Abstract
The effective shear and bulk viscosity, as well as dynamic viscosity, describe the rheological properties of the ceramic
body during the liquid phase sintering process. The rheological parameters depend on the physical and thermo-mechanical
characteristics of the material such as relative density, temperature, grain size, diffusion coefficient, and activation
energy. Thermal behavior of the ceramic body during sintering process including the viscose flow deformation,
anisotropic shrinkage, heterogeneous densification, as well as sintering stress, have significant influence on the both
final body dimensional precision and densification process. In this paper, the numerical-experimental method has been
developed to study both rheological and thermal behavior of hard porcelain ceramic body during liquid phase sintering
process. After raw materials analysis, the standard hard porcelain mixture as a ceramic body was designed and prepared.
The finite element method for the ceramic specimens during the liquid phase sintering process are implemented in the
CREEP user subroutine code in ABAQUS. Densification results confirmed that the bulk viscosity was well-defined with
relative density. It has been shown that the shrinkage along the normal axis of slip casting is about 1.5 times larger
than that of casting direction. The stress analysis proved that the sintering stress is more than the hydrostatic stress
during the entire sintering time so, the sintering process occurs completely. The inhomogeneity in Von-Misses, pressure,
and principal stress intensifies the relative density non-uniformity. Dilatometry, SEM, XRD investigations as well as
bulk viscosity simulation results confirmed that the “mullitisation plateau” was presented as a very little
expansion at the final sintering stage, because of the highly amount of mullite formation.
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