An investigation of microstructure and properties of magnesia-magnesium aluminate spinel refractory promoted with Titania for steel industries

Alkaline bricks, especially magnesia refractory products containing spinel, are the most important refractory materials that are used in many industries such as steel, cement and non-ferrous industries due to their special physical, chemical and mechanical properties. In this study, the effect of titania addition on the properties and microstructure of chrome spinel free magnesium alkali refractories was studied. After sintering of the product samples at two temperatures of 1500 °C and 1600 °C, different physical and mechanical properties such as density, apparent porosity, cold compressive and bending strength, load retardation and warm rupture modulus were evaluated according to ASTM standards. The results showed that with increasing Titania up to 6% by weight after sintering at 1600 °C compared to the reference sample without additive, density and apparent porosity due to the formation of spinel phases especially magnesium titanate increased and then decreased, respectively. Also, as the titania amount increased to 4% cold compressive and bending strength increased. To further increase, due to the increase in volume percentage of magnesium titanate and magnesium aluminate spinel phases, cold compressive and bending strength decrease and increase, respectively. The results also show that by increasing the Titania up to 6% by weight compared to the sample without additives, the modulus of warm rupture (thermomechanical properties) increases at 1000 °C and 1400 °C and on the delay under load by increasing the amount of titania to 2% by weight from temperature T0 =1570 ºC is added to 1620 ºC under load 2 Kg / cm2.