关键词: MgO-C砖, 富镁尖晶石微粉, 物理性能, 抗氧化性, 热膨胀性

Abstract: To improve the service life of MgO-C bricks,based on analyzing the damage mechanism of MgO-C bricks in the slag line of a 210 t refining ladle with a high refining ratio in a steel plant in China,MgO-C bricks were prepared using fused magnesia grade 97,flake graphite,MgO-rich spinel micropowder,antioxidant (Al powder and Si powder),and phenolic resin as raw materials.The effects of the equivalent substitution of MgO-rich spinel micropowder (0,3% and 6%,by mass) for fused magnesia fines on the physical properties,oxidation resistance,and slag resistance of the samples were studied.The results show that compared with the sample without MgO-rich spinel micropowder,the sample with 3% MgO-rich spinel micropowder has significantly improved physical properties,oxidation resistance,and hot modulus of rupture,as well as decreased linear expansion rate;however,as the MgO-rich spinel micropowder addition increases to 6%,the overall performance of the sample shows a downward trend. After applying the MgO-C bricks with 3% MgO-rich spinel micropowder in the ladle slag line under the smelting condition of high refining ratios,the problems such as “steamed bread” melting loss and vertical cracks of MgO-C bricks were significantly relieved.

Key words: magnesia-carbon bricks, magnesia-rich spinel micropowder, physical properties, oxidation resistance, thermal expansion