DEVELOPMENT OF SHS-METHOD ON A DRY BASIS
FOR PREPARING CORUNDUM POWDER
A. V. Hmelov
Translated from Novye Ogneupory, No. 8, pp. 20 – 26, August, 2013.
Original article submitted April 4, 2013.
Development of corundum phase, crystal dimensions, degree of crystallization, specific surface, and
microstructure are demonstrated, and data are shown for the practical yield of powder prepared in the course
of combustion at a surface and within specimens using an SHS-method on a dry basis with application of two
different fuels, i.e., citric acid and saccharose. Combustion within a specimen facilitates corundum phase de
velopment to the greatest extent independent of the fuel selected, crystal growth, and an increase in the degree
of crystallization using citric acid. The greatest amount of heat of combustion released and its greater accumu
lation within a specimen with use of citric acid in the course of combustion facilitates development of a
coarse-grained microstructure with coarser pores within the powder, and a little more specific surface
(26.5 – 25.1 m
/g) in contrast to powder (25.6 – 23.9 m
/g) obtained in the course of combustion using
saccharose, and correspondingly a greater practical yield of corundum powder.
Keywords: SHS on a dry basis, corundum powder, phase composition.
Recently various forms of SHS-combustion based on
water exhibiting certain uniqueness and universality [1 – 4]
have recommended themselves. However, they have certain
disadvantages [5, 6] limiting their application in practice.
This is connected with use of only water-soluble compo-
nents, and an external heat source, i.e., a plate for initiating
and developing combustion, and also with a location for per
forming combustion synthesis [1 – 4, 7]. In order to resolve
this problem some authors [9 – 11] have selected a very orig
inal method, based on changing the aggregate state of start
ing components. This approach proposes mixing starting
components not in a water-soluble state, but in the form of
melts. Mixing starting components in a molten form and
their dissolution in a melt formed occurs at a molecular level
[9, 12], i.e., a melt is a specific solvent [7, 13]. Mechanisms
of complex formation and preparation of fuel complexes
(FC) do not differ significantly from a similar scheme pre
sented in .The only difference is that the process of com
plex formation, acidity, and basicity of the molten mixture
obtained for starting components is regulated in the melt it
self [8, 9], i.e., in situ, and this means complex formation oc
curs more rapidly under action of high temperature for melts
of starting components.
For example, in practice this approach is used for prepar-
ing magnesia-spinel powder by means of self-propagating
high-temperature synthesis (SHS)  using oxidizing agent
and fuel as starting components, capable of forming melts.
The method is so effective that it is used for synthesizing ce-
ramic powders with piezo-, ferro-, and semiconductor prop
erties [10, 11]. Development of the method has facilitated the
possibility of synthesizing oxide powders in a molten me
dium . However, the SHS-method of powder synthesis
based on a dry basis is not used as a result of certain disad
vantages/features indicated below [10, 11].
– use of both water-soluble and water insoluble starting
– no requirement to have data for water solubility;
– convenience and simplicity of mixing starting compo
– product in the course of melting components is pre
pared in the from of a pasty mass;
– convenience and simplicity of initiating combustion
– the possibility of carrying out combustion in a pasty
mass itself and in a compacted specimen;
– the possibility of carrying out combustion in an open
Refractories and Industrial Ceramics Vol. 54, No. 4, November, 2013
1083-4877/13/05404-0312 © 2013 Springer Science+Business Media New York
Institute of Silicate Materials of Riga Technical University, Riga,