| SU Yongyao,PENG Hao,XU Zhaoying,ZHANG Tengfei,WANG Jinbiao,YU Weijie,RUAN Haibo.Tribological Properties of Mo-DLC/Mo Films in Methanol[J],54(9):121-129 |
| Tribological Properties of Mo-DLC/Mo Films in Methanol |
| Received:September 19, 2024 Revised:December 18, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.09.010 |
| KeyWord:magnetron sputtering DLC film transition layer friction and wear methanol |
| Author | Institution |
| SU Yongyao |
College of Materials Science and Engineering, Chongqing University of Arts and Sciences, Chongqing , China |
| PENG Hao |
College of Materials Science and Engineering, Chongqing University of Technology, Chongqing , China |
| XU Zhaoying |
College of Materials Science and Engineering, Chongqing University of Arts and Sciences, Chongqing , China |
| ZHANG Tengfei |
College of Materials Science and Engineering, Chongqing University of Arts and Sciences, Chongqing , China |
| WANG Jinbiao |
College of Materials Science and Engineering, Chongqing University of Arts and Sciences, Chongqing , China |
| YU Weijie |
School of Intelligent Manufacturing and Transportation, Chongqing Vocational Institute of Engineering, Chongqing , China |
| RUAN Haibo |
College of Materials Science and Engineering, Chongqing University of Arts and Sciences, Chongqing , China |
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| Abstract: |
| The application of methanol fuel presents significant challenges for the stable and efficient operation of key moving components in internal combustion engine injection systems. These challenges are primarily manifested in the increased friction and wear rates experienced by these components when exposed to methanol, which can lead to premature failure and decreased operational efficiency. To address these issues, there is an need for the development of materials with superior friction-reducing and wear-resistant properties. The work aims to meet this demand by designing and fabricating molybdenum-doped diamond-like carbon (Mo-DLC) films on high-speed steel surfaces, with a focus on enhancing their performance in methanol-based environments. Therefore, the Mo-DLC films were prepared with magnetron sputtering technology, a widely recognized method for depositing thin films with precise control over their composition and structure. To study the impact of the Mo transition layer, Mo-DLC films with and without Mo layer were prepared on high-speed steel substrates. The comparative study was conducted to evaluate the differences in their micro-structural, morphological, mechanical and tribological properties. The micro-structural characterization of the films was performed with laser Raman spectroscopy, providing information on the chemical bonds and disorder within the films. Scanning electron microscopy (SEM) was employed to observe the cross-sectional morphology and identify any defects. The mechanical properties, including hardness and elastic modulus, were assessed through nano-indentation. Finally, the tribological properties of the films were evaluated with a wear tester in methanol and air. The results of the study revealed that the Mo