Effects of cement content on the microstructural evolution and mechanical properties of cement-bonded corundum castables

Preparation of Al2O3@CaCO3 aggregates and its effects on the thermal shock resistance of Al2O3‐MgO castables

“…From Table 5, HMOR decreased obviously due to the low melting point phases of castables, compared with CMOR. 6 In this test, the HMOR value of castables with different aggregates increased slightly and then decreased. However, the HMOR does not show obvious fluctuation due to the formation of CA 6 phase is not complete at 1350°C.…”

“…[3][4][5] Thermal stress is concentrated at the tip of the cracks, which accelerates crack propagation and generation of new innercracks or surface cracks, further leading to structural fracture after repeated cycles of cooling and heating. [6][7][8][9] Hence, an effective method to restrain crack growth is essential for solving the thermal shock failure problems of Al 2 O 3 -MgO castables.…”

“…Platelet-or plate-like calcium hexaaluminate (CaAl 12 O 16 , often denoted as CA 6 ) is widely used as toughening phase in ceramic matrix composites because of its special morphology, which is prone to make cracks propagate along its cleavage face, and the crack propagation path becomes tortuous and the internal thermal stress is buffered. [10][11][12] Many studies have found that platelet-or plate-like CA 6 can be produced by introducing Ca 2+ in different forms into castables, which can effectively improve the TSR of refractory castables.…”

“…This work uses citric acid aqueous solution and CaCO 3 powders as raw materials to prepare the precursor solution, and then micron-scale CaCO 3 coating was prepared on the surface of the plate-shaped corundum aggregates by heating the aggregates impregnated with the precursor solution at 430°C. The effects of Ca 2+ concentration on the microstructure of the CaCO 3 coating as well as the effects of the in situ formed CA 6 2. The raw materials were dry-mixed in a mixer for 60 s and then wet-mixed for 180 s. After mixing, the castables were molded into the prismatic bars (40 × 40 × 160 mm) and cured at room temperature for 24 h. After demoulding, the castables were cured at room temperature for 24 h, and dried at 110°C for another 24 h. Finally, the as-prepared samples were calcined at 1100°C and 1600°C for 3 h, respectively.…”

“…However, the application and development of the Al 2 O 3 ‐MgO castables were limited by its thermal shock resistance (TSR) because the ladle lining was suffered from periodical thermal shock in service, and then the microcrack appeared in the castables which tends to exist at weak binding sites 3–5 . Thermal stress is concentrated at the tip of the cracks, which accelerates crack propagation and generation of new inner‐cracks or surface cracks, further leading to structural fracture after repeated cycles of cooling and heating 6–9 . Hence, an effective method to restrain crack growth is essential for solving the thermal shock failure problems of Al 2 O 3 ‐MgO castables.…”