José Carlos Krause de Verney

Properties of SBS and sisal fiber composites: ecological material for shoe manufacturing

The worldwide trend toward using cheap, atoxic and durable materials from renewable resources contributes to sustainable development. Thus, the investigation of the potential use of vegetal fibers as reinforcing agent in polymeric composites has gained new significance. Sisal fiber has emerged as a reinforcing material for polymers used in automobile, footwear and civil industries. In this work, properties such as hardness, tensile strength and tear strength of polymer composites composed by block copolymer styrene-butadiene-styrene (SBS) and 5, 10 and 20% by weight of sisal fiber were evaluated. The influence of conventional polymer processing techniques such as single-screw and double-screw extrusion, as well as the addition of coupling agent on the composite mechanical performance was investigated. Also, the morphology and thermal stability of the composites were analyzed. The addition of 2 wt. (%) maleic anhydride as coupling agent between sisal fiber and SBS has improved the composite mechanical performance and the processing in a double-screw extruder has favored the sisal fiber distribution in the SBS matrix.

Efeito da utilização de areia de britagem em concretos de cimento Portland

The use of crushed sand (artificial sand) for the production of Portland cement concrete can be an alternative, considering the high cost of natural sand in some regions of the State of the Rio Grande do Sul and the environment damages that its exploration can cause. This work presents a study on the viability of sand use from basaltic rock crushing, from the region of the medium plateau in the State of the Rio Grande do Sul, replacing natural quartz sand. Compressive strength and water absorption tests has been carried out in concretes produced with different mix proportioning and different crushed sand content (0%, 30%, 60% and 100%). The result has showed a reduction in the compressive strength and an increase in water absorption with the increase of artificial sand content, considering the greater amount of water required. At a same level of strength, the use of crushed sand has shown good results. Concrete with water/cement ratios of 0.55 and 0.60 with a crushed sand content of 60% and concrete with a water/cement ratio 0,65 with crushed content of 100% have presented favorable results for compressive strength.

AVALIAÇÃO ECONÔMICA DA SUBSTITUIÇÃO DO PROCESSO DE MICROFUSÃO PELA TECNOLOGIA DO PÓ APLICADA AO MECANISMO IMPRESSOR

This work presents a study of the application of new manufacturing processes and the use of new materials for the production of a component of print heads employed in dot matrix printers manufactured by industry. The manufacturer employs a ferromagnetic component produced by casting, which has many steps of manufacturing until the final assembly. During these steps, there is a high rejection rate of parts. The development of a new production process of the ferromagnetic component by powder metallurgy, with the employment of other ferromagnetic alloys and a new geometric model are extremely important to reduce costs of manufacturing. The study involves the production and the evaluation of the performance of samples of ferromagnetic alloys obtained by the powder metallurgy process and the comparison of the results with those generated by samples produced by the process of casting. The replacement of the manufacturing process will propitiate to the manufacturer a reduction of about 36% in manufacturing costs, allowing a more competitive marketing. Keywords: Powder metallurgy; dot-matrix print head; ferromagnetic alloy; manufacturing costs.

Influence of Milling Time During the Mechanical Alloying Process on the Properties of Fe-3Si-0.75P Alloy

In this study the soft magnetic alloy Fe-3Si-0.75P (wt%) was obtained by mechanical alloying through powder metallurgy. The processing included the formulation of metallic powder, wet milling for 1 h, 3 h, 6h and 9 h, in an attritor mill using alcohol P.A. as a lubricant. Cold compaction was then performed in a floating die under 600 MPa pressure and, finally the ring-shaped test specimens were sintered at 1150 °C for 1h. The electrical, physical and magnetic properties were then analyzed using the following assays: Laser granulometry, density, metallography, hysteresis curve and AC permeability, resistivity and XRD. The results showed a strong influence of milling time on magnetic properties of the alloy. There was a decrease in grain size with the milling time, which is likely the cause of increased in magnetic properties.

Avaliação do emprego de carepa de aço como agregado miúdo em concreto

Mill scale is a solid waste formed on the steel’s surface during the lamination step of steel manufacture, usually deposited outdoors at steelmaking industries. This work aims to evaluate the use of mill scale in Portland cement concrete, as a replacement for natural fine aggregate. Concretes with mix proportioning 1:3,5, 1:5,0 and 1:6,5 were produced varying the mill scale content from 0% to 40%, with a given slump 110±10mm, for determination of compressive strength and water absorption. Concrete with mill scale has demanded greater water content to maintain the workability. The results indicated that concretes with water/cement ratios of 0.55 and 0.65 have a compressive strength reduction and greater water absorption as the mill scale content increases.

Desenvolvimento de ímãs para sensor de velocidade para motor de arranque de avião

The aim of this work is develop ferrite magnets used in speed sensor for outburst motor of an airplane, manufactured by the company Aeromot (Canoas – RS). Two magnets types were requested by the company, in the cylinder form and in the ring form. For the magnets manufacturing a raw material was used with known magnetic properties, however, the obtained pieces were appraised starting from the hysteresis curve. Finally the magnets was mounted in the speed sensor prototypes, and submitted the acting tests for the Aeromot company.