Interphase mechanical behaviors of nickel/yttria-stabilized zirconia cermets: A study by nanoindentation and molecular dynamics simulations

The metal/ceramic interface is of great importance in a variety of basic science research and technological applications. In this paper, the interphase mechanical behaviors of the nickel/yttria-stabilized zirconia (Ni/YSZ) system serving as an anode material in solid oxide fuel cells are investigated by nanoindentation experiments and molecular dynamics (MD) simulations. The experimental results indicate that the interface effect can greatly enhance the Young's modulus and hardness of Ni near Ni/YSZ interface, while a reduction is observed in the aforementioned mechanical properties of YSZ near the interface. In addition, the change in the mechanical properties and the affected region of the YSZ component due to the interface effect are both much larger than those of its Ni counterpart. Our MD simulation results reveal that the different effects of Ni/YSZ interface on the mechanical properties of Ni and YSZ near the interface can be ascribed to different transport capabilities of deformations generated in these two components across the interface. Based on MD simulation results, an interface barrier model and a model considering the structural compliance are proposed here for theoretically predicting the interphase hardness and Young's modulus of the Ni/YSZ system.