siliceous porcelain formulation. The firewood ash waste was obtained from a ceramic plant located in south-eastern Brazil (Campos dos Goytacazes-RJ). For this purpose, siliceous porcelain formulations containing up to 4.2 wt.% of firewood ash waste as a replacement for sodium feldspar were prepared. Disk specimens were pressed and fired at 1300 °C using a fast-firing cycle. The porcelain specimens were tested to determine their technical properties (linear shrinkage, water absorption, apparent porosity, apparent density, tensile strength, and electrical resistivity). The results indicated that test specimens containing up to 4.2 wt.% of firewood ash waste have high potential for use as electrical siliceous porcelain material. Thus, an alternative use of firewood ash waste is proposed, which can be converted into economic gain and also contribute for the environmental sustainability.

RESUMO O sistema de iluminação vem sofrendo algumas transformações no decorrer dos anos. Atualmente o sistema a LED ( Light Emitting Diode - diodo emissor de luz) tem se destacado, mostrando que tem potencial para emitir luz de forma mais eficiente e ainda reduzindo o consumo de energia elétrica. O objetivo principal deste trabalho foi a análise da fotoluminescência dos filmes produzidos utilizando a técnica de deposição spray-pirólise que tem como característica ser um sistema simples, de baixo custo e eficiente. Além disso, foram investigados os efeitos da co-dopagem com cério, térbio e manganês nas propriedades morfológicas, estruturais e óticas de filmes de alumina. Foi analisada a influência da temperatura de substrato, que variou entre 300 e 450 oC, sobre os espectros de absorbância, transmitância e emissão fotoluminescente para filmes depositados por spray-pirólise sobre substratos de vidro. O fluxo da solução precursora adotado foi de 0,5 mL/min e o tempo de deposição de 3 minutos. Através da co-dopagem com 5% at. de Ce, 1% at. de Tb e 1% at. de Mn nos filmes de alumina foi possível obter a emissão de luz branca. A melhor condição de emissão luminescente foi a amostra depositada em 300°C. A deposição por spray-pirólise mostrou-se eficiente na obtenção de filmes fotoluminescentes, confirmando a capacidade para aplicações em sistemas de iluminação eficientes, como por exemplo, em w-LED ( White Light Emitting Diode - diodo emissor de luz branca).

ABSTRACT The lighting system has undergone some changes over the years. Currently the LED (Light Emitting Diode) system has stood out, showing that it has the potential to emit light more efficiently and still reducing the consumption of electric energy. The main objective of this work was the analysis of the photoluminescence of the films produced using the spray-pyrolysis deposition technique, which has the characteristic of being a simple, low cost and efficient system. In addition, the effects of co-doping with cerium, terbium and manganese on the morphological, structural and optical properties of alumina films were investigated. The influence of the substrate temperature, which varied between 300 and 450 °C, on the absorbance, transmittance and photoluminescent emission spectra for films deposited by spray-pyrolysis on glass substrates was analyzed. The precursor solution flow was set at 0.5 mL/min and the deposition time of 3 minutes. By co-doping with Ce (5 at.%), Tb (1 at.%) and Mn (1 at.%) in alumina films was possible to obtain white light emission. The best luminescent emission condition was the sample deposited at 300 °C. The spray pyrolysis deposition technique proved effective in obtaining photoluminescent films, confirming the ability for applications in efficient lighting systems, such as w-LED (white light emitting diode).

RESUMO Os filmes Cu0,6In0,4Se2 foram depositados em substrato de vidro pela técnica de spray-pirólise, para utilização como camada absorvedora de células fotovoltaicas. Foram adotados os seguintes parâmetros de deposição: temperatura de substrato entre 250 e 400ºC, fluxo da solução precursora de 1 mL/min e tempo de deposição de 30 min. As propriedades estruturais, elétricas, morfológicas e óticas dos filmes preparados foram analisadas em função da variação da temperatura de substrato. A análise por difração de raios X mostrou que os picos mais intensos são de orientação (204/220) e que os filmes possuem as fases de CuSe, CuSe2 e CuInSe2. Para o processo de condução elétrica foi observada uma única energia de ativação com valor médio de 0,73 eV. A resistência de folha variou entre 0,277 a 0,576 MΩ/□. Os valores de resistividade elétrica apresentaram pequenas variações tendo um valor médio de 1,44 KΩm. As análises da morfologia dos filmes realizadas por microscopia confocal revelaram que de um modo geral as amostras apresentam-se sem trincas, sendo que as superfícies dos filmes com maior temperatura de deposição foram mais uniformes. A caracterização ótica foi realizada no intervalo de comprimento de onda de 350 a 1100 nm e os filmes apresentaram coeficiente de absorção na ordem de 103 cm-1 no comprimento de onda de 550 nm e gap ótico com valor médio de 1,5 eV.

ABSTRACT The Cu0.6In0.4Se2 films were deposited on a glass substrate by the spray-pyrolysis technique, for use as a photovoltaic cell absorber layer. The following deposition parameters were adopted: substrate temperature between 250 and 400ºC, precursor solution flow of 1 mL/min and deposition time of 30 min. The structural, electrical, morphological and optical properties of the prepared films were analyzed as a function of substrate temperature variation. X-ray diffraction analysis showed that the most intense peaks are oriented (204/220) and that the films have CuSe, CuSe2 and CuInSe2 phases. . For the electric conduction process, a single activation energy with an average value of 0.73 eV was observed. Sheet resistance ranged from 0.277 to 0.576 MΩ/□. The values of electrical resistivity presented small variations having an average value of 1.44 KΩm. The analysis of the morphology of the films made by confocal microscopy revealed that in general the samples presented no cracks, and the surfaces of films with higher deposition temperature were more uniform. The optical characterization was performed in the wavelength range of 350 to 1100 nm and the films had an absorption coefficient in the order of 103 cm-1 at the wavelength of 550 nm and optical gap with an average value of 1.5 eV.

The aim of this work was to study the incorporation of lead containing TV tube glass waste as a method to provide alternative raw material for aluminous electrical porcelain. For this purpose, aluminous porcelain formulations containing up to 30 wt.% of TV tube glass waste as a replacement for traditional flux material (sodium feldspar) were pressed and fired in air at 1300 ºC using a fast-firing cycle (< 60 min). X-ray diffraction (XRD), scanning electron microscopy (SEM), linear shrinkage, apparent density, water absorption, and electrical resistivity have been carried out. The results indicated that the aluminous porcelain pieces containing up to 30 wt.% of TV tube glass waste rich in PbO with water absorption between 0.42 and 0.45% and volume electrical resistivity between 1.91 and 2.93 x 1011 Ω.cm have high potential to work as electrical insulator material. This use of lead containing TV tube glass waste can contribute greatly to reducing the environmental impacts related to it, and also save the sources of non-renewable raw materials used in the electrical porcelain sector.

ABSTRACT Studies have been developed in last decades in order to produce NiO-based material to be used as anode in solid oxide fuel cell (SOFC). Aqueous-based tape casting was used to produce NiO-GDC substrates with smooth and homogeneous surfaces and good flexibility. Physical and mechanical properties were obtained in green tapes sintered at temperatures ranging from 1200 to 1400 ͦ C. The tapes sintered in 1400 ͦ C showed the best density and porosity values and mechanical strength between 7 and 25 MPa. SEM micrographs show a dense material with cracks and pores. The sintered material shows the presence of nickel oxide and gadolinium cerium oxide.

Doped lanthanum chromite-based ceramics are the most widely used interconnector material in solid fuel cells (SOFC) since they exhibit significant electrical and thermal conductivity, substantial corrosion resistance and adequate mechanical strength at ambient and high temperatures. The disadvantage of this material is its high cost and poor ductility. The aim of this study is to determine the mechanical and oxidation behavior of a stainless steel (AISI 444) with a LaCrO3 deposition on its surface obtained through spray pyrolisis. Coated and pure AISI 444 materials were characterized by mechanical properties, oxidation behavior, X-ray diffraction and scanning electronic microscopy. Results indicated that the coated material displays better oxidation behavior in comparison to pure stainless steel, but no improvement in mechanical strength. Both materials indicate that deformation behavior depends on testing temperatures.