| ZHAO Yanhui,YU Zeyang,GUO Zhaoxin,YU Xiaoming.Effect of C2H2 Content on the Structure and Mechanical Properties of DLC Coatings[J],54(7):98-108 |
| Effect of C2H2 Content on the Structure and Mechanical Properties of DLC Coatings |
| Received:July 05, 2024 Revised:November 14, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.07.008 |
| KeyWord:DLC coating C2H2 content nano hardness tribological properties electrochemical corrosion |
| Author | Institution |
| ZHAO Yanhui |
Sino-German Institute of Engineering, Shanghai Technical Institute of Electronics & Information, Shanghai , China |
| YU Zeyang |
College of Materials Science and Engineering, Shenyang Ligong University, Shenyang , China |
| GUO Zhaoxin |
College of Materials Science and Engineering, Shenyang Ligong University, Shenyang , China |
| YU Xiaoming |
College of Materials Science and Engineering, Shenyang Ligong University, Shenyang , China |
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| Abstract: |
| DLC coating is a metastable amorphous carbon coating material composed of diamond structure (sp3 hybrid bond) and graphite structure (sp2 hybrid bond) hybrid bonds. Compared with DLC coatings without hydrogen, DLC coatings with hydrogen have advantages in certain friction fields. In recent years, an arc enhanced glow discharge (AEGD) technology has been proposed, which is generally used for sputtering cleaning of the substrate surface before coating. The work aims to adopt the AEGD as an ion source, which is ionized by introducing carbon containing gas to generate plasma, and then deposited onto the surface of the substrate to form a hydrogen-contained DLC coating. A multifunctional vacuum hybird coating equipment produced by China was adopted, consisting of 5 arc targets and 1 AEGD ion source. The base materials were M2 high-speed steel and 304 stainless steel, with dimensions of ϕ20 mm×3 mm. Before coating, high-energy argon ions generated by AEGD were used to bombard and sputter the substrate surface for 50 minutes to remove the oxide layer and pollutants on the substrate surface. Next, Cr and CrC transition layer was deposited on the substrate surface with a Cr target (99.95%) before depositing the DLC. Then, in order to investigate the effect of C2H2 gas flow rate on the performance of DLC coatings, the C2H2 gas flow rates were controlled at 28, 38, 55, 77, 88 mL/min, and the coating time was 60 min. The surface morphology of the DLC coating was observed with a ZEISS Sigma 300 scanning electron microscope (SEM), the surface roughness was tested with an LS4000 laser 3D microscope produced by Olympus Corporation in Japan, the chemical composition and bonding were measured with Raman spectroscopy, and the composition and bonding status of the DLC coating were tested with an XPS (ESCALAB 250 spectrometer, Thermo Fisher Scientific). The nano hardness and elastic modulus were measured with a Nano Indentation G200, with an indentation depth of 80 nm. The HSR-2M high-speed reciprocating friction and wear testing machine produced by Lanzhou Zhongke Kaihua was used to test the friction and wear performance of DLC coatings. ZrO2 ceramic balls with a diameter of 5 mm were selected as the friction pair, and the contact form was ball surface point contact. Hydrogen-contained DLC coatings were successfully prepared by arc enhanced glow discharge assisted arc ion plating equipment at 25%-80% (volume percent) C2H2. The SEM results showed that the effect of C2H2 content on the surface morphology of DLC coatings was relatively low. The structure of DLC coatings prepared with different C2H2 contents varied, with coatings prepared with 33% C2H2 content showing significantly higher sp3 hybrid bond content (78.17%) than those prepared with other C2H2 contents, while coatings prepared with other C2H2 contents generally had lower sp3 hybrid bond content. The highest hardness (61 GPa) and elastic modulus (414 GPa) of DLC coating were obtained at 33% C2H2. The mechanical properties of coatings prepared with 33% C2H2 were significantly higher than other parameters. Within the range of 25%-80% C2H2, the contact angle gradually decreased with the increase of C2H2 content. The coating prepared with 33% C2H2 had the lowest friction coefficient, the lowest wear rate, and the best wear resistance. Within the range of 25% to 70% C2H2, as the C2H2 content increases, the electrochemical corrosion current density of the prepared DLC coating gradually decreases. The coating prepared with 70% C2H2 has the lowest self-corrosion current density, the highest self-corrosion potential, and the best corrosion resistance. |
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