Aging of oxygen and hydrogen plasma discharge treated a-C:H and ta-C coatings
| Autor: | S. Hesse, Jan Morasch, Robert W. Stark, Suman Narayan, L. Hussein, Lisa Krell, Marcus Schulze, Svenja Bachmann, Johann Schnagl |
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| Rok vydání: | 2016 |
| Předmět: |
Materials science
Hydrogen Analytical chemistry General Physics and Astronomy chemistry.chemical_element 02 engineering and technology Surfaces and Interfaces General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Surface energy 0104 chemical sciences Surfaces Coatings and Films Contact angle Adsorption X-ray photoelectron spectroscopy Amorphous carbon chemistry Surface modification Wetting 0210 nano-technology |
| Zdroj: | Applied Surface Science. 371:613-623 |
| ISSN: | 0169-4332 |
| Popis: | Surface modification with gas plasma is an efficient and easy way to improve the surface energy and the tribological behavior of diamond-like carbon (DLC) coatings, e.g., in biomedical implants or as protective coatings. However, the long-term performance of the plasma treated DLC coatings is not fully clear. We thus studied the long-term stability of two kinds of DLC coatings, namely (a) hydrogenated amorphous carbon (a-C:H) and (b) tetrahedral amorphous carbon (ta-C) treated at different radio frequency (RF) power and time of oxygen (O2) and hydrogen (H2) plasma. Their surface properties, e.g. surface wettability, structure and tribological behavior, were studied at regular intervals for a period of two months using contact angle goniometer, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), lateral force microscopy (LFM) and ball on disc apparatus. The surface energy of both the coatings decreased upon aging. The higher the RF power and time of treatment, the higher was the hydrophobicity upon aging. XPS analysis showed that the increase in hydrophobicity could be due to adsorption of unavoidable volatile organic components in the atmosphere. The H2 plasma treated ta-C was capable of rearranging its structural bonds upon aging. The nano-friction measurements by LFM showed that the coefficient of friction of plasma treated a-C:H and ta-C decreased upon aging. The results indicate that the surface properties of plasma treated a‐C:H and ta‐C are not stable on long-term and are influenced by the environmental conditions. |
| Databáze: | OpenAIRE |
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