AN ELECTROPHORETIC DEPOSITION METHOD FOR MOLDING
COMPONENTS FROM SLIPS OF INORGANIC MATERIALS
E. I. Suzdal’ysev
and D. V. Kharitonov
Translated from Ogneupory i Tekhnicheskaya Keramika, No. 3, pp. 13 – 17, March, 2003.
Studies have been conducted showing that, for molding components from aqueous slips, the traditional casting
technology based on the use of plaster molds can be replaced by a new technique of electrophoretic deposi
tion. The new technique, using copper plates for both anode and cathode, saves processing time significantly
(by several tens) and improves the quality of molded preforms.
The technology of molding in which aqueous slips (sus
pended inorganic materials) are cast in porous plaster molds
[1 – 3] has a serious drawback — it takes long to build up the
preform material (to mold a preform with wall thickness
d = 20 mm from a slip based on lithium alumina-silicate
glass, the time needed is 35 – 40 h, and based on quartz,
10 – 20 h). Therefore saving the material buildup time is a
challenging problem for the slip casting technology.
The electrophoretic deposition method is a promising
technique for saving time and effort in the preform material
A literature survey has shown that for effective imple-
mentation of the electrophoretic method, a range of practical
problems are to be solved, in particular, the selection of an
anode material suitable for making the electrodes of an elec
trophoretic unit [4 – 6] and an adequate design of this unit
[7, 8]. Routes toward solving these problems have been con
sidered in this study.
The slips used in our work were prepared from lithium
alumina-silicate glass. The materials for the anode were: du
ralumin, aluminum (foil), copper, and brass. Potential use of
these metals as the material for anode was earlier considered
in [4, 6]. To our knowledge, no data were reported in the li
terature on the specific role of the anode material in the elec
trophoretic deposition method for molding preforms from
aqueous slips based on lithium alumina-silicate glass. It was
thought therefore that an adequate technique developed in
the field would be of both interest and help for technologists.
It was found that the kind of anode material used for that
purpose is essential for the quality of cast products (Table 1).
It can be seen from Table 1 that aluminum used as the
anode material adds little to the high product quality: pre
sumably, this is due to the fact that aluminum oxide films set
a barrier to binding oxygen produced by water electrolysis,
where gaseous hydrogen is released on the cathode, and oxy-
gen — on the anode. The failure to bind oxygen results in its
accumulation on the surface of the anode and, ultimately,
there is no way for oxygen to escape from the cavity of the
mold. The ensuing effect is the electric breakdown through
the material deposited on the anode resulting in the occur-
rence of air holes and closed porosity (Fig. 1).
The problem with duralumin was its rough surface resis-
tant to fine finish, which resulted in a strong adhesion of the
cast material to the anode and rendered its easy extraction
from the mold impossible.
Anodes of copper and brass showed better performance.
Specimens deposited on these anodes had an even, smooth
surface, and an equal density through the thickness and
throughout the height. These benefits are due to the fatc that
the total oxygen released on the anode remains bound to the
material of the anode (Fig. 2a ).
These data are in agreement with results reported in
[4, 6] where anodes made of zinc and lead were used; the
preforms, molded from a porcelain mixture, developed a
color due to metal oxides, and the color persisted in calcined
Refractories and Industrial Ceramics Vol. 44, No. 4, 2003
1083-4877/03/4404-0232$25.00 © 2003 Plenum Publishing Corporation
Tekhnologiya Research and Production Association Federal State
Unitary Enterprise, Obninsk, Kaluga Region, Russia.
TABLE 1. Quality Characteristics of Preforms Cast on the Anode
from an Aqueous Lithium Alumina-silicate Glass Slip
Duralumin High adhesion to anode Greenish-gray
Aluminum Soft material, high closed poro
sity, air holes in places
Copper Good Greenish-orange
Brass Good Brown-orange