High-temperature oxidation of AlN-SiC-TiB2 ceramics in air

• Published in: Journal of the European Ceramic Society 2005, Vol.25 (10), p.1781-1787
• Main Authors: LAVRENKO, Vladimir A, DESMAISON, Jean, PANASYUK, A. D, DESMAISON-BRUT, Martine, FENARD, E
• Format: Article
• Language: English
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Cermets, ceramic and refractory composites; Chemical industry and chemicals; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Other materials; Physics; Specific materials; Structural ceramics; Technical ceramics
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2004.12.008

The oxidation behaviour of AlN--SiC--TiB2 composite materials with 2, 5 and 10 mass% TiB2 and 3 mass% Fe additive obtained using powder metallurgy methods was studied in air up to 1500 deg C by thermogravimetry (TG) and differential thermal analysis (DTA) techniques. The phase composition and structure of the oxide films formed were investigated using metallography, X--ray diffraction (XRD) and electron probe microanalysis (EPMA) methods. The two--stage character of non--isothermal oxidation kinetics (heating rate of 15 grade/min) of composites was established. During the first oxidation stage (up to 1350 deg C), the formation of alpha--Al2O3, TiO2 (rutile), B2O3 and beta--cristobalite as well as different aluminium borates was found. They formed as a result of interaction between Al2O3 and melted B2O3. During the second stage (above 1350--1400 deg C), the mullite 3Al2O3*2SiO2 proved to be a main oxidation product in the scale; besides, some amounts of beta--Al2TiO5 were formed as well. The iron additive dissolved in the mullite and aluminium titanate phases that led to the stabilization of a scale formed. It was established that for the three different TiB2 contents, oxidation isotherms follow the parabolic or paralinear rate law. The slope change on the Arrhenius plot given by the dependence of the parabolic rate constants on the reciprocal temperature, suggests a change of the oxidation mechanism in the temperature range of 1300--1350 deg C. For example, for the (AlN--SiC)--5% TiB2 composite specimen, the calculated values of apparent activation energy are equal to 285kJ /mol (1100--1300 deg C) and 500kJ/mol (1350--1550 deg C), respectively. The AlN--SiC--TiB2 ceramics developed here can be recommended as high--performance materials for a use in oxidizing medium up to 1450 deg C.