the optimization of dispersant content in alumina castable containing nano-titania

In this research, two series of ultra-low cement high alumina refractory castables containing 0 and 0.4 wt.% of nano-titania were prepared using different amounts of polycarbonic acid (dolapix ff 26) as a dispersant. several characteristics including microstructure, flowability, mechanical strength, bulk density and apparent porosity of the samples were analyzed. the results showed that the optimum amount of the dispersant was 0.13 wt.% and 0.20 wt.% for castable having no nano-titania and the one containing 0.4 wt.% nano-titania, respectively. the strength of castable containing 0.4 wt.% nanotitania dispersed by 0.20 wt.% of dolapix ff 26 was 1.5 times higher than that of castable without nano-titania (dispersed by 0.13 wt.% of dolapix ff 26). this can be explained by the fact that when the optimum amount of dispersant is used, the welldispersed nano-titania particles act as a catalyst in the cement hydration reactions and will result in higher strength of the refractory castables.