Morphological regulation and simulation of β-Sialon and its effect on thermo-mechanical properties of Al2O3-C refractories

Abstract

In this work, β-Sialon of different morphologies was generated using in situ morphological regulation and simulation. Their effects on the thermo-mechanical properties of Al2O3-C refractories were then investigated. The results indicate that columnar, plate-like, and hexagonal prism β-Sialon were formed from specimens without additives, with Fe2O3 as a catalyst, and with Ni as a catalyst, respectively. Transmission electron microscope (TEM) analysis results confirmed that the three morphologies of β-Sialon grow along with (110), (101), and (100), respectively. Density functional theory (DFT) results show that the addition of catalyst atoms could reduce the adsorption energy of gaseous Al2O on different crystal planes, which promotes the formation of β-Sialon. The formation of three different shapes of β-Sialon gave rise to materials with good mechanical strength. The cold modulus of rupture (CMOR) and cold crushing strength (CCS) of the specimen containing plate-like structure was slightly higher than those with a columnar and hexagonal prism, with maximum CMOR and CCS values of 27.2 MPa and 105.2 MPa, respectively. In addition, good thermal shock resistance was obtained due to the formation of β-Sialon; the residual strength ratio of the specimen with columnar β-Sialon was 78% after five thermal shock cycles, and those with plate-like and hexagonal prism reached 93% and 86%, respectively.