Title Solbonded Alumina-Silica Monolithics New Developments, Recent Experiences and Future Possibilities
Thematic area Monolithics for Various Applications
Presenter Mr. Milos Blajs
Authors Mr. Milos Blajs, RHI AG, Leoben - Austria
Mr. Bernhard Pribil, RHI AG, Leoben - Austria
Mr. Gerald Reif, RHI AG, Leoben - Austria

In the last years a new generation of castables, shotcreting and gunning mixes with colloidal silica bonding technology has provided enormous advantages in terms of processing and material properties, the most important being an easy-drying behavior, excellent thermal shock resistance, low brittleness, as well as hot erosion and corrosion resistance. As a consequence, in many different industries like cement, steel, non-ferrous, energy, environmental and chemistry applications, these materials show significant performance improvements and lifetime increases compared to commonly used cement bonded castables. Nevertheless, continuative research and development efforts in the field of solbonded monolithics lead to further improvements and innovations.

The sol-binding system provided the basis for further developments in the field of new and innovative matrix design for Alumina monolithics. For the carbon containing Oxycarbide-mixes colloidal silica function as the initial binding system. By increasing temperature various in-situ phase formations provide an extraordinary strong refractory matrix with non wetting properties against steel and slag. The mixes show impressive results in several hot metal and steel industry applications.

Another example are “Mullite-bonded” mixes, which represent the latest innovation in the field of cement-free refractory castables. The material properties are tailored to the very demanding conditions experienced in the EAF-roof lining, which include high thermal radiation, mechanical wear and thermal shocks.

Till now, the major disadvantage of solbonded mixes was that the commonly used sol-binder is water based and therefore freezes below 0°C. Frost irreversibly destroys the liquid binder. This problem had to be bypassed via logistic means like heat transport and heat storage at customer site. Therefore a new frost-proof sol-binder was developed that allows storage and transport at very low temperatures, even below -30°C without harming the binder.

The paper provides the fundamentals of recently developed solbonded materials with innovative matrix design, the advantageous properties are illustrated by presenting the results of extensive research work and comparative results from different application areas are shown. Furthermore research efforts and results from the devolpment of a frostproof solbinder are presented.