Sintering studies on ultrafine ZrB₂ powder produced by a self-propagating high-temperature synthesis process

A detailed study on the sintering behavior of zirconium diboride powder produced by the self-propagating high-temperature synthesis (SHS) process was carried out in the temperature range of 1500–1800 °C. The fine powder prepared by the SHS process exhibited excellent sinterability and could be sintered at 1800 °C for 1 h to approximately 94% of the theoretical density. The apparent activation energy of densification in the range of 1500–1800 °C was estimated to be 248 ± 4 kJ mol⁻¹. A zirconium dioxide layer formed on the surface of the sintered body and was attributed to boron oxide formation during sintering and concurrent surface oxidation by the oxygen generated from the reduction of boron oxide in the carbonaceous atmosphere. Sintering aids like Fe and Cr appeared to help in densification of ZrB₂ powder.