Effect of magnesium-aluminate spinel nano-particles on microstructure and properties behaviors of doloma-containing refractories

摘要

In recent years, the main challenge for producers and consumers of doloma-containing refractories has been to increase the performance of this kind of refractories. In this study, the addition effect of magnesium-aluminate spinel nano-particles (MgAl2O4) on various properties of doloma-containing refractories such as bulk density, apparent porosity, hydration resistance and cold compressive strength have been evaluated. From 0 to 8 wt % magnesium-aluminate spinel nano-particles added to the specimens. The prepared cylindrical specimens (50*50mm(2)) were putted in a dryer (at 110 degrees C for 24 h) and then placed in an electrical furnace (at 1650 degrees C for 3 h). Ceramic phase's identification and microstructural evaluation of the fired specimens were donned by helping X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM/EDX) techniques, respectively. Results showed that the bulk density increased up to 8 wt % nano-spinel. Also, the cold compressive strength values of the samples increased up to 6 wt % nano-spinel whereas the apparent porosity values were reduced. However, for the higher additive value (8 wt % nano-spinel), this trends is reversed and the cold compressive strength was decreased and apparent porosity was increased. The reason for this variation can be attributed to the formation of some micro-cracks in the specimen's matrix. As well as, due to the formation of dense microstructures by utilization of magnesium-aluminate spinel nano-particles the resistance to hydration of the specimens has increased significantly.