Zirconium Diboride Laminates for Improved Damage Tolerance at Elevated Temperatures

The mechanical response was studied for dense laminates containing layers of ZrB ₂ (~145 µm) and graphite—10 vol% ZrB ₂ (~20 µm). Individual layers were formulated by mixing starting powders with thermoplastic polymers and pressing into sheets. Laminates were produced by stacking and warm pressing the sheets, debinding, and hot pressing at 2050°C, 32 MPa, in Ar. The laminates were fractured at temperatures up to 2000°C in Ar. Laminates exhibited room temperature flexure strength of 260 MPa, increasing to 300 MPa at 1600°C, and then decreasing to 160 MPa at 2000°C. Inelastic work of fracture was 0.6 kJ/m ² at room temperature, reached a maximum of 1.3 kJ/m ² at 1400°C, and reverted to linear elastic failure at 2000°C. During fracture, cracks were deflected at the interfaces between the strong ZrB ₂ layers and the relatively weak C-ZrB ₂ layers, which led to an increased inelastic work of fracture by more than an order of magnitude compared to conventional ZrB ₂ ceramics. This study demonstrated that laminate architectures are a promising approach for improving the damage tolerance of ZrB ₂ -based ceramics at elevated temperatures.