Analysis of the Effect of Temperature on the Ultimate Strength of Refractory Materials

Abstract

The energy efficiency of high-temperature batch aggregates largely depends on the modes of their heating and cooling. The modes of heating and cooling of aggregates in which thermal stress does not exceed the critical values of the ultimate strength of the refractories make it possible to increase their service life. The increase in the service life of refractories will lead to a reduction in the number of lining repairs and a decrease in the specific consumption of refractory materials per ton of technological product. Shorter warm-up and cool-down times result in lower energy consumption. Reducing the time for variable modes for casting ladles increases their turnover (the number of melt discharges into the ladle per day). Increasing ladle turnover not only reduces the number of ladles but also improves the economic performance of the enterprise. The ultimate strength of the refractory material significantly affects the rate of temperature change during heating and cooling of the refractory masonry. The purpose of this research is to study the dependence of the ultimate compression and tensile strengths of chamotte materials of the ShKU brand on temperature. The determination of the compression and tensile strengths was carried out on new samples of refractory materials as well as on samples of refractories that were in operation until the intermediate repair. To determine the ultimate compression strength of chamotte refractories, the standard technique for axial compression of the test specimen until its destruction was used. To determine the ultimate tensile strength, a three-point bending test was used with additional control of the surface temperature of the test sample during the test. The ultimate compression strength of chamotte refractories of the ShKU-32 brand increased for the new refractories by a maximum of 44%. For refractories that were in operation until the intermediate repair, the ultimate compression strength increased by a maximum of 56%. The value of the ultimate tensile strength at elevated temperatures turned out to be higher than the value at a temperature of 20 °C. For new refractories, the maximum ultimate tensile strength is 25% higher than the ultimate tensile strength under normal conditions. For refractories that were in operation until the intermediate repair, the maximum ultimate tensile strength increased by 24%. The obtained results can be used to increase the rate of heating or cooling of linings.

Analysis of the Cooling Modes of the Lining of a Ferroalloy-Casting Ladle

“…During the operation of the casting ladle, a change occurs in the thermophysical and strength properties of the lining refractories. Research carried out in [12] showed that the properties of the new refractory material differ from the properties of the material after three fuses. The ultimate tensile strength of chamotte refractories of the ShKU-32 brand after three fuses in the temperature range from 20 • C to 800 • C is lower than the ultimate tensile strength of the refractory material that has not been in operation.…”

“…The certificate specifications of refractory materials do not always contain the data necessary to analyze the heating rate of the linings. To obtain the missing data, laboratory studies of the characteristics of refractory materials are carried out [12][13][14][15][16].…”