Mullite coatings on graphite for application in carbon containing monolithic refractory

Abstract

Mullite forming sol was prepared by proper selection of hybrid precursors having both organic and inorganic origins. X-ray diffraction (XRD) and infrared spectroscopy (IR) were performed to distinguish between the two sets of precursors. Refractory grade flaky graphite was coated by the sol, dried and heat treated for microstructural analysis. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) studies with energy dispersive spectroscopy (EDS) were carried out to illustrate the characteristics of mullite forming aluminosilicate coating over graphite. The stability of this surface-modified graphite was also evaluated in comparison with the uncoated one by thermogravimetric analysis (TGA). The amount of casting water required for a monolithic refractory composition prepared by these graphites was also examined. Finally, the increase of the performance of castable containing coated graphite has been estimated by determining its physical properties such as bulk density and apparent porosity.