Sintering mechanisms and kinetics were investigated for ZrB2 ceramics produced using reaction hot pressing. Specimens were sintered at temperatures ranging from 1800-C to 2100-C for times up to 120 min. ZrB2 was the primary phase, although trace amounts of ZrO2 and C were also detected. Below 2000⁰C, the densification mechanism was grain-boundary diffusion with an activation energy of 241 ± 41 kJ/mol. At higher temperatures, the densification mechanism was lattice diffusion with an activation energy of 695 ± 62 kJ/mol. Grain growth exponents were determined to be ~4.5, which indicated that a grain pinning mechanism was active in both temperature regimes. The diffusion coefficients for grain growth were 1.5 x 10-16 cm4/s at 1900⁰C and 2.1 x 10-15 cm4/s at 2100⁰C. This study revealed that dense ZrB2 ceramics can be produced by reactive hot pressing in shorter times and at lower temperatures than conventional hot pressing of commercial powders.
- Activation energy,
- Ceramic materials,
- Chemical activation,
- Diffusion,
- Grain boundaries,
- Hot pressing,
- Reaction kinetics,
- Sintering,
- Commercial powders,
- Densification mechanisms,
- Grain growth exponent,
- Grain-boundary diffusion,
- Lower temperatures,
- Reactive hot pressing,
- Sintering mechanism,
- Temperature regimes
Available at: http://works.bepress.com/greg-hilmas/178/