RESEARCH IN THE FIELD OF PREPARING MOLDED
AND UNMOLDED REFRACTORIES BASED ON HIGH-ALUMINA HCBS.
PART 5. EFFECT OF FIRING TEMPERATURE ON PROPERTIES
OF MATERIALS PREPARED FROM COMPOSITE HCBS
WITH ADDITION OF REFRACTORY CLAY
Yu. E. Pivinskii,
P. V. Dyakin,
and L. V. Ostryakov
Translated from Novye Ogneupory, No. 4, pp. 24 – 29, April 2016.
Original article submitted September 22, 2015.
The effect of firing temperature in the range 800 – 1600°C and heat treatment duration (60 h at
1350 – 1400°C) on shrinkage and growth indices, porosity, and strength for specimens based on HCBS of
composite composition (bauxite and VFQG), and also with added clay, is studied. Depending on specimen
composition there is low shrinkage within the limits of 0.4 – 1.15% in the range 1100 – 1200°C and signifi-
cant growth (2.0-.27%) as a result of secondary mullite formation occurring at 1300 – 1500°C.
Keywords: bauxite, corundum, refractory clay, very fine quartz glass (VFQG), HCBS, mullite formation,
shrinkage, sintering, strength in bending.
In the preceding article of the present series  results
are provided for studying the effect of adding refractory clay
on the properties of HCBS of composite composition cast-
ings based upon them. The effect of nonisothermal heating
up to 1500°C on shrinkage indices during sintering and
growth during specimen secondary mullite formation with
refractory clay has been studied in a high-temperature
Previously the problem was raised on the basis of speci
mens prepared from original HCBS of composite composi
tion, and also with addition of refractory clay (1 – 10%), to
study the effect of firing temperature with exposure for 1 h
on linear shrinkage indices, ultimate strength in bending, and
to establish the effect of porosity and shrinkage on specimen
). With the aim of predicting material properties
during prolonged service studies have been performed for
the effect of prolonged (about 60 h at 1350 – 1400°C) firing
in a dinas furnace of OAO Dinur. Properties of the original
materials, and also properties of HCBS of different composi-
tions are given in articles [2 – 4]. In the present work both
original specimens and also those containing 1.0, 2.5, 5.0,
and 10% refractory clay have been studied.
A dependence is shown in Fig. 1 for linear shrinkage on
firing temperature for specimen of all test compositions.
With respect to the nature of the dependence of linear shrink
age on firing temperature two intervals have been separated
(I and II).
The first temperature range corresponds to the region
800 – 1100°C, and the second to 1100 – 1250°C. A distin
guishing feature of firing is the fact that in the range for the
first interval there is predominance of classical sintering ac
companied by material compaction and corresponding
shrinkage [2, 3], and in the second interval apart from
sintering there is secondary mullite formation. In contrast to
sintering this process is accompanied by certain material vol
umetric growth. As firing temperature increases the volume
increase is nullified by a sintering “compaction” mechanism.
It follows from Fig. 1 that maximum linear shrinkage
values YL for specimens of all forms corresponds to a firing
temperature of 1100°C. With an increase to 1200°C these in
dices change little, i.e., in spite of a marked increase in tem
Refractories and Industrial Ceramics Vol. 57, No. 2, July, 2016
1083-4877/16/05702-0180 © 2016 Springer Science+Business Media New York
Parts 1 – 4 of the article published in Novye Ogneupory Nos. 8,
10, and 12 (2015) and No. 2 (2016).
OOO NVF Kerambet-Ogneupor, St. Petersburg, Russia.
FGBOU VPO St. Petersburg State Technological University
(Technical University), St. Petersburg, Russia.
OAO Dinur, Pervoural’sk, Sverdlov Region, Russia.