Performance of B4C/CeB6 composites fabricated via hot pressing under different processes

Abstract

AbstractIn this work, CeO2 sintering additive reinforced B4C ceramic composites were prepared by hot‐pressing reaction sintering under different processes of low temperature–long holding time (1980°C, 30 MPa, 3 h, 4 wt% CeO2) and high temperature–short holding time (2050°C, 30 MPa, .5 h, 4 wt% and 6 wt% CeO2). The effect of sintering process and CeO2 content on the microstructure and mechanical properties of B4C‐CeB6 composites were investigated. The existed impurities in the obtained composites were also analyzed. Results show that CeO2 is an active sintering additive. CeB6 is formed by the reaction between CeO2, B4C and C in sintering process. The densification of B4C ceramics is enhanced, and the grains can be refined by the formed CeB6, which promotes the strength. The thermal expansion coefficient mismatch, crack deflection, and fracture mode change caused by the in situ formed CeB6 improve the toughness. The process of low temperature–long holding time is more suitable for playing the role of CeO2 additive in sintering of B4C, under which condition the relative density, flexural strength, fracture toughness, and hardness reach 99%, 417 MPa, 5.32 MPa·m1/2, and 30.66 GPa, respectively. The impurities in the composites are the kinds of Ti‐contained, C‐O‐Mg‐Ca‐contained, C‐O‐Ca‐S‐contained, and Si‐contained impurities.