USSR Cooperative Research on Heat and Mass Transfer During Directional Solidification in a Centrifuge

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This is a joint research project between Clarkson University and the Laboratory of Materials Science in Space at the Space Research Institute (IKI) of the USSR Academy of Sciences to elucidate the transport phenomena that occur during directional solidification in a large centrifuge. Clarkson University and the Space Research Institute (IKI) are uniquely configured to accomplish this goal. Prior research on transport phenomena in large centrifuges has shown unexpected results that have not yet been fully explained. For example, a critical rotation rate was found for the onset of temperature oscillations, with a higher critical rotation rate for cessation of temperature fluctuations. Several directional solidification experiments exhibited a "magic g" at which impurity segregation and microstructure became what one would expect from a complete lack of convection in the melt during solidification. Theoretical models will be developed at Clarkson University to predict convection and mass transfer in the melt, temperature distribution in the solid, solid-liquid interface shape, and freezing rate during solidification in the centrifuge. Predictions of these models will be compared with experiments carried out on the Soviet apparatus. Clarkson and IKI scientists will work together to modify the Soviet apparatus to permit temperatures to be measured inside the material during solidification, and to determine the heat transfer coefficient between the material and the steel cartridge. We will add either current interface demarcation or vibration interface demarcation to allow us to determine the interface shape and freezing rate versus time. We will also cooperate in development and execution of flow visualization experiments in the centrifuge.