Sintered specimens were prepared from the ingots of fusion cast dunite obtained by the methods descrived in the previous papers (J. Ceram. Assoc., Japan, 68 [10] 237 (1960); J. Ceram. Assoc., Japan, [12] 294 (1960)), and their appearance and thermal properties were investigated.
The specimens made from dunite alone or from the mix added with MgO secured the stability under load at high temperatures when the mol ratio MgO/SiO2 of the ingot was larger than 2.
In the case of the ingots added with Al2O3 the same result was obtained when the composition represented on the triaxial diagram MgO-Al2O3-SiO2 was richer in MgO than the line connecting the points MgO⋅Al2O3 and 2MgO⋅SiO2.
Dissociated from the composition of the ingots all specimens gave the thermal expansion of about 1% at 1, 000°C without showing any anomaly. As the thermal conductivity was smaller than ordinary basic refractories the author expects the practical use of the above sintered bricks for the ceiling of industrial furnaces.