Designing Insulating Ceramic Foams for High-Temperature Furnace Lining
Traditional materials have high fused silica content to lower thermal expansion, absorb thermal radiation and enhance thermal shock resistance. However, silica migrates to surfaces under a reducing atmosphere, because solid SiO2 converts to SiO vapour. Commercial Al2O3–SiO2 and Al2O3–ZrO2–SiO2 linings present high porosity (70–85 vol.-%), but densify during use due to silica based binders. An alternative should be a plain Al2O3 insulating lining, but it presents low thermal shock performance and higher thermal conductivity. This work presents
the design and application of Al2O3-based foamed lining refractories with low and stable thermal conductivity (0,25 W/m·K), high porosity (84 vol.-%), good compressive strength and high resistance to thermal shock. This material was applied as insulating lining in a glass melting furnace operating at 1700 °C. The proposed porous ceramic showed lower energy consumption when compared to commercial ones.