The Variation of Apparent Porosity Through a Slip-Cast Sillimanite Tank-Block

JSGT 1944 V28 T152-T157

Determinations were made of the apparent porosity of forty-five representative specimens taken from different parts of a slip-cast sillimanite tank-block, and they were repeated after the samples had been subjected to each of three successive refiring treatments at 1500° for 4hours. The mean value for the whole block, as received, was 20.3%, but individual values varied from 18.9 to 21.4%. The highest values ranged, in general, round positions 6 to 9 inches from the bottom of the block when cast. Thus, the mean porosity values at depths of 1 inch, 3 inches, 6 inches, 9 inches and 11 inches were 19.8, 20.4, 20.5, 20.6 and 20.1%, respectively. Prolonged firing gradually decreased the porosity of each specimen, the mean values for the whole block being 18.6, 17.9 and 17.6 per cent., after 4, 8 and 12 hours refiring at 1500°, respectively. Suggestions were made to explain the observed differences in porosity.

James Boow