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 1 550 ℃ 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.
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