Elucidating the role of Ti3AlC2 and Ti3SiC2 in oxidation mechanisms of MgO–C refractories

Two types of Ti-containing layered ternary carbides, Ti3AlC2 and Ti3SiC2, were incorporated to fabricate low-carbon MgO–C refractories, and the oxidation behaviors after exposure to 1100 °C and 1500 °C were investigated in the present work. The oxidation resistances of the samples with Ti3AlC2/Ti3SiC2-adding have an approximately 50% increase over that of conventional MgO–C with 4 wt% graphite. CT results indicated stress cracks occurred in the sample with Ti3AlC2/Ti3SiC2-adding after exposure to 1100 °C, it was attributed to the anomalous oxidation behavior of Ti3AlC2/Ti3SiC2 grains and the formation of TiO2 with volume expansion at ∼600 °C according to TG and corresponding XRD results. At 1500 °C, a white reaction product layer was formed at the boundaries of oxide/non-oxide layers of the sample with Ti3AlC2/Ti3SiC2-adding, which was confirmed as magnesium titanate spinel. The oxidation behaviors of the samples with Ti3AlC2/Ti3SiC2-adding showed a mass gain process owning to the further disintegration of Ti3AlC2/Ti3SiC2. Furthermore, the oxidation mechanism and the roles of Ti3AlC2/Ti3SiC2 grains were elucidated in detail.