Finite Element Simulation of Pyroplastic Deformation, Anisotropic Shrinkage and Heterogeneous Densification for Ceramic Materials During Liquid Phase Sintering Process

Pyroplastic deformation is a distortion of the ceramic shape during the sintering process. It occurs because of the flow of the vitreous phase at high temperature and the applied stress due to the weight of the product during the sintering process. The aim of this paper is to describe a numerical-experimental method to evaluate the pyroplastic deformation, to predict the anisotropic shrinkage and heterogeneous densification for ceramic materials during the liquid phase sintering process, as a function of the sintering time. For this purpose, three experimental configurations including midpoint deflection, sinter bending, and free sintering test were designed. The finite element method is implemented by the CREEP user subroutine code in ABAQUS. The fair accordance between simulation results and experimental data reveals that the shear and bulk viscosity modulus as well as dynamic viscosity used in the simulation are near the real ones. The anisotropic shrinkage factor 𝐾𝑥𝑦 has been proposed to investigate the shrinkage anisotropy. It has been shown that the shrinkage along the normal axis of casting slip is about 1.5 times larger than that of casting direction. The inhomogeneity in Von-Misses, pressure, and principal stress intensifies the density non-uniformity in the samples.