Application of SiC whiskers synthesized from waste rice husk in low-carbon MgO–C refractories

In this study, we converted renewable rice husk into SiC whiskers and added them to low-carbon MgO–C refractories to investigate their effect on the structure, thermomechanical properties, and slag resistance of the refractories. Overall, the addition of 1 wt% SiC whiskers promoted the growth of columnar β-Si3N4 and flaky Mg2SiO4, and the refractories maintained high mechanical properties after thermal shock as compared to the refractories without addition of SiC whiskers. In particular, the CMOR and CCS before and after thermal shock were increased by 32%, 16%, 17%, and 19%, respectively. Further, the SiC whiskers loaded with catalyst (denoted as SiCwsc, 1 wt%) were introduced into refractories, the presence of the catalyst resulted in a change in the whisker structure to a chain-bead morphology, which improved the bonding strength with the matrix. Moreover, the introduced catalyst also promoted the formation of columnar β-Si3N4 and flaky Mg2SiO4. The mechanical properties, thermal shock resistance, and slag resistance of the refractories were further enhanced, its CMOR and CCS before and after thermal shock were 11.0 MPa, 9.3 MPa, 68.8 MPa, and 56.0 MPa, respectively.