Several mechanisms contribute to the observed pattern formation during current sintering in systems like aluminum doped zinc oxide: Temperature and stress dependent particle rearrangement, particle coarsening, mobility of dopants, phase transformation, heterogeneous Joule heating, and Peltier effect. To be able to simulate and analyze this complex phenomenon, we combine transport calculations by means of a network model, discrete element simulations of particle motion, and a kinetic model for shrinkage and mass transfer between particles. This approach covers conventional sintering, hot pressing, current-activated pressure-assisted densification and other experimental protocols to convert a powder into a polycrystalline bulk solid.
Crucial elements of the model have been successfully developed and applied to special cases: Our model of shrinkage and mass exchange between particles unifies and generalizes previous models. This has been combined with transport calculations in temperature gradients and electrical fields, as well as the possibility of local phase transformation. As a result, two different types of patterns were found depending on the electrical response.