AN INVESTIGATION ON THE EFFECTS OF TIO2 ADDITION ON THE PROPERTIES OF ALUMINA SPINEL REFRACTORY CASTABLES

The effects of TiO2 addition on properties of alumina spinel refractory castables werer investigated in this research. For this purpose three different composition with 0, 6 and 9 perecent TiO2, (SP), (SP-6T) and (SP-9T), were prepared in order to test and measure the properties of the castables. Then the samples were sintered from 1000-1600ºC in an electric furnace. The characterization results showed that the presence of TiO2 in these compositions led to sintering modification by increasing temperature. Phase analysis of the samples revealed calcium titanate formation due to TiO2 reaction with CaO at temperature higher than 1000ºC so the sintering process was modified and caused increase the density and cold crushing strength of the samples. On the other hand, TiO2 and Al2O3 form aluminium titanate while temperature goes above 1400ºC which improved sintering. It can be concluded that TiO2 addition into the alumina spinel refractory castable increases density up to 3.68 gr/cm3 at 1600ºC. Also by increasing TiO2 up to 9% wt., cold crushing strength and permanent linear changes (PLC) were increased in the samples fired att 1600ºC although the hot properties of the samples were slightly decreased. So when TiO2 content increased to 9% and above, the hot modulus of rupture and refractoriness under load of the samples will be declined.