Sintering of Glass Frit

Abstract

The objective of this work is to understand the relationship between viscosity and the sintering of glass frit and to show that glass densification occurs via viscous flow within a narrow and predictable viscosity range. In conjunction to this, surface area may only have a marginal influence over viscous sintering and therefore, the sintering viscosity (ηs) should not change with varying particle size. Viscous flow is the primary mechanism for glass densification and the contrast between sintering glass and sintering ceramics is discussed. Hot stage microscopy (HSM) area variance data was analyzed to identify the glass transition temperature (Tg) and sintering temperature (Ts) for compact frit pellets. Sintering temperatures were determined by consolidating glass frit samples and firing them over a range of temperatures in air for two hours. For this work, a system was considered densified when the transition was made from continuous to closed porosity. Microstructural analysis was conducted using scanning electron microscopy (SEM). Photomicrographs revealed that densification mechanisms obeyed the viscous sintering model. Viscosity versus temperature curves were generated using SciGlass and MYEGA calculations. Experimentally determined sintering temperatures were matched with respective viscosities revealing that each glass sintered within the sintering range, ηs=10^(9.6 ± 1.9) Pa·s.