Effects of Light-burned MA90 Spinel Content on Microstructure and Performance of Corundum-Spinel Castables

The corundum-spinel castables with different light-burned spinel content were prepared by fixing total spinel content of 23.5wt% and changing the mass ratio of light-burned and dead-burned MA90 spinel, and then the ladle slag corrosion tests were conducted at 1 600 ℃. The microstructures and slag resistance of the castables were studied. The results show that with the light-burned spinel content increased from 0 to 23.5wt%, the linear shrinkage of the castables increased, the apparent porosity and volume density remained unchanged, and strengths decreased. The cracks were observed in the uncorroded matrix and more cracks were observed in the matrix with a higher content of light-burned spinel after corrosion. With the increase of light-burned spinel content, the slag corrosion resistance of the castables decreased while the slag penetration resistance increased. When the light-burned spinel content was 17.6wt%, the specimen had the optimum performance, which was with the porosity of 15.7%, flexural strength of 26.9 MPa, crushing strength of 107.8 MPa, slag corrosion index of 0.32 and penetration index of 0.91.