Scale resistance of some refractory concretes

Conclusions

The scale resistance of refractory concretes when the latter interact with molten scale varies, and is primarily determined by the composition of the concretes. The highest scaleresistance is found in the dunite concretes and the lowest in the high-alumina; the chromemagnesite, chromite, and corundum concretes occupy the intermediate position.

The scale in the solid state hardly interact with the concretes at all.

The wear of the high-alumina and corundum concretes by molten scale occurs as the result of the formation of FeO·Al₂O₃ hercynite which forms a low-melting eutectic with the iron oxides (hercynite-wustite eutectic at 1330°C); hercynite is next replaced by magnetite and hematite which, after changing into FeO, form low-melting fayalite 2FeO·SiO₂ with SiO₂. The process of hercynite-formation and its replacement by iron oxides are accompanied by an increase in volume of roughly 16% and this leads to the swelling and deformation of the concretes.

The wear of the chrome-magnetite and chromite concretes is accompanied by the appearance of new formation of the magnomagnetite and high-iron chrome-spinel type.