FUTURE APPLICATION OF ALUMINOSILICATE REFRACTORIES
FOR ALUMINUM ELECTROLYZERS. PART 4. WETTABILITY
OF ALUMINOSILICATE REFRACTORIES WITH MOLTEN INDUSTRIAL
ELECTROLYTE AND SODIUM FLUORIDE
V. V. Sharapova,
B. P. Sereda,
D. Yu. Bogoslavskii,
I. P. Malyshev,
V. D. Troyan,
and N. A. Troshenkov
Translated from Novye Ogneupory, No. 1, pp. 17 – 21, January 2008.
Original article submitted July 5, 2007.
Optical microscopy is used to determine wetting angles for aluminosilicate refractories with molten industrial
electrolyte and NaF. Kinetic wetting parameters and interaction of electrolyte with refractory are determined.
It is shown that removal of silicon from refractory also occurs in the form of silicon monoxide. It is established
that aluminosilicate refractories, prepared with addition of mullite-corundum chamotte, are wetted worse by
fluoride salts, but the corrosion resistance of them is better than for refractories prepared by normal technology.
In an aluminum electrolyzer surface forces at the bound-
ary of the liquid – gas – solid substance determine the inten-
sity of penetration of materials by molten electrolyte and
their corrosion rate. The overall index characterizing equilib-
rium of surface tension at a three-phase interface is the con-
tact wetting angle q:
q = arccos(s
are interphase energies at the boun
daries of the solid and liquid with vapor respectively; s
the interphase energy at the solid – liquid boundary.
The value of q is affected by the nature of all phases par
ticipating in equilibrium, their physicochemical properties,
preparation methods, temperature conditions, and polariza
tion. The contact wetting angle, connected with the work of
by the relationship W
(1 + cosq), may
serve as a criterion for selecting materials used in electro
lyzers. Knowing the contact wetting angle it is possible to
improve production schemes for preparing the cathode as
sembly of an aluminum electrolyzer.
Wetting of refractory materials by cryolite has been de
scribed in . According to data in  the contact wetting
angle for aluminosilicate materials by molten electrolyte is
close to zero. The corrosion resistance of refractory material
is mainly affected by the diameter of its permeable pores
(and consequently gas permeability), the optimum distribu-
tion of pres with to size, porosity, density [2, 3]. According
to data in  the microstructure of a refractory is subject
more intense chemical reaction than its macrostructure.
A high mullite content, particularly in the microstructure,
provides a high resistance to the chemical action of gases re
leased from the heated anode in the furnace (residues of
in ash) , since mullite is chemically more
stable than cristobalite or glass.
Previous studies by the authors of this article  estab
lished that aluminosilicate refractory ShPD
with addition of mullite-corundum chamotte, is more resis
tant to the action of molten industrial electrolyte than refrac
tory ShPD-43 prepared by normal technology. The aim of the
present work is to study wetting of different aluminosilicate
refractories by molten industrial electrolyte with a.o. = 2.4
and chemically pure sodium fluoride in the absence of polar
ization. The results obtained serve as a characteristic for the
test refractories from the point of view of their future appli
cation in electrolyzers with hearth units containing 50%
Studies were performed using optical microscopy and
also x-ray spectrographic rapid analysis in an ÉDAR of a
REM-MA-202-M set of equipment. In the course of an ex
periment a substrate was prepared from refractories ShPD
and ShPD-43 . Cubes with an edge of 3 mm made of in
Refractories and Industrial Ceramics Vol. 49, No. 1, 2008
1083-4877/08/4901-0009 © 2008 Springer Science+Business Media, Inc.
* Parts 1 – 3 of the article were published in the journal Novye
Ogneupory Nos. 9, 10 and 12 for 2007.
UkrNIIspetsstal’, ZGIA, OAO ZalK, OAOZaporoshogneupor,