Finite element, meso-scale models provide a means to probe the mechanistic driving forces for particle evolution during sintering and were applied in a companion paper [Djohari, H., Martínez-Herrera J., Derby, J.J., 2009. Transport mechanisms and densification during sintering: I. Viscous flow versus vacancy diffusion. Chem. Eng. Sci., in press, doi:10.1016/j.ces.2009.05.018.] to compare different behaviors of the sintering of glassy particles by viscous flow and the sintering of idealized crystalline systems without a grain boundary via vacancy diffusion. Here, the effects of a grain boundary are included in the meso-scale model and resultant behavior is compared to prior cases. A grain boundary acts as a sink for vacancies, drawing a flux toward itself and allowing for their accumulation and collapse. The resultant solid-body motion of the particles leads to significant shrinkage at the onset of sintering; neck growth with little shrinkage was observed in systems without a grain boundary. These effects are scaled by the magnitude of the grain boundary diffusivity and the size of the dihedral angle.
Bibliographical noteFunding Information:
Acknowledgment is made to the Donors of the American Chemical Society Petroleum Research Fund and to the Minnesota Supercomputing Institute for partial support of this research.
Copyright 2009 Elsevier B.V., All rights reserved.
- Materials processing
- Mathematical modeling
- Powder technology
- Transport processes