Reactive Hot Pressing of Zirconium Diboride

The reaction of zirconium and boron was investigated as a potential route to form dense monolithic zirconium diboride (ZrB2) ceramics. Attrition milling of the precursors produced nanosized (less than 100 nm) zirconium metal particles that reacted with boron to form ZrB2 with an average particle size of less than 100 nm at temperatures as low as 600 °C. Scanning electron microscopy of ZrB2 compacts heated to 1450 °C and 1650 °C showed average particle sizes of 0.6 μm and 1.0 μm, respectively, suggesting that the fine particle size was maintained during densification. Ceramics with a relative density of ∼99% were produced by hot pressing at 2100 °C. Dense ZrB2 produced by the reactive hot pressing process had mechanical properties that were comparable to ceramics produced by conventional processes. The four-point flexure strength of ZrB2 produced in this study was 434 MPa.