Influence of h-BN particle size on fracture behavior and thermal shock resistance of Al2O3-C refractories

h-BN can be applied in Al_(2)O_(3)–C refractories to substitute graphite due to their similar crystal structure and better resistance to molten steel and oxidation.The effects of h-BN particle size on the mechanical properties and fracture behavior of Al_(2)O_(3)–C refractories were investigated through wedge splitting test and microstructural analyses.The obtained results demonstrated that the addition of larger-sized h-BN was conducive to the growth of in situ formed SiC whiskers,which contributed to the highest flexural strength(42.63±3.10 MPa)of specimen D10.In comparison,the smaller-sized h-BN can induce more crack propagation paths along the interface and within matrix,leading to more tortuous crack propagation paths,and thus the thermal shock-related parameters such as specific fracture energy,characteristic length,and thermal shock resistance were improved.Consequently,the residual strength ratio of Al_(2)O_(3)–C refractories was increased from 35.5%to 42.5%with decreasing the h-BN particle size from 10 to 0.1μm.