EFFECT OF CAPILLARY-PRESSURE ON INTERDENDRITIC LIQUID FLOW

Translucent borneol-paraffin organic binary alloys were used to measure apparent permeability. The top free surface of a mushy zone composed of columnar dendrites was exposed to air and the interdendritic liquid made to flow down out of the specimen by applying pressure differences. The liquid flow rate was measured as functions of applied pressure head, fraction liquid and primary and secondary arm spacings of dendrites lying parallel to the flow direction. It is suggested that capillary pressure is an important factor in the formation of porosity in castings when the free surface of the riser solidifies to form a mushy zone.