Advances in Ma terials Ph ysics and Ch emistry, 2012, 2, 96-98
doi:10.4236/ampc.2012.24B026 Published Online December 2012 (
Copyright © 2012 SciRes. A MPC
Development and Characte r i zation of Ultra Low Ce ment
Castable Cordierites by Thixotropic Properties Mixtures
Ana M. Paniagua-Mercado1, Arturo Méndez-Sánc he z 1, Elvia Díaz Valdés1,
Concepción Mejía García1, Paulino Estrada Díaz2
1Depto. de Fí sica, Escuela Superior de Física y Matemáticas, Instituto Politécni co Nacional, Col. Lind avista, México
2Sector-Ceramics an d Re f r acto ries, Manuchar International, México
Received 2012
The main target in this investigation was to take advantage of the reology properties of the tixotropic mixes in Ultra Low Cement
Castabl es (ULCC). The cor di erit e ph ase in refracto ry mix can be o b tain ed usin g raw materials with magnesi u m oxid e in it s composi-
tion, such as, Mg(OH)2 or H2Mg3(SiO3)4 (Talc mineral), with a content of 63.5% SiO2, 31.7% MgO and 4.8% H2O. In this investiga-
tion, as magnesium sou rce, a commercial c alcined magnesi te with 90% M gO was u sed. This mineral was selected in stead of Talc
mineral, b ecause this last contains more impurities in its composition that tend to form more amounts of liquid phases with low fu-
sion points. For this work two different ULCC mixes were designed. These were fired at 1260ºC, the cordierite phase was quantified
in each mix.
Keywords: Reology; Thixotropic Mixtures; Ultra Low Cement Castabl es ; Cordierite
1. Introduction
There are in the market, several industrial methods and a wide
of conventional raw materials to produce cordierite mixes
(MgOAl2O3SiO2). The complete phase transformation is
around 1300ºC depending on the raw material used in the mix
[1]. The industrial application is mainly focus where high ther-
mal shock resistant, low thermal expansion and corrosion resis-
tance are demanded. Such is the case o f the cord ierite refractory
plates used for the conventional firing of sanitary and tableware,
or recently used as substrate material in microelectronics [2].
The main manufacturing processes to develop cordierite phase
are the sol-Gel method [3], co-precipitation [4], solid-state re-
action [5] and by slurry. Aluminosilicate based ultra low ce-
ment castab les (ULCC) ar e widely used mainly in t he Steel and
cement industries due to improved refractory properties at high
temperatures. The bonding system in ultra low cement castables
is achieved by using high alumina calcium alu min ate cement .
Increasing the cement content in the concrete mix also in-
creases the amount of liquid phases as the anorthita (CaAl2Si2
O8) and gelenite (Ca2Al2SiO7). These both tend to reduce the
amount of free silica and decrease, in an important way, its
chemical corrosion resistance. This last affects negatively their
mechanical properties at high temperatures and in consequence
the thermal shock resistant comes down. The lime/silica ratio is
very important in the formation of liquid phases and its viscosity
at high temperatures, because it affects the strength and corro-
sion resistance [6]. The use of very low amounts of high alu-
mina cement in ULCC is principally to avoid the liquid phases
formatio n ins ide the refractor y matrix. O ther impo rtant variab le
is the particle size distribution because it has a major impact in
the reology of ULCC and in the final physical properties [7].
2. Experimental Procedure
Table 1 shows the chemical formulation of the two concrete
mixes tested in this investigation. For each one of the designed
mixes the preparation was as follows. First, the raw materials
were dry mixed for at l east 1 min u te, after t hat , th e defloccu lan t
(sodium tripolifosfate); the polypropylene fibers and the high
alumina ce ment were add ed to the final mix. At once, th e water
was added slowly and mixed 10 second more. After the mix
was placed in a vibratory table (3000 cps), for no more than 30
seconds up to the mix, it got a thixotropic behavior.
After the vibratory step, the mix was allowed to dry and it
was set for 12 hours at room temperature (25ºC). Afterwards
the mix was dried 24 h in a laboratory stove at 110ºC. Finally,
the mix was calcin ed b etween 1 26 0°C - 1280°C during 5 h, in a
gas furnace. In order to determine the cordierite forming and
main phases present, the calcined samples were analyzed by
X-ray diffraction in a Siemens D-500 diffractometer, with Kα
of Cu in the Bragg-Brentano configuration, in a 2 range of 10º-
120º. Micrographs of each one of the two calcined mixes were
obtained with secondary electrons, at 800X of magnification, in
a scanni ng electro n microscopy JEOL-6300.
