Anisotropic sintering stress for sintering of particles arranged in orthotropic symmetry

Recovery strain of ceramics during sintering

“…They found interestingly that the sintering stress can become negative for small values of the dihedral angle, which means that no further densification occurs for that type of material beyond a given density. This result was recently confirmed by Wakai 28,29 . He proved by different methods (energy, force balance and volume averaging) on isotropic as well as anisotropic packings that the sintering stress components are always positive except for low dihedral angle and high densities.…”

Effect of grain boundary sliding on shear viscosity and viscous Poisson’s ratio in macroscopic shrinkage during sintering

“…If the microscopic viscosity is independent of the grain size, Eq. (17) gives g * = 0.005 from r = 150 nm, dD gb = 4.8 Â 10 À26 m 3 s -1 at 1150°C, and X = 8.47 Â 10 À30 m 3 for a-alumina. Here we considered the effect of grain growth during sinter forging.…”

“…The surface curvature and the size of a grain boundary are obtained numerically as functions of these state parameters. The sintering stress tensor is calculated rigorously from the microstructure as has been fully described previously for cubic structures [16] and anisotropic structures [17].…”

“…Riedel et al [7] developed a method to provide a reliable estimate of macroscopic viscosities from the local structure, and derived the constitutive equation by considering both grain boundary diffusion and grain boundary sliding. Their method was recently applied to calculate the sintering stress tensor [17] and the viscosity tensors [18] of anisotropic systems. The macroscopic properties of a powder compact with a random and isotropic structure are calculated by averaging local structure properties over all possible orientations [7].…”

Anisotropic sintering behavior of grain-oriented strontium barium niobate ceramics

“…The shrinkage behavior predicted by the model corresponded to a degree with their experimental results of particle-oriented alumina tapes; with the degree of anisotropic sintering being larger along the direction with more necking per unit length. F. Wakai et al 12), 13) treated the subject using a 3D model. They concluded that in a simple orthorhombic structure in equilibrium, the anisotropic shrinkage rate was dominated by the deviatoric component of the viscous tensor, which was approximately proportional to the logarithm of the aspect ratio of a volume element, and acted so as to deform the elongated structure to be more isotropic.…”