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Sintering Mechanisms and Kinetics for Reaction Hot‐Pressed ZrB 2
Author(s) -
Lonergan Jason M.,
Fahrenholtz William G.,
Hilmas Greg E.
Publication year - 2015
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.13544
Subject(s) - activation energy , sintering , materials science , hot pressing , grain boundary diffusion coefficient , grain growth , ceramic , grain boundary , lattice diffusion coefficient , kinetics , grain size , diffusion , metallurgy , composite material , microstructure , effective diffusion coefficient , chemistry , thermodynamics , medicine , physics , quantum mechanics , magnetic resonance imaging , radiology
Sintering mechanisms and kinetics were investigated for ZrB 2 ceramics produced using reaction hot pressing. Specimens were sintered at temperatures ranging from 1800°C to 2100°C for times up to 120 min. ZrB 2 was the primary phase, although trace amounts of ZrO 2 and C were also detected. Below 2000°C, 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 × 10 −16 cm 4 /s at 1900°C and 2.1 × 10 −15 cm 4 /s at 2100°C. This study revealed that dense ZrB 2 ceramics can be produced by reactive hot pressing in shorter times and at lower temperatures than conventional hot pressing of commercial powders.