Computer Simulations of Binder Removal From 2-D and 3-D Model Particulate Bodies.
Computer Simulations of Binder Removal From 2-D and 3-D
Model Particulate Bodies.
Lewis, J. A.; Galler, M. A.; Bentz, D. P.
Journal of the American Ceramic Society, Vol. 79, No.
5, 1377-1388, 1996.
binder removal; building technology; capillary
transport; computer models; microstructure; particulate
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.