High temperature oxidation behavior of electroconductive TiN/O′-Sialon ceramics prepared from high titania slag-based mixture

• Published in: Transactions of Nonferrous Metals Society of China 2011-12, Vol.21 (12), p.2638-2643
• Main Authors: JIANG, Tao, XUE, Xiang-xin, LI, Zhe-fu, DUAN, Pei-ning
• Format: Article
• Language: English
• Subjects: Activation energy; electroconductive ceramics; high titania slag; Law; Oxidation; oxidation behavior; Protective; Scale (corrosion); Tin; TiN/O′-Sialon; Titanium dioxide; Titanium nitride
• ISSN: 1003-6326
• DOI: 10.1016/S1003-6326(11)61103-5

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 Fe 2MgTi 3O 10, SiO 2 and TiO 2 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 SiO 2 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 1.574×10 5 J/mol, and at the late-mid stage, the oxidation of the samples obeys the parabolic law with the apparent activation energy of 2.693×10 5 J/mol. With the increase of TiN content, mass gain of the materials increases significantly.