RESEARCH IN THE FIELD OF PREPARING MOLDED
AND UNMOLDED REFRACTORIES BASED ON HIGH-ALUMINA HCBS.
PART 3. EFFECT OF FIRING TEMPERATURE ON SINTERING
AND MULLITIZATION OF MATERIALS PREPARED ON THE BASIS
OF COMPOSITE COMPOSITION HCBS
Yu. E. Pivinskii,
P. V. Dyakin,
and L. V. Ostryakov
Translated from Novye Ogneupory, No. 12, pp. 25 – 33, December 2015.
Original article submitted August 26, 2015.
The effect of firing temperature on sintering and mullitization of six batches of specimens prepared from
HCBS based on high-alumina bauxite and very fine quartz glass (VFQG) is studied. In the range
900 – 1200°C (soaking 1 h) normal sintering is noted accompanied by insignificant (0.4 – 0.5%) shrinkage
and a sharp increase in ultimate strength in bending (110 – 130 MPa). In the range 1200 – 1400 of 1500°C
(depending on composition) specimen growth by 1.0 – 2.5% is noted, due to mullitization. Depending on
composition and solid phase fineness the start of sintering for mullitized specimens is noted at temperatures
exceeding 1400 – 1500°C. Specimen material modeling a matrix system of high-alumina refractories has high
strength and volume constancy after prolonged thermal ageing.
Keywords: bauxite, corundum, mullite, very fine quartz glass, HCBS, nanostabilization, growth, shrinkage,
thermal ageing, wet grinding, ultimate strength in bending.
Previously  in the initial stages of sintering and sec
ondary mullite formation for specimens based on composite
composition HCBS, prepared by combined wet milling of
high-alumna bauxite [1, 2] and fuzed quartz, have been stud
ied. It was detected that the initial sintering stage develops in
the range 900 – 950°C, and mullite formation develops in the
range 1100 – 1150°C. In this work six batches of specimens
have been used the same as in , prepared from HCBS hav
ing different SiO
and dispersed solid phase particle content,
and sintering and mullitization have been studied over quite
a broad (900 – 1600°C) temperature range. In addition, by
means of prolonged heat treatment for specimens in an in
dustrial furnace for dinas firing (overall duration in the range
1350 – 1400°C about 60 h) the effect of thermal ageing on
test materials properties has been studied.
STARTING HCBS AND CASTING PROPERTIES,
SPECIFIC NATURE OF THEIR CHEMICAL PHASE
AND DISPERSION COMPOSITIONS
General properties of chemical and phase compositions
of the original bauxite have been provided in previous publi
cations [1, 2]. Data are given in Table 1 not only the compo
sition and properties of the original HCBS, but also some
properties of slip castings prepared from them, heat treated at
900°C. Distinguishing features of the original HCBS compo
sition have been considered in .
All of the materials presented in the present series of
publications are based on HCBS prepared by wet milling un
der production conditions in industrial mills.
Concerning the effect in question of firing temperature
on material properties it should be noted that the effect clari
fied in  of a reduced temperature for the initial sintering
stages and mullitization is due to the specific features of wet
Refractories and Industrial Ceramics Vol. 56, No. 6, March, 2016
1083-4877/16/05606-0648 © 2016 Springer Science+Business Media New York
Parts 1 and 2 of the article published in Novye Ogneupory Nos. 8
and 10 (2015).
OOO NVF Kerambet-Ogneupor, St. Petersburg, Russia.
FGBOU VPO St. Petersburg State Technological University
(Technical University), St. Petersburg, Russia.
OAO Dinur Pervoural’sk, Sverdlovsk Region, Russia.