GRK 2802: EFFECT OF THE INITIAL THERMAL CYCLE ON THE THERMAL DIFFUSIVITY OF AN MgO-C REFRACTORY

Abstract

The thermal diffusivity of MgO-C refractories is strongly influenced by their composition, internal structure, and temperature. The present study demonstrates that the thermal history of the material also plays a significant role. This effect was investigated using a representative MgO-C sample measured by the laser flash method over a temperature range from room temperature to 700 °C. During the initial heating, the thermal diffusivity decreased continuously with increasing temperature, with the most pronounced decrease occurring at lower temperatures. During subsequent cooling, the thermal diffusivity increased with decreasing temperature. However, the cooling curve followed a different path from the initial heating curve and exhibited a considerably flatter temperature dependence. The observed behaviour highlights the importance of considering thermal history when interpreting temperature-dependent thermal diffusivity measurements of heterogeneous MgO-C refractory materials.