High temperature innovative zirconia-alumina ramming mass

Abstract

Zirconia and high alumina ramming masses stand out as efficacious variants within the domain of unshaped refractories. In the interface between these materials, the utilization of transitional zirconia-alumina ramming mass is recommended. This study delves into the impact of alumina additive on the fundamental properties of ramming mass samples based on calcium oxide-stabilized zirconia, employing a phosphate bond. The investigation encompasses both the characterization of these samples, ranging from cold to heat-treated states across temperatures spanning 200–2100 °C, and an analysis of phase evolution throughout these conditions. The alterations in ZrO2 phases during thermal processing in the presence of Al2O3 and P2O5, along with the ramifications of these transformations on the properties of the ramming mass, are elucidated. Notably, the most comprehensive interaction between P2O5 and cubic ZrO2 materializes within the temperature interval of 1200–1400 °C, resulting in a marked destabilization of the cubic ZrO2 phase accompanied by a marginal reduction in sample strength that remains acceptable. The process of cubic ZrO2 phase destabilization reaches completion at 1700 °C. Elevating the heat treatment temperature of samples from 1700 to 2000 °C engenders the disintegration of aluminium, calcium, and zirconium phosphates, consequently leading to the re-stabilization of ZrO2. This, in turn, fosters densification and fortification of the sample structure. Designed for constituting the functional layer of linings at the interface of combustion and reaction zones within carbon black production reactors, the zirconia-alumina ramming mass with a phosphate bond showcases noteworthy potential. Experimental validation of this developed ramming mass at a carbon black plant has yielded favourable outcomes.