EFFECT OF PYROPHILLITE ON THE PHYSICOMECHANICAL
PROPERTIES AND ACID RESISTANCE OF ACID-PROOF MATERIALS
E. S. Abdrakhimova
Translated from Novye Ogneupory, No. 5 pp. 15 – 19, May 2009.
Original article submitted June 20, 2008.
It is established that introduction of pyrophyllite into the composition of ceramic mixes markedly improves
the physicomechanical properties and acid resistance of acid-proof materials. The method of linear regression,
used for optimizing the composition of ceramic mixes with respect to the physicomechanical properties of
acid-proof materials has shown that the difference in model results from actual results, obtained in the course
of an experiment, lies within the limits of model nonconformity.
Keywords: pyrophyllite, Zhana-Daursk kaolin, ceramic mixes, acid resistance, ultimate strength in compres
sion, frost resistance, regression analysis.
Currently in order to prepare acid-proof materials there is
mainly use of argillaceous materials with a high Al
tent (>18%), and a small content of iron and calcium oxides
< 3,5%, CaO < 2%). It is almost impossible to pre-
pare high quality acid-proof materials from a mix based on
refractory clay with an high Fe
and CaO content, and
with a low Al
content [1 – 4].
Chamotte is used as an inert component in the produc-
tion of acid-proof materials in ceramic mixes. It is prepared
on firing clay in the range 1200 – 1250°C (up to water ab
sorption <5%). It is very difficult to prepare high quality
chamotte based on acid-proof refractory clays. Therefore it is
impossible to obtain a high quality acid-proof material from
a mix consisting of low quality refractory clays and
chamotte. In addition, the requirements for acid-proof mate
rials are satisfied by import from other countries, although
development of ferrous metallurgy and the chemical industry
requires a considerable increase in the production of all
forms of acid-proof material objects. In view of this the de
velopment of compositions of ceramic mixes for producing
acid-proof materials based on inexpensive raw material is an
In [1 – 3] the fundamental possibility has been demon
strated of using Zhana-Daursk kaolin and pyrophyllite in the
production of acid-proof materials. The chemical composi-
tion of the starting components is presented in Table 1.
Zhana-Daursk kaolin is not related to high quality argil-
laceous raw material, but to semi-acid clay with an increased
content of colored oxides (Fe
> 3%). With respect to the
content of particles with a size of less than 1 mm (35 – 38%)
kaolin is fine, it has little sensitivity with respect to drying, in
refractoriness it is difficult to melt (refractoriness
1540 – 1570°C), and concerning sintering it is medium-
sintering with a sintering range of 100 – 120°C. The mineral
composition of Zhana-Daursk kaolin is represented by the
following minerals, wt.%: kaolinite 45 – 50, feldspar
20 – 30, quartz 10 – 20, calcite 2 – 4, iron oxides 1 – 3, or
ganic admixtures (humus substance) 1.8 – 2.0.
It is only possible to prepare high quality acid-proof ma
terial objects with introduction into the ceramic mix of a
component with a high Al
content, and this relates to
pyrophyllite [1 – 4]. Nikol’sk pyrophyllite Al
is similar in properties to talc [1 – 4]. Due to its softness vari
ous objects are turned from pyrophyllite, that retain shape
and dimensions after firing; the mineral has been studied
[1 – 4] for producing acid-proof material plates.
In contrast to normal sedimentary clays pyrophyllite
forms in zones of considerable metamorphism at
Refractories and Industrial Ceramics Vol. 50, No. 3, 2009
1083-4877/09/5003-0174 © 2009 Springer Science+Business Media, Inc.
S. P. Korolev Samara State Aerospace University, Samara, Russia.
TABLE 1. Chemical Composition of Starting Components, %
Zhana-Daursk kaolin 69.14 17.38 3.1 2.0 1.42 0.20 6.08
Pyrophillite 52.85 34.88 0.4 0.22 0.1 0.09 7.88