POROUS CERAMIC MADE FROM POWDERS
PREPARED BY CHEMICAL DISPERSION OF ALLOY Al–Mg (20 wt.%)
A. A. Vasin,
V. P. Tarasovskii,
V. V. Rybal’chenko,
and A. Yu. Omarov
Translated from Novye Ogneupory, No. 11, pp. 47 – 49, November, 2014.
Original article submitted September 15, 2014.
Scanning electron microscopy and x-ray phase analysis results are presented for powders prepared by chemi
cal dispersion of alloy Al–Mg (20 wt.%) and specimens of porous ceramic materials made from these pow
ders. Different powder fractions are obtained during chemical dispersion of aluminum-magnesium alloy. A
powder fraction finer than 50 mm is selected for study. Ceramic specimens are prepared by semidry compac
tion. Features of phase composition and structure of heat-treated powders and ceramic prepared with a high
magnesium content in the original alloy are described.
Keywords: porous ceramic, chemical dispersion, alloy Al–Mg (20 wt.%), fracture surface fractogram.
Currently in industrial production it is necessary to use
different ceramic material objects, in particular porous per-
meable materials for creating new forms of filter elements
and highly efficient heat insulation objects. Therefore prepa-
ration of porous ceramic material with a high level of operat-
ing parameters and prescribed pore space structure is impor-
The aim of this work is to study the microstructure and
properties of powder prepared by chemical dispersion of
Al–Mg (20 wt.%) alloy and ceramic material based upon it.
STUDY PROCEDURE FOR CHEMICAL
DISPERSION OF ALLOY Al–Mg (20 wt.%)
The starting powder of mixed hydroxides was prepared
by chemical dispersion of Al–Mg alloy by treating it with
20% aqueous caustic soda solution. The powder obtained
from mother liquor was fired, repeatedly washed with dis
tilled water by filtration under vacuum, and calcined at
1250°C for 1 h .
A distinguishing feature of the powder obtained is the
fact that it consists of two fractions, finer than 50 mm, and
from 315 to 630 mm. The fraction finer than 50 mm was se
lected for study. Ceramic specimens were prepared by
semidry pressing (150 MPa) followed by sintering (1450°C,
holding 1 h). After sintering specimens had an apparent den-
sity of 1.72 g/cm
, open porosity 58.41%, and ultimate
strength in compression 175 MPa.
POWDER RESEARCH RESULTS
Powders were studied in a FEI Helios NanoLab
DualBeam scanning electron beam microscope at different
magnification (Fig. 1). Particles of micron and submicron
sizes are present within the powder (Fig. 1a, grey-white
field, phase 4 ). Powder particles of finely dispersed phase
are represented both by individual isometric particles and
those combined into agglomerates. Sharp-angle (see Fig. 1a,
phase 3 ), spherical (single, phase 1 ), agglomerated over the
surface of finely crystalline phase (Fig. 1b, phase 1 ), and
lamellar particles (Fig. 1b, phase 2 ), are observed. The di
mensions of lamellar powder particles comprise from
1–5mm, and spherical particles from 1 to 15 mm. For spher
ical particles of this fraction there is typically presence of
chemical etching channels (see Fig. 1b, phase 1 ) whose for
mation is probably caused by a reduction in spherical particle
Powder phase composition of was studied in a Thermo
Fisher Scientific ARL XTRA x-ray diffractometer (see Ta
ble 1). The main crystalline phases of the powder after syn
thesis are spinel MgAl
and periclase. Abundant spinel
Refractories and Industrial Ceramics Vol. 55, No. 6, March, 2015
1083-4877/15/05506-0532 © 2015 Springer Science+Business Media New York
FGBOU VPO Moscow State Industrial University, Moscow, Rus
ZAO NTTs Bakor, Shcherbinka, Moscow Region, Russia.