The effects of ZrSiO4 and ZrO2 additions on mechanical, thermal shock and corrosion behaviours of MgO-MgAl2O4 refractories

Mechanical properties, thermal shock and corrosion behaviours of different compositions obtained from the additions of 5, 10, 20 and 30 (weight) percent zircon (ZrSiO4) and zirconia (ZrO2) into the MgO-spinel composite refractories have been examined, the variations occurred have been determined, and the parameters affecting those factors have been investigated with the reasons. The density, strength, Young?s modulus, fracture toughness, fracture surface energy, work of fracture, critical defect size and mean MgO grain size values of the samples produced were measured and evaluated. Microstructural variations and fracture surfaces have been examined and the formation of new phases was identified depending on the additive type and quantity. The relationships between mechanical properties and structural variations for different compositions have been examined. Thermal stress/shock parameters (R, R???, Rst) and ?WOF/?S ratios that are used for determining high temperature performance of refractory materials were calculated. Thermal shock behaviour of the samples tested at500 °C and 1000 °C has been examined and the compositions showing high thermal shock resistance have been determined by evaluating the measured mechanical properties. Furthermore, corrosion resistance has been determined by measuring the penetration depths and spreading areas of the refractories tested. The incorporation of Zircon and ZrO2 into MgO-spinel refractories has improved the mechanical properties, thermal shock and corrosion resistance significantly, and the optimum compositions have been identified.Keywords: MgO, Spinel, Zircon, ZrO2, Refractory, Mechanical Properties, Thermal Stress/Shock Parameters, Corrosion