球形镁碳复合骨料对MgO-C耐火材料热震性能的影响

Effect of thermal shock resistance of magnesia-carbon refractories by spherical MgO-C composite aggregate

目前钢包用镁碳耐火材料中较高的碳含量会导致耐火材料向钢水中增碳,并且会使材料有较高的导热系数,导致热量的大量损失。降低碳含量则会导致材料的抗热震性能显著下降,而改变碳源的引入方式可以提高材料的使用性能,为降碳工作提供可能。针对上述问题提出了一种以成球造粒法制备球形镁碳复合骨料,并替代鳞片石墨以提高材料抗热震性能的新方法。结果表明:将球形镁碳复合骨料引入到镁碳耐火材料后,材料的力学性能和抗热震性能均有所提高,其中1100与1550℃热处理后最佳替代量耐火材料的抗折强度与断裂能分别提高了27.93%、15.17%和4.12%、8.84%,热震保持率与残余强度分别提高了9.15%和0.8 MPa,并且热震后的裂纹扩展表现出更多的穿骨料断裂,这主要是球形镁碳复合骨料的加入引入了微裂纹且骨料与基质的同相烧结使基质间结合更紧密所导致的。

At present,the high carbon content in magnesia carbon refractories used in steel ladles can cause the carburization of the refractories into the molten steel and result in refractories with a high thermal conductivity,leading to significant heat loss.Reducing the carbon content will significantly decrease the thermal shock resistance of the material,while changing the way the carbon source is introduced can improve the performance of the material and provide possibilities for carbon reduction.In view of the above problems,a new method was proposed to the prepare spherical magnesium-carbon composite aggregates by the pellet granulation method and replace flake graphite to improve the thermal shock resistance of the material.The results show that the mechanical properties and thermal shock resistance of the materials are improved after the introduction of the spherical magnesium-carbon composite aggregate into the magnesium-carbon refractories.The flexural strength and fracture energy of the best substitution amount of refractories after heat treatment at 1100℃and 1550℃are increased by 27.93%,15.17%and 4.12%,8.84%,respectively.The thermal shock resistance and residual strength are increased by 9.15%and 0.8 MPa,respectively.Moreover,the crack propagation after thermal shock showed more through aggregate fracture,mainly due to the introduction of microcracks by the addition of spherical magnesium carbon composite aggregate and the tighter bonding between the aggregate and matrix caused by the in-phase sintering of the aggregate and matrix.