Effect of reactive alumina addition on properties of activated magnesia bonded corundum-spinel castables
To enhance their performance,reactive MgO-bonded corundum-spinel castables were prepared using tabular corundum,reactive alumina,reactive MgO and aluminum lactate as raw materials.The influ-ence of the reactive alumina addition(0,8％,13％and 18％,by mass)on the microstructure,phase com-position,physical properties,as well as the resistance to slag corrosion and penetration of the castables was investigated.The results reveal that:(1)the reactive alumina promotes the sintering of the reactive MgO-bonded corundum-spinel castables,enhancing the bonding between aggregates and matrix,thus densifying the microstructure;(2)with the increase of the reactive alumina addition,the volume stability of the samples increases,the apparent porosity decreases,the bulk density increases,and the cold modulus of rupture and cold crushing strength as well as the slag resistance are improved;(3)the reactive MgO-bonded corundum-spinel castable with 18％reactive alumina shows optimal comprehensive performance,with the bulk density of 3.05 g·cm-3,apparent porosity of 18.5％,permanent linear change rate after heating of 0.31％,cold modulus of rupture of 13.5 MPa and cold compressive strength of 73.8 MPa,as well as the best slag resistance.However,considering particle size distribution and raw material costs,there is no need to further increase the reactive alumina addition.
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