Fabrication of ZrB₂ ceramics by reactive hot pressing of ZrB and B

Abstract

Zirconium diboride (ZrB2) ceramics were prepared by reactive hot pressing of ZrB+B powder mixture. Formation of a transient liquid due to eutectic reaction of ZrB2+Zr→Leu(ZrB2+Zr) at 1661°C following peritectic decomposition of 2ZrB=ZrB2+Zr at 1250°C during heating up of the ZrB+B mixture facilitated densification. The liquid phase was subsequently eliminated via reaction of B with Zr in the eutectic liquid Leu(ZrB2+Zr) to result in a dense ZrB2 ceramic. Full density was reached after reactive hot pressing at 1900°C under 30 MPa for 1 h. The ZrB2 ceramic had a refined microstructure consisting of grains of <1.5 μm in size and relatively good Vickers hardness (21 ± 2 GPa) and flexural strength (595 ± 63 MPa).

Effect of CaO and SiO2 on the properties of Y2O3-based ceramic core materials

“…In Figure 13, the main distribution area of Y was different from that of Ca, it shows that there is solid solution between Y 2 O 3 and CaO without obvious sintering reaction. So the leach basic principle of ceramic cores is attributed to the reaction of CaO with H 2 O, as shown in reaction Eq.7 [37].…”