Preparation Of Unfired Corundum-Spinel Purging Plug Brick For Steel Ladle

Secondary refining has become an indispensable processing during modern steel-making with the development of science and technology and the requirement to steel quality.As the most important functional component for ladle in secondary refining,purging plug brick has received more and more attentions by domestic and foreign researchers.Traditional purging plug brick has some disadvantages such as the lower high temperature strength,thermal shock and corrosion resistance,and thereby cracks and penetration by molten steel occur during secondary refining.Therefore,the study of purging plug brick with excellent performance for ladle has very important meaning.Based on the previous study,aimed at improving the strength,slag resistance and thermal shock,corundum-spinel purging plug brick samples were prepared using tabular corundum,spinel,activeα-Al₂O₃ micro-powder,pure calcium aluminates cement as main starting materials in this paper.The influences of pure calcium aluminates cement,α-Al₂O₃ micro-powder,SiO₂ micro-powder,spinel and water-reducing agents on the properties of samples were investigated.Slag resistance was compared with the domestic sample with better properties.The microstructures were analyzed by SEM.The results show that:1) The influences of pure calcium aluminates cement on the properties of the samples are different at different heat-treatment temperatures.Considering the factors of fluidity,the samples have optimum performances when the content of pure calcium aluminates cement is 10%.2) Activeα-Al₂O₃ micro-powder is help for optimizing the structure of matrix.The interaction of activeα-Al₂O₃ micro-powder,cement and spinel at high temperature can improve the physical properties.Bending strength and compression strength achieve 25MPa and 115MPa at 1600℃×3h,respectively.SiO₂ micro-powder can improve the room temperature strength of samples whereas high temperature properties deteriorate.3) The performances of samples using fused spinel are better than that using sintered spinel.The samples have optimum performance when the content of fused spinel particles is 15%and fused spinel powder is 5%,respectively. Bending strength and compression strength are 37MPa and 192MPa at 1600℃×3h, respectively.4) The effect of samples using A and F are better than that using polyphosphate and calcium lignosulfonate.