MATRIXDESIGN FOR BETTER CASTABLES

Abstract

The use of monolithic refractories has spread throughout various industries over the past few decades. Today it is common practice to install monolithics in wear areas where, in the past, only refractory bricks were used. Unlike bricks the unshaped products require sintering in the application to obtain their final properties. The service temperatures in industrial applications are often below 1200 °C so castables lack sufficient energy for strong sintering reactions. However, industrial applications also demand improved castable properties such as better chemical stability, mechanical strength or abrasion resistance in the intermediate temperature range. The matrix is an important part of a refractory castable, which determines not only the workability and strength, but also the performance in application. Calcined and reactive aluminas and dispersing additives contribute significantly to the improvement of the matrix performance with respect to water demand, setting control and strength development. By optimising the overall particle size distribution of the fine and superfine materials, including the binder, not only can a better workability be achieved, but also the physical properties, especially in the intermediate temperature range can be improved. This paper reviews the role of matrix alumina in castables for intermediate temperature range applications and provides solutions for further improvement of ordinary low cement castables. Ill. 13. Ref. 7. Tab. 1.