Creep and Densification During Sintering of Glass Powder Compacts

The simultaneous creep and densification of glass powder compacts was studied as a function of low applied uniaxial stress, temperature, and particle size. The creep rate can be expressed as the sum of the contribution from the applied stress that varies linearly with stress, and a contribution due to anisotropic densification that varies linearly with the densification rate. For a constant applied stress, the ratio of the creep rate to the densification rate is almost independent of both termperature and density. While these observations are consistent with the model of Scherer for the viscous sintering of glass, other observations show significant deviations from the model. Both the densification rate and the creep viscosity, which has an exponential dependence on porosity, show much stronger dependence on density compared with theoretical predictions.