Preparation, growth mechanism and slag resistance behavior of ternary Ca2Mg2Al28O46 (C2M2A14)

The ternary phase Ca2Mg2Al28O46 (C(2)M(2)A(14)) in the CaO-Al2O3-MgO system was synthesized by reaction sintering using analytically pure CaO, MgO and Al2O3 as raw materials. The solid-solution reaction between CaAl12O19 (CA(6)) and MgAl2O4 (MA) takes place at 1650 degrees C and hexagonal thick flake C(2)M(2)A(14) are produced at 1750 degrees C. Due to the substitution of Al3+ for Mg2+ in the spinel unit of C(2)M(2)A(14), C(2)M(2)A(14), CM(2)A(8) and CA(2) appear in the product batched with stoichiometric ratio. When the firing temperature is 1750 degrees C and the solid soluble amount of Al3+ is 0.2, C(2)M(2)A(14) with high purity of 96.5 wt % is obtained. As for the growth mechanism, it follows a two-dimensional nucleation theory, i.e., MA forms two-dimensional nuclei on the (0001) plane of CA(6) and provide growth steps for atomic deposition. When the temperature reaches a certain point, MA's crystallization interface obtains great growth driving force and MA on the layer begins to merge with the CA(6) matrix to form hexagonal thick flake C(2)M(2)A(14). During the slag corrosion, the formation of dense coating layer with CA(2) as the main component improve the high temperature stability and corrosion resistance. Therefore, C(2)M(2)A(14) is of great potentiality to be applied in the ladle lining.