The effect of liquid‐phase preoxidation on the use of carbon fibers in Al ₂ O ₃ ‐C refractories

Abstract Short carbon fibers were treated with an ultrasonic‐enhanced liquid‐phase oxidation method and introduced into Al 2 O 3 ‐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 Al 2 O 3 ‐C refractories. Appropriate liquid‐phase preoxidation treatment for carbon fibers can enhance their strengthening effect on the mechanical properties of Al 2 O 3 ‐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 Al 2 O 3 ‐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 Al 2 O 3 ‐C refractories.