Oxidation Rate of Magnesia-Carbon Refractory with Aluminum Additive

Abstract

An effect of addition of 2 mass % aluminum powder on the oxidation rate of magnesia-carbon refractory, MgO-C, containing 5 mass % carbon has been investigated by measuring weight change with a thermobalance for the cubic specimens in the temperature range from 1073 to 1823 K in air. The oxidation rate of carbon was measured by analyzing the residual carbon in the specimens at some oxidation time. The variations of the weight with oxidation time at temperatures from 1273 to 1673 K showed the similar tendency. The oxidation rate of carbon in the MgO-C refractory with 2 mass % of aluminum additive was a little smaller than that of the MgO-C refractory with no additives. When the oxidation temperature increased to 1823 K, the weight change became very small. It was suggested that the gaps between MgO grains in the thin oxidation layer were bridged by MgO·Al2O3, which was identified by a X-ray diffraction method.

Slag corrosion of MgO–C refractories during secondary steel refining

“…6 with the gas constant R (58?31447 J mol 21 K 21 ), the activation energy E a for the dissolution rate of the MgO-C refractory into the steel refining slag was estimated to 26 kJ mol 21 . This value is lower than that reported in the earlier studies 323, 4 192 11 and 328. 12 The activation energy value derived from Arrhenius equation (9) shows how much the dissolution process of…”

“…The above assumption is based on the fact that the dissolution rate of the MgO-C refractory into molten slag has previously been shown to increase with an increased rotation speed. 4,11 Equation ( 1) can be transformed into equation ( 2), expressing the concentration of solute in weight fractions (wt-%)…”

“…The above assumption is based on the fact that the dissolution rate of the MgO–C refractory into molten slag has previously been shown to increase with an increased rotation speed. 4,11 Equation (1) can be transformed into equation (2), expressing the concentration of solute in weight fractions (wt-%) where K is the rate constant (m s −1 ), ρ b is the bulk density of the slag phase (2790 kg m −3 , according to the Slag Atlas), 15 and (wt-%) s and (wt-%) b are the MgO concentration in the slag at the interface and the bulk respectively. Meanwhile, the concentration of the oxide component to be dissolved into the liquid slag is denoted c b in the bulk and c s at the interface respectively.…”

“…with high iron oxide content. In addition, the earlier studies have either focused on the kinetics of refractory wear through laboratory experiments [11][12][13] or examined thermodynamically the stability of refractory materials at different working conditions or in contact with given ladle slag compositions. 9,14 For real industrial conditions, the wear of the slag lining is a complex process involving different mechanisms as mentioned above.…”

The Effect of Zirconium Disilicide (ZrSi2) Additions on the Carbon Oxidation Behavior of Alumina/Graphite Refractory Materials

“…3) .................... (2) .... (3) Sunayama et al 4) have investigated the influence of aluminum additions on the oxidation rate of Magnesia/ graphite refractory, which showed a slight improvement of the oxidation resistance at temperatures below 1 823 K. Wang et al 5) have investigated the influence of Al 8 B 4 C 7 additions on the decarburization resistance of magnesia/ graphite refractory. In addition, Gokce et al 3) have evaluated the effects of various antioxidants such as Si, Al, B 4 C and SiC on the decarburization resistance of magnesia/ graphite refractory. Overall, only a few researchers such as Youqi et al 6) and Dejiang et al, 7) have investigated the effects of antioxidants on the decarburization resistance of alumina/graphite-based refractory materials.…”