3. Results and discussion
3.1. Volume combustion synthesis (VCS)
Preliminary VCS experiments were conducted in air atmosphere. The ignition temperature of the reaction in air atmosphere, which was determined by the inserted thermocouple into the reaction crucible as explained in the experimental section, was measured as 758 °C. The XRD pattern of this product is given in Fig. 1(a). As can be seen from this pattern, the product contained ZrB2 and MgO as the major phases, indicating the occurrence of Reaction (1). However, minor phases such as zirconium oxynitride (Zr2ON2) and magnesium borate (Mg3B2O6) were present in the products. Moreover, the presence of ZrO2 peaks indicated that ZrO2 could not be completely converted into ZrB2. Zr2ON2 may have formed due to the reaction of unreacted ZrO2 with N2 gas in air during the reduction of ZrO2 by Mg. Formation of Mg3B2O6 may have been the result of the reaction between unreacted B2O3 and the formed MgO according to Reaction (2).