Research on Corrosion Resistance of Al2O3-MgAl2O4 Refractories and SiC-MgAl2O4 Refractories to Gasifier Slag

Abstract Spinel-containing refractory is a kind of potential chromium-free refractory for coal gasification because MgAl 2 O 4 spinel has good slag resistance. Corundum-spinel refractories with w (Al 2 O 3 )=94%, w (MgO)=5% and SiC-spinel refractories with w (SiC)=64%, w (Al 2 O 3 )=5% were prepared. The crucible specimens were tested for slag corrosion with commercial gasifier slag at 1 500°C for 1 h in reducing atmosphere. XRD analysis were researched on the sidewall of the crucible after slag test. Microstructure and chemical composition of samples in slag corrosion zone were analyzed by SEM and EDS. The results show that the slag resistance of SiC-MgAl 2 O 4 refractory was significantly better than Al 2 O 3 -MgAl 2 O 4 refractory. The corundum particles were decomposed into fine particles by the slag, and the microstructure was destroyed. The oxidation of the surface of the silicon carbide particles formed a high-viscosity glass phase with the infiltrated slag, which was benefit to prevent the slag penetration into the interior. And a solid solution of (Mg, Fe)O·Al 2 O 3 composite spinel was formed in matrix of the sample after slag penetration because MgAl 2 O 4 absorbed FeO in the slag. It is speculated that the spinel solid solution repairs and strengthens the structure of the matrix, which improves the slag resistance.