Parameters influencing the characteristics of sol-gel bonded aluminosilicate based refractory castables

Refractory castables (monolithic refractories) have gained much more attention in recent years compared to the shaped refractories due to easy and cheap installation. Castables composition is composed of aggregates, filler, binder and additives. Replacing calcium aluminate cement as hydraulic binder by silica sol as sol-gel binder for refractory castables is known to reduce the drawbacks of hydraulic binders but still comprehensive information regarding the effect of various raw materials and additives are required. In this research bauxite, andalusite and argellite were chosen as aluminosilicate aggregates and silica sol as binder and the effect of citric acid, micro silica and cement as setting agent were investigated for different compositions. Mechanical strength of the obtained castables at different temperatures of ۱۱۰, ۱۰۰۰ and ۱۴۰۰℃ were probed for various compositions. Finally based on the mechanical strength data, workability and flowability of the castables optimum compositions were selected. The effect of sol-gel binder on the corrosion resistance of the optimized compositions were investigated in contact with molten sodium silicate using static cup test. Field emission scanning electron microscopy (FESEM) was used to scan the corroded region. Bauxite based castables showed mechanical strength higher than andalusite-argellite ones, while the later exhibited better corrosion resistance which related to the intrinsic characteristics of the used aggregates.

کلیدواژه ها:

silica sol ، refractory castable ، nano bond ، bauxite ، andalusite ، corrosion resistance