Microstructure,properties, and application of low carbon Al2O3-C refractories used as submerged entry nozzles

With the aim to achieve the application of low carbon Al₂O₃-C refractory as submerged entry nozzle (SEN) materials, a comprehensive study on the microstructure, thermo-mechanical properties, as well as application performance during use in the continuous casting was carried out by comparing with the traditional one. Both hot and cold modulus of ruptures of the low carbon Al₂O₃-C refractory were superior to the traditional one, and its thermal shock resistance still kept in an acceptable level. The increase in the amount of SiC whiskers and the enhancement in the sintering are considered as the strengthening mechanism. In the industrial trial, the rapid loss of graphite caused by the large level fluctuation made the traditional Al₂O₃-C refractory more susceptible to flux corrosion. For the low carbon Al₂O₃-C refractory, however, the dense structure and the adhesion of viscous slag layer suppressed the slag penetration. Besides, the remaining SiC phases were also difficult to be wetted and dissolved by the flux. As a consequence, a better corrosion resistance was obtained, achieving a decrease of 27.6% in the average depth of the corrosion groove after working for 8 hous.