PHYSICOCHEMICAL CHARACTERISTICS OF COMPOSITE MATERIALS
BASED ON ALUMINUM NITRIDE
L. B. Khoroshavin,
D. A. Beketov,
and A. R. Beketov
Translated from Ogneupory i Tekhnicheskaya Keramika, No. 2, pp.5–8,February, 2002.
Nonmetallic composites based on aluminum nitride,
owing to their unique properties — high melting point, high
heat conductivity, low electric resistance, and high stability
in gaseous, salt and metallic media — can find widespread
application in many branches of industry [1 – 4].
In this paper, we present the results of a study of compo
sites based on aluminum nitride and different binders. Rele
vant compositional characteristics are given in Table 1.
Porosity is an important characteristic of a material. The
properties of a porous structure, in particular its stability, are
decisive for the performance parameters of a composite such
as thermal and electric conductivity, gas permeability, elec-
tric resistance, and others. The total porosity was determined
as recommended by the State Standard GOST 18898–73 .
Relevant results are given in Table 2.
The heat conductivity of composites with different types
of binder were determined by the method of  for room
temperature; for the range of 500 – 1400 K, a thermal diffu
sivity method  was used. Relevant experimental data are
given in Table 3.
Aluminum nitride crystallizes in a crystal lattice of the
wurtzite type , which, as one would expect, must deter
mine the anisotropy of its characteristics in a single-crystal
state. However, we are unaware of any literature data on the
thermophysical properties of aluminum nitride. A high-pu
rity single-crystal AlN was reported to have a heat conduc
tivity of about 320 W/(m × K) . For a sintered AlN with
minor amounts of carbon and oxygen of up to 4 wt.%, heat
conductivity was 16 W/(m × K) at room temperature and
tended to decrease monotonically to 4 W/(m × K) with tem
perature (up to 1600 K) .
Data on heat conductivity of a phosphate binder could be
found in the monograph  where electric and thermal
physical properties of an Si
composite with an aluminum
phosphate-based binder were studied. A numerical analysis
using an additive model of the characteristics of individual
components showed the heat conductivity of a phosphate
binder to fall into a range of3–4W/(m × K).
Keeping in mind that heat conductivity of AlN used in
our study was about 30 W/(m × K) and the porosity of the
composite with a phosphate binder was about 30%, we ob-
tain, within our model, a heat conductivity of the material of
Refractories and Industrial Ceramics Vol. 43, Nos.1–2, 2002
1083-4877/02/0102-0045$27.00 © 2002 Plenum Publishing Corporation
Eastern Institute of Refractories Research and Production Associ
ation Joint-Stock Co., Ekaterinburg, Russia; Ural State Technical
University, Ekaterinburg, Russia.
TABLE 1. Composites Studied
Component concentration, vol.%
1 40 60 –
PB) phosphate binder.
PFB) phenol-formaldehyde binder.
TABLE 2. Densities and Porosities of the Materials
TABLE 3. Heat Conductivity of Composite
Materials with Different Types of Binder
vity, W/(m × K)
1 30 9.2
2 30 6.2