Effect of reaction of periclase and iron-chrome spinel on the properties of periclase-spinel refractories

Conclusions Using a typical composition of the type MgO-Mg(Al_1–x–yCr_xFe_y)₂O₄ a study was made of the effect of the processes involved in the processing and decomposition of solid solutions of periclase and spinels on the technical properties of the fired products.During cooling from 1600–1750°C decomposition occurs in the solid solutions of periclase and spinel; the crystals of spinel separating under these conditions are able to grow to large sizes which inevitably should lead to the development of stresses inside the periclase grains.The decomposition of the solid solution of periclase and spinel adversely affects the strength and thermal-shock resistance of the fired specimens.The best technical properties are possessed by combinations of periclase with small (up to 15%) quantities of high-alumina (x=0.16 and 0.46) spinels.The use of compositions of periclase with high-alumina spinels of the type x=0.16 and 0.46 enables us to obtain denser and more thermal-shock resistant refractories.Translated from Ogneupory, No.6, pp. 44–47, June, 1970.