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Rheology of YBa2Cu3O7−x Precursors

Published online by Cambridge University Press:  15 February 2011

Timothy M. Green  and
Mufit Akinc
Timothy M. Green
Affiliation:
Ames Laboratory, Iowa State University, Ames, IA 50011
Mufit Akinc
Affiliation:
Ames Laboratory, Iowa State University, Ames, IA 50011
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Abstract

Nitrate and acetate precursors to Ba2Cu3O7−x (123) are prepared using a molten salt technique. The viscosity and shear stress of the paste are controlled by evaporation of water from the paste. The pastes contain ˜20 - 80 volume percent solids. Rheometry over strain rates of 0 - 200 sec−1 shows both systems are shear-thinning. Both systems are thixotropic. The nitrate system may be described by a two-stage Bingham Plastic model, the acetate by a Hershel-Bulkley model. The existence of more than one region of flow behavior suggests that there are at least two mechanisms which contribute to flow. In the low strain rate region, flow resistance is due to the existence of flocs in the colloidal assembly. At higher strain rates, flow is probably controlled by interlaminar drag interactions. Precursors produced by both methods have been used to form fibers of YBa2Cu3O7−x, by ram extrusion.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 289: Symposium M – Flow and Microstructure of Dense Suspensions , 1992 , 141
Copyright
Copyright © Materials Research Society 1993

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