The effect of graphite addition on thermal conductivity, microstructure, and electrochemical impedance spectroscopy of AlN ceramics

Graphite/aluminum nitride (AlN) multiphase ceramics are pressureless sintered under 1850 °C using Dy 2 O 3 and CaF 2 as sintering additives. The effects of added graphite on microstructure, thermal conductivity, and electrochemical impedance spectroscopy of AlN ceramics were investigated. It was fou...

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Bibliographic Details
Published in:Journal of materials research 2022-09, Vol.37 (17), p.2749-2760
Main Authors: Wang, Tun, Xie, Jianjun, Zhang, Lei, Lu, Tao, Ding, Maomao, Fan, Lingcong, Zhou, Ding, Shi, Ying
Format: Article
Language:English
Subjects:
Additives
Aluminum nitride
Applied and Technical Physics
Biomaterials
Ceramics
Chemical reduction
Chemistry and Materials Science
Electrochemical impedance spectroscopy
Graphite
Heat transfer
Impurities
Inorganic Chemistry
Materials Engineering
Materials research
Materials Science
Microstructure
Multiphase
Nanotechnology
Thermal conductivity
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Summary:Graphite/aluminum nitride (AlN) multiphase ceramics are pressureless sintered under 1850 °C using Dy 2 O 3 and CaF 2 as sintering additives. The effects of added graphite on microstructure, thermal conductivity, and electrochemical impedance spectroscopy of AlN ceramics were investigated. It was found that with 1wt% graphite addition the thermal conductivity of AlN in the through-plane to can achieve 210 W/(m K), which 25% higher than that of AlN without graphite. The graphite addition eliminates the oxygen impurity in AlN by a carbon reduction reaction in form of nanosized Dy 2 O 3 particles. From electrochemical impedance spectroscopy manifested that the activation energy ( E a,g ) of samples in grains is increased from 0.784 to 1.112 eV, suggesting that the concentrations of defects and impurities of Graphite/AlN multiphase ceramics are lower than those of monophase AlN ceramics. Graphical abstract
ISSN:0884-2914
2044-5326
DOI:10.1557/s43578-022-00633-y