Modeling the composite hardness of multilayer coated systems

Abstract

The change in the composite hardness with penetration depth derived from nanoindentation tests conducted on coated systems, which involve the deposition of multilayer coatings, in general exhibits a complex shape, as a consequence of the sequential contribution of each coating layer to the composite hardness during indentation loading. In spite that there are a number of models, which have been proposed for describing the change of the composite hardness with penetration depth for monolayer coatings, as well as for determining the coating and substrate hardness, very few research works have addressed the problem of describing this kind of data for multilayer coatings. In the present communication, a rational approach is proposed for extending two models widely used for the analysis of monolayer coatings, in order to describe the composite hardness data of multilayer coatings, as well as for determining the hardness of each individual layer and that of the substrate. Thus, a modified form of the models earlier advanced by Korsunsky et al. and Puchi-Cabrera, as well as their computational instrumentation, are proposed. The extension of both models to deal with multilayer coatings is conducted on the basis of the model developed by Iost et al., in order to adapt the Jönsson-Hogmark model to the analysis of indentation data of multilayer coatings. Such a methodology provides a means of computing the volume fraction of each individual layer in the coating, which contributes to the composite hardness. According to the results obtained, this scheme seems to be general enough to be applicable to different hardness models other than the Jönsson-Hogmark model. The proposed modified models are validated employing nanoindentation results obtained from a 2024-T6 aluminum alloy coated with a diamond-like carbon film, employing electroless NiP as intermediate layer. The advantages and disadvantages of the different models employed in the analysis are thoroughly discussed.

Mechanical characterization of a prototype a-C:Cr,Si and its tribological behavior at high temperature

“…Prior to indentation, the tip calibration was carried out on fused silica. The calibration curves for the fused silica standard have been reported elsewhere [19]. A total of 20 indentations were conducted over the three different samples tested for this purpose and the elastic modulus, E, and hardness, H, were recorded continuously versus the indentation depth, h, up to approximately 2000 nm, at a constant indentation rate of 0.05 s À 1 and maximum applied loads of 700 mN.…”

“…Thus, the hardness versus penetration depth curve for this bilayer coating can be readily analyzed following the methodology recently advanced by Puchi-Cabrera et al [19], which allows the extension of any hardness model employed for the description of the composite hardness of systems involving monolayer coatings, to the analysis of multilayer coatings under indentation loading. Accordingly, the extension of the model proposed by Puchi-Cabrera [25,26] for the analysis of this bi-layer coating can be computationally instrumented in the following manner.…”

“…Change in hardness with penetration depth for the a-C:Cr, Si/CrCSi/M42 steel coated system, considering its bilayer architecture. The data have been described with the model advanced by Puchi-Cabrera [25,26], modified for multilayer coatings [19]. The hardness values computed for the individual layers, as well as the substrate hardness are given on the plot.…”

Investigations on the mechanical properties of the elementary thin films composing a CuIn 1−x Ga x Se 2 solar cell using the nanoindentation technique

“…For example, if the indentation depth is lower than the seventh of the film thickness, then A f = A; A s = 0 and therefore H c = H f . This model was generalised to multilayers materials [5,8,9].…”

Dependence of mechanical and tribotechnical properties of multilayered TiN/ZrN coatings on deposition

“…They can be widely used to increase lifetime of the highspeed cutting tools operating under the influence of high temperatures, as well as to increase the reliability of different friction pairs. A review of scientific sources [3][4][5][6][7][8][9][10][11][12][13][14][15][16], and our own experience in this area [17][18][19] showed, that multilayered coatings, which consist of alternating 20-30 nm layers of hard refractory metals nitrides, are rather perspective in modern materials science. Such coatings are characterized by high hardness, because the alternating stress fields prevent the movement of dislocations.…”