The influence of hydrogenated amorphous carbon coatings (a-C:H) on the fatigue life of coated steel specimens

Schaufler, Jens; Durst, Karsten; Haas, Thomas; Nolte, R; Höppel, Heinz Werner

doi:10.1016/j.ijfatigue.2011.09.008

Cited by 7 publications

(2 citation statements)

References 27 publications

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“…The failure of numerous medical devices is induced by fatigue loading [23]. Nevertheless, there are very few publications on the corrosion fatigue behavior of DLC-coated materials [24,25]. The importance of the adhesion promotion interlayer under corrosion fatigue has been previously mentioned, but not thoroughly investigated [26].…”

Section: Introductionmentioning

confidence: 99%

Corrosion fatigue in DLC-coated articulating implants: an accelerated methodology to predict realistic interface lifetime

Pardo

Ilic

Thorwarth

et al. 2019

Science and Technology of Advanced Materials

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We present a methodology to accelerate and estimate the lifetime of an interlayer under dynamic loading in body-like media. It is based on accelerating corrosion fatigue processes taking place at the buried interface of a Si-based adhesion-promoting interlayer in articulating implants on a CoCrMo biomedical alloy; the implants are coated with diamond-like carbon (DLC). The number of interface loading cycles to delamination is determined by reciprocal loading in corrosive fluid. Its dependence on the load is summarized in a Wöhler-like curve of a DLC/DLC-Si/CoCrMo system in body working conditions: cyclic stresses at 37°C in phosphate buffered saline (PBS). The presence of oxygen as a contaminant strongly affects the lifetime of the interface under corrosion fatigue. The main parameters acting on the prediction, with a special emphasis on simulated in vivo conditions, are analyzed and discussed: the media (PBS, Milli-Q water, NaCl, Ringers' solution and bovine calf serum), the load, the frequency and the composition of the interface determined by X-ray photoelectron spectroscopy.

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Section: Introductionmentioning

confidence: 99%

Corrosion fatigue in DLC-coated articulating implants: an accelerated methodology to predict realistic interface lifetime

Pardo

Ilic

Thorwarth

et al. 2019

Science and Technology of Advanced Materials

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“…Beside the undesirable aspects of residual stresses in coating systems, they also can be advantageous to a certain extent under specific loading conditions. Schaufler et al observed for well adhering coatings [24] a strongly enhanced fatigue life time of coated steel substrates, which they attributed to the high residual compressive stress level of the coatings [25]. Moreover, the degradation rate of a-C:H coatings under erosive load could be reduced by increasing the residual compressive stresses of the coating [26].…”

Section: Discussionmentioning

confidence: 99%

Tailored Mechanical Properties and Residual Stresses of a-C:H:W Coatings

Schmid

Hetzner

Tremmel

et al. 2014

AMR

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In this study, three different a-C:H:W coatings with predefined hardness values, ranging from 10 up to 16 GPa, were deposited by selecting suitable parameter set points and adjusting substrate bias voltage of the reactive unbalanced magnetron sputtering process according to a previously created regression model. To obtain this model, the four main process parameters had been varied according to a central composite design and their influence on the mechanical properties of the a-C:H:W coating had been investigated previously by nanoindentation. The three coating variants of this study were investigated in terms of microstructure, mechanical properties and residual stresses. It turned out, that by the use of the regression model, indeed a-C:H:W coatings of tailored mechanical properties can be deposited. Residual stresses were measured by means of focused ion beam milling of a double-slit geometry, which causes the internal stresses to relax, and mapping of the resultant relief strain by digital image correlation. A nearly linear relation between the applied bias voltage and the hardness, the modulus of elasticity of the coating as well as the determined relief strain was observed. Thus, residual stresses of the coatings increase disproportionately with applied bias voltage. The obtained results can be helpful for tailored coating design and further optimization of a-C:H:W coatings.

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