CONSTRUCTION OF A FURNACE DEVICE FOR DETERMINING
REFRACTORINESS ACCORDING TO GOST 4069–69 AND ISO 528–83
I. Yu. Khlebnikova
and A. V. Zuev
Translated from Novye Ogneupory, No. 9, pp. 63 – 64, September 2007.
Original article submitted May 4, 2007.
A furnace construction has been developed in order to determine refractoriness according to GOST 4069–69
and ISO 528–83. According to the level of reproducibility of results, the accuracy of determining the refracto
riness of test materials, and values of the life characteristics, the construction surpasses domestic analogs.
One of the most important properties governing the de
sired choice of refractories for heating units is refractoriness.
Refractories that are heterogeneous multiphase systems melt
in a certain temperature range, and therefore they are charac-
terized not by the melting temperature, but by refractoriness
determined according to the temperature of the collapse of a
pyrometric cone. Reliable determination of refractoriness is
very important for the classification and use of refractories.
In Russia determination of refractoriness is regulated by
GOST 4069–69 and abroad by national standards that are
versions of MS ISO 528–83. In order to determine refractori-
ness special equipment is necessary for which there are a
number of serious specifications: uniformity of temperature
field in the working space, a controlled heating rate, the pos
sibility of controlling temperature in an automatic regime
with sufficiently high accuracy, high indices for life charac
teristics of heating elements and materials of the working
chamber, presence of free oxygen in the furnace atmosphere
during the whole process, conformity to contemporary health
standards, and accuracy of determining the instant of contact
of the tip of cones with the support.
Technical solutions developed in the USSR and abroad
for implementing this method have marked differences, ad
vantages and disadvantages (Tables 1 and 2). Determination
of refractoriness in kryptol furnaces is connected with the
complexity of regulating the temperature regime and creat
ing a uniform temperature field. This is connected with the
nonuniform change in petroleum coke resistance that during
heating sinters and is partly oxidized with formation of car
bon monoxide. Graphite and gas-flame furnaces have the
same disadvantages as kryptol furnaces, and performing tests
in different atmospheres leads to divergence of test results.
Thermal decomposition of lanthanum chromite at high
temperature, as a result of which there is release into the at-
mosphere of hexavalent chromium, leads to degradation of
the whole working chamber, ecological safety is under-
mined, and to all appearances the behavior of a cone during
testing is affected. In addition, domestic heating elements
Refractories and Industrial Ceramics Vol. 48, No. 4, 2007
1083-4877/07/4804-0310 © 2007 Springer Science+Business Media, Inc.
OOO Scientific and Technical Center (NTTs) Ogneupory, ZAO
TABLE 1. Main Technical Characteristics of Devices for Deter-
mining Refractoriness with Different Furnace Constructions
Graphite Horizontal Protective 1800 On the side
Kryptol Vertical Air 1800 From above
» » 1700 »
» » 1700 »
TABLE 2. Main Advantages (+) and Disadvantages (–) of Furnace
Unit Construction for Determining Refractoriness
Furnace heater element material
Life characteristics + – – +
Free oxygen content in
Ecological safety + – – +