Enhanced oxidation resistance of low‐carbon MgO–C refractories with Al₃BC₃–Al antioxidants: A synergistic effect

Abstract

The synergistic effects of Al3BC3–Al antioxidants on optimizing the oxidation resistance of low‐carbon MgO–C refractories were investigated. The results indicated that the oxidation index and rate constant of low‐carbon MgO–C refractories with optimized Al3BC3–Al additions were 13% and 1.10 × 10−4 cm2 min−1 at 1400°C for 3 h, respectively, which is much lower than that of Al or Al3BC3 containing ones. Single Al3BC3 is not a suitable antioxidant for low‐carbon MgO–C refractories; however, if Al3BC3 was initially protected and Al reacted as the antioxidant, enhanced oxidation resistance at high temperature can be achieved. The formation of dense MgO–MgAl2O4–Mg3B2O6 layer contributed to superior oxidation resistance, and the temperature for the generation of this layer was as low as 1100°C due to liquid and vapor phase–assisted reactions with Al3BC3–Al. Furthermore, a self‐repairing function was achieved at 1600°C with the combination of Al3BC3–Al additions in spite of the faster oxidation rate.

Effect of In Situ Mg-Sialon on the Oxidation Behavior of Low-Carbon MgO-C Refractories

“…The oxygen diffusion was significantly dependent on porosity and pore structure [14,15]. In general, the oxidation rate of the sample would be higher when it has an uncomplicated pore structure.…”

“…The structure and processes of evolution and transformation have an obvious influence on the oxidation behavior of MgO-C refractories [14]. Figure 6 shows the transition region of samples ASM0 and ASM5 after oxidation.…”

“…Extensive studies have been explored to prevent the oxidation of graphite in unburned MgO-C refractories, such as the application of additives [7][8][9], the usage of anti-oxidation coating [10,11], and the modification of carbon source [12,13]. Meanwhile, the in situ formed oxide ceramic phases, like Mg 2 SiO 4 or MgAl 2 O 4 , could influence the mechanical strength, thermal shock resistance, and oxidation resistance of MgO-C refractories [14][15][16]. In order to further enhance the service performance of low-carbon MgO-C refractories, the high-temperature nitridation of MgO-C refractories was performed, i.e., the in situ Si 3 N 4 reinforced MgO-C refractories have been proven to be effective with their optimized mechanical properties and slag resistance [17][18][19].…”

Microstructure and properties of microporous MgO–Al2O3 refractory aggregates from Mg(OH)2 and Al(OH)3

“…MgO-Al 2 O 3 refractories are widely used in steel making and cement production due to their excellent corrosion resistance and high-temperature mechanical properties. [1][2][3][4][5][6][7][8][9] In recent years, efficient thermal insulation refractories have been constantly studied for energy conservation and carbon emission reduction. [10][11][12][13][14] Among these, the lightweight design that used microporous aggregates instead of dense aggregates fabricating the working lining refractories was an efficient method for realizing energy conservation in high-temperature industries.…”

“…MgO–Al 2 O 3 refractories are widely used in steel making and cement production due to their excellent corrosion resistance and high‐temperature mechanical properties 1–9 . In recent years, efficient thermal insulation refractories have been constantly studied for energy conservation and carbon emission reduction 10–14 .…”