Elastic anisotropy of coatings by AFM analysis of microindentations

Abstract

Atomic force microscope analysis of low load Vickers and Knoop indentation marks was performed to obtain a statistically consistent method for the mechanical characterisation of physical vapour deposition (PVD) coatings and the evaluation of elastic anisotropy. Indents shape analysis were elaborated with three different models for the evaluation of Young's modulus. Subsequently, roughness, elastic/plastic behaviour and intrinsic hardness have been numerically evaluated. Results showed that the intrinsic hardness evaluation of the films for applied loads as low as 50 mN is statistically supported by atomic force microscopy analysis of the indents, especially when diagonal length is smaller than 2/3 m. Moreover, some of magnetron sputtering PVDPlease confirm definition of MS. coatings showed mechanical anisotropy: normal to surface Young's modulus was higher than in plane Young's modulus. Such information would not have been obtained by nanoindentation testing alone and could be extremely important for the process development and production of high performance coatings for specific tribological applications\ud \ud Keywords: Microindentation, AFM, Modulus, Hardnes

On the study of mystical materials identified by indentation on power law and Voce hardening solids

“…The instrumented indentation test has grown out of its humble origins as little more than a surface hardness testing procedure [1] and slowly but surely established itself as a viable non-destructive alternative to the conventional tensile test under certain conditions. Today it is widely used to probe the constitutive relationships of a variety of engineering materials [2][3][4][5][6]. However, the available literature on indentation-based mechanical characterization indicates that the uniqueness, or lack thereof, of the solution to the final inverse identification problem has, particularly in recent years, become a focal point of research [7][8][9][10][11][12][13], calling into question the quality of the solution(s) obtained.…”

Study on the AFM Force Curve Common Errors and Their Effects on the Calculated Nanomechanical Properties of Materials

“…Burnham and Colton [3] used AFM in a nanoindentation study for the first time and measured nanomechanical properties of material surfaces at piconewton resolution. The AFM nanoindentation technique has since been used on various types of materials such as rat fibroblasts [4], tomato fruit cells [5], scaffolds [6], gels [7,8], bulk metallic glass [9], polymers [10,11], and especially thin coating layer [12]. However, there are some common errors in the AFM force curve due to the AFM piezo's hysteresis and using cantilevers with low spring constant which make it difficult or even impossible to extract the mechanical properties of the material from the AFM's force curve [13][14][15][16][17][18].…”