Research On Al₂O₃-SiC-C Castables For Blast Furnace Trough Strengthened By Sialon In-situ Synthesized

The paper mainly aims at the unsatisfied status that service life of castables for iron trough has not been greatly improved for decades. According to the in-situ reaction mechanism and thermodynamics calculation, castables with excellent performance and long service life, which called as Sialon strengthening Al2O3-SiC-C castables for iron trough, have been successfully prepared by adding presursor of Sialon and changing binder agent.Technical factors affecting the properties of the developed castables have been systematically studied, among which the adding amout of presursor is the research emphasis. The reason and mechanism that the Sialon strengthening castables possess high physical performance and good resistance to molten iron and slag have also been analysized and discussed by means of XRD and SEM in the present paper. The results show that the excellent properties of the advanced castables essentially depend on Sialon synthesized by the in-situ reaction of Si3N4 and Si with Al2O3, which would change the combining formation of matrix and further improve the solid-solid combination rate of matrix.Replacing high-aluminous cement with silica-alumina colloid powder as binder agent, the properties of Sialon-strengthening castalbes can be improved further, especially in terms of hot modulus of rupture. Besides, the effect of amount of nano-powder on the properties of the Al2O3-SiC-C castables has been investigated. Explanation to the acquisition of improved performance has also been presented through microstrucrure analysis.The developed castables have been successfully used with the molten iron passed by one trough once (without repairing) more than 150 thousand tons, reaching the leading level in the native. It is resulted that the Sialon-strengthening castables have high fluidity, good installation properties and excellent resistance to molten and slag. Its usage can evidently reduce the cost of per ton iron, alleviate the labour intensity, improve the production environment and reduce producton cost of iron-making accordingly.