Research Of Dry Vibratable Materials For Tundish Working Lining And It's Mechanism Corrosion Resistance By Slag

Tundish is one of key apparatus in liquid steel continuous casting process, which receives the liquid from ladle and makes it become continuous and steady flow then falls it into crystallizer. It also adjusts liquid steel flow and takes the non-metallic inclusions out from the liquid for clean steel in the course. It is very important to select the appropriate refractories to prolong tundish's severlife. The capital problem presently is researching and developing some dry vibratable materials for tundish working lining, which could clean liquid steel and have long servelife.The phase constitutions of Magnesia-based dry vibratable materials is designed by the analysis of phase equilibrium digrams, in which the periclase is host crystalline phase, the Spinel, Forsterite and Monticellite et al are the bonding phase in matrix. Some of the materials have been investgated about their properties and microstructure. The result shows that adding modifiers A to the materials can improve its sintering performance, diminish the pore diameter and promote the distribution of the pore diameter in matrix. Adding spinel powder to it can improve its constitution in matrix. Adding chromite powder to it can promote its sintering properties and the constitution of matrix, increase the wetting dihedral angles of solid-liquid, and the chromite powder dissolving into slag can increase the viscosity of slag. All of these will promote the corrosion resistance and penetration resistance of dry vibratable materials by slag.The optimize formula had been selected from lots of experiment and had made it as dry vibratable materials ,which was used in 12-t tundish at one steel plant more than one year. Its average servelife is 40 hours, the maxium is 45 hours. The result shows that the materials has a good integrativty, long servelife, no pollution to liquid steel, baking time short, tundish's volume steady, low slagging, good heat-insulation and separation from tundish easily. Using the materials will cut the cost of steel produce down, diminish the ratio of casting scrap and promote productivity, which is benefit to enterprise and wholesociety markly.An investigation to the microstructure of worn sample of dry vibratable materials for tundish working lining after using 40 hours shows that the materials changes the properties of slag by the chemical filter, increases the viscosity of slag, forms a dense layer at slag/refactories interface, then blocks the more slag penetrate in it. The complex phase formed at the interface, such as magnesiowusite and complex spinel et al, would absorb in more low-melting point minerals, then degrade its melting point and dissolve into slag, which forms low-melting point silicate phase, penetrates into dry vibratable materials along with Monticellite and Merwinite bonding phase by diffusion.