Investigation of pore structure and high-temperature fracture behavior of lamellar hydrates bonded alumina-spinel castables

Abstract

Lamellar hydrates of CAC were designed with the introduction of Mg-Al hydrotalcite (M-A-H), and the effects on the early setting behavior, demolding strength, pore structures, mechanical properties, and fracture behavior of alumina-spinel castables were investigated. The results showed that Mg-Al hydrotalcite stimulated rapidly the hydration of CAC and the formation of lamellar C2AH8 and C4AcH11 when curing at 25 and 40 °C. In comparison, CAH10 and C2AH8 were detected without M-A-H and were transformed completely into C3AH6 at 40 °C. The formation of lamellar C2AH8 and C4AcH11 would contribute to a more complicated pore structure, especially in the range of 1–10 µm. Meanwhile, the incorporation of MgO from M-A-H also regulates the distribution of CA6 and spinel (pre-formed and in-situ). Consequently, the optimized microstructure and complicated pore structure can induce the deflection and bridging of cracks, thus facilitating the consumption of fracture energy when testing at 1400 °C.