Resumo Diferentes gravidades, maiores ou menores que a terrestre, influenciam no processo de solidificação dos materiais. A fim de estudar esses efeitos, em ligas metálicas e semicondutores, iniciou-se o desenvolvimento de uma centrífuga no Laboratório Associado de Sensores e Materiais do Instituto Nacional de Pesquisas Espaciais (LAS/INPE). O objetivo do equipamento é simular altas acelerações durante as fases da solidificação de materiais e simular as condições de lançamento do foguete VSB-30, veículo que atinge cerca de 180 RPM (rotações por minuto) durante o voo ascendente, utilizado para realização de experimentos em ambiente de microgravidade. Assim, esse trabalho apresentará o projeto, a fabricação de componentes e a montagem da centrífuga para estudo da influência da aceleração da gravidade na solidificação de materiais. Palavras-chave: Centrifuga; Solidificação; Alta gravidade.
Brazil has a Microgravity Program mainly based on experiments using sounding rockets. This paper presents a brief account of the Program and the experiments made on the Brazilian rockets. Up to now three missions carrying a total of 26 experiments were made. In all flights a fast solidification furnace, capable of producing temperatures up to 900• C, was tested with semiconductor and metal alloys. This paper describes the construction and the performance of that furnace during the last parabolic flight, occurred in 2010. The solidification furnace is now qualified and ready to be used by other institutions in sounding rocket flights.
Rotary friction welding process (RFW) is one of the most used processes in the world for manufacturing bimetallic components that require high mechanical strength. All process occurs in solid state at temperatures below the melting point of the involved materials, having as the main bonding mechanisms the diffusion and mechanical mixture. The purpose of this work was to carry out an experimental thermal analysis of the dissimilar joint AA6351 T6 aluminum and AISI 304L stainless steel during the friction welding operation through system of thermocouples. Gradients of temperature obtained had their data analyzed and recorded. Results of the experimental thermal analysis showed the behavior of the temperature in the bonding interface, how the dissipation occurs in the radial and longitudinal direction, heating rates, cooling, maximum temperatures reached, its relationship with the different stages of the process and the influence on mechanical properties of welded joint. This study is of great importance for relating the temperature distribution in the bonding interface with atomic diffusion and mechanical resistance of junction.
The Brazilian Microgravity Program is mainly based on experiments carried out on sounding rockets. Up to present days, three missions carrying a total of experiments were made. n all ights, a fast solidi cation furnace, capable of producing temperatures up to 900º C, was used to process metal and semiconductor alloys in microgravity environment. This paper has described the furnace and the solidi cation experiment made during the last parabolic ight, called Maracati Mission, which has occurred in ecember, 0 0.
Brazil has a Microgravity Program mainly based on experiments using sounding rockets. Up to now, four missions have been carried out with approximately 35 experiments submitted in total. In all flights, the Associate Laboratory of Sensors and Materials of the Brazilian Space Research Institute (LABAS/INPE) participated with a fast solidification furnace, capable of producing temperatures up to 900 °C, which was tested with semiconductor and metal alloys. This paper describes the construction and the performance of that furnace during the last parabolic flight, Rio Verde Mission, occurred in 2016. The solidification furnace is now qualified and ready to be used by other institutions in sounding rocket flights.
The study of materials processed in centrifuges improves the understanding of the acceleration influence in the convection behavior in materials processing. This work aims to study the influence of high gravity in PbSn eutectic alloy solidification using a small centrifuge designed and built in the Associate Laboratory of Sensors and Materials of the Brazilian Space Research Institute (LAS/INPE). The samples were analyzed by densitometry and scanning electron microscopy (SEM).
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