Microstructural Characterisation and Investigation of the Effects of ZrSiO4-Y2O3 Additions on Corrosion Behaviour of MgO-Spinel Composite Refractories

Abstract

Corrosion resistance of MgO-Spinel (M-S) composite refractories containing various amounts of ZrSiO4-Y2O3 constituents was investigated. Density and open porosity values were measured and evaluated. Corrosion tests of refractories were carried out statically under standard conditions using cylindrical shaped samples in terms of determining the interaction with cement clinker. Corrosion resistance was determined by measuring the values of penetration and depth of the corroded regions of refractories. The influence of corrosion resistance based on the microstructural changes occurred as a result of solubilities of constituents in the interface of clinker-refractory for various regions was examined using SEM and the results were evaluated using EDX analysis. It was observed that there was a significant increase in density values and decrease in porosity data for most of the compositions obtained from the additions of ZrSiO4-Y2O3 to MgO-spinel. As a consequence of microstructural characterisation performed at the interface of clinker-refractory, the observations made were determined as follows: i) the formation of ZrO2 and Mg2SiO4 phases among the MgO grains during sintering, ii) the formation of CaZrO3 phase during penetration, iii) prevention of penetration by new phases formed that make a barrier effect against clinker with the improvement in densification, and iv) the decrease in the amount of CaO based on the EDX analysis made from clinker to refractory in a corroded region. The incorporation of ZrSiO4-Y2O3 into MgO-spinel reduced the values of penetration and depth of the corroded regions of refractories and improved the corrosion resistance. The penetration of clinker to refractory showed a minimum level for the composition of M-20%S-20%(ZrSia(4)d-Y2O3) and an improvement by a factor of 1.42 as compared to M-20%S. This development is also combined with a long service life of M-S-(ZrSiO4+Y2O3) containing composite refractories for industrial uses.