Abstract
The evaluation of the thermal stability of three different fully dense AlN materials in the temperature range of 600 °C to 1400 °C in air indicates the strong effect of the starting composition on the oxidation process. The oxidation resistance of pure AlN and Y2O3-doped AlN was found to be good up to ≈1350 °C. The kinetics are linear (1100≤T≤1400 °C) and the process is governed by a surface reaction that gives rise to the formation of a porous, nonprotective oxide scale, where Al2O3 and Y-aluminates (i.e., AlN-Y2O3) have been found as crystalline reaction products. For AlN-CaC2, higher oxidation rates indicate that the outward migration of Ca modifies the reaction mechanisms. Linear kinetics in the range 1100≤T≤1200 °C are followed by parabolic kinetics at higher temperatures (T>1250 °C); with regard to the latter behavior, an activation energy of 160 kJ/mole could indicate the diffusion of oxygen through the oxidation scale as the rate-controlling mechanism.
Original language | English (US) |
---|---|
Pages (from-to) | 565-572 |
Number of pages | 8 |
Journal | Journal of Materials Research |
Volume | 8 |
Issue number | 3 |
DOIs | |
State | Published - Mar 1993 |
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering