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https://hdl.handle.net/10316/17980
Title: | Thermal stability in oxidative and protective environments of a-C:H cap layer on a functional gradient coating | Authors: | Louro, C. Moura, C. Wagner Carvalho, N. Stueber, M. Cavaleiro, A. |
Keywords: | DLC; Plasma CVD; Oxidation; Thermal stability | Issue Date: | Feb-2011 | Publisher: | Elsevier B.V. | Citation: | LOURO, C. [et al.] - Thermal stability in oxidative and protective environments of a-C:H cap layer on a functional gradient coating. "Diamond and Related Materials". ISSN 0925-9635. 20:2 (2011) 57-63 | Serial title, monograph or event: | Diamond and Related Materials | Volume: | 20 | Issue: | 2 | Abstract: | Three types of hydrogenated amorphous carbon (a-C:H) coatings were synthesized on stainless steel substrates by a Plasma Assisted CVD process, containing hydrogen contents in the range from 25 to 29 at.%. The effect of annealing up to 600 °C in two different environments on both the structure and the mechanical properties of the coatings were investigated by means of Differential Scanning Calorimetry/Thermogravimetry (DCS/TG), Raman Spectroscopy and Depth Sensing Indentation. The results indicate that the structural modifications occurred in the coatings in both protective and oxidative atmospheres up to 400 °C were due to a complex atomic rearrangement involving the dehydrogenation reaction. A small weight loss, detected by isothermal TG analysis confirmed the H2 effusion. This dense effect proceeds without a change of hardness which was maintained in the diamond-like regime. The annealing in non-oxidative ambiance at temperatures above 500 °C causes both gaseous products effusion and sp3 to sp2 transformation. Raman parameters and hardness values were, under these conditions, similar to those known for a typical graphite-like regime. While the onset temperature of the graphitization process was found to be almost independent of the H content range investigated, the situation was completely different in relation to the oxidation reaction. The highest oxidation resistance was found for coatings with the lowest H content. | URI: | https://hdl.handle.net/10316/17980 | ISSN: | 0925-9635 | DOI: | 10.1016/j.diamond.2010.11.010 | Rights: | openAccess |
Appears in Collections: | FCTUC Eng.Mecânica - Artigos em Revistas Internacionais |
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Thermal Stability in Oxidative and Protective Environments.pdf | 324.11 kB | Adobe PDF | View/Open |
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