Investigating the effect of sintering rate and solvent type on the liquid transport kinetics of α-alumina powder compacts

The ceramic materials' properties and the penetrating liquid both influence liquid transport into ceramic catalytic materials. Terahertz pulsed imaging (TPI) in combination with a flow cell was used to investigate the transport process of polar and less polar solvents into a range of α-alumina powder compacts. The TPI results show that the alumina samples with the largest heating rate (200 °C h−1) have the fastest water transport. The TPI results also reveal that 1-octanol takes much longer to transport through the alumina samples than water, as the viscosity of 1-octanol is much larger than that of water. Since 1-octanol is semi-transparent to terahertz radiation, it was possible to study the liquid transport process and the structural changes behind the liquid front, such as the change in the refractive index of the compact and the fill fraction of 1-octanol in the compact as a function of time.