Evaluation of Stoney equation for determining the internal stress of DLC thin films using an optical profiler

Shiri, Sheida; Ashtijoo, Parisa; Odeshi, A.G.; Yang, Q.

doi:10.1016/j.surfcoat.2016.07.098

Cited by 48 publications

(15 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This behaviour is in agreement with the FEM results of Guyot et al [20]. These results were presented in a different way in a previous study [21], and the experiments were reproduced by Shiri et al [22] in the case of DLC films, adding roundshape substrates. In opposition to the present results, they found for all substrate shapes a constant stress value of 760 MPa ± 100 MPa, about 5 times higher than in our study.…”

Section: Influence Of the Sample's Shape And Sizesupporting

confidence: 90%

Curvature radius measurement by optical profiler and determination of the residual stress in thin films

Besnard

Ardigò

Imhoff

et al. 2019

Applied Surface Science

View full text Add to dashboard Cite

The Stoney formula, based on the measurement of the substrate curvature, is often used for the determination of the thin films' residual stress. In this study, titanium nitride coatings were deposited by DC reactive magnetron sputtering on silicon substrates. An optical profiler was used to determine the curvature of the surface before and after coating. Two radii were then obtained, along the principal perpendicular directions of the surface curvature. A simple and efficient method to determine the experimental error on the stress calculation was developed taking into account the film thickness dispersion and the radii dispersion. Using constant deposition parameters, some samples' characteristics were tested: film and substrate thickness, size, shape and crystallographic orientations of the substrates. With the help of the developed error method, we analyzed what can be conclude about the influence of these characteristics on the calculated stress values, obtained from the experimental measurements.

show abstract

Section: Influence Of the Sample's Shape And Sizesupporting

confidence: 90%

Curvature radius measurement by optical profiler and determination of the residual stress in thin films

Besnard

Ardigò

Imhoff

et al. 2019

Applied Surface Science

View full text Add to dashboard Cite

show abstract

“…Significant compressive residual stresses levels of a-C phases can initiate buckling and delamination under the operating conditions of PEMFCs, compromising their application. 38,39 A common means 40,41 of internal stress measurement is based on curvature measured before and after film deposition using the Stoney equation (eq 4): 1)…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

“…As the thickness of an a-C layer increases, high levels of compressive internal stress has become a major concern compromising performance. Significant compressive residual stresses levels of a-C phases can initiate buckling and delamination under the operating conditions of PEMFCs, compromising their application. , A common means , of internal stress measurement is based on curvature measured before and after film deposition using the Stoney equation (eq ): where E s is Young’s modulus, ν s is the Poisson ratio, h s is the thickness of the substrate, h f is the thickness of the thin film, and R 0 and R are the curvature radii of samples before and after deposition, respectively. Curvature radii are measured by confocal laser scanning microscopy (KEYENCE) and are fitted by a circular arc.…”

Section: Experimental Methodsmentioning

confidence: 99%

Impact of Film Thickness on Defects and the Graphitization of Nanothin Carbon Coatings Used for Metallic Bipolar Plates in Proton Exchange Membrane Fuel Cells

Zhang

Peng

et al. 2018

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

Metallic bipolar plates (BPPs) are considered promising alternatives to traditional graphite BPPs used in proton exchange membrane fuel cells (PEMFCs). Major auto companies, such as Toyota, GM, Ford, and BMW, are focusing on the development of metallic BPPs. Amorphous carbon (a-C) coating are widely known to be effective at enhancing the performance of metallic BPPs. However, a-C coatings prepared by sputtering are mostly micrometers thick, which can render mass production difficult due to their low deposition rates. In this study, we investigate effects of thickness on the formation of defects and the graphitization of nanothin a-C layers deposited by magnetron sputtering from scanning electron microscope (SEM) and transmission electron microscope (TEM) observations, internal stress measurements, X-ray diffractometer (XRD) data, Raman spectra, and X-ray photoelectron spectroscopy (XPS). Furthermore, corrosion and interfacial contact resistance (ICR) test results show that an approximately 69 nm a-C layer, with a deposition time of only 15 min, can meet ex situ technical targets of US Department of Energy. As the thickness of a-C layers increases, vacancy-like defects become more pronounced, which is accompanied by stress relaxation. Furthermore, the larger the graphite-like clusters, the more sp-hybridization carbon atoms found in loose a-C films. The good properties of nanothin a-C layers are attributed to their limited defects and proper graphitization.

show abstract

“…The scanning angle ranged from 20 to 90° at a scanning speed of 2°/min. Moreover, after using residual stress tester (JLCST022, Korea) to measure the curvature radii of the CrN coatings deposited on the Si substrate (length–width ratio ≥ 10), the residual internal stress changes with coating growth were calculated by the Stoney equation. − …”

Section: Methodsmentioning

confidence: 99%

Continuously Growing Ultrathick CrN Coating to Achieve High Load-Bearing Capacity and Good Tribological Property

Wang

Cheng

et al. 2018

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

Continuous growth of traditional monolayer CrN coatings up to 24 h is successfully achieved to fabricate ultrathickness of up to 80 μm on the 316 stainless steel substrate using a multiarc ion plating technique. The microstructures, mechanical properties, and tribological properties evolution with the CrN coating continuously growing was evaluated in detail. The transmission electron microscopy observations and inverse Fourier-filtered images reveal a relaxation mechanism during the continuous growth of CrN coating, which can lead to a decrease in the residual stress when coating growth time exceeds 5 h. The scratch test and friction test results both show that the load-bearing capacity of coating is significantly increased as CrN coatings growing thicker. During the scratch test, the ultrathick CrN coating of thickness 80.6 μm is not failed under the load of 180 N, and the dominant failure mechanism is the cohesive failure including wedge spallation and cracking. The dry-sliding friction test results show the mean coefficient of friction and the wear rate of ultrathick CrN are respectively decreased by 17.2 and 56.8% at most compared with the thin coating (thickness is 5.4 μm). The ultrahigh load-bearing capacity and excellent tribological property are attributed to the relaxation mechanism and limited contact pressure as the coating grows continuously.

show abstract

Evaluation of Stoney equation for determining the internal stress of DLC thin films using an optical profiler

Cited by 48 publications

References 11 publications

Curvature radius measurement by optical profiler and determination of the residual stress in thin films

Curvature radius measurement by optical profiler and determination of the residual stress in thin films

Impact of Film Thickness on Defects and the Graphitization of Nanothin Carbon Coatings Used for Metallic Bipolar Plates in Proton Exchange Membrane Fuel Cells

Continuously Growing Ultrathick CrN Coating to Achieve High Load-Bearing Capacity and Good Tribological Property

Contact Info

Product

Resources

About