Dynamic hardness and elastic modulus calculation of porous SiAlON ceramics using depth-sensing indentation technique

Interest in characterizing the mechanical properties of porous materials at micro-/nanometer scales has increased due to recent development of micro-/nanosystems. Depth-sensing indentation (DSI) systems, also referred to as nanoindentation, are strong tools for performing indentation measurements. The load-displacement curves of SiAlON-based porous ceramics were measured under different peak load (200–1800 mN). The most commonly used Oliver–Pharr method was used to analyze the unloading segments of these curves. The experimental results revealed that the dynamic hardness (Hd) and reduced elastic modulus (Er) exhibit peak-load dependence, i.e., indentation size effect (ISE). Such peak-load dependence requires calculation of the load-independent hardness (HLI) and elastic modulus (Er). The experimental hardness data were analyzed using Meyer's law, Hays–Kendall's model, the proportional specimen resistance (PSR) model, and the modified PSR (MPSR) model. As a result, the modified PSR model is found to be the most effective one for Hd determination of these SiAlON ceramics.