Abstract
The first high damage resistant ultra-high temperature ceramic ScB2C2 with excellent hydrolysis resistance was successfully prepared through boron carbon thermal reduction and hot pressing sintering using Sc2O3, B4C and graphite as raw materials. The Vickers hardness, flexural strength, fracture toughness, Young’s modulus, shear modulus, bulk modulus and Poisson’s ratio of as-prepared ScB2C2 ceramic are 6.0 ± 0.2 GPa, 246 ± 17 MPa, 4.11 ± 0.18 MPa·m1/2, 240 GPa, 101 GPa, 127 GPa and 0.18, respectively. In the a-b plane (B2C2 sheet) and along the c-axis direction, ScB2C2 exhibits extremely strong anisotropy of chemical bonds and elastic properties. The high residual strength, damage tolerance factor Dt and fracture toughness to strength ratio KIc/σf indicates that ScB2C2 has excellent damage tolerance. In addition, ScB2C2 displayed remarkable thermal shock resistance and hydrolysis resistance. These unique features endow ScB2C2 with significant potential for future ultra-high temperature applications.
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