SCIENTIFIC RESEARCH AND DEVELOPMENT
NANOSTRUCTURED DISAGGREGATED ALUMINUM HYDROXIDE
AND OXIDE POWDERS
A. V. Bersh,
D. Yu. Mazalov,
R. Yu. Solov’ev,
L. V. Sudnik,
and A. V. Fedotov
Translated from Novye Ogneupory, No. 7, pp. 37 – 42, July, 2016.
Original article submitted April 15, 2016.
Results are provided for an experimental study of disaggregation of aluminum hydroxide (boehmite) powder
prepared by hydrothermal oxidation of aluminum powder. The effect of heat treatment temperature, drying
with heated steam, milling in ball and knife mills, treatment in rotary pulsating equipment, addition of
surfactant on original powder disaggregation and preparation of nanostructured boehmite and aluminum ox
ide, are studied. Process parameters are determined for preparing nanostructured powders.
Keywords: nanostructured boehmite, hydrothermal synthesis (HTS), pressure discharge method, nano-
structured condition, cavitation.
Aluminum oxide nanopowders, in particular boehmite,
are a most valuable resource in the production of molded alu-
minum oxide products, since it is possible to use them to pre-
pare thinners, catalysts, and catalyst carriers. Another field of
application of aluminum oxide and hydroxide is for refrac
tory material production for numerous applications, and
growing leucosapphire. It may be said that aluminum oxide
materials are used extensively, and without them it is impos
sible to increase in the intensity of existing aggregate opera
tions, and to develop electronics, instrument building, nu
clear technology, and power generation.
Over the last decade there has been active development
of hydrothermal synthesis (HTS), i.e., a promising high pro
ductivity method for preparing nanostructured aluminum
monohydroxide, i.e., boehmite, and technology for its appli
cations in various fields [1, 2]. One the main achievements of
HTS is use of industrial powders of finely dispersed alumi
num ASD-4, ASD-6, PAD-4, and PAD-6. The chemical reac
tor used is a classical ideal-displacement unit (IDU) . The
process of boehmite HTS by oxidation in an aqueous me
dium with micron aluminum powder proceeds in a moist sat
urated vapor up to and around a critical region at 330°C at a
pressure of 15 MPa for several minutes. High values of tem-
perature, pressure, and time during synthesis promote strong
boehmite particle aggregation. Aggregates may nullify the
valuable quality of the nanostructured material condition for
many of its applications. An aggregate structure forming in
nanopowders is extremely nonuniform and is hardly amena
ble to disintegration by means of known refining methods.
The task of this work is to study boehmite disaggregation
to a nanosize condition with drying of a boehmite suspension
by heated steam, heat treatment with preparation of alumi
num oxide, and also with treatment in rotary-pulsed equip
ment for preparing a boehmite suspension with water.
Powder particle size distribution was studied by
conductometry and in a SolverNExt scanning probe micro
scope. The structure of particle size distribution
(GrainAnalysis method) was accomplished by means of an
ImageAnalysis program from NT-MDT. Research was car
ried out on dried powder by a semi-contact method. The res
olution obtained by a SolverNext microscope equals the
point radius of the probe used. Foer standard ceramic probes
it equals 10 nm. Morphological features of individual parti
cles and aggregates were studied in a TESCAN MIRA 3
LMU scanning electron microscope.
Refractories and Industrial Ceramics Vol. 57, No. 4, November, 2016
1083-4877/16/05704-0364 © 2016 Springer Science+Business Media New York
FGBNU All-Russia Scientific Research Technological Institute
of Machine and Tractor Fleet Maintenance and Repair, Moscow,