Among the vast applications in which the α-alumina can apply, the literature has reported researches which aim to achieve better features of these materials varying the obtainment methodology and some post-obtainment techniques. Thus, this paper aims to evaluate how different milling time lengths of 15, 30, 45 and 60 minutes alter the structure and morphology of α-alumina powders synthesized by combustion reaction. The time and temperature of the combustion reaction were evaluated during the synthesis of the alumina. The samples of non-milled and milled alumina were characterized by XRD and particle size analysis. The results showed that the maximum achieved temperature of reaction was 598°C. The milling time length variation did not alter the stable α-Al2O3majority crystal phase present in all samples. The average particle diameter was reduced from 23.3 to 10.5 μm comparing the non-milled and the sample milled for 60s.

RESUMOEsse trabalho tem como objetivo obter membranas cerâmicas assimétricas para aplicação em processos de microfiltração e avaliar a influência do tempo de deposição (5 e 10 s) de uma dispersão de argila sobre um suporte tubular de alumina comercial e bentonita. O suporte tubular foi caracterizado por microscopia ótica e eletrônica de varredura e por porosimetria. A membrana assimétrica foi caracterizada por microscopia eletrônica de varredura e por porosimetria. Os resultados mostraram suportes porosos com espessura de 1092mm, diâmetro médio de poro de 0,99 mm e porosidade de 39%. A membrana assimétrica foi obtida com sucesso para os tempos de deposição avaliados, sendo classificada para aplicações em processos de microfiltração atingindo diâmetro médio de poro de 0,25 mm e porosidade de 35%.Palavras-chave: membrana assimétrica, membrana tubular, deposição, microfiltração. ABSTRACTThis paper aims to obtain asymmetric ceramic membranes for application in microfiltration processes and evaluate the influence of the deposition time (5 and 10 s) of a clay dispersion on commercial alumina and bentonite tubular support. The tubular support was characterized by optical and scanning electron microscopy and porosimetry. The asymmetric membrane was characterized by scanning electron microscopy and porosimetry. The results showed porous substrates with thickness of 1092mm, average pore diameter of 0.99 mm and porosity of 39%. The asymmetric membrane was successfully obtained for the evaluated deposition times, being classified for microfiltration processes applications.Keywords: asymmetric membrane, tubular membrane, deposition, microfiltration. INTRODUÇÃOA tecnologia de separação com membranas tem sido amplamente utilizada em biotecnologia, indústrias farmacêuticas e de alimentos ou para tratar outros efluentes industriais. Essa tecnologia oferece uma ampla gama de procedimentos capazes de recuperar, concentrar ou purificar solventes valiosos em todos estes campos científicos [1].As membranas inorgânicas apresentam vantagens sobre as orgânicas por poderem atuar sob condições em que as orgânicas apresentam restrições, como por exemplo, na presença de solventes, elevadas temperaturas e pressões. Procedimentos agressivos de limpeza química e/ou mecânica e esterilização são geralmente empregados em membranas e são propensos a causar danos na estrutura da membrana especialmente para as membranas orgânicas [2]. Entretanto, as membranas inorgânicas são normalmente mais caras do que as orgâ-nicas habituais. Nesse sentido, novas pesquisas com membranas usando materiais cerâmicos de custo mais baixo devem difundir o uso da tecnologia de membranas, especialmente para países emergentes, onde muitos problemas ambientais podem ser resolvidos com a utilização de membranas.

This work aims to evaluate the behavior of four samples of biodegradable lubricants in the differential sticking coefficient of aqueous drilling fluids. Eighteen formulations of fluids containing bentonite clay, lubricants and biodegradable polymers in different concentrations were studied. The experiment focused on observing the samples' rheological properties, its filtration, the cake thickness, the lubricity coefficient, and, finally, the coefficient of the differential sticking. The results showed that the polymer additives improved rheological and filtration properties significantly. Also, the findings confirmed the idea that the presence of a lubricant leads to a reduction in lubricity, LC, and affects the differential sticking coefficient, DSC, of the fluids. However, the experiment observed a small variation on the LC as a result of an increase in the lubricant content. Overall, the results of the LC and the DSC of the fluids containing biodegradable lubricant additives were outstanding, being similar to the ones observed for oil-based fluids.

Smart materials are a class of materials characterized by having a different behavior due to external stimulation, which can be mechanic, thermal, electric, or magnetic. This chapter approaches the different types of smart materials and their classification according to the material’s nature (fluid, ceramic, polymeric and metallic). Emphasis is given to the theoretical study of the metallic materials with shape memory, presenting the fundamentals, crystallographic study and the mathematical methods of phase transformation. Due to these metallic material’s unique features, shape memory effect and super elasticity, the usage in the production of composite structures has gained space. Such materials present several advantages if compared to traditional composites being subject of research for several industrial applications

Industrial wastes reuse becomes attractive to raw materials economy and to avoid environmental problems. The aim of this study is to develop and characterize tubular ceramic membranes using in their composition inorganic residues generated in the industries, such as, granite, alumina residue from calcination process and kaolin. Initially, it was performed the physical chemical and mineralogical characterization of the residues. Different formulations of ceramic masses have been studied with incorporation of residue, clay and additives for producing tubular membranes through the extrusion process. The membranes were characterized by SEM and flow measurements with distilled water. The membranes were applied to effluent treatment from textile and oil industry. The granite residue showed a high content of SiO2and Al2O3in its chemical composition and significant amount of iron and calcium oxides resulting from the granite processing. The granite residue presented average particle size of 13.98 µm. The residue from alumina process contain gibbsite and α-alumina, and average particles size of 15.68 µm. The residue from kaolin processing presented high content of quartz and alumina and average particles size of 29.0 µm. The tubular membrane produced with granite residue presented porosity from 17 to 30%, pores size in the range of 0.06 to 0.14µm and water flow from 10 (at 2 Bar) to 24 L/h.m2(at 4 Bar). These membranes retained 100% of indigo particles and was effective in the separation of indigo. The membrane prepared with alumina residue presented porosity close to 58% , pore size of 0.96 µm and water flow from 68 to 80 L/h.m2(at 2 Bar). These membranes were applied with successes in the separation of water from emulsion (100 ppm oil/water) with rejection above 96%. The membrane prepared with kaolin residue presented pore size from 0.16 to 0.22 µm, porosity from 41 to 44% and water flow from 53 to 70 L/h.m2. The ceramic membranes with industrial residues were successfully produced and applied in the treatment of industrial effluents.