Densification of irregular polydispersed glass particles described as a complex relaxation process

Abstract

The sintering of compacts of irregular non-crystallising glass particles was studied by isothermal and constantrate heating experiments in a hot stage microscope. The resulting data fitted very well to kinetic equations developed in this study, in which sintering is assumed to be a complex relaxation process, described by the Kohlrausch–Williams–Watts (KWW) relaxation function. The effect of compact pressing pressure, heating rate, and particle size distribution on the sintering curve was determined. It was generally verified that the effect of temperature on the sintering rate could be described by the effect of temperature on the inverse of glass viscosity. For industrial particle size distributions, that the pre-exponential factor of the process rate constant (or inverse of relaxation time) increased with pressing pressure and decreased with the inverse of particle mean radius. For abnormally wide particle distributions a combination of KWW functions were required.