SCIENTIFIC RESEARCH AND DEVELOPMENT
PRINCIPLES OF THE DESIGN OF VARIATROPIC
HEAT-INSULATING STRUCTURAL REFRACTORIES
V. N. Sokov
and V. V. Sokov
Translated from Novye Ogneupory, No. 5, pp. 24 – 26, October, 2011.
Original article submitted June 30, 2011.
The time has come to begin designing the structures of heat-insulating refractories with regard for the service
conditions they encounter in high-temperature equipment. It is proposed that a change be made from homoge
neous refractories to variatropic refractories. Homogeneous refractories are converted to the variatropic state
by internally redistributing their properties without changing the dimensions, weight, or average composition
of the material. The conversion has three effects: a technological effect and effects related to the design and
use of the new refractory.
Keywords: variatropic state, electrohydrothermal loading, self-packing molding mix, directional heterogene-
ity, internal redistribution of properties.
The entire history of development of technologies for the
production of heat-insulating refractories is a history of com-
promises that have been made between the desire to maxi-
mize these materials’ porosity (thus reducing their thermal
conductivity, the unit consumption of these materials, and the
weight of structural elements made with them) and the need
to maintain adequate density (which helps increase strength,
durability, and service life); in the situation being discussed
in this article, we believe that the fundamental solution to
this problem is ensuring that the components of these materi
als have a variatropic structure.
This is an area of heat-insulating refractories technology
that has not advanced as much as it should have, despite its
obvious potential . The different service conditions to
which an element as a whole or the opposing sides of its mid
dle plane may be subjected make it necessary that the ele
ment have a correspondingly suitable internal structure; this
applies in particular to cases in which one side of the element
is subjected to aggressive media, high temperatures, the ac
tion of slag and metal, or other effects. Thus, it is time to be
gin to design the structure of materials used in high-tempera
ture equipment with consideration of their service conditions
in that equipment. However, it is also necessary to keep in
mind that the creation of a variatropic heat-insulating refrac
tory makes sense only when the complexities of the manu
facturing technology do not completely negate the benefits
from optimization of the material’s structure. Thus, we chose
to study a technology in which a bulk refractory is made to
undergo self-packing by a method we developed [1 – 7] that
is based on the use of an electrothermomechanical load.
Proceeding from this starting point, we made the follow
ing assumptions in the working hypothesis that will be used
in this investigation.
1. Forced heating of a mineral-polystyrene mass in rigid
perforated molds by industrial-frequency current will make it
possible to accelerate the self-packing process and improve
the structure of the finished product.
2. Heat-insulating refractories of varying density can be
produced on the basis of different mineral raw materials by
regulating the mechanism of the filtration process through
directional mass transfer. Directional mass transfer is created
by creating substantial temperature and pressure gradients,
which in turn is done by selecting certain regimes for electric
heating of the molding mix as it undergoes self-packing in
the rigid perforated mold.
3. By creating directional heterogeneity in the material,
i.e. by converting it from the homogeneous state to the
variatropic state, it becomes possible to improve its service
characteristics without changing the dimensions, weight, or
average composition of the product. This effect is achieved
solely as a result of an internal redistribution of the material’s
Refractories and Industrial Ceramics Vol. 52, No. 5, January, 2012
1083-4877/12/05205-0328 © 2012 Springer Science+Business Media, Inc.
Moscow State Construction University, Moscow, Russia.