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Publication
The Influence of H Content on the Properties of a-C(W):H Coatings
Advisor(s)
Abstract(s)
Diamond-like-carbon “DLC” coatings can be deposited in many different ways, giving a
large range of material properties suitable for many different types of applications. Hydrogen content
significantly influences the mechanical properties and the tribological behavior of DLC coatings,
but its determination requires techniques that are not available in many research centers. Thus, it is
important to find alternative indirect techniques, such as Raman spectroscopy or nanoindentation
(hardness measurements), which can give comparative and indicative values of the H contents in
the coatings, particularly when depositions with a reactive gas flow are being studied. In this work,
“DLC” composite coatings with varying H content were deposited via Physical Vapor Deposition
(PVD) magnetron sputtering in a reactive atmosphere (Ar + CH4). An Ion Beam Analysis was used
to determine the elemental depth profile across the coating thickness (giving both average C:W:H
ratios and film density when combined with profilometer measurements of film thickness). The
hardness was evaluated with nanoindentation, and a decrease from 16 to 6 GPa (and a decrease in
the film density by a factor of two) with an increasing CH4 flow was observed. Then, the hardness
and Raman results were correlated with the H content in the coatings, showing that these indirect
methods can be used to find if there are variations in the H content with the increase in the CH4 flow.
Finally, the adhesion and tribological performance of the coatings were evaluated. No significant
differences were found in the adhesion as a function of the H content. The tribological properties
presented a slight improving trend with the increase in the H content with a decrease in the wear rate
and friction.
Description
Keywords
DLC coatings metal doped hydrogen content Raman spectroscopy mechanical properties film density ERD
Citation
Evaristo, M.; Fernandes, F.; Jeynes, C.; Cavaleiro, A. The Influence of H Content on the Properties of a-C(W):H Coatings. Coatings 2023, 13, 92.