Abstract Bonding phases play a crucial role in refractories as they significantly affect the mechanical properties of these materials. Wedge splitting test (WST) was used to reveal the influence of… Click to show full abstract
Abstract Bonding phases play a crucial role in refractories as they significantly affect the mechanical properties of these materials. Wedge splitting test (WST) was used to reveal the influence of in-situ non-oxides bonding phases on fracture behaviour of alumina-based castables with different binding systems. The results show that in-situ non-oxide bonded alumina-based castables can be prepared by incorporating Si powders and then in situ nitriding. Unlike oxide bonded alumina-based castables, the castables bonded with in situ non-oxides display typical non-linear fracture behaviour. The index of toughness, GF/σNT, was 44.2–55.4 μm for the non-oxide bonded alumina-based castables, which is nearly twice the corresponding value for the oxide bonded alumina-based castables (20.3–28.9 μm). The improvement in toughness is attributed to formation of micro-crack network in the microstructure of non-oxide bonded alumina-based castables, which caused by coefficient of thermal expansion (CTE) mismatch existing between corundum aggregates and in-situ non-oxide bonding phase. Compared with oxide bonded alumina-based castables, the fracture behaviour of in-situ non-oxide bonded alumina-based castables is not sensitive to changes in the bonding system.
               
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