The effect of liquid-phase preoxidation on the use of carbon fibers in Al2O3-C refractories

Short carbon fibers were treated with an ultrasonic-enhanced liquid-phase oxidation method and introduced into Al₂O₃-C refractories. The effects of different liquid-phase preoxidized carbon fibers on the mechanical properties and thermal shock resistance of the refractories were compared and investigated. The results indicate that ultrasonic-enhanced liquid-phase preoxidation can effectively modify the surface of carbon fibers, thereby affecting the structural evolution and usage effect of carbon fibers in Al₂O₃-C refractories. Appropriate liquid-phase preoxidation treatment for carbon fibers can enhance their strengthening effect on the mechanical properties of Al₂O₃-C refractories. After the addition of carbon fibers treated with liquid-phase preoxidation for 20 min, compared to the refractories without carbon fibers, the cold modulus of rupture, cold crushing strength, and hot modulus of rupture of Al₂O₃-C refractories (after 1300°C heat treatment) increased by 15.4%, 10.3%, and 36.7%, respectively. Furthermore, the introduction of liquid-phase preoxidized carbon fibers can have a positive effect on the thermal shock resistance and toughness ratio of Al₂O₃-C refractories.