Modified scratch test for study of the adhesion of ductile coatings

2009

JOMMS

Scratching of thin coatings on hard substrates is studied experimentally and numerically, in the latter case by use of the finite element method. In particular the delamination behaviour at scratching, by increasing the normal load up to failure, is of interest. The adhesion of the coating to the substrate is modelled as a cohesive zone where relevant model parameters are determined experimentally using the double cantilever beam test with uneven bending moments (DCB-UBM). Good correlation between experimental and numerical results were achieved and the most important finding confirms the fact that the delamination behaviour was very much dependent on the critical energy release rate of the film/substrate interface. The results achieved are directly relevant for thin film polymer coatings but can also be applied in more general situations as a comprehensive parameter study is performed using the finite element method.

Section: Introductionmentioning

confidence: 99%

Delamination of thin coatings at scratching: experiments and numerics

2009

JOMMS

“…These investigations have been devoted to severe scratching, i.e., fracture, delamination etc., cf. e.g., reference (18), as early as 1960, [19][20][21][22][23] as well as attempting to determine a more general understanding of the behavior of different global (and also local) scratch variables at these types of problems, cf. e.g., Larsson and Wredenberg 24 and Wredenberg and Larsson.…”

Section: Introductionmentioning

confidence: 99%

On scratch testing of pressure-sensitive polymeric coatings

2009

J Coat Technol Res

Scratching of polymeric coatings on hard substrates is studied experimentally and numerically from a mechanical point of view. In particular, the behavior of local and global mechanical properties, as well as the delamination behavior, at scratching due to pressure-sensitive effects is of interest. The numerical investigation is performed using the finite element method (FEM) where pressure sensitivity is modeled using the classical Drucker-Prager plasticity model (Drucker, Prager, Q. Appl. Math., 10 157-165 (1952)) while the adhesion of the coating to the substrate is modeled as a cohesive zone where relevant model parameters are determined experimentally using the double cantilever beam test with uneven bending moments (DCB-UBM). Good correlation between experimental and numerical results were achieved and the most important finding concerns the fact that the dependence of pressure sensitivity proved to be different for different mechanical quantities.

“…Also, thin film scratching has been studied quite frequently, cf., e.g., references (24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34) considering different aspects of the problem such as fracture, delamination, the behavior of different global and local scratch variables (global scratch variables include normal and tangential hardness, apparent coefficient of friction and contact area) and alternative constitutive behavior. In reference (33), the local stress fields at thin film scratching were examined in some detail and an important conclusion from this study was that high shear stresses are the dominant factor leading to delamination initiation and growth.…”

Section: Introductionmentioning

confidence: 99%

On the stability of delamination growth at scratching of thin film structures

2011

J Coat Technol Res

Scratching of thin film/substrate structures is studied theoretically and numerically. The results are discussed in connection to delamination initiation and in particular subsequent growth at scratching. The material behavior of the film is described by classical elastoplasticity accounting for large deformations. The deformation of the substrate is neglected indicating that the results are pertinent to soft thin films. The numerical investigation is performed using the finite element method (FEM) and the numerical strategy is discussed in some detail. The results from this study show that delamination growth at thin film scratching is a stable feature with crack arrest occurring at a decreasing load.