THE EFFECT OF ZrSiO4 ADDITION INTO MgO-SPINEL COMPOSITE REFRACTORIES ON CORROSION BEHAVIOUR

Corrosion behaviour of composite refractories obtained from the addition of various amount of ZrSiO4 into MgO-spinel was examined. Density and porosity values were measured. Corrosion tests of refractories had been carried out statically under standard conditions using cylindrical and square shaped samples in terms of determining the interaction with cement clinker. Corrosion resistance was determined by measuring penetration and spreading areas 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. The incorporation of ZrSiO4 into MgO-spinel increased the density values significantly due to the decrease in porosity. On the basis of microstructural characterisation carried out in the interface of clinker-refractory, the following observations were determined: i) the formation of ZrO2 and Mg2SiO4 phases among the MgO grains after sintering, ii) the formation of CaZrO3 phase during penetration, iii) prevention of penetration by making a barrier effect against to clinker with the improvement in densification, and iv) the decrease in the amount of CaO and the increase in the quantity of MgO based on the EDX analysis made from clinker to refractory in a corroded region. As a result of those reasons indicated, the addition of ZrSiO4 reduced the values of penetration and spreading areas of the corroded regions of refractories and improved the corrosion resistance. For example, The improvement has been achieved at the distance of penetration and spreading area of a material having M-%30S-%30Zircon composition in comparison with M-%30S by factors of 2.2 and 1.8, respectively. This is also associated with a long service life of M-S-Zircon based refractories for industrial applications