Preparation of zirconium, titanium, and magnesium diborides by metallothermic reduction
Ceramic compositions based on carbides, nitrides, and borides are widely used due to their outstanding resistances to wear, creep at high temperatures, thermal shock, and oxidation. In order to assure that these properties are attained, a defect-free microstructure must be obtained by using homogeneous and high surface area powdered starting materials. In this work we prepared zirconium, titanium, and magnesium diborides by a metallothermic reduction process. The obtained materials were examined by X-ray diffraction (XRD), laser granulometry, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Thermodynamic calculations were carried out using the FactSageÒ thermochemical software and databases. We observed that a great part of the samples obtained in this work showed significant amounts of MgO in their structures. A potential application of these materials could be as antioxidants for magnesia-carbon refractories since this industrial application does not require the removal of magnesia. It is well established that magnesium, zirconium, and titanium diborides exhibit great stability in reducing atmospheres.