Investigating on Viscosity Variation of Molten Zinc via Different Temperatures

Viscosity measurement could provide valuable information for melting and solidification base processes. In this paper a falling ball viscometer is used for measuring molten zinc viscosity. The molten metals are not transparent, some changes are done in the structure of conventional method for tracing ball movement. To solve this problem and in order to trace the movement of the ball (as a falling object) in the melt, a thin steel rod was connected to the ball. The displacement of the ball could then be evaluated from the rod end, which is outside the melt.Viscosity changes versus temperature is studied and as expected the viscosity of the liquid tends to decrease by increasing the temperature. In the beginning the rate of viscosity reduction was high (0.004 cP/°C) but then with increasing temperature the rate of viscosity reduction was decreased (0.0001 cP/°C). Molten zinc is a shear thinning fluid which means by increasing shear rate and mean speed of falling ball the viscosity of molten zinc would drop.