SrBi 4 Ti 4 O 15 ceramics were prepared via ordinary firing (OF) and hot forging (HF). Characterization using scanning electron microscopy and X-ray diffractometry shows platelike grains that were highly oriented (F = 0.95) after hot forging. Ferroelectric, dielectric, and piezoelectric characterizations revealed that polarization reorientation was restricted to the ab plane of the orthorhombic structure, parallel to the (Bi 2 O 2 ) 2+ layers. The thickness coupling factor for OF samples was only half that for HF samples oriented parallel to the HF direction (in the ab-plane), as a consequence of poling restrictions in randomly oriented grains.

This study proposes a new method to obtain hydrophobicity classification (HC) in high voltage polymer insulators. In the method mentioned, the HC was analyzed by fractal dimension (fd) and its processing time was evaluated having as a goal the application in mobile devices. Texture images were created from spraying solutions produced of mixtures of isopropyl alcohol and distilled water in proportions, which ranged from 0 to 100% volume of alcohol (%AIA). Based on these solutions, the contact angles of the drops were measured and the textures were used as patterns for fractal dimension calculations.

Many researchers have been studying coconut fibers due to its being a natural and renewable source. Moreover, coconut waste is discarded in landfills, bringing environmental problems because this material, although natural, takes time to be degraded. The use of natural fibers such as coconut fibers has become industrially attractive because of its low cost, high availability and desired mechanical properties for some applications, such as panels, ceilings, and partition boards and automotive components. In this study, polymers with coconut fiber composites were made by injection processing and mechanically characterized by tensile and dynamic testing. The fiber content ranged from 0 to 30wt%. The results of Young's modulus obtained from both methods decreased with fiber load and were nearly identical up to 15wt% of fiber, about 1.1GPa, but the increase in fiber concentrations distinctly interferes with each method in the values obtained.

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It is well known that the heating mechanism and powder precursor defi ne the microstructural characteristics of ceramics. Especially abnormal grain growth of pure alumina ceramics developed during conventional sintering method suggests that this material is a potential candidate to be treated in microwave sintering process. Alumina ceramics produced with commercial (A1K) and chemically synthesized powders were sintered in conventional and microwave furnaces. Two methods were employed to prepare the chemically synthesized nanosized powders: Pechini method and emulsifi cation with oleic acid. The microwave sintered samples were characterized by apparent density and scanning electron microscopy and compared with the samples sintered in a conventional furnace. Alumina ceramics sintered in the microwave furnace had fi ne grained microstructure, not related with the starting powders. This characteristic was achieved in a sintering time shorter than those produced in the conventional furnace. However, satisfactory densifi cation was observed only to A1K ceramics (3.95 g/cm 3 ) sintered during one hour in microwave furnace.

Although the hydrophobicity is usually an arduous parameter to be determined in the field, it has been pointed out as a good option to monitor aging of polymeric outdoor insulators. Concerning this purpose, digital image processing of photos taken from wet insulators has been the main technique nowadays. However, important challenges on this technique still remain to be overcome, such as; images from non-controlled illumination conditions can interfere on analyses and no existence of standard surfaces with different levels of hydrophobicity. In this paper, the photo image samples were digitally filtered to reduce the illumination influence, and hydrophobic surface samples were prepared from wetting silicon surfaces with solution of water-alcohol. Furthermore norevious studies triying to quantify and relate these properties in a mathematical function were found, that could be used in the field by the electrical companies. Based on such considerations, high quality images of countless hydrophobic surfaces were obtained and three different image processing methodologies, the fractal dimension and two Haralick textures descriptors, entropy and homogeneity, associated with several digital filters, were compared. The entropy parameter Haralick's descriptors filtered with the White Top-Hat filter presented the best result to classify the hydrophobicity.