Interrelation between the parameters of equations of viscous flow and chemical composition of glassforming melts

3D diagrams of equations of viscous flow of silicate glass-forming melts

“…Using the expression from [26], mentioned in the Introduction, that T o /T g = 1 − A/α we obtain for the VFT function…”

“…The MYEGA equation represented by expression (4) will be transformed in such a way to include parameter α, using the same relation as in [26] that m=17α/1.2. In addition we take that logη Tr = 13 [dPa·s].…”

“…(3) it is necessary to express logη ∞M through logη ∞A . For that reason we compared the values of these two parameters from [18] which refer to the oxide glasses discussed there, since the correlations in [26] refer to them. Fig.…”

“…Also assuming that fragility index m must be the same and independent of the model, Avramov in [26] finds a correlation between the parameters characteristic for the VFT and the AM equation. Avramov assumes that pre-exponential factors in the VFT and AM equations are not necessarily the same so he denotes them in a different way and finds a relation between them.…”

Dependence of the parameters of equations of viscous flow on chemical composition of silicate melts

“…The problem is that in the temperature interval of practical interest 2 3 b Tr T b1 one can find for each of the equations suitable parameters making the predictions of power and hyperbolic functions quite similar. Therefore, it was found [14] that there is a correlation between parameters of AM equation and those of VFT equation. The important difference appears at temperatures well below T r where hyperbola tends to infinity.…”