USING NANOINDENTATION TECHNIQUES FOR THE CHARACTERIZATION OF COATED SYSTEMS - A CRITIQUE

Ultralow load indentation testing, or nanoindentation, has considerable potential for studying the near-surface mechanical properties of solids and seems especially suited to the mechanical characterization of thin-film-coated systems where both low contact loads and high spatial precision can be advantageous. This paper assesses the current possibilities for, and limitations of, nanoindentation for assessing the properties of coated systems. In particular, the pursuit of hardness values alone is questioned, especially when the continuous load and depth data from the indentation cycle provide a far more complete mechanical ''fingerprint'' from which a number of important parameters describing the system behaviour can be calculated. The further difficulty of assessing the properties as a function of the depth into the coated system is also demonstrated. The additional information accessible through post facto microstructural characterization of the indentations themselves, the possible use of various indenter geometries and the need for parallel computer modelling to predict response are also discussed.