Effect of temperature on the densification/creep viscosity during sintering

Abstract

The densification and creep rates of polycrystalline zinc oxide and of alumina powder compacts have been measured simultaneously in a loading dilatometer, under constant heating rate and constant temperature conditions. The data show that the ratio of the densification to the creep rate is remarkably constant within a wide temperature range for densification, from the earliest stages of densification to at least the onset of the final stage. As a consequence, the ratio of the densification to the creep viscosity is nearly independent of temperature or sintered density. The analysis leads to a simple method for determining the simultaneous densification over the creep rate ratio. The implications of the result for the processing of heterogeneous ceramics and composites are discussed.