SYNTHESIS AND MICROWAVE ABSORPTION CHARACTERISTICS
OF CORUNDUM-MULLITE REFRACTORIES
and Jinhui Peng
Translated from Novye Ogneupory, No. 5, pp. 41 – 45, May, 2014.
Original article submitted September 10, 2013.
A new technology is proposed for the production of corundum-mullite refractories. The crystal structures of
the raw materials before and after sintering were determined by XRD. An analysis showed that corundum and
mullite were mainly crystalline compounds in the sintered samples. The microwave-absorption characteristics
of corundum-mullite refractories are optimal when particle size in the refractories is 75 µm.
Keywords: Microwave-absorption properties; corundum-mullite refractories; microwave cavity perturbation
technique; digital signal processing technique.
Corundum-mullite materials are attractive for the pro-
duction of refractories. They have higher values for
emissivity, density and strength than other materials and ex-
hibit good resistance to heat. Such materials are used in the
heat-resistant (1350 – 1650°C) linings of high-temperature
furnaces and kiln furniture in the ceramics and refractories
industries, as well as in other high-temperature equipment
that is frequently subjected to thermal shocks [1, 2]. How
ever, the production operations carried out in these facilities
pollute the environment . In connection with this, it is nec
essary to develop a new method of making corun
dum-mullite refractories that will consume little energy and
New experimental methods have recently been devised
to measure the absorption characteristics of various materials
in the microwave frequency range [4, 5]. These methods
make use of microwave technology and technologies devel
oped for digital signal analysis, with the results that are ob
tained subsequently being subjected to analysis. One method
that has become particularly prominent is the measurement
of perturbations in a microwave cavity. The microwave cav-
ity perturbation technique is the preferred method for study-
ing materials in the microwave range. Huang et al  have
invented the leading microwave sensor to measure the prop-
erties of a drop of liquid. The sensor can be used in the mi-
crowave treatment of materials. It has been established that
the theory of microwave sensors agrees well with the exist-
ing experimental data. Huang and Peng  used the method
of measuring perturbations in a microwave resonator to de
termine the moisture content of the concentrate of a sulfide
mineral. Guo, et al.  used microwave technology to ana
lyze the microwave absorption characteristics of different
carbon-bearing reducing agents and oxidized ilmenite. The
results showed that the microwave absorption characteristics
of the reducing agents (coconut-based activated carbon,
coke, and graphite) are superior to those of oxidized ilmenite
for a particle size within the range 147 – 175 mm. Maik, et al.
 developed a noncontact method of measuring the electri
cal conductivity and complex permittivity of specimens of
single crystals and polycrystals in a direct-flow reactor
within the temperature range 20 – 500°C. The furnace atmo
sphere was composed of different gases.
Corundum-mullite refractories were made using analyti
cally pure powders of Al
, and MgO. The micro
wave absorption characteristics of the refractories were stud
ied by the microwave cavity perturbation technique. The
main focus of the investigation was the effect of particle size
on attenuation and frequency shift in corundum-mullite
Refractories and Industrial Ceramics Vol. 55, No. 3, September, 2014
1083-4877/14/05503-0231 © 2014 Springer Science+Business Media New York
Key Laboratory of Unconventional Metallurgy, Kunming Univer
sity of Science and Technology, Kunming, China.
Faculty of Metallurgical and Energy Engineering, Kunming Uni
versity of Science and Technology, Kunming, China.
Chemical Engineering Program, The Petroleum Institute, Abu
Dhabi, United Arab Emirates.