Oxidation behaviors of MgO-C refractories with different Si/SiC ratio in the 1100–1500 °C range

Abstract

The oxidation behaviors of the MgO-C refractories using different Si-containing antioxidants (including Si, SiC, Si/SiC mixtures or Si/SiC-rich solid waste powders) were investigated under a controlled air flow in the range of 1100-1500 °C. For the tested samples with antioxidants of similar grain-size, the obtained results indicated the slopes of the weight loss-time curves all were -0.012 during soaking processes at 1100 and 1300 °C. It meant that the types of antioxidants have no significant effect on the oxidation rates of MgO-C refractories at 1100 °C and 1300 °C under this laboratory conditions. The oxidation processes at mid-temperatures were governed by the direct contact reaction between graphite and O2 and related to the physical characteristics, shapes and particle sizes of additives. Moreover, the amount of SiO (g) in the surrounding resulting from original Si-containing antioxidants played a vital role in considering of the oxidation behaviors observed at 1500 °C. The SiO(g) output efficiency in the surrounding atmosphere of Si additive was much higher than that of SiC in the range of 1100-1500 °C. This led to a lower mass loss rate of the MgO-C refractory with Si-adding at 1500 °C compared to the sample with SiC-adding.