MICROSTRUCTURAL CHARACTERISTIC OF MAGNESIA-CALCIUM ZIRCONATE SUBSTRATES SUBJECTED TO CLINKER ATTACK

摘要

Magnesia-calcium zirconate materials have been suggested as chrome-free refractories for cement kilns to replace to the magnesia-chromite bricks. The analysis of MgO/CaZrO_3 materials as refractory in rotary cement kilns carried out by Kozuka et al. point out a good behavior on service. However, the attack mechanism involved was not actually established at all. In the present work, microstructural characteristics produced by clinker attack at 1500°C on rich-MgO and rich-CaZrO_3 substrates was studied. Microstructural analysis performed by OM and SEM showed that both substrates presented a clinker layer with good adherence. In the reaction zone, the attack yield to the formation of a MgO layer on the rich MgO substrate or a CaZrO_3 layer on the rich CaZrO_3 substrate. Finally under the reaction zone substrate remains as their initial microstructure and only a small quantity of liquid diffused throughout grain boundary and pores. The results obtained showed that a good behaviour of the materials studied and support their use as refractory matrix in magnesia-chrome free brick for the burning zone of rotary cement kilns.