Estudo de conformação de cerâmicas à base de zircônia para aplicação em células a combustível do tipo óxido sólido / STUDY OF TAPE CASTING OF YTTRIA STABILIZED ZIRCONIA FOR APPLY IN SOLID OXIDE FUEL CELL

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The hydrogen economy has been risen as new option for supply the growing global demand for energy. A fuel cell is an electrochemical device able to use hydrogen as a energy source. Carbon dioxide (CO2) emission is very low so it is ecologically friendly, once energy is produced by a reaction of hydrogen and oxygen. The production of energy from hydrogen fuelled devices can be done even in small unities and in a distributed way. It can bring energy for isolated communities, where traditional energy distribution systems can not be reached. A fuel cell is composed essentially of 3 components: anode, cathode and the electrolyte. In present days, there are many materials proposed for use as electrolyte in fuel cells. Among then, yttria stabilized zirconia (YSZ) is the most studied and effectively used in solid oxide fuel cell. Tape casting technology is a cheap, simple and efficient way to cast ceramics slurries in laminates thick enough to be used as components for fuel cells. Considering theses aspects, in this work, ceramic thin film forming was studied using tape casting technology with raw materials prepared from Brazilian zircon ores. It is described in literature that ceramic slurries are generally made from powders with low surface area (often between 0,5 to 10m2/g), and the powders used in this study had larger surface area (often between 40 to 80m2/g). The use of zeta potential is indicated to study the stability of a suspension of ceramic powders. However, for suspensions with large concentration of solid, it is also necessary to determine the flow curve, because in these conditions, the double electric layer formed during the stabilization of suspensions can be compressed. In the rheologic properties study, calcined ceramic powders were classified using a set of ABNT series screens and separated and retained by the de mesh 60 screen. Flow curve of suspension was determined in aqueous suspensions of these powders. For tape casting processing, a binder and a plasticizer have to be added to the suspensions to produce YSZ substrates. Poly(vinyalcohol) (PVA) and glycerine were used as binder and plasticizer, respectively, in this work. By the effect of both additives, at a glycerine to PVA rate of 2,25:1, it was possible to produce YSZ substrates.

ASSUNTO(S)

zircônia estabilizado zircônia estabilizado colagem de fitas (tape casting) células a combustível de óxido sólido colagem de fitas (tape casting) células a combustível de óxido sólido eletrólito sólido eletrólito sólido

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