This presentation will focus on the mechanical properties of zirconium diboride ceramics. Diboride ceramics offer a combination of properties that include high elastic modulus, hardness, strength, and moderate fracture toughness to elevated temperatures. However, like all structural ceramics, their mechanical properties are controlled by microstructure wherein grain size, dispersion and size of second phases, and impurities limit their potential use at elevated temperatures, particularly for proposed extreme environment applications at temperatures exceeding 2000°C. As an example, the flexure strength of nearly phase pure ZrB2 ranges from 300 to >600 MPa at room temperature but retains a strength of >300 MPa at temperatures >1500°C. Further, the fracture toughness of ZrB2 ceramics is generally low, typically in the range of 3 to 4 MPa-m1/2, at both room and elevated temperatures.

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