Effect of process parameters on the properties of alumina-zirconia-graphite refractories (Part 1) - Forming pressure and baking temperature

Alumina-zirconia-graphite (AZG) refractories were obtained through a baking technique using fused Al2O3, partially stabilized ZrO2 and flake graphite as the starting materials with Al, Si, and SiC powder additives. A particle size distribution was designed by the Furnas model for coarse Al2O3 (500-1 000 mum/medium Al2O3 (61-125 mum/fine Al2O3 ( < 44 mum, in which the conten ts of coarse, medium and fine Al2O3 powders were varied with a constant amo unt of fine particles in the matrix. The bulk density increased from 3.05 t o 3.29 g.cm(-3) for the sample with a mass ratio of (coarse Al2O3) / (mediu m Al2O3) = 2.14 the forming pressure being from 100 to 150 MPa. However, wh en the forming pressure increased from 150 to 170 MPa, the bulk density gra dually decreased from 3.29 to 3.26 g.cm(-3). The lowest porosity (5.1%) was achieved by compacting the powders with a mass ratio of 2.14 at 150 MPa. T he average pore size readily decreased from 5.3-5.8 to 3.1-3.9 mum as the f orming pressure increased from 100 to 150 MPa. Besides, the average pore si ze gradually decreased from 3.1-3.9 to 3.0-3.7 mum when the forming pressur e increased from 150 to 170 MPa. The bulk density increased with increasing baking temperature and attained an inflection value at 200 degreesC above which it gradually increased up to 240 degreesC.