Effect of micro-Al2O3 powders on oxidation and corrosion behaviors of low-carbon MgO–C refractories

To solve the problem of poor high-temperature service performance caused by low carbonization of MgO–C refractories, low-carbon MgO–C refractories with excellent thermal shock, oxidation and corrosion resistances were successfully designed by using SiC whiskers as reinforcing phases and introducing micro-Al 2 O 3 powders as additives. The results indicated that the addition of micro-Al 2 O 3 powders optimized the internal structure of the material, like the columnar β-Si 3 N 4 with a stepped distribution and the mosaic structure formed between granular and flaky Mg 2 SiO 4 , which synergistically strengthened and toughened the material and gave the material excellent mechanical properties and thermal shock resistance. Specifically, the cold modulus of rupture and cold crushing strength after thermal shock were increased by 4.1 and 20.3 MPa, respectively. Moreover, the addition of micro-Al 2 O 3 powders promoted the formation of fine particles of Mg 2 SiO 4 , MgAl 2 O 4 and MgO, as well as a dense protective layer of Mg 2 SiO 4 in the material under high-temperature environment. Furthermore, spinel and high-temperature solid solution were formed in the corrosion environment. The oxidation and corrosion resistances were greatly improved by 41% and 15%, respectively.