Abstract
The presence of dispersed TiN particles in an Si3N4 matrix deeply affects the oxidation resistance at low (600-1000°C) and high temperatures. The thermal stability of dense Si3N4TiN composites up to 1350°C in air results in different oxidation regimes: up to 1000°C only the oxidation of TiN to TiO2 (rutile) takes place, where the second-order reaction is likely to be the governing step. From 1000 to 1200°C diffusion (O2 or N2) through a TiO2 layer could be indicated as the rate-limiting step. At T {greater-than or approximate} 1200°C, parabolic oxidation kinetics indicates diffusion mechanisms. The diffusion of yttrium and aluminium cations from the bulk to the reaction interface is believed to govern the process in the baseline matrix; for the composites the structure and composition of the bulk and the development of complex product layers modify the migration mechanisms of the various mobile participants. However, a strong increase in the oxidation rate is associated with the presence of TiN.
Original language | English (US) |
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Pages (from-to) | 115-122 |
Number of pages | 8 |
Journal | Materials Science and Engineering A |
Volume | 127 |
Issue number | 1 |
DOIs | |
State | Published - Jan 1 1990 |
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering