N. A. Puchkelevich

Thermophysical properties of tar-bonded refractories

ConclusionsAn investigation was carried out of the thermal diffusivity of as-molded, heat-treated, and coked dolomite, magnesite and dolomite-magnesite tar-bonded refractories by the even-rate heating of flat specimens to 200–1600°C in an inert medium.The relation was determined between the thermal diffusivity and the heat-treatment conditions and composition of the specimens; it was established that the disturbance of the monotonic temperature dependence of the thermal diffusivity arises primarily from Ca(OH)2 dehydration; it was shown that the thermal diffusivity is a function not only of the temperature but also of the rate of heating.The thermal capacity was determined by a known method for 1000–1900°C and calculated from the additivity of the thermal capacity of coked tar-dolomite refractories. The determined and calculated values differed by not more than 5–10%.The thermal conductivity of tar-bonded refractories was determined from the data relating to the thermal diffusivity and thermal capacity and compared with published findings. Up to 1000–1400°C the results obtained in this investigation lie within the spread of the published data.

Thermal diffusivity of resin-bonded refractories over a wide temperature range

Results are shown of thermal diffusivity measurements made on resin-bonded refractories of various compositions and structures.

Standard materials on the thermophysical properties of refractories

The authors discuss the acquisition and standardization of thermophysical property data for refractories used as liners and thermal insulation in the steel and other industries in the Soviet Union. They present methodologies used by the All-Union and Eastern Refractory Institutes for computing these standards and describe the publications made available by these institutes to industry at large.

Hot-wire method of determining the thermal conductivity of refractory materials

ConclusionsThe advantages of the hot-wire method of determining the thermal conductivity of refractory products lie in the fact that it makes it possible to determine the true thermal conductivity directly in relation to a given temperature of the specimen. This fact distinguishes this method favorably from the methods based on the use of tablets and cylinders in which the thermal conductivity is related to the mean temperatures of the hot and cold sides on the specimen.The hot-wire method gives satisfactory results even when λ is low, i.e., 0.05–0.18 W/ m·deg K [in the standard method (GOST 12170-76) the lower limit in the determination of the thermal conductivity of refractories is 0.18 W/m·deg K]. The method is convenient for determining the thermal conductivity of refractories in granular and powder form.Among the disadvantages of the method are the fact that it cannot be used to determine the thermal conductivity of anisotropic materials, the complexity of the measuring process and the high degree of skill demanded from the operator, and the long duration of the measuring process at a given temperature.The investigations on the experimental device developed at the All-Union Institute of Refractories demonstrated that the hot-wire method can be used for refractories with a low or moderate thermal conductivity [λ<2–2.5 W/m·deg K] over the temperature range 20–900°C with an error of about 10%. The method is a promising one for determining λ also at a high temperature (up to about 1400°C).

Thermal conductivity of magnesite refractories in the range 500–1800°C

ConclusionsAn experimental setup was developed for studying the thermal conductivity of refractories up to 2300°C on the hot face of the specimen.In the average temperature range of 500–1800°C a study was made of the thermal conductivity of magnesite refractories of different porosity. The experimental data obtained satisfactorily agree with well-known literature and calculated values for the thermal conductivity coefficients.