Nanoindentation. Mechanical Engineering Series

Fischer-Cripps, A. C.; Nicholson, David W.

doi:10.1115/1.1704625

Cited by 112 publications

(43 citation statements)

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“…Finally, the different values of hardness and indentation modulus revealed by micro‐ and nanoindentation test for the same materials reflect the well‐known issue related to indentation size effect. Indeed, it is generally accepted that the indentation hardness measured even with geometrically self‐similar pyramidal indenter (i.e., the commonly used Berkovich indenter) increases with decreasing indentation depth or force …”

Section: Resultsmentioning

confidence: 99%

Multi‐analytical approach for the morphological, molecular, and mechanical characterization after photo‐oxidation of polymers used in artworks

Saviello

Andena

Gastaldi

et al. 2018

J of Applied Polymer Sci

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For a proper preservation of plastics objects, it is essential to study the degradation processes involved in both exposed and hidden areas of the polymeric materials. In fact, surface properties can differ significantly from the bulk and can have a strong effect on the artistic perception and the correct conservation strategy. In this work, a multi-analytical investigation, including spectroscopic techniques, optical, and electronic microscopic observations and mechanical tests, was carried out to deeply investigate changes in the physic-chemical and mechanical surface properties of selected polymers used in design objects and contemporary artworks. Accelerated photo-oxidative ageing was performed on acrylonitrile butadiene styrene (ABS), poly(vinyl chloride) (PVC), polypropylene (PP), high density polyethylene, and linear low density polyethylene. Overall, the analyzed materials have shown different behaviors following photo-oxidation. The molecular and microscopic analyses highlighted the formation of different products of oxidation due to the dissimilar patterns of ageing leading to surface cracking and strong yellowing of the specimen, mainly for ABS, PVC, and PP. Moreover, mechanical properties, such as the variation of hardness and elastic modulus, were investigated at different depth scales (from 100 down to 1 mm) by using different techniques such as microscratch, micro-, and nanoindentation. The selected polymers showed different mechanical behavior at different depth scales.

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Section: Resultsmentioning

confidence: 99%

Multi‐analytical approach for the morphological, molecular, and mechanical characterization after photo‐oxidation of polymers used in artworks

Saviello

Andena

Gastaldi

et al. 2018

J of Applied Polymer Sci

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“…Since there is no theory applicable to the determination of mechanical properties of such micro- to nano-meter thick films, presently, the analytical method used in this paper is just an approach to approximately estimate the true film hardness and modulus in the direction perpendicular to the indentation surface, in which the main purpose is to use these mechanical parameters as references to check multilayer design variables and compare different film-forming conditions. The hardness defined by the applied load divided by the corresponding projected area is the mean contact pressure and is found to be proportional to the film’s yield or flow stress in compression for isotropic materials [34]. The hardness of multilayers has a similar physical meaning if the same concept is assumed valid.…”

Section: Discussionmentioning

confidence: 99%

“…It can also be used for thin films on substrate, provided that the maximum indentation depth is less than 10% of the film thickness to avoid the stiffness contribution of the substrate to the indenter-sample contact [15]. Much effort has been devoted to finding methods of deriving the film modulus and hardness from the measured composite response of tip-film-substrate system, e.g., introduction of the exponential weighting factors to divide contributions of the film and substrate to the composite modulus by Doerner et al, King et al and Saha et al [28,29,30]; a closed-form solution based on moduli-perturbation method by Gao [31]; an extrapolating method of the best-fit curve of experimental data by Mencik et al [32] and Fisher-Cripps [33,34]; the deconvolution of film properties method modified from Hu’s solution [35] by Jung et al [36]. In this paper, the method proposed by Korsunsky et al [37] and Tuck et al [38] based on an energy-based analysis of indentation testing is used to extract the film hardness H f by:

H_{c} = H_{s} + \frac{H_{f} - H_{s}}{1 + {[(h / t) / β_{0}]}^{X}}

…”

Section: Methodsmentioning

confidence: 99%

Micromechanical Properties of Nanostructured Clay-Oxide Multilayers Synthesized by Layer-by-Layer Self-Assembly

et al. 2016

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Clay-based nanostructured multilayers, such as clay-polymer multilayers and clay-oxide multilayers, have attracted growing attention owing to their remarkable mechanical properties and promising application in various fields. In this paper, synthesis of a new kind of nanostructured clay-oxide multilayers by layer-by-layer self-assembly was explored. Nano-mechanical characterization of 18 clay-based multilayer samples, prepared under as-deposited (i.e., air-dried) and annealing conditions at 400 °C/600 °C with different precursor cations and multilayer structure, were carried out using nanoindentation testing, atomic force microscopy (AFM), and X-ray diffraction (XRD). The influencing factors, including as-deposited and annealing conditions and clay concentrations on the mechanical properties were analyzed. Results show that all of the multilayers exhibit high bonding strength between interlayers. Higher modulus and hardness of clay-based multilayers were obtained with lower clay concentrations than that with higher clay concentrations. Different relationships between the modulus and hardness and the annealing temperature exist for a specific type of clay-oxide multilayer. This work offers the basic and essential knowledge on design of clay-based nanostructured multilayers by layer-by-layer self-assembly.

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“…The second hold step (v) was also included at the end of the unloading from maximum load. Additionally, we put in our experiment the total time from the start of the test to the beginning of the unloading to be of 25 s, which is in the range of the time calculated for the PE film, using an equation proposed by Feng and Ngan . They found that if the total time from the start of the test to the beginning of the unloading ( t h ) has values in the range of the calculated by eq.…”

Section: Methodsmentioning

confidence: 95%

“…To correct for thermal drift, the nano‐indentation instruments allow for a hold series of data points to be accumulated at either maximum load or at the end of the unloading from maximum load . The first is creep within the specimen material as a result of plastic flow, which manifests itself when the load is held constant, and the depth readings increase as the indenter sinks into the specimen.…”

Section: Methodsmentioning

confidence: 99%

Mechanical behavior at nanoscale of chitosan‐coated PE surface

Stoleru¹,

Tsekov

Kotsilkova

et al. 2015

J of Applied Polymer Sci

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Chitosan coating of polyethylene (PE) was proposed as a new procedure to improve its biocompatibility and surface properties. The functionalization of the PE film surface by covalent bonding of chitosan coating and its effect on the surface mechanical properties, as surface elasticity, stiffness, and adhesion (that are important in different biological processes) were investigated by nano-indentation, scratch, and atomic force microscopy. It has been established that chitosan grafting onto corona functionalized PE surface using various coupling agents significantly improves the surface hardness and elastic modulus although they decrease in depth of the layer. Compared to the neat PE substrate, the chitosan coated samples show significant improved friction properties and tear resistance. The surface roughness features correlate with the micro-mechanical parameters. Therefore, the covalent immobilization of the chitosan onto PE leads to a stable coating with better mechanical performance being recommended as a promising material for medical applications and food packaging.

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Nanoindentation. Mechanical Engineering Series

Cited by 112 publications

References 0 publications

Multi‐analytical approach for the morphological, molecular, and mechanical characterization after photo‐oxidation of polymers used in artworks

Multi‐analytical approach for the morphological, molecular, and mechanical characterization after photo‐oxidation of polymers used in artworks

Micromechanical Properties of Nanostructured Clay-Oxide Multilayers Synthesized by Layer-by-Layer Self-Assembly

Mechanical behavior at nanoscale of chitosan‐coated PE surface

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