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Mass Transfer Processes During Multicomponent Bender Thermolysis

Published online by Cambridge University Press:  25 February 2011

Jennifer A. Lewis  and
Michael J. Cima
Jennifer A. Lewis
Affiliation:
University of Illinois at Urbana-Champaign, Dept. of Materials Science and Engineering, Urbana, IL 61801, (217) 244-4973.
Michael J. Cima
Affiliation:
Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, Cambridge, MA 02139, (617) 253-6877.
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Abstract

Both the binder viscosity and the % saturation will change during the removal of multicomponent binder systems. The effects of these changes were evaluated for the polyvinyl butyral (PVB) - dibutyl phthlate (DBP) system as the plasticizing constituent was selectively removed at isothermal conditions (Tiso < 170°C). Experiments were performed to determine the viscosities of the PVB-DBP system at various isotherms and at different concentrations of DBP. A scaling model was developed to determine the relative importance of capillary forces on the distribution of binder within ceramic compacts during thermolysis. This model was modified to account for the influence of fluid saturation on both the capillary driving force and the permeability of the wetting phase (i.e., binder). Two important results are derived from this analysis: (1) the change in binder viscosity affects the length scale (h) over which capillary forces act to redistribute the PVB-DBP to a greater degree than the change in saturation, and (2) the value of h can be significantly lower than the representative macroscopic dimension of the green compact and still permit a capillary-controlled distribution process for multicomponent binders.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 249: Symposium Q – Synthesis and Processing of Ceramics: Scientific Issues , 1991 , 363
Copyright
Copyright © Materials Research Society 1992

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References

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