STUDY OF CERMET SYNTHESIS FROM POWDERS
PREPARED BY CHEMICAL DISPERSION OF Al–Mg (20 wt.%)-ALLOY
A. A. Vasin,
V. P. Tarasovskii,
A. Yu. Omarov,
and V. V. Rybal’chenko
Translated from Novye Ogneupory, No. 6, pp. 62 – 65, June 2015.
Original article submitted September 30, 2014.
Powders are obtained containing metal particles during chemical dispersion of Al–Mg (20 wt.%)-alloy. A
method of high-temperature self-propagating synthesis is used in order to prepare cermet. Reaction sintering
in a filtering combustion regime for a powder workpiece is implemented by heating in air at 550 – 600°C fol
lowed by initiation of metal exothermic reaction combustion.
Keywords: cermet, aluminum hydroxide, powder, filtering combustion, microstructure, chemical dispersion.
Development of cermets with different phase composi-
tion and structure types makes it possible to obtain new com-
posite materials with a set of properties promising for their
use in various areas of technology. Interest in cermet of the
MgO–Al composition is due to the fact that it is possible to
achieve a combination within it of high strength and refracto-
riness, inherent for magnesium oxide, and plasticity and ther-
mal conductivity, typical for aluminum. This cermet, by hav
ing relatively low density, may exhibit quite good crack re
sistance, impact strength, and fatigue failure resistance. It
should be noted that a potential favorable property for a
cermet may be good thermal shock resistance due to pres
ence of a very heat conducting metal component. In addition,
it may also be promising for use as some elements of
high-temperature technology structures, operating in an air
atmosphere under thermal stress conditions.
Cermets are currently prepared by various methods. The
main methods are quite complex, and require special expen
sive equipment. Judging from individual publications , a
promising and very economic for cermet preparation of the
MgO–Al composition may be reaction sintering of
workpieces of chemically dispersed aluminum Al–Mg
(20 wt.%)-alloy. However, in view of a lack of information
required for practical implementation of this method, it is im
portant to study and develop a production process for prepar
ing cermet of MgO–Al composition by reaction sintering.
Results are given in this article for studying reaction
sintering of powder prepared by chemical dispersion of
Al–Mg (20 wt.%)-alloy and development on the basis of this
effective technology for preparing cermet of the MgO–Al
composition, characterized by a combination of high strength
and thermal shock resistance with low density.
PROCEDURE FOR Al–Mg (20 wt.%)-ALLOY
POWDER SYNTHESIS FOR CERMET PREPARATION
Chemical dispersion of Al–Mg-alloy was carried out by
treating it with 20% aqueous caustic soda solution  in a
vessel made of thermally stable and chemically resistant
glass with continuous heat removal and mixing. The residue
prepared from mother liquor was filtered and washed repeat
edly with distilled water by filtration under vacuum. The vol
ume of water expended for each washing cycle was 1 liter.
The change in medium pH index (residue in the form of
a suspension) after each washing cycle was determined using
an HI 98108 pH meter (Hannah Instruments). pH indices of
the medium after n-fold residue washing by decanting are
pH 12.8 12.6 12.5 12.0 11.8 11.5 11.3 11.3 11.2 10.0 9.7 9.6 9.6 9.2 9.2 9.1 9.1 9.1 9.1
* The pH value with n = 0 relates to the original residue before washing.
** The pH value with n = 1 corresponds to the maximum degree of residue washing.
A distinguishing feature of chemical dispersion of
Al–Mg alloy is a significant overall yield of coarse powder
particles, relating to fractions from <50 to 315/200 mm, ob
tained using wet screen analysis. The distribution of the ox
Refractories and Industrial Ceramics Vol. 56, No. 3, September, 2015
1083-4877/15/05603-0310 © 2015 Springer Science+Business Media New York
FGBOU VPO MGIU, Moscow, Russia.
ZAO NTTs Bakor, Shcherbinka, Moscow, Russia.