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10 pages, 2148 KiB

Open AccessFeature PaperArticle

Diamond-Like Carbon Films with Low Internal Stress by a Simple Bilayer Approach

by Koumei Baba, Ruriko Hatada, Stefan Flege and Wolfgang Ensinger

Coatings 2020, 10(7), 696; https://doi.org/10.3390/coatings10070696 - 19 Jul 2020

Cited by 4 | Viewed by 2561

Amorphous carbon films with a high hardness usually suffer from high internal stress. To deposit films with a hard top surface but reduced internal stress, a simple bilayer approach was used. Films were prepared by plasma source ion implantation, using only hydrocarbon precursors. [...] Read more.

Amorphous carbon films with a high hardness usually suffer from high internal stress. To deposit films with a hard top surface but reduced internal stress, a simple bilayer approach was used. Films were prepared by plasma source ion implantation, using only hydrocarbon precursors. The single layer with the highest hardness (deposited by a low direct current (DC) voltage and radio frequency (RF) generation of the plasma) has the highest internal stress with more than 3.5 GPa. By adding an interlayer with a lower hardness, the resulting stress of the bilayer film can be reduced to below 1.4 GPa while maintaining the high hardness of the top layer. By avoiding metallic interlayers or dopants within the films, the deposition process can be kept simple and cost-effective, and it is also suitable for three-dimensional samples. Full article

(This article belongs to the Special Issue Synthesis and Characterization of Diamond-Like Carbon Composite Films)

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11 pages, 1768 KiB

Open AccessArticle

The Influence of Preparation Conditions on the Structural Properties and Hardness of Diamond-Like Carbon Films, Prepared by Plasma Source Ion Implantation

by Ruriko Hatada, Stefan Flege, Muhammad Naeem Ashraf, Arne Timmermann, Christoph Schmid and Wolfgang Ensinger

Coatings 2020, 10(4), 360; https://doi.org/10.3390/coatings10040360 - 6 Apr 2020

Cited by 16 | Viewed by 2432

Abstract

Diamond-like carbon (DLC) films were prepared from a hydrocarbon precursor gas by plasma source ion implantation (PSII), in which the plasma generation and the film deposition were coupled; i.e., the plasma was generated by the applied voltage and no additional plasma source was [...] Read more.

Diamond-like carbon (DLC) films were prepared from a hydrocarbon precursor gas by plasma source ion implantation (PSII), in which the plasma generation and the film deposition were coupled; i.e., the plasma was generated by the applied voltage and no additional plasma source was used. Several experimental parameters of the PSII process were varied, including the sample bias (high voltage, DC or pulsed), gas pressure, sample holder type and addition of argon in the plasma gas. The influence of the deposition conditions on the carbon bonding and the hydrogen content of the films was then determined using Raman spectroscopy. Nanoindentation was used to determine the hardness of the samples, and a ball-on-disk test to investigate the friction coefficient. Results suggest that films with a lower sp² content have both a higher hydrogen content and a higher hardness. This counterintuitive finding demonstrated that the carbon bonding is more important to hardness than the reported hydrogen concentration. The highest hardness obtained was 22.4 GPa. With the exception of a few films prepared using a pulsed voltage, all conditions gave DLC films having similarly low friction coefficients, down to 0.049. Full article

(This article belongs to the Special Issue Synthesis and Characterization of Diamond-Like Carbon Composite Films)

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11 pages, 1746 KiB

Open AccessArticle

Preparation of Aniline-Based Nitrogen-Containing Diamond-Like Carbon Films with Low Electrical Resistivity

by Ruriko Hatada, Stefan Flege, Wolfgang Ensinger, Sabine Hesse, Shuji Tanabe, Yasuhisa Nishimura and Koumei Baba

Coatings 2020, 10(1), 54; https://doi.org/10.3390/coatings10010054 - 8 Jan 2020

Cited by 8 | Viewed by 3436

Abstract

The intrinsic high electrical resistivity of diamond-like carbon (DLC) films prevents their use in certain applications. The addition of metal or nitrogen during the preparation of the DLC films leads to a lower resistivity of the films, but it is usually accompanied by [...] Read more.

The intrinsic high electrical resistivity of diamond-like carbon (DLC) films prevents their use in certain applications. The addition of metal or nitrogen during the preparation of the DLC films leads to a lower resistivity of the films, but it is usually accompanied by several disadvantages, such as a potential contamination risk for surfaces in contact with the film, a limited area that can be coated, deteriorated mechanical properties or low deposition rates of the films. To avoid these problems, DLC films have been prepared by plasma source ion implantation using aniline as a precursor gas, either in pure form or mixed with acetylene. The nitrogen from the precursor aniline is incorporated into the DLC films, leading to a reduced electrical resistivity. Film properties such as hardness, surface roughness and friction coefficient are nearly unchanged as compared to an additionally prepared reference sample, which was deposited using only pure acetylene as precursor gas. Full article

(This article belongs to the Special Issue Synthesis and Characterization of Diamond-Like Carbon Composite Films)

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