The effect of amount and type of spinel on the thermo-mechanical properties of magnesite refractories

The repitation of temperature variations causes or propagates cracking in refractories. Therefore, knowledge of the thermo-mechanical properties plays an important role in terms of using the refractories safely. Fused and sinter spinel were added to magnezite brick and the effects of additives on the physical, thermal and mechanical properties were investigated. In this study, water absorption, density, porosity, cold crush strength, hot strength, thermal expansion, three point bending strength and thermal shock experiments were carried out on the refractories prepared with the addition of different amounts fused and sinter spinel. Minerological and phase analysis of the representative samples were analysed by X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Mechanical and thermal properties of fused spinel containing refractories were better than sinter spinel containing refractories. Finally, thermal shock tests were carried out under 500oC and 1000oC. The variations of bending strength, elastic modulus and relative strength values were investigated. As a result, The mechanical and thermal properties of the refractories containing MgO-fused spinel were found better than the refractories containing MgO-sinter spinel and optimum amount of spinel in the refractories was determined.