A CERAMIC CORUNDUM-MULLITE ADHESIVE:
USES AND APPLICATIONS
T. F. Baranova
Translated from Novye Ogneupory, No. 10, pp. 32 – 38, October, 2004.
Original article submitted August 24, 2004.
The properties of a high-temperature adhesive and its uses for bonding complex-shaped components based on
oxides, corundum-mullite and corundum refractories, and Si
and SiC ceramics are re
ported. A compositional variant using a boron aluminophosphate binder is considered, with adhesive joints of
thickness 0.1 to 2 mm; the shearing strength of the adhesive joint varies from 5 to 25 MPa depending on the
porosity of the adherend material and bond-line thickness.
In the fabrication of ceramic components of block-like or
more complex configuration [1 – 3], refractory linings for
thermal power units  and kiln trucks  etc., phosphate
composites are used that consist of fillers (mullite, zircon,
chamotte, oxides SiO
) and phosphate binders
, boron aluminophosphate, chromium aluminophos-
phate, or aluminophosphate bonds). These composites ex-
hibit the behavior of polymeric materials and are capable of
forming long polymer chains via binding phosphates and oxi-
des into crystal hydrates thereby providing the hardening in a
cold state. Their binding properties are associated with col
loidal dispersions that form owing to the involvement of spe
cies with functional phosphate groups in the precursor mix.
The subsequent heat treatment that initiates hardening and
strengthening under controlled concentration and crystalliza
tion conditions yields products with tailored properties .
The hardening of phosphate composites proceeds via
acid-base coagulation and polycondensation of intermediate
products and formation of metallophosphates. The compos
ites exhibit adhesive strength over a wide temperature and
resistance to gas combustion products. The terminology for
such composites in the literature is somewhat ambiguous.
They are occasionally referred to as refractory solutions
[2, 4], mortars [1, 6, 7], adhesives [2, 5, 8, 9], or phosphate
binders . Actually, phosphate-based composites exhibit a
set of properties characteristic of all these materials.
As is known, an important condition for the efficiency of
a ceramic adhesive is that the adhesive by its chemical com
position must be similar to that of the material of the
adherend [2, 3]; another factor is the occurrence of interme-
diate layers in the adhesive-bonded joint where different ma-
terials are bonded (ceramic – ceramic, ceramic – graphite,
ceramic – metal), to compensate for the difference in the co-
efficient of linear thermal expansion (CLTE).
The present paper is concerned with adhesive composi-
tes — phosphate mixtures based on a refractory mortar .
They are used as adhesive agents in the fabrication of com-
plex engineering components [2, 3] by bonding together sep
arate elements, for example, a corundum-mullite pattern die
or a silicon nitride nozzle assembly (Fig. 1). The thickness of
the adhesive joint is, as a rule, 0.1 – 0.5 mm. Adhesive com
posites are also used for full-life restoration of decommis
sioned equipment. Specifications and service conditions of
ceramic adhesives based on BAPC and AKhFS-type phos
phate binders with a corundum-mullite filler doped with
and clay can be found in [1 – 3].
However, for a particular mortar to be effective in spe
cific applications (bonding of ceramic and refractory compo
nents), preliminary tests are to be carried out to optimize the
composition and dispersity of mortar-based adhesive mixes.
In this paper, new adhesive composites based on the con
ventional corundum-mullite mortar  of composition, wt.%:
corundum-mullite chamotte, 27 – 73; aluminum oxide,
3 – 10; zircon concentrate, 3 – 28; phosphate binder, 20 – 30,
and clay are considered. The concentration of clay (if present
in the composition) was minimum; the powders of corun
dum-mullite chamotte differed in Al
phosphate binders were commercial products: boron alu
Refractories and Industrial Ceramics Vol. 45, No. 6, 2004
1083-4877/04/4506-0402 © 2004 Springer Science+Business Media, Inc.
Tekhnologiya Research and Production Enterprise, Obninsk,
Kaluga Region, Russia.