Tabl e 1. Chemical Formulation of Mixtures.
Compound MIX I ( %) MIX II (%)
CaO 0.80 1.08
1.08 0.82
*Work supported by Instituto Politécnico Nacional through project SIP-
Copyright © 2012 SciRes. AMPC
3. Results and Discussion
3.1. Chemical Analysis
Speci fic raw materi als were sel ected t o design the U LCC cordie-
rites. Oxide or other non-clay powders generally have poor worka-
bility when they are mixed with water and settling rapidly at
lower water levels. For this reason, it was utilized so me defl o c-
culating chemicals to get a thixotropic behavior. In ULCC mix
the amount of water is a problem because higher amount of
water, than that required, is to the detriment of the final physical
properties of the refractory concrete as %Porosity and density
(see Table 2).
3.2. Physical Properties
The physical properties of the mixtures were calculated and
they are shown in Table 3.
The physical properties reported for the mix I, with a greater
amount of fine particles than for mix II, table III, the fines are
because t he raw materials used for mix I are more than fo r mix
II, show that it was required more water in its preparation than
for mix II.
It can b e also observed from mix I, that at h igher water con-
tent in the mixII, the density decreases and the porosity too,
Table 3.
Increases water resulting in a negative effect for the final
physical properties. For Mix II, with a greater amount of coarse
particles, until the raw mix, the demand of water was lower
than for mix I, and this was reflected in its final physical prop-
3.3. X-ray Diffraction
In the patterns of X-ray diffraction shown in Figure 1, the dif-
ferent phases contained in the mixes I and II are presented.
These were quantified with the peaks getting b y X-ray diffrac-
tion of mixes burned.
Tabl e 2. Physical properties of the mixtures.
Proper ty Setting
Time (min) Water
Mixe d (mL) Density
(g/cm3) Absorption
(%) Porous
MIX I 160 1 2 .5 1.95 13.8 27 .0
MIX II 80 8.5 2.07 9 .6 20.0
Tabl e 3. Granulometry and density of raw materials.
Raw materials Particle Size
(µm) Density
Magnesium Oxide 5 90 3.10
Calcined Kaolin 74-2380 2.52
Microsilica 44 2.70
High Alumina Cement 53 0 .90
Calcined Bauxite 74 3.15
The X-ray diffraction patterns reported a higher amount of
cordierite phase for mix I than for mix II, as it is observed in
Table 4. The mix I had a big amount of fine particles which
contributed in an important way to the formation of the cordie-
rite phase, however, it was utilized a bigger amount of water for
its preparation and the physical properties for this mix were
poor in comparison with those ones of the mix II. Other main
phases detected in this analysis were mullite, cristobalite, al-
pha-alumina and magnesium oxide. It is necessary to remark
that particulate size distribution is a very important factor in the
quantity and type of phases formed for this ULCC.
Figure 1. Patterns of X-ray Diffractions: (a) mix I, (b) mix II
Tabl e 4. Phase quanti ty i n the mixture s.
Phase Cordierite
(%) Mullite
(%) Cristobalite
α Al2O3
(%) MgO
MIX I 31.87 18.64 35.23 8 .0 4 6.22
MIX II 14.27 29.00 37.29 5.18 14.26
Copyright © 2012 SciRes. AMPC
Figure 2. Micrographs: (a) mix I and (b) mix II.
3.4. Scanning Electron Microscopy
In the micrographs shown in Figure 2 we can o bserve material
like flakes corresponding to cordierite, and liquid phases with
composition of Fe2O3, Na2O, K2O and GeO formed with the
presen ce of SiO2 and detected b y Micro anal yses of SEM, all of
these h ave low fusion points.
4. Conclusions
1. It was processed a refractory Cordierite ULCC mix, with
level of cordierite phase commercially acceptable and with
thixotropic properties .
2. The main physical properties of this type of ULCC are
subj ected to a very restricted particle sizes distribution to obtain
the b etter physical propert ies after fired .
3. Further research work must be doing to improve in a better
way the cordierite performance phase and also the final physi-
cal properties of the castable.
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