CORROSION BEHAVIOR OF Al_2O_3-C BASED REFRACTORIES IN MELTS OF SMELTING REDUCTION WITH IRON BATH

摘要

The corrosion rate of the Al_2O_3-C based refractories in the melts of smelting reduction with iron bath was investigated in the condition of quasi-static immersion and rotary immersion. The corrosion rate of Al_2O_3-C based refractories is decreased with the addition of TiO_2 and ZrO_2 in the Al_2O_3-C based refractories. The corrosion rate in the condition of quasi-static immersion is lower than that of the rotary immersion. The important factors that influence the corrosion rate are FeO content in melts, relative rotary rate between refractory and melts, temperature of the molten bath. The most important factor is FeO concentration. The original constituents of the Al_2O_3-C refractories are Corundum, Mullite, α-Al_2O_3, and graphite. The interaction between the melts and refractories are occurred in the immersion test and the new products of Zirconolite, CaO.SiO_2, Fe_3C and metal Fe are found in the deteriorate layer. The corrosion tendency of Al_2O_3- C-ZrO_2 refractories is lower in the smelting reduction melts than that of the Al_2O_3-C refractories. Zirconolite, CaO.SiO_2, Fe_3C and metal Fe are produced during the interaction between the melts and refractories. The Al_2O_3-C-TiO_2 refractories (AT) have the better corrosion resistance in the smelting reduction melts than that of AC and AZ refractories. The original constituents of AT refractory are TiC network, Mullite, α- Al_2O_3, and graphite carbon. The compounds of TiC, CaTiO_3 and CaSiO_3 are found in the deteriorate layer. Network TiC can improve the corrosion resistance of the AT refractories greatly. The corrosion mechanism of Al_2O_3-C-ZrO_2 refractory is: graphite oxidized in advance, deteriorate layer of refractory and new compounds formed due to the interaction between the constituents of refractory and melts.