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

Schmid, Christoph and Hetzner, Harald and Tremmel, Stephan and Hilpert, Felix and Durst, Karsten (2014):
Tailored Mechanical Properties and Residual Stresses of a-C:H:W Coatings.
In: Advanced Materials Research, Trans Tech Publications, Switzerland, pp. 14-21, 996, ISSN 1662-8985, [Online-Edition: http://dx.doi.org/10.4028/www.scientific.net/AMR.996.14],
[Article]

Abstract

In this study, three different a-C:H:W coatings with predefined hardness values, ranging from 10 up to 16 GPa, were deposited by adjusting bias voltage according to a previously created regression model. For this purpose, the influence of the main process parameters of the used reactive unbalanced magnetron sputtering process on the mechanical properties of the a-C:H:W coating was investigated previously by nanoindentation. For a systematical evaluation of the single effects, parameters were varied according to a central composite design. 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, a-C:H:W coatings with 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 linear relation between the applied bias voltage and the hardness, the modulus 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.

Item Type: Article
Erschienen: 2014
Creators: Schmid, Christoph and Hetzner, Harald and Tremmel, Stephan and Hilpert, Felix and Durst, Karsten
Title: Tailored Mechanical Properties and Residual Stresses of a-C:H:W Coatings
Language: English
Abstract:

In this study, three different a-C:H:W coatings with predefined hardness values, ranging from 10 up to 16 GPa, were deposited by adjusting bias voltage according to a previously created regression model. For this purpose, the influence of the main process parameters of the used reactive unbalanced magnetron sputtering process on the mechanical properties of the a-C:H:W coating was investigated previously by nanoindentation. For a systematical evaluation of the single effects, parameters were varied according to a central composite design. 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, a-C:H:W coatings with 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 linear relation between the applied bias voltage and the hardness, the modulus 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.

Journal or Publication Title: Advanced Materials Research
Volume: 996
Publisher: Trans Tech Publications, Switzerland
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Physical Metallurgy
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 03 Dec 2014 12:47
Official URL: http://dx.doi.org/10.4028/www.scientific.net/AMR.996.14
Identification Number: doi:10.4028/www.scientific.net/AMR.996.14
Funders: The authors gratefully acknowledge the funding of the German Research Council (DFG) within the DFG project Du-424/7-1 and the scope of the Transregional Collaborative Research Centre on sheet bulk metal forming (SFB/TR 73) in the subproject B4.
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