Novel no-cement refractories
For the areas in cement plants impacted by high wear or corrosion, refractory specialists have developed new no-cement refractory materials based on electrochemical bonding. A 25 per cent silicon carbide material has been successfully installed in a cement kiln riser duct and is reported to be performing well to date, more than one year after its installation. By James Hemrick, Gary Bader, Gary Hoyson and Elmer Reno, Reno Refractories Inc, USA
Figure 1: example of microstructures for 70 per cent Al2O3 refractory compositions –
A. electrochemically-bonded, B. low-cement bonded, C. no cement-bonded
Recent advances in refractory technology have generally focussed on increasing physical, thermal or mechanical properties in an effort to improve interaction between the refractory and the service environment or to increase the maximum service temperature of the refractory. Therefore, the resulting new materials are stronger, more corrosion-, erosion- and abrasion resistant, more refractory and ultimately longer lasting. To achieve this, research is often aimed at identifying alternative raw materials (new or higher-purity materials or components with higher melting points), improving how these materials are put together (packing and microstructure refinement), or improving the bonding of newly-developed materials to enhance properties or service temperatures (the past technological progression from conventional refractories to low-cement materials, to ultra-low cement materials, to no-cement materials). As an example of the latter, the advances made in bond type and its impact on the property of elevated service temperature for alumina-containing materials are shown in Table 1.
