Mechanical and tribological performance of (TiNbTaWMo)C high-entropy ceramics in a wide temperature range

Abstract

High-entropy carbide ceramics have attracted extensive attentions for potential applications as high temperature structural materials, the mechanical and tribological performance of (TiNbTaWMo)C high-entropy carbides over wide temperature range combined with the oxidation behavior were investigated in the present study. (TiNbTaWMo)C high-entropy carbides were successfully prepared from five kinds of carbide powders by spark plasma sintering at 2000 °C. The mechanical properties of (TiNbTaWMo)C and the tribological performance at room temperature –800 °C were studied. The Vickers hardness, bending strength and fracture toughness of the sintered (TiNbTaWMo)C high-entropy carbides are 21.31 ± 0.43 GPa, 477.15 ± 34.17 MPa, and 6.41 ± 0.85 MPa m1/2, respectively. At room temperature, the friction coefficient is stable at 0.35, and the wear rate is as low as 3.39 × 10−7 mm3/Nm. With temperature increasing, friction coefficient increases firstly and decreases above 600 °C, which is contributed by the formation of oxide films at high temperatures. The wear mechanisms of (TiNbTaWMo)C high-entropy ceramics at different temperatures were discussed in detail by microstructures and phase analysis of the worn surfaces together with the oxidation behaviors of (TiNbTaWMo)C at 600 °C and 800 °C.