OXIDATION BEHAVIOR OF MONOLITHIC TIN AND TIN DISPERSED IN CERAMIC MATRICES

The mechanism and kinetics of high-temperature (up to 1500-degrees-C) oxidation of pressureless-sintered TiN and hot-pressed silicon nitride-TiN, alumina-TiN, aluminum nitride-TiN, and AlON-TiN ceramic composites were studied in air under isothermal and nonisothermal conditions. Analysis of the oxidation products revealed the formation of rutile in the temperature range from 600 to 1000-degrees-C An interaction of TiO2 with the matrix and/or its oxidation products was observed at higher temperatures. The oxidation of TiN-containing composites shows different behavior depending on the temperature. The presence of fine isolated inclusions of TiN (< 30 mass %) in the silicon-nitride matrix does not change the mass gain during oxidation or increases it only slightly, as compared with a TiN-free material. For materials containing a continuous skeleton of TiN (> 30 mass %) a noticeable increase of the oxidation rate was observed.