Effect of peak load on the determination of hardness and Young's modulus of hot-pressed Si3N4 by nanoindentation

The indentation load-displacement curves of a hot-pressed silicon nitride were measured under different peak load levels. The unloading segments of these curves were analyzed using the widely adopted Oliver-Pharr method. It was found that both the hardness, H, and the Young's modulus, E, exhibit significant peak-load-dependence. Empirical approaches were then proposed to determine the load-independent hardness and modulus. The hardness and modulus deduced from these empirical approaches were proven to be comparable with the literature reported data measured with conventional methods.