3-D Modeling of nanoindentation experiment on a coating-substrate system

Abstract

The validity of indentation tests for the characterization of the mechanical properties of coatings relies greatly on the indentation depth. Deep indentation concludes to unreliable results due to the substrate effect on the measured properties. At shallow depths the size effect can also be an important error factor. The purpose of the present study is the determination of the critical ratio of coating thickness to indentation depth, up to which the substrate properties have a negligible effect on the force versus indentation depth curve and thus on determined mechanical properties of the coating. The analysis required, was conducted using ®nite element method. A spherical (ball) indenter was used and a three dimensional model of the indenter/coating-substrate system was applied. The effect of the coating to substrate Yield strength ratio, on the critical coating thickness to indentation depth ratio, was investigated for three different coating to substrate Young's modulus ratios. The results of this work provide considerable insight for the determination of the con®dence indentation depth during micro-indentation for layered systems with different properties.

Cross-Linking the Surface of Cured Polydimethylsiloxane via Hyperthemal Hydrogen Projectile Bombardment

“…The decrement of PDMS surface modulus could be easily attributed to substrate effect, as discussed in a previous work involving a hard thin film on a soft substrate. 60,61 The variations of these mechanical properties as a function of depth indicated that the thickness of the cross-linked layer was less than 100 nm, as shown in Figure 10; and we need to establish another method for measure the cross-linking depth.…”

Microscale interpretation of tribological phenomena in Ti/TiN soft-hard multilayer coatings on soft austenite steel substrates

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Nonlinear constitutive models from nanoindentation tests using artificial neural networks

“…a soft coating on a hard substrate system. Vlachos et al (2001) also considered a hard film on a soft substrate material system that was assumed as elastic perfectly plastic, but they used 3D FE models.…”