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Computer Simulations of Binder Removal From 2-D and 3-D Model Particulate Bodies.


pdf icon Computer Simulations of Binder Removal From 2-D and 3-D Model Particulate Bodies. (1401 K)
Lewis, J. A.; Galler, M. A.; Bentz, D. P.

Journal of the American Ceramic Society, Vol. 79, No. 5, 1377-1388, 1996.

Keywords:

binder removal; building technology; capillary transport; computer models; microstructure; particulate body; simulation

Abstract:

A series of computer simulations were developed to investigate the removal of multicomponent, thermoplastic binders from two- and three-dimensional model particulate bodies. Monosized particles with varying diameters were randomly placed in such systems, and all unoccupied pixels were assigned to the binder phase at ratios of 1:9, 1:2, or 1:1 plasticizer (volatile) to polymeric (nonvolatile) species. Simulations were carried out under isothermal conditions to study the influence of liquid-phase transport processes, i.e., plasticizer diffusion in the binder-filled pore network and capillary-driven redistribution of the binder phase, on plasticizer removal rates. Plasticizer diffusion was modeled by a random-walk algorithm, and nonplanar pore development arising from capillary-driven binder redistribution was modeled by an invasion percolation algorithm. For comparison, simulations were also carried out on systems in which binder redistribution was not permitted. In such cases, pore development was modeled as an advancing or nonadvancing planar front. Visualization of transport phenomena on a microscopic scale has provided the first quantitative assessment of plasticizer concentration profiles, C(t) and C(z), and binder-vapor interfacial development during removal. Removal rates were significantly enhanced when capillary-driven binder redistribution was assumed, and they depended strongly on initial plasticizer content under those conditions.