Mechanochemical and volume combustion synthesis of ZrB2

Formation of ZrB2 by volume combustion synthesis (VCS) and mechanochemical process (MCP) from ZrO2-Mg-B2O3 was studied. Production of ZrB2 by VCS in air occurred with the formation of side products, Zr2ON2 and Mg3B2O6 in addition to MgO and ZrB2. Zr2ON2 formation was prevented by conducting VCS experiments under argon. Wet ball milling was applied to the VCS products before leaching for easier removal of Mg3B2O6 phase. MgO and Mg3B2O6 were removed from wet ball-milled products by leaching in 5 M HCI for 2.5 h. In MCP, 30-hour ball milling was found to be sufficient for the formation of ZrB2 with no minor phase formation. Leaching of MCP products in 1 M HCI for 30 min was sufficient to remove MgO. Complete conversion of ZrO2 to ZrB2 did not take place in both production methods, even with excess amounts of Mg and B2O3. Therefore, formed ZrB2 contained residual ZrO2