A comparison of nanoindentation pile-up in bulk materials and thin films

Moharrami, Noushin; Bull, Steve

doi:10.1016/j.tsf.2014.06.060

Cited by 72 publications

(30 citation statements)

References 35 publications

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“…It is seen that both results are well correlated since it agrees with finite element solutions. We can point out that the values determined for the elastic properties correspond to typical values reported in the literature for Si 3 N 4 [7,10,13] and Aluminum [14][15].…”

Section: Resultssupporting

confidence: 82%

Numerical Modeling Approach for the Assessment of Elastic Properties of bi-layer Thin Films Measured by Bulge Test

Tinoco¹

2019

Preprint

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The present work shows a load-deflection bulge test method to characterize mechanical parameters of thin films by means of a numerical modelling approach. A methodology based on the combination of finite element analysis and classical analytical equations is presented and discussed. Finite element modeling was conducted for monolayer (Si3N4) and bi-layer (Si3N4/Al) membranes with the aim to determine a set of elastic parameters (Young's modulus and Poisson's ratio) which satisfied the load-deflection curves experimentally measured by the bulge test method. It is well known that in a traditional bulge test analysis only biaxial elastic modulus, i.e. a combination of Young's modulus and Poisson's ratio, can be determined. It is due to the mechanical coupling that exists between the two elastic parameters. However, in this study both mentioned elastic constants can be determined independently through a proposed numerical procedure that includes error functions for minimizing the displacement with a specific set of optimal elastic parameters. Results shows that the estimated Young's modulus (Al 64 GPa and Si3N4 236 GPa) agree with corresponding values determined by other methods in the literature of the studied thin films.

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Section: Resultssupporting

confidence: 82%

Numerical Modeling Approach for the Assessment of Elastic Properties of bi-layer Thin Films Measured by Bulge Test

Tinoco¹

2019

Preprint

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“…These images can be used to map the surface of the materials before indentation to understand where the indentation takes place in addition to understanding, for example, the effects of surface roughness on the data obtained. Mapping the surface of the samples by AFM after indentation tests can be used to measure the true contact area in case of appearance of pile-up or sink-in [23]. Prior to the nanoindentation tests, the Oliver and Pharr method [24] was used to calibrate both the instrument stiffness and the tip-end shape.…”

Section: Nanoindentation Testingmentioning

confidence: 99%

Mechanistic Study of the Wear of Ceramic Heads by Metallic Stems in Modular Implants

2016

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Titanium-based and cobalt-chrome alloys as well as some ceramics have been widely used in orthopaedic applications as these materials can significantly enhance the quality of human life as implant materials. However, the in vivo performance of some large-diameter metal-on-metal joints is unsatisfactory, and concerns have been expressed over the wear behaviour of the materials and released metal ions affecting local tissue and more distant organs. The longevity of these materials is highly influenced by their mechanical properties and this has driven the development of alternative ceramic components with greatly improved tribological performance. Even these novel materials are not immune to damage, for instance in some devices alumina-based ceramic components articulate with titanium alloy counterfaces (e.g. in the taper connections of titanium alloy stems and zirconiatoughened alumina femoral heads in modern modular designs) and damage has been reported of the harder ceramic surface by the softer titanium alloy component. In such contacts, the chemically inert ceramic component is not expected to corrode, so the electrochemical damage mechanisms often suggested for metal-metal contacts are not appropriate. This study attempts to understand why this wear might occur by investigating bulk and surface mechanical properties (such as hardness and Young's modulus) of a number of hip implants and test samples using a Hysitron Triboindenter. AFM images were also obtained to determine the contact area and hence, pileup correction factors for the metallic material. It was found that the alumina ceramic heads were generally subject to chemomechanical softening after exposure to water for an extended period whilst titanium alloy oxidised preferentially generating a hard oxide surface which was not softened by water. Furthermore, the oxidised titanium showed significantly higher hardness values therefore damaging the chemomechanically softened alumina material.

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“…Here we exclude the AFM photodetector nonlinearity and scanner creep by using a closed-loop scanner and calibrating the photodetector. Besides, several studies have confirmed that there are some errors in the measured mechanical properties due to the influence of the substrate on the results [50][51][52]. However, the substrate effect is neglected in this work.…”

Section: Resultsmentioning

confidence: 62%

Atomic force microscopy indentation to determine mechanical property for polystyrene–silica core–shell hybrid particles with controlled shell thickness

2015

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A comparison of nanoindentation pile-up in bulk materials and thin films

Abstract: This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License Newcastle University ePrints -eprint.ncl.ac.uk Moharrami N, Bull SJ. A Comparison of Nanoindentation Pile-up in Bulk Materials and Thin Films.

Cited by 72 publications

References 35 publications

Numerical Modeling Approach for the Assessment of Elastic Properties of bi-layer Thin Films Measured by Bulge Test

Numerical Modeling Approach for the Assessment of Elastic Properties of bi-layer Thin Films Measured by Bulge Test

Mechanistic Study of the Wear of Ceramic Heads by Metallic Stems in Modular Implants

Atomic force microscopy indentation to determine mechanical property for polystyrene–silica core–shell hybrid particles with controlled shell thickness

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