This test method covers the determination of the resistance to deformation or shear of refractory shapes when
subjected to a specified compressive load at a specified
temperature for a specified time.
Significance and Use
The ability of refractory shapes to withstand prescribed
loads at elevated temperatures is a measure of the high temperature service potential of the material. By definition,
refractory shapes must resist change due to high temperature;
and the ability to withstand deformation or shape change when
subjected to significant loading at elevated temperatures is
clearly demonstrated when refractory shapes are subjected to this test method. The test method is normally run at sufficiently
high temperature to allow some liquids to form within the test
brick or to cause weakening of the bonding system. The result
is usually a decrease in sample dimension parallel to the
applied load and increase in sample dimensions perpendicular
to the loading direction. Occasionally, shear fracture can occur.
Since the test provides easily measurable changes in
dimensions, prescribed limits can be established, and the test
method has been long used to determine refractory quality. The
test method has often been used in the establishment of written
specifications between producers and consumers.
3.2 This test method is not applicable for refractory materials that are unstable in an oxidizing atmosphere unless means
are provided to protect the specimens.
Apparatus
The apparatus shall consist essentially of a furnace and
a loading device. It may be constructed in accordance with Fig.
1 or Fig. 2 or their equivalent.
The furnace shall be so constructed that the temperature is substantially uniform in all parts of the furnace. The
temperature as measured at any point on the surface of the test
specimens shall not differ by more than 10°F (5.5°C) during
the holding period of the test or, on test to failure, above
2370°F (1300°C). To accomplish this, it may be necessary to
install and adjust baffles within the furnace. A minimum of two
burners shall be used. If difficulty is encountered in following
the low-temperature portion of the schedule (particularly for
silica brick), a dual-burner system is recommended, one to
supply heat for low temperatures and another for the higher
temperatures.
The temperature shall be measured either with
calibrated5,6,7 platinum – platinum – rhodium thermocouples,
each encased in a protection tube with the junction not more
than 1 in. (25 mm) from the center of the side or edge of each
specimen or with a calibrated 5,6,7 pyrometer. A recording form
of temperature indicator is recommended. If the optical pyrometer is used, observations shall be made by sighting on the face
of the specimens and in the same relative positions as those
specified for the thermocouples.
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