CORROSION OF ALUMINOSILICATE REFRACTORIES
BY MOLTEN ALUMINUM AND MELTS BASED UPON IT
IN MELTING AND CASTING UNITS
A. L. Yurkov
and I. A. Pikhutin
Translated from Novye Ogneupory, No. 5 pp. 53 – 61, May 2009.
Original article submitted November 17, 2008.
Corrosion mechanisms are proposed for aluminosilicate refractories by molten aluminum taking account of
new ideas about physicochemical reaction of molten aluminum with refractory. With a negative volumetric ef
fect for aluminum reactions with components of aluminosilicate refractories reaction products will not form a
continuous film, and with a positive volumetric effect the reaction products will split pores and cause material
cracking. A porous aluminum oxide film will not be a barrier for the reaction of aluminum with refractory. The
possibility for aluminosilicate refractories of wetting by molten aluminum and the size of pores permeable for
penetration of molten aluminum in relation to presence or absence of antiwetting additions are determined.
Keywords: corrosion, aluminosilicate refractories, molten aluminum and alloys based upon it, chemical reac-
tion, melting and casting equipment, wetting, wetting contact angle, flux, antiwetting addition, barium sul-
phate, celsian, aluminum fluoride, wollastonite, porous film.
Action of aluminum on refractory materials involves
chemical reaction (increasing with introduction of alloying
additions), erosive action, thermal shock (with metal pour-
ing), and mechanical action (with loading of ingots). Ac-
count should also be taken of the action of fluxing additions
(although considerably less than in ferrous metallurgy).
Integration into the world market has required in our
country both examination of ideas about the reaction of alu
minosilicate refractories laid down in 1960 – 80s, and intro
duction of new refractory materials for the aluminum indus
try, more resistant to the action of molten aluminum. Ideas
formulated in the 1960 – 80s about the physicochemical re
action of aluminum with refractories required considerable
reworking. Not all possible reactions with refractory compo
nents were considered for the alloys based on aluminum and
fluxing addition components, and almost no attention was
devoted to wetting of refractories by molten aluminum, and
the structure of refractories for producing aluminum alloys.
In previous work for introduction of corundum
refractories into the melting and casting units of the alumi
num industry no consideration was given to the fact that
magnesium is one of the main components of aluminum al
loys of the 5 – 6th group, and it reacts with Al
mation of aluminum-magnesium spinel. A first approxima-
tion is given in Table 1 [1 – 3] for information about the pos-
sible reaction of molten aluminum with oxides comprising
refractory materials. On the basis of data about enthalpy val-
ues for oxide formation it is may be noted that all oxides
placed to the right of Al
cannot be reduced by molten alu
minum. Conversely, TiO
, and FeO have a capacity to
react with molten aluminum:
4Al + 3SiO
+ 3Si. (1)
In the presence of magnesium spinel formation is possible:
Mg + Al + 2SiO
Data in Table 1 do not take account of the following situ
in molten aluminum there are always both impurities (al
kali metals, gases) and additions (magnesium, strontium, zir
conium, etc.) that on one hand are corrosive agents, and on
the other hand in view of their activity, strengthen the corro
sive action of aluminum;
oxides in a bonded state (for example SiO
silicate, magnesium silicate and even in aluminum silicate)
are less active and less inclined towards interaction;
Refractories and Industrial Ceramics Vol. 50, No. 3, 2009
1083-4877/09/5003-0212 © 2009 Springer Science+Business Media, Inc.
OOO RusInzhiniring (RUSAL), Moscow, Russia.
ITTs OOO RusInzhiniring, Krasnoyarsk, Russia.