Showing papers by "Yury Gogotsi published in 1993"
TL;DR: In this article, the mechanism and kinetics of high-temperature (up to 1500°C) oxidation of pressureless-sintered TiN and hot-pressed silicon nitride-TiN, alumina-TiNs, aluminum-nondiscriminated TiN, and AlON-aluminum-nodes ceramic composites were studied in air under isothermal and nonisothermal conditions.
Abstract: The mechanism and kinetics of high-temperature (up to 1500°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°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 %) a noticeable increase of the oxidation rate was observed.
29 citations
TL;DR: In this article, the effect of stress corrosion on mechanical properties is discussed and an exponential dependence of mass gain on stress is found, which can be interpreted as stress corrosion in oxygen-containing environments.
Abstract: Silicon nitride ceramics show an accelerated oxidation rate under load in air. This phenomenon was observed for porous and dense ceramics with and without additives in a wide temperature range (700--1,450 C) and can be interpreted as stress corrosion in oxygen-containing environments. Stresses cause an alteration of the amount and composition of oxidation products, formation of pits and cracks on stressed parts of specimens, and changes of the surface coloration and oxide scale morphology. Both tensile and compressive stresses can affect the oxidation process. An exponential dependence of mass gain on stress was found. On the other hand, oxidation of silicon nitride-based ceramics can affect the material response to mechanical stresses as, for example, deformation, cavitation and cracking. Stress-assisted chemical reaction at lower temperatures and stress-affected diffusion at higher temperatures seem to be the main reasons for the susceptibility of Si[sub 3]N[sub 4] ceramics to stress corrosion. The effect of stress corrosion on mechanical properties is discussed.
27 citations