Dring Behaviour and Explosion Resistance of No-Cement Refractory Castables
Elkem Silicon Materials, Kristiansand/Norway
Volume 11, Issue 4, Pages 62 - 66
For cement bonded refractory castables explosive spalling due to removal of free water and/or dehydration of cement hydrate have always been challenging. Naturally, cement free castables are very interesting due to fast dry-out and excellent hot properties. However, their green strength is often so low that even the removal of free water becomes a challenge, particularly in larger pieces. Drying industrial-scale specimens are not straight forward and always more complicated than lab-scale samples. In this paper, the dry-out behaviour and explosion resistance of microsilica-gel bonded No-Cement Refractories (NCCs) have been evaluated based on testing of large industrial-scale specimens. The mechanism of fast dry-out behaviour of microsilica-gel bonded NCC with and without drying agents was evaluated by TGA analysis and SEM characterisation. Replacing cement bond with microsilica-gel bond results in true fast dry-out and improved explosion resistance. The explosion resistance can further be signifcantly improved by using a specialty drying agent (EMSIL-DRY™); as demonstrated by the problem free production of a perfect 400 kg block of microsilica-gel bonded NCC using a fast fring schedule (20–850 °C at a heating rate of 50 °C/h).
dry-out behaviour, fast heat-up, fast dry-out, no-cement castable NCC, microsilica-gel bond, microsilica
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