Three-step reactive hot pressing of B₄C-ZrB₂ ceramics

详细信息    查看全文

• 作者：Wei-Ming Guo^a ; ^c ; ^{guo1238@126.com" class="auth_mail" title="E-mail the corresponding author} ; Li-Xiang Wu^a ; Yang You^b ; Hua-Tay Lin^a ; Guo-Jun Zhang^c
• 关键词：B4C&ndash ; ZrB2 ceramics ; Reactive hot pressing ; Thermodynamic analysis ; Microstructure ; Mechanical properties
• 刊名：Journal of the European Ceramic Society
• 出版年：2016
• 出版时间：March 2016
• 年：2016
• 卷：36
• 期：4
• 页码：951-957
• 全文大小：2070 K

文摘

B₄C–ZrB₂ ceramics were reactively hot pressed by three-step process using B and C with Zr (C–B–Zr mixtures) or ZrO₂ (C–B–ZrO₂ mixtures) as raw materials. Based on thermodynamic analysis and experimental results, the C–B–Zr or C–B–ZrO₂ mixtures were firstly held at 1000 °C, then held at 1650 °C, and finally held at 2000 °C under 30 MPa. B₄C–ZrB₂ ceramics were obtained by using the three-step process and controlling the reaction sequence. The ZrB₂ grains in B₄C–ZrB₂ ceramics from C–B–Zr mixtures had a bimodal grain size distribution including fine grains with size of 1–2 μm and large agglomeration-like grains with size of 10–30 μm, while that in the ceramics from C–B–ZrO₂ mixtures showed homogeneous distribution with small grain size of 1–2 μm. The B₄C–ZrB₂ ceramics from C–B–ZrO₂ mixtures showed higher relative density, more homogeneous and fine-grained microstructure, higher hardness (33.0 ± 1.3 GPa), and comparable toughness (4.1 ± 0.2 MPam^1/2), compared with the ceramics from C–B–Zr mixtures.