High temperature oxidation behavior of electroconductive TiN/O′-Sialon ceramics prepared from high titania slag-based mixture
(1. School of Materials and Metallurgy, Northeastern University, Shenyang 110819, China;
2. Institute of Metallurgical Resources and Environmental Engineering, Northeastern University,
Shenyang 110819, China)
2. Institute of Metallurgical Resources and Environmental Engineering, Northeastern University,
Shenyang 110819, China)
Abstract: The oxidation behavior of electroconductive TiN/O′-Sialon ceramics prepared using high titania slag as main starting material was studied at 1 200−1 300 °C in air. The isothermal and non-isothermal oxidation processes were investigated by DTA−TG. Phase compositions and morphologies of the oxidized products were analyzed by XRD, SEM and EDS. The results indicate that the oxidation of TiN and O′-Sialon occurs at about 500 °C and 1 050 °C, respectively. After oxidation at 1 200−1 300 °C, a protective scale that consists of Fe2MgTi3O10, SiO2 and TiO2 is formed on the surface of the materials, which effectively prevents the oxidation process. The formation of a protective scale is relative to TiN content and apparent porosity of the samples, the amount of SiO2 and amorphous phase in the oxidation product. At the initial oxidation stage, the oxidation kinetics of the materials follows perfectly the linear law with the apparent activation energy of 1.574×105 J/mol, and at the late-mid stage, the oxidation of the samples obeys the parabolic law with the apparent activation energy of 2.693×105 J/mol. With the increase of TiN content, mass gain of the materials increases significantly.
Key words: TiN/O′-Sialon; high titania slag; electroconductive ceramics; oxidation behavior