| 摘要: |
| 工业生产过程中管道内壁经常受到输送物质的腐蚀和磨损，对管道内壁进行涂层防护十分必要，而目前鲜有在大长径比管道内壁镀膜的报道，且缺乏对大长径比管道内壁膜层性能的研究。采用等离子体增强化学气相沉积（PECVD）技术在直径 100 mm、长 10 m 管道内壁沉积类金刚石（DLC）薄膜，并研究管道内工作气体的等离子体放电辉光光谱、膜层表面亮度、 水静态接触角、硬度、摩擦因数和拉曼光谱等。结果表明：管道内等离子体光谱显示管内等离子体中有 Ar+ 和乙炔分解成的 C2、H 和 CH；膜层表面的亮度 L*最高达到 37.4 和色差 ΔE*最大 1.9，膜层拉曼光谱结果表明靠近管道两端和中间位置膜层的 ID / IG均匀，膜层水静态接触角显示靠近管道两端的膜层接触角略小；靠近管道两端膜层硬度相比中间位置的膜层硬度高， 并且磨损测试中膜层均未出现破损剥落，膜层具有高的耐磨性。试验实现了在大长径比的管道内壁沉积耐磨损的 DLC 膜层， 为长管道内壁均匀镀膜提供了理论支持和技术指导。 |
| 关键词: 等离子体增强化学气相沉积(PECVD) 长管道 内壁镀膜 类金刚石 |
| DOI：10.11933/j.issn.1007-9289.20230227003 |
| 分类号:TG156；TB114 |
| 基金项目:国家自然科学基金（12075071, U2241233）；黑龙江省头雁创新团队计划（HITTY-20190013）；黑龙江省自然科学基金（LH2019A014）资助项目 |
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| Deposition and Properties of DLC Film on the Inner Wall of a 10-m-Long Stainless-steel Tube |
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JIN Pengli1,2, TIAN Xiubo1, GONG Chunzhi1
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1.School of Materials Science and Engineering, Harbin Institute of Technology University,Harbin 150000 , China;2.Songshan Lake Materials Laboratory, Dongguan 523000 , China
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| Abstract: |
| During industrial production, the inner wall of a tube is often corroded and worn by the conveying material; therefore, it must be protected. Currently, research on the coating of the inner wall of a tube is limited, and research regarding the performance of the inner wall of a large-aspect-ratio tube is lacking. Thus, this study attempts to solve the problem of a diamond-like carbon(DLC) film on the inner wall of a long tube. Herein, the internal surface of a 304 stainless-steel tube, which is 10 m long and 100 mm in diameter, is coated with DLC using plasma-enhanced chemical vapor deposition(PECVD). The hollow cathode discharge of gas into the tube, brightness of the film, contact angle, surface hardness, friction factor, and Raman spectroscopy results are characterized using different tests. During the preparation of the inner coating, the plasma spectrum in the 300-800 band at position 3 of the pipe is analyzed using a spectrometer and optical focusing platform. After the film is prepared, its surface brightness is measured using a color difference meter to determine the L*, a*, and b* values of the film, where L* represents the brightness, a* represents red and green, and b* represents yellow and blue. Scanning electron microscopy(SEM) is used to observe the section morphology of the film. The surface roughness of the film is measured using atomic force microscopy(AFM). A friction and wear-testing machine is used to test the wear resistance of the film. A GCr 15 ball with a diameter of 3 mm is selected as the grinding pair, and the experimental parameters of load, rotational speed, and test time are set as 3 N, 200 r / min, and 120 min, respectively. A nanoindentation hardness instrument is used to measure the nanohardness of the film. A measuring meter for the static contact angle of water is used for measurement; the measurement requires 2 μl of each drop. Each sample is tested three times, and the average value is calculated as the final test result. The film is measured by a laser Raman spectrometer using a 532 nm laser source from 800 to 2 000 cm–1, and a Gaussian curve is employed to fit the Raman spectrum. The results demonstrate that in the coating process of the inner wall, the first step is the entry of Ar gas into the pipe for glow discharge cleaning. Ionization and excitation occur during the process of Ar gas discharge, thereby producing Ar+ and Ar0 ; additionally, C2, H, and CH decompose from acetylene. The SEM results of the cross-sections of the films at different positions reveal that the cross-section of the film is uniform and dense, with no cracks, pinholes, or other defects. Further, no cracks are observed in the binding transition between the film and matrix, thickness of the film at different positions, and thickness of the film near the ends of the pipeline, thus indicating that the plasma density in this region and the deposition rate of the film are high. The largest L* and ΔE* values of the film are 37.4 and 1.9, respectively. The AFM results demonstrate larger bulges on the film surface at positions 3 and 7, which result in high surface-roughness, and uniform distribution of the bulges at positions 3 and 9. The water contact angles of the films are smaller at both ends. The results of the wear tests indicate that the friction factor of the film decreases in the first 20 min from 0.225 to approximately 0.175. For a prolonged time, the friction factor remains stable at 0.17. The hardness of the film near the ends of the pipe is slightly higher. Further, no damage or film-peeling is noted in the pin-on-disk test, and the film is characterized as having a good wear resistance. The Raman spectra of the films at different positions reveal that in contrast to positions 1 and 9, the G peaks at positions 3 and 7 exhibit a shift toward the peak level, thus indicating a high stress in the film at both ends. Considering the distribution trend of ID / IG in the film, a low ratio of ID / IG is determined at both ends of the tube. The glow discharge and DLC deposition in the long tube with a large length ratio provides theoretical support and technical guidance for the uniform coating of the walls of long pipes. |
| Key words: plasma enhanced chemical vapor deposition (PECVD) long tube inner coating diamond-like carbon |
