Glass sintering with concurrent crystallisation. Part 2. Nonisothermal sintering of jagged polydispersed particles

PRADO, M. O.; FREDERICCI, CATIA; ZANOTTO, EDGAR DUTRA

PHYSICS AND CHEMISTRY OF GLASSES-EUROPEAN JOURNAL OF GLASS SCIENCE AND TECHNOLOGY PART B

SOC GLASS TECHNOLOGY

Año: 2002 vol. 43 p. 215 - 223

1753-3562

We propose a model, translated into an algorithm, to simu-late nonisothermal sintering of polydispersed glass un-dergoing concurrent crystallisation. The model is basedon the two classical sintering stages proposed by Frenkeland Mackenzie?Shuttleworth. The input parameters aregreen density, particle size distribution, surface tension,viscosity, number of surface nucleation sites (Ns) andcrystal growth velocity. We test the model using physical parameters and densification rates for two distinct glasses: a (devitrifying) cordierite glass having a narrow distri-bution of jagged particles and an alumino-borosilicate glass, ABS (which is stable against crystallisation) hav-ing widely polydispersed jagged particles. The experimen-tal densities of the compacts saturate at slightly different values than predicted. Entrapped gases or glass degassing explains the residual porosity in ABS while partial sur-face crystallisation accounts for density saturation in cordierite glass. The algorithm provides a powerful simu-lation tool to design the densification of (devitrifying or stable) glass compacts having any particle size distribu-tion, subjected to any heating rate, thus minimising the number of time consuming laboratory experiments.