THERMAL SHOCK-RESISTANT CERAMIC COMPOSITES
BASED ON ZIRCONIUM DIOXIDE
V. V. Promakhov,
I. A. Zhukov,
S. A. Vorozhtsov,
A. S. Zhukov,
and A. B. Vorozhtsov
Translated from Novye Ogneupory, No. 11, pp. 39 – 44, November 2015.
Original article submitted April 20, 2015.
Changes in structure, phase composition and crystal structure parameters are studied for materials of the
–MgO system after cyclic thermal shock effects. Features are revealed for formation of ceramic structure
and phase condition with implementation of internal stresses connected with a sharp change in temperature.
Optimum compositions are established for refractory materials based on ZrO
answering high specifications
for thermal shock resistance and refractoriness.
Keywords: ceramic composites, ZrO
–MgO system, thermal shock resistance, zirconium dioxide, coherent
scattering region (CSR).
It is well known that thermal shock resistance is an im-
portant functional property for materials operating under
conditions of frequent cyclic temperature changes. Among
thermal shock resistant materials are ceramic materials in-
tended for operation under thermal shock conditions and
high temperature gradients arising with high heat flows
through ceramic .
Considerable attention of researchers is devoted to oxy
gen-free ceramics, in particular silicon nitride and carbide,
and composites based upon them [2 – 5]. In spite of a high
melting temperature for oxygen-free ceramic its use for oper
ation under thermomechanical action conditions in oxy
gen-containing atmospheres is limited by the oxidation tem
perature (~1100°C). Refractory materials based on ZrO
hibit a unique combination of high (~2700°C) melting tem
perature, high strength, low thermal conductivity, good crack
resistance, wear resistance, and thermal and chemical resis
tance. The LTEC of ZrO
is close to that of metals, which
makes it possible to use zirconia ceramic in hybrid metal-ce
ramic structures and composites.
Currently an important question is theoretical and experi
mental study of composite ceramic material thermal shock
resistance. This is due to the fact that within composites it is
possible to form new properties governing their high resis-
tance to thermal shock effects and improved refractory prop-
erties. Of considerable significance in the field of thermally
shock resistant ceramic materials are composites with addi-
tion of MgO due to its high thermal stability [6, 7]. In partic-
ular, it has been shown  that addition of 0.2% MgO to
in a-phase facilitates a reduction in sintering tempera
ture for ceramic to 1500°C with 1 – 2% porosity for the com
posite obtained. A temperature drop with which there is ther
mal crack generation is (873 ± 444°C), which significantly
exceeds the limiting temperature drop for pure Al
ever, today there is no unambiguous answer about the effect
of thermal loads on the microstructure and phase composi
tion of oxide ceramic composites forming a macrostructural
response. In addition, a considerable amount of work in this
area has been carried out on materials with a structural ele
ment size in the micron range, and a reduction in subgrain
size to tens of nanometers may lead to marked changes in ce
ramic resistance to thermal loads.
RESEARCH MATERIALS AND PROCEDURES
The starting materials used were powders of the
–MgO system prepared by thermal decomposition of
aqueous solution of zirconium and magnesium nitrate salts in
a low-temperature plasma. According to the composition di
agram for the ZrO
–MgO system (Fig. 1) the ratio of compo
Refractories and Industrial Ceramics Vol. 56, No. 6, March, 2016
1083-4877/16/05606-0610 © 2016 Springer Science+Business Media New York
Proceedings of the International Conference of Refractory
Workers and Metallurgists (19 – 20 March 2015, Moscow).
National Research Tomsk State University, Tomsk, Russia.