Pool boiling cooling for melt spinning quench wheels

Abstract

The production of rapidly quenched metal ribbons by melt spinning on a cylinder produces very high average heat fluxes through the cylinder. The problem of maintaining a low average casting surface temperature can be solved by boiling on the plain interior of the cylinder. An experimental, boiling cooled, amorphous iron alloy ribbon casting wheel was constructed to verify the concept and expand the available data on boiling heat transfer. Experiments were performed with water, near atmospheric pressure, in pools less than 0.03 m deep and at accelerations between 100 and 200 times earth gravity. Heat fluxes between 0.6 and 3.5 million W/m2 were achieved. Heat transfer coefficients up to 0.1 million W/m2 • K were measured. A loss of cooling occurred in a number of instances, at heat fluxes well below the predicted critical heat flux, and at heat flux conditions which were duplicated or exceeded in the remaining experiments. These conditions, possibly precipitated by local variations in the boiling heat transfer coefficient, are not considered to represent new boiling phenomena associated with high acceleration.