O conteúdo dos artigos e seus dados em sua forma, correção e confiabilidade são de responsabilidade exclusiva dos autores. 2018 Permitido o download da obra e o compartilhamento desde que sejam atribuídos créditos aos autores, mas sem a possibilidade de alterá-la de nenhuma forma ou utilizá-la para fins comerciais.

Polymeric syntactic foams are composites made from the mixture of Hollow Glass Microspheres (HGM) and polymer matrices. One of their main characteristics is their low density and the production of these composites using a matrix derived from renewable sources potentiates their development without neglecting sustainability. In this paper , the properties of High Density Polyethylene (HDPE)/HGM syntactic foams containing 1% and 5% w/w HGM and 5% w/w of a compatibilizer are assessed. The composites were prepared by two processing routes: single screw extruder and twin screw extruder. The morphology and mechanical properties (tensile and impact) of the syntactic foams thus manufactured were ascertained. Morphological analysis indicated that matrix/filler adhesion was poor for all samples and that the best HGM dispersions were obtained in twin screw extruded samples. Mechanical properties were affected by the processing route adopted and by the content of hollow glass microspheres added. Elastic modulus, tensile strength and strain were reduced by 20, 10 and 23%, respectively, in systems processed in a twin screw extruder. Impact strength was the exception, with an increase of more than 300%. Higher contents of hollow glass microspheres led to reductions in mechanical strength of the syntactic foams, varying from 5% for the elastic modulus to 50% for strain.

Hot tensile and creep data were obtained for 2.25Cr-1Mo steel, ASTM A387 Gr.22CL2, at the temperatures of 500-550-600-650-700 °C. Using the concept of equivalence between hot tensile data and creep data, the results were analyzed according to the methodology based on Kachanov Continuum Damage Mechanics proposed by Penny, which suggests the possibility of using short time creep data obtained in laboratory for extrapolation to long operating times corresponding to tens of thousands hours. The hot tensile data (converted to creep) define in a better way the region where β=0 and the creep data define the region where β=1, according to the methodology. Extrapolation to 10,000 h and 100,000 h is performed and the results compared with results obtained by other extrapolation procedures such as the Larson-Miller and Manson-Haferd methodologies. Extrapolation from ASTM and NIMS Datasheets for 10,000 h and 100,000 h as well as data from other authors on 2.25Cr-1Mo steel are used for assessing the reliability of the results.

It was sought, in this research, to evaluate the effects of fertilizer solutions on water retention by hydrogel as well as if the application methods and fertilizers affect water retention when the hydrogel is added to the soil. In laboratory works (experiment 1), the completely randomized design was used taking into account four treatments: distilled water; Urea (UR – 2.0 g L-1 ) and Magnesium Sulfate + Monoammonium Phosphate (MS + MAP – 2.0 g L-1  each). Regarding the experiment 2, considering soil columns, a 2x3x2 factorial was used, corresponding to two hydrogel application methods: dry and mixed to the soil or diluted in water and concentrated in the center of the column; three fertilizer solutions: distilled water, UR (2.0 g L-1 ) and MS + MAP (2.0 g L-1  each) with two cycles and three repetitions. An additional witness (hydrogel free) was also added. Total water volume absorbed by hydrogel, volume stored in the soil after each cycle, pH and electrical conductivity (EC) of leached solutions were all analyzed. The MS solution was the one who impacted the most the water absorption by the hydrogel, principally when the hydrogel was not present in the soil. The pH and EC of leached solutions evidenced the fertilizer solutions salinity.

No abstract

2,25Cr-1Mo steels are much used in thermoelectric generation systems, submitted to creep, may have their degraded properties in service provoked by typical microstructural changes, therefore, the knowledge of the heat treatment cycles of this steel are of extreme importance to achieve high mechanical strength combined with low corrosion. In this work, sought to investigate the impact of heat treatment of annealing on microstructure and on the mechanical properties of steel, for such, steel samples were austenitization in argon atmosphere for 2h to 950 ºC and cooled to the oven. The microstructural characterization showed phase perlite and ferrite and presence of carbides dispersed in the array. Hardness testing showed that the treated samples suffered a considerable reduction in their values, whereas the hot traction tests showed a better mechanical strength only in the temperature of 25 ºC end 500 ºC.

This article aims to propose teaching educational techniques that support the understanding of soil erosion and the importance of soil conservation. This port, soil as it is an important natural element that permeates our daily lives, whether through the supply of food, as in the purity of surface and underground waters. In this way, providing educational techniques associated with Soil Education becomes relevant. With this, we provide, through didactic illustrations, to provide this understanding so that it can be improved and disseminated to the academic and school community.