Effect of In-situ Formed β-Sialon Phases on Performance of Low-carbon Al2O3–C Refractories

The low-carbon Al2O3–C materials were prepared in a coke bed at 1 200 to 1 400 °C with tabular alumina, graphite and reactive α-Al2O3 powder as main raw material. The metallic Al and elemental Si powder were used as additives. The phenol resin was used as a binder. The effects of temperature and β-Sialon phases on the thermo-mechanical properties of low-carbon Al2O3–C materials were investigated. The results show that specimens have Si3N4 whiskers, SiC whiskers and short columnar AlN formed at 1 200 °C. The β-Sialon of whiskers and two-dimensional flake can be generated at 1 400 °C. The formation of SiC whiskers and β-Sialon phases promotes the comprehensive performance of Al2O3–C refractories at 1 400 °C, the cold crushing strength (CCS) is increased by 30.38% (i.e., 87.75 MPa), the cold and hot modulus of rupture (CMOR and HMOR) are increased to 20.01 MPa and 15.69 MPa, respectively, the elastic modulus and the load displacement are increased by >12%. After 3-cycle thermo-shock, the CCS is decreased to only 8.23 MPa. The in-situ formation of phases (i.e., SiC and β-Sialon) significantly improves the thermo-shock stability of refractories.

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