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Effect of Heat Treatment on the Microstructure and Properties of Dense AIN Sintered with Y 2 O 3 Additions
Author(s) -
Mitra Shantanu,
Dutta Geeta,
Dutta Indranath
Publication year - 1995
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/j.1151-2916.1995.tb08666.x
Subject(s) - microstructure , oxygen , lattice constant , thermal conductivity , analytical chemistry (journal) , atmospheric temperature range , thermal treatment , materials science , lattice (music) , crystal structure , nitrogen , reducing atmosphere , mineralogy , chemistry , thermodynamics , metallurgy , composite material , crystallography , physics , organic chemistry , diffraction , acoustics , optics , chromatography
The secondary phase constitution in two sintered AIN ceramics (1.8% and 4.2% Y 2 O 3 additions) was studied as a function of heat treatment temperatures between 1750° and 1900°C under pure nitrogen atmosphere. The effect of the phase constitution on the physical properties, such as density, thermal conductivity ( K ), and lattice constants, and on the mechanical properties in three‐point bending, was also investigated. Y 3 Al 5 O 12 was found to getter dissolved oxygen from the AIN lattice below 1850°C, but evaporated at 1850°C and above. Y 4 Al 2 O 9 appeared to sublimate below 1850°C in the atmosphere used in this study. Depending on the secondary phase constitution, heat treatment affected thermal conductivity favorably or adversely. Occasionally, samples with similar lattice oxygen contents were found to have different thermal conductivities, suggesting that factors besides dissolved oxygen can also influence K . Lattice parameter measurements indicated that, within the small range of lattice oxygen concentrations in the AIN samples studied, the c‐axis was more sensitive than the a ‐axis to oxygen content.