ALUMINUM OXIDE AND CERAMICS BASED ON IT:
21st CENTURY MATERIALS
E. S. Lukin,
E. V. Anufrieva,
N. A. Makarov,
N. A. Popova,
V. S. Bakunov,
and I. I. Nagayuk
Translated from Novye Ogneupory, No. 3, pp. 155 – 160, March, 2008.
Original article submitted November 8, 2007.
Some forms of corundum ceramic are considered, as corundum has so far been the most widely used material
in various areas of engineering. Various materials are considered that have high strength, particularly in
combination with partially stabilized zirconium dioxide. Information is given on additives to finely divided
powder (<1 mm) in the form of nanopowders, and these are used for making strong and especially strong
components. A possible sintering mechanism for finely divided powders with added nanopowders is
considered in relation to the corundum ceramic Koral-2.
Ceramics have some unique physicochemical properties
that do not occur in any single class of materials. High-
strength ceramic materials based on oxides allow one to
make new components with a high level of properties for the
latest technologies. Such materials have been developed on
the basis of aluminum oxide, zirconium dioxide, combina-
tions of these, spinel, mullite, and so on [1 – 3].
Corundum ceramics are distinguished amongst oxide
materials being the most widely used in many areas of
engineering because of their combination of good physico
technical properties. Corundum has been used in various
ceramics with small-crystal structure and with bending
strength 300 – 800 MPa, as well as very good electrical
insulation behavior, high thermal conductivity, transparency
to light, and radiation stability, as well as chemical stability,
elevated hardness, wear resistance, biological inertness, and
use up to 1750 – 1800°C [4 – 7].
Ceramics based on aluminum oxide have high sintering
temperatures, which for materials not containing special
additives constitute 1700 – 1800°C, or in the presence of
fluxes 1550 – 1650°C [8, 9]. Such sintering temperatures are
responsible for accelerated wear on the equipment and in
creased consumption of refractory components and electri
city. Also, they lead to extensive recrystallization and the
formation of porosity within and between crystals, and
There are difficulties in making new high-grade ceramic
oxide items because commercial powders do not fully
correspond to the latest technological specifications. Even
prolonged grinding of raw materials fails to give powders
with grain size 1 – 2 mm [5, 10]. Such powders cannot be used
in ceramics with adjustable structure and optimum properties
without the use of special technologies and additives.
Special additives and appropriate preparation produce
powders from which one can make dense fine-grained
corundum ceramics with bending strength exceeding 500 MPa
. Recent advances in ceramic technology and sintering
theory have shown that oxides and their compounds can be
used in new ceramics with elevated mechanical strength,
resistance to wear, and simultaneous action of high tempera
tures and pressures. Improvements have been made in
existing technologies and in the quality of ceramic materials,
with considerable extension in the applications of ceramics
as a result of advances in powder technology, new techniques
in forming components from finely divided powders, better
principles for choosing additives, and advances in sintering
One can now develop ceramic materials suitable for a
new generation of instruments, machines, and equipments.
This applies particularly to the automobile, aviation, space
research, general engineering, electronic equipment, night-
vision systems, and so on. However, one should not expect a
rapid advance in the technology of new ceramic materials
because in Russia there is practically no industrial produc
tion of high-grade raw materials based on aluminum oxide
Refractories and Industrial Ceramics Vol. 49, No. 2, 2008
1083-4877/08/4902-0142 © 2008 Springer Science+Business Media, Inc.
Mendeleev Russian Chemical Engineering University, Joint High
Temperatures Institute RAS, and VIAM, Russia.