Ceramics-Silikáty 53 (4) 297-302 (2009)

Non-cement refractory castables containing nano-silica: Performance, microstructure, properties

S. H. Badiee, S. Otroj

In this study, the effect of nano-silica sol content on the self-flow characteristics, microstructure, physical and mechanical properties of high-alumina self-flowing non-cement castable has been studied. The self-flow characteristics such as: self-flow value and working time has been evaluated. The bulk density, apparent porosity, mechanical properties and microstructure of fired castables at different temperatures has been investigated. The results show that the proper nano-silica content for achieving self-flowing performance of such castables and sufficient strength is 10-11 %. By increasing of firing temperature up to 1000°C, porosity and pore sizes of castable tend to decreasing, because of complete dehydration of reminder hydroxyl groups, which can leads to increasing of strength. Because of using nanometer-sized colloidal silica particles with high surface area, the solid phase sintering of the nano-sized particles and also, mullite formation can be occurred in the low temperatures up to 1300°C.

Keywords: Nano-silica, Self-flow, Castable, Mechanical properties, Microstructure