Beschreibung
Field Assisted Sintering Technology, or Spark Plasma Sintering(FAST/SPS), is a new innovative sintering and synthesis technique where high heating rates and short cooling periods are achieved. With assistance from the application of external pressure, it enables the drastic reduction of the sintering time, thereby reducing the production time and improving the microstructure and material properties. FEM has been proven to be the best numerical tool to visualize the FAST/SPS process, and numerous modelling methods have been proposed in the literature. Although detailed modelling procedures are available, certain physical aspects have been neglected, such as the effect of electrical field/current on the microstructure evolution during sintering. In this work, a Multiphysics FEM model has been developed to investigate the sintering of a broad spectrum of materials. Gadolinium doped ceria(GDC) and stainless steel 316L(SS 316L) were investigated. The sintering kinetics were studied in detail, and sintering mechanisms for both materials have been proposed. At elevated temperatures and dwell periods, the GDC samples exhibited the development of asymmetrical microstructures even under low electrical fields. This effect has been observed for the first time. Enhanced grain growth was observed at the anode region, and this was attributed to the migration of oxygen ions under an electrical field to the anode, which led to high grain boundary mobility in that region. This experimental observation was also successfully modeled, with the simulations showing accurate results. Furthermore, the modelling procedure was also verified by using the other class of material, SS 316L. In this case, the effect of pressure on sintering was studied and numerically verified.
