Eduardo Luis Schneider

Analysis Method of Mobile Phone Batteries Remaining State of Charge

The cell phone is among the electronics which have quickly attracted consumers throughout the world with an average usage time of a year and a half, generating with this, a considerable environmental impact. This paper presents a literature review on components of batteries, important factors in battery performance, state of charging and health determination. In this study, through the unloading constant current CC test, it was possible to obtain, in a fast and efficient way, the amount of energy remaining and the state of charge from the lithium-ion mobile batteries discarded by the population, showing that many of the discarded batteries could still be reused as an energy source.

Argamassas geopoliméricas à base de cinzas volantes álcali-ativadas contendo areia de fundição

Casting processes comprise the steps of melting and pouring metal into molds, obtaining the required solid shape. Among the materials employed in molds, sand casting mold is the most common process due to lower cost. The casting industry uses sand mixed with organic, inorganic and mixed resins for the production of the cores and molds, in which the metal is cast to form several parts. This process generates a large amount of residual sand, called sand of casting, which has to be discarded in special landfills. Thus, this study aims to investigate the feasibility of using sand of casting to replace conventional sand of building in alkali-activated mortars. These mortars were prepared from alkali-activated fly ash, and metakaolin with four different sand of casting substitution levels: 25%, 50%, 75% and 100%. After 7 and 28 days of curing at room temperature the samples were tested for compressive strength. Microstructural characterization was performed at the age of 28 days with the help of X-ray diffractometer and infrared spectrometer. In the different traits were perceived a need to increase the water of the mortar composition as the proportion of sand of casting was increased. This increase in water influenced the decrease of compression strength of mortar to the extent that the level of replacement of sand of casting was increased.

Heat Treatment as an Alternative to Brass Warping

This paper proposes the reduction of warping after the machining of alloys of brass with lead. For this purpose the brass alloys were submitted to heat treatment and analyzed before and after the machining process. Elongation and dimensional variation, microstructure and chemical microanalysis of the samples were assessed. It was found that warping may be related to the chemical composition of the alloy, added to the rolling process used to obtain the material to be machined. The results showed that heat treatment before the machining process eliminates the warping seen in the workpieces.

Superficies Nanoestructuradas de la Aleación Ti6Al4V: Influencia del Tiempo de Electropulido

The aim of the present research was to study the influence of operational parameters in the electropolishing process of titanium alloys, involving nanostructured surfaces. The electropolishing operational parameters influence the formation of nanostructured materials, promoting the obtainment of specific properties. In this work, a variation time was studied to produce nanostructured surfaces by the electropolishing process. The surfaces obtained were evaluated by atomic force microscopy and surface hydrophobicity was determined by the measurement of the contact angle. Preliminary results showed that the control on the size and depth of nanostructures on these surfaces is possible by electropolishing time variation.