High-Temperature Oxidation of AlN–TiCrB2 Composites in Air. II. Structure and Phase Composition of Oxide Layers Formed on AlN–TiCrB2 Composites in Air up to 1600°C

Abstract

The high-temperature oxidation of AlN–TiCrB 2 composites in air up to 1600°C is studied in the composition range from 5 to 50 wt.% TiCrB 2 . The structure and phase composition of oxide layers formed in the temperature range 1200–1600°C are determined by thermal gravimetry, metallography, electron microprobe analysis, and scanning electron microscopy. It is established that Ti–Cr–O lower solid solutions (Cr 2 Ti 7 O 7 and Cr 2 Ti 4 O 11 ), α-Al 2 O 3 , and TiO 2 (rutile) form in the temperature range 1200–1350°C during oxidation of the samples. When temperature increases to 1500–1550°C, the oxidation products contain Cr 2 TiO 5 , β-Al 2 TiO 5 , and (AlCr 2 )TiO 3 . They form a homological series of isomorphic solid solutions, representing a fine self-reinforced oxide film, which leads to exceptionally high oxidation resistance (>1600°C) of the AlN–TiCrB 2 ceramic composites.