Influence of Particle Size Distributions with Maximum Grain Size of 1 mm on the Density, Density Gradients and Strength of Uniaxially Die-pressed Refractories

Abstract

This study investigates the influence of particle size distributions on the density, density gradients and strength of alumina refractories. To design the particle size distributions, a modified Andreasen model was applied which allows separate adjustment of fine and coarse fractions. Cylinders were uniaxially two-sided die-pressed. Bulk densities and cold crushing strengths o1 fired cylinders were measured. Some samples were axially and radially cut to analyse their density distribution and gradients. Bulk density and strength correlated and were highest for increasing amounts of the finest fraction <0.02 mm up to about 55 mass-%. Density gradients decreased with increasing fine and decreasing coarse fraction amounts. The densest compacts with lowest density gradients were achieved by particle size distributions with about 65 mass-% fine particles (<0.l mm), 1 0 mass-% medium sized grains and about 25 mass-% coarse particles (>0.5 mm).