Part II. Dynamic corrosion of Al2O3-ZrO2-SiO2 and Cr2O3-containing refractories by molten frits. Microstructural study

Autores: Baudin, C.|Criado, E.|Bakali, JJ.|Pena, P.
Fuente: J. Eur. Ceram. Soc.
31 (5), 705-714
2011

In this work results on dynamic corrosion studies of fused cast Al2O3-SiO2-ZrO2 and isostatically
pressed and sintered Cr2O3-based refractories by two crystalline (transparent) frits are described. Experiments have
been performed using the «Merry Go Round» test at congruent to 1500 degrees C.
Microstructural and mineralogical analyses of selected areas from the corroded regions of the studied refractories
were performed by reflected light optical microscopy and scanning electron microscopy with analysis by X-ray
dispersive energy.
Significant differences between the corrosion mechanisms acting in the two types of materials were found. In the
fused cast Al2O3-SiO2-ZrO2 specimens corrosion took place by the dissolution of alumina and zirconia in the frit
and in the glass formed by the reaction between the frit and the refractory. In the Cr2O3-based materials the
corrosion process was controlled by the capillar penetration of the molten frit through the open pores. The reaction
between the ZnO from the frits and Cr2O3 led to the formation of spinet (ZnCr2O4), a high-melting point bonding
phase that retarded the frit penetration. Results are discussed using the relevant phase equilibrium diagrams