A Capacitance Probe for Measurement of Bubbles in Molten Metals

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    • FU Qian
    • Department of Materials Science and Mineral Engineering, University of California


A probe has been developed for measuring bubble size, velocity and frequency in molten metals. The probe has been tested on a low melting point alloy (Belmont alloy) and on aluminum. Bubble signals are discernible in either metal. The probe measures the change in capacitance between a wire and the metal as a bubble passes. Because there is no electrical contact necessary between the wire and the metal, the wire may be sheathed with a material (<I>e.g.</I> alumina) that is inert to the metal. The ruggedness of this design was demonstrated by its use for three hours in aluminum. A bridge circuit which can measure the small capacitance change was devised and a deconvolution procedure has been developed whereby bubble size distributions can be obtained. Measurements have been made of the bubble size and velocity above J-shaped nozzles through which argon was injected. Similar measurements have been made of the bubble size distribution above a porous alumina plug and the bubbles were larger than those observed in water at a comparable flowrate.


  • Transactions of the Iron and Steel Institute of Japan  

    Transactions of the Iron and Steel Institute of Japan 39(4), 309-318, 1999-04-15 

    The Iron and Steel Institute of Japan

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