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Highly thermally conductive hexagonal boron nitride/alumina composite made from commercial hexagonal boron nitride
Author(s) -
Hung Chingcheh,
Hurst Janet,
Santiago Diana,
Lizcano Maricela,
Kelly Marisabel
Publication year - 2017
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.14638
Subject(s) - materials science , composite material , boron oxide , amorphous solid , nitride , oxide , aluminium , layer (electronics) , electrical conductor , hot pressing , boehmite , hexagonal boron nitride , chemical engineering , nanotechnology , metallurgy , graphene , crystallography , chemistry , engineering
Hexagonal BN is an unusual material in that it is both highly thermally conductive as well as an electrical insulator. Additionally, hBN is also thermally stable in air. This unusual combination of properties makes hBN of significant interest for thermal management. Unfortunately, hBN is not easily consolidated into substrates without the addition of second phases which generally result in poorer thermal performance. This research investigates the potential to utilize this material to dissipate heat from high‐voltage, high‐power electrical devices. Specifically, a process to coat individual platelets of commercial hexagonal BN powder with a layer of amorphous aluminum oxide was developed. The coated hexagonal BN was then hot‐pressed to form a highly thermally conductive substrate. The process to coat hexagonal BN platelets with aluminum oxide was accomplished by mixing hexagonal BN with AlCl 3 containing some water, then evaporation of excess AlCl 3 to form a Al, Cl, and O layer on hexagonal BN . This product was then heated in air to convert the surface layer into aluminum oxide. Following hot pressing to 1950°C and 10 ksi, the consolidated composite has through‐plane and in‐plane thermal conductivity of 14 and 157 W·(m·K) −1 , respectively, at room temperature.