Comparative Study on the Effect of In Situ MgAl ₂ O ₄ and ZnAl ₂ O ₄ on the Properties of Al ₂ O ₃ –SiC–C Based Trough Castables

ABSTRACT Blast furnace troughs play a crucial role in transferring hot metal to transport vessels. Over time, trough refractories have evolved from hydrous clay‐based materials to anhydrous masses, SiC‐containing materials, and low‐cement Al 2 O 3 –SiC‐based castables. However, refractory linings remain susceptible to slag and metal corrosion, as well as mechanical and thermal spalling, abrasion, and oxidation during service. This study examines the effect of in situ spinel formation—zinc aluminate (ZnAl 2 O 4 ) and magnesium aluminate (MgAl 2 O 4 )—on the properties of Al 2 O 3 –SiC–C (ASC) castables. Spinel‐forming compositions were prepared by adding 2.8 wt% MgO and 4.4 wt% ZnO. The castables were designed using the Dinger and Funk particle size distribution model ( q = 0.21) and evaluated for physical and mechanical properties. Corrosion resistance was tested using blast furnace slag via the static cup method, along with phase and microstructural analyses. Results show that the ZnO‐modified castable achieved higher bulk density, lower apparent porosity, and greater cold crushing strength after firing at 1500°C compared to MgO‐modified and reference samples. XRD and microstructural analyses confirmed ZnAl 2 O 4 spinel formation, enhancing densification and reducing slag penetration, indicating its strong potential for refractory applications.