Two scaling domains in multiple cracking phenomena

Handge, Ulrich A.; Leterrier, Y.; Rochat, G.; Sokolov, I. M.; Blumen, A.

doi:10.1103/physreve.62.7807

Cited by 28 publications

(22 citation statements)

References 29 publications

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“…As a result, the maximum stress in a fragment cannot reach the unperturbed far-field level, which leads to a marked reduction of the fragmentation rate. The first two stages are in fact intimately correlated, as was demonstrated by Handge et al [279]. Transverse buckling failure of coating fragments is often observed during this second stage, due to lateral contraction of the substrate resulting from Poisson's ratio effects [83,[280][281][282] (Fig.…”

Section: The Three Stages Of Coating Fragmentationmentioning

confidence: 87%

Durability of nanosized oxygen-barrier coatings on polymers

Leterrier

2003

Progress in Materials Science

472

341

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Research on silicon oxide thin films developed as gas-barrier protection for polymer-based components is reviewed, with attention paid to the relations between (i) coating defects, cohesive strength and internal stress state, and (ii) interfacial interactions and related adhesion to the substrate. The deposition process of the oxide from a vapor or a plasma phase leads in both cases to the formation of covalent bonds between the two materials, with high adhesion levels. The oxide coating contains nanoscopic defects and microscopic flaws, and their respective effect on the barrier performance and mechanical resistance of the coating is analyzed. Potential improvements are discussed, including the control of internal stresses in the coating during deposition. Controlled levels of compressive internal stresses in the coating are beneficial to both the barrier performance and the mechanical reliability of the coated polymer. An optimal coating thickness, with low oxygen permeation and high cohesive strength, is determined from experimental and theoretical analyses of the failure mechanisms of the coating under mechanical load. These investigations are found relevant to tailor the interactions and stress state in the interfacial region, in order to improve the reliability of the coating/substrate assembly. #

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Section: The Three Stages Of Coating Fragmentationmentioning

confidence: 87%

Durability of nanosized oxygen-barrier coatings on polymers

Leterrier

2003

Progress in Materials Science

472

341

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“…8 To study multiple cracking phenomena of brittle films on compliant substrates, in situ fragmentation tests have been conducted. [9][10][11][12] This method, in which the progressive development of crack density in the coating is analyzed as a function of substrate elongation, has proven to be efficient for (i) the determination of the strength distribution in the film and the type of strain transfer (linear or nonlinear) between film and substrate 9,13 and (ii) the calculation and modeling of adhesive and cohesive fracture toughness. 10,[14][15][16][17] More direct measurements of fracture toughness of thin films on compliant substrates are possible by bulge testing of circular membranes 18 and a special buckling test.…”

Section: Introductionmentioning

confidence: 99%

Brittle-to-ductile transition in ultrathin Ta/Cu film systems

2009

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Current semiconductor technology demands the use of compliant substrates for flexible integrated circuits. However, the maximum total strain of such devices is often limited by the extensibility of the metallic components. Although cracking in thin films is extensively studied theoretically, little experimental work has been carried out thus far.Here, we present a systematic study of the cracking behavior of 34 to 506 nm thick Cu films on polyimide with 3.5 to 19 nm-thick Ta interlayers. The film systems have been investigated by a synchrotron-based tensile testing technique and in situ tensile tests in a scanning electron microscope. By relating the energy release during cracking obtained from the stress-strain curves to the crack area, the fracture toughness of the Cu films can be obtained. It increases with Cu film thickness and decreases with increasing Ta film thickness. Films thinner than 70 nm exhibit brittle fracture, indicating an increasing inherent brittleness of the Cu films.

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“…The topic of multiple cracking of coatings on high elongation substrates (and matrices in composite laminates) has motivated a considerable amount of work, for instance to obtain statistical strength parameters from crack spacing distributions (Hui et al, 1999;Leterrier et al, 1997a,b;Ochiai et al, 2007) and layer toughness (Kim and Nairn, 2000;Nairn, 2000). Prior analyses of experimental data, however, are limited to single coatings (Andersons et al, 2007;Handge, 2002;Handge et al, 2000;Howells et al, 2008;Hsueh and Yanaka, 2003;Leterrier et al, 2004;Tang et al, 2001;Yanaka et al, 1999). In this case, the interfacial shear strength (IFSS, representative of practical adhesion) can be derived from an interfacial stress transfer analysis.…”

Section: Introductionmentioning

confidence: 99%

Models for saturation damage state and interfacial shear strengths in multilayer coatings

Leterrier

Waller

Nairn

2010

Mechanics of Materials

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a b s t r a c tThe present work investigates the saturation damage state of a two-layer coating on a substrate (layer 1/layer 2/substrate) under uniaxial tensile loading in order to derive expressions for the interfacial strength between layer 1 and layer 2, and between layer 2 and substrate. It is based on experimental data on specimens where layer 1 is an inorganic film, layer 2 is an organic coating and the substrate is a polymer. The analysis is relevant to the cases where layer 1 cracks first, followed by layer 2, in which cracks appear due to stress concentrations caused by the cracks in layer 1. It considers the cases where at least one interface is completely yielded with shear stress equal to the interfacial shear stress, and where the crack density in layer 1 is equal to or higher than the crack density in layer 2. The possible situations depend on the relative shear strengths between layers 1 and 2 and between layer 2 and the substrate. The interfacial shear strength between layer 1 and layer 2, and between layer 2 and substrate are derived for elastic and yielded stress transfer cases and found to frame experimental values obtained with single-layer coatings.

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Two scaling domains in multiple cracking phenomena

Cited by 28 publications

References 29 publications

Durability of nanosized oxygen-barrier coatings on polymers

Durability of nanosized oxygen-barrier coatings on polymers

Brittle-to-ductile transition in ultrathin Ta/Cu film systems

Models for saturation damage state and interfacial shear strengths in multilayer coatings

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