CARBIDE FORMATION AT A CARBON-GRAPHITE
LINING CATHODE SURFACE WETTABLE WITH ALUMINUM
E. S. Gorlanov,
V. Yu. Bazhin,
and S. N. Fedorov
Translated from Novye Ogneupory, No. 6, pp. 23 – 27, June, 2016.
Original article submitted February 28, 2016.
For protecting a cathode block surface and a whole electrolyzer lining it is proposed to use boron and titanium
compounds in the form of an active substrate of their carbides (TiC and B
C) that under successive
electrodeposition conditions with transformation and reaction transitions create a layer wettable with alumi
num. Combined synthesis processes are studied for wettable coatings and the mechanism of carbide formation
on carbon cathode surface layers. Possible processes of aluminum carbide formation with its transition into
carboxide surface substances are suggested for discussion.
Keywords: aluminum carbide, carboxide suspension, titanium boride, aluminum, cathode lining, wettable
coating, electrochemical boriding.
An increase in the life of carbon-graphite lining of an
electrolyzer under conditions of a molten cryolite-alumina
corrosive medium is a strategic task for the aluminum indus-
try. Recently in view of an increase in ampere load, and con-
sequently an increase in cathode current density with intense
action of a layer of molten aluminum (20 – 25 cm), at the
cathode of a carbon-graphite lining of large aluminum
electrolyzers problems arise connected with development of
local breakdown, mechanical wear, and chemical erosion, es
pecially at the surface.
Previously in many works processes and mechanisms of
electrochemical and chemical synthesis of compounds in a
dense surface layer of a carbon cathode, responsible for the
effect of its wetting by molten aluminum, have been dis
cussed in detail. In a publication  there is comprehensive
and systematic research for creation of a Ti–B–C coating on
a carbon-graphite cathode wettable with aluminum. How
ever, there was no consideration or systematic study of the
overall volume of processes of carbide formation in some ar
eas of a cathode surface of a lining layer.
There is scientific and technical interest in development
and more profound clarification of processes and problems
connected with high-temperature electrochemical synthesis
at a cathode surface of an aluminum electrolyzer lining of a
coating wettable with aluminum. Work was carried out in
two directions :
– successive electrodeposition of compound compo
nents (Ti and B) from molten cryolite;
– electrochemical boriding of a carbon-titanium cathode
DEVELOPMENT OF A METHOD
FOR SUCCESSIVE ELECTRODEPOSITION
OF TITANIUM COMPOUNDS
It has been proposed that the first deposited component
on a cathode carbon surface during a sufficient period of time
should form a layer of active substrate of carbide (TiC or
C). Then there should be reaction with a carbide layer and
carbon cathode to form complex compounds in the Ti–B–C
system. A layer wettable by aluminum only forms at the sur
face of a carbon cathode within a limited period of the
electrolyzer start-up (72 h) and with increased concentration
of titanium and boron in electrolyte. Experiments under labo
ratory conditions were carried out in an electrolytic cell with
an electrolyte temperature 990ºC and current density of
0.7 – 1.3 A/cm
Refractories and Industrial Ceramics Vol. 57, No. 3, September, 2016
1083-4877/16/05703-0292 © 2016 Springer Science+Business Media New York
OOO ÉKSPERT-AL, St. Petersburg, Russia.
FGBOU VPO National Mineral Raw Material University Gornyi,
St. Petersburg, Russia.