Description and interpretation of the two phase flow behaviour of melts with suspended crystals

New phenomenological flow equations, sigma(epsilon) and eta(epsilon), are developed for the non-Newtonian flow behaviour of suspended particles in a non-Newtonian fluid with 'shear-thinning effect'. These can also be used for glass-ceramic melts (crystals in high-viscous glass melts) based on the superposition of recently developed flow equations for the non-Newtonian flow behaviour of single-phase glass melts. The viscosity decrease of two-phase systems is a two-step decrease in contrast to the one-step decrease of one-phase fluids. This difference is shown experimentally and described well by these new equations. The measured values of two different glass-ceramic melts from the lithium disilicate systems were fitted by the equations with coefficients of regression, R(2) = 0.87 to 0.96.