Method for Determining Film Hardness and Thickness by Indentation

Thin films are widely employed in critical structures such as aerospace and nuclear industries, providing effective protection to substrates. Characterization of film hardness and thickness is crucial for assessing the reliability and lifespan of engineering materials. Currently, extracting these properties relies on distinct testing methods, lacking a unified approach capable of simultaneously measuring both film hardness and thickness through one or two simple tests. To address this limitation, we propose a novel numerical method based on an indentation theoretical model. This method calibrates dimensionless parameters within the model using film-substrate systems with known film thickness. Employing a segmented fitting strategy enables the simultaneous extraction of key mechanical properties-including film hardness, film thickness, and substrate hardness-with only a limited number of indentation experiments. Crucially, the method decouples film thickness, film hardness, and substrate hardness directly from indentation data. Its validity was rigorously verified through finite element simulations.