Kinetic field approach to study liquid phase sintering of ZnO based ceramics

Liquid phase sintering kinetics in the system ZnO–Bi₂O₃–Sb₂O₃ was studied using closed crucibles and an optical dilatometer. A modified kinetic field technique was applied for the first time to investigate the densification rates. The values obtained were assessed with existing liquid phase sintering models. Grain growth data were derived from the kinetic field diagram and compared to those obtained from microstructure analysis of quenched samples. Good agreement was obtained between both techniques. Values for both the activation energies (activation energies for grain growth and densification) were also reported for the ZnO–Bi₂O₃–Sb₂O₃ system for the first time. In the initial sintering stage mechanisms were identified which retard densification and are essentially unaffected by temperature. It was shown how the position and slope of the iso-strain lines in the modified kinetic field diagram can be used for a qualitative understanding of the interaction of coarsening, liquid redistribution and densification during sintering.