On the Thermal Properties of Electro-molten Mass Containing Dunite as Principal Ingredient

Abstract

The studies of the thermal properties obtained by load and spalling tests of the electro-molten masses appeared in previous papers, J. Ceram. Assoc., Japan, 68 [10] 237, J. Ceram. Assoc., Japan, 68 [12] 294 (1960), were carried out. The matrix was separated by heavy solution, and was subjected to chemical analysis. Based on the summary of the results obtained the author disscussed the relation between the structure and the thermal properties of the electro-molten masses composed mainly of dunite.The results of load test, thermal expansivity, thermal conductivity as well as spalling have shown a considerable increase with the increasing ratio MgO/SiO2 of MgO containing masses. With the addition of calcic materials the properties of the mass were put under the control of the ratios MgO/SiO2 and CaO/SiO2, and up to 7.5% CaO was effective for improving the results of load and spalling tests, while more lime than this limit lowered the load bearing temperature.The effect of high aluminous materials were different in both sides of the line connecting MgO⋅SiO2 and 2MgO⋅SiO2 in the ternary system, MgO-SiO2-Al2O3. In the domain rich in Al2O3 gave the refractories of higher load bearing temperature than in the other one. In general, the addition of alumina lowered the thermal expansion and improved the thermal conductivity and spalling. A trend was found that SiO2, Al2O3, Fe2O3, CaO, and ZrO2 intermixed in the matrix of the mass as solution or as microcrystals.