RESEARCH IN THE AREA OF PREPARING MATERIALS
BASED ON FUZED QUARTZ HCBS.
PART 8. EFFECT OF ALKALI ADDITIONS ON CERAMIC SINTERING
AND CRISTOBALITIZATION IN A NONISOTHERMAL HEATING REGIME
Yu. E. Pivinskii,
P. V. Dyakin,
and A. Yu. Kolobov
Translated from Novye Ogneupory, No. 1, pp. 22 – 28, January 2016.
Original article submitted November 14, 2015.
Results are provided for a study of the effect of alkali additions based on dispersed silicate lump (sodium
metasilicate) on quartz ceramic sintering and cristobalitization in a nonisothermal heating regime in a
high-temperature dilatometer. Depending on additive content the difference in initial sintering temperature
reaches 300°C, and for the initial stage of cristobalitization it reaches 400°C.
Keywords: HCBS, fuzed quartz, silicate lump, thermal expansion, shrinkage, heating rate, UKhAKS-
In previous articles of the current series [1 – 5] it has
been shown that in contrast to quartz ceramic based on high
purity quartz glass similar materials prepared on the basis of
fuzed quartz and characterized by high impurity content, are
distinguished by resistance to cristobalitization. Production
factors are important in this process. Whereas during prepa
ration of technical quartz ceramic wet milling of quartz glass
is accomplished in ball mills lined with fuzed quartz, and the
milling bodies used are rods of transparent quartz glass, dur
ing HCBS preparation on the basis of fuzed quartz in refrac
tory manufacture lining and milling body materials used are
of high-alumina composition (75 – 80% Al
) with a
marked content of glass phase of complex composition
, MgO, CaO, Fe
O, etc.) [1, 6, 7]. Grinding
away of milling bodies and lining may reach 0.5 – 1.0% (de
pending on milling body composition and wear stage). In ad
dition, whereas distilled water is used in quartz ceramic pro
duction during milling, then in the production of quartz
refractories running water is used predominantly character
ized by unsteady pH and containing impurities. As a result of
this the SiO
content in steel-pouring refractories may be re-
duced to 98.5 – 99.0%. In the original fuzed quartz its
amount reaches 99.5% [1, 2, 7, 8].
In addition, as applied to manufacturing and operating
technology for refractories a very important question is
cristobalitization kinetics during high-temperature service in
view of the fact that of all silica modifications cristobalite is
more refractory and chemically stable [1, 2, 7 – 9]. In quartz
refractory technology involving firing, the associated
cristobalitization is undesirable. In different versions of un
fired technology [1, 7, 8, 10 – 12], excluding preliminary ob
ject heat treatment, the cristobalitization process proceeds
during high-temperature operation. All versions of this tech
nology provide introduction of insignificant additions or wa
ter glass solutions.
In order to prepare similar materials, strengthened by
means of chemical activation of contact bonds with imple
mentation of a “cold-sintering” mechanism  (UKhAKS
materials) (strengthened by chemical activation of contact
bonds) a feature of using water glass for UKhAKS strength
ening consists of the fact that in this case they are used pre
dominantly as an alkaline component governing the dissolu
tion mechanism for SiO
-containing materials followed by
condensation of the interstitial solution formed [13, 19].
As applied to preparation of unfired quartz refractories,
as will be shown in the concluding articles of the current se
Refractories and Industrial Ceramics Vol. 57, No. 1, May, 2016
1083-4877/16/05701-0027 © 2016 Springer Science+Business Media New York
Part 1 of the article was published in Novye Ogneupory No. 7
(2014), and parts2–7inNos. 1, 3, 4, 6, 7, and 9 (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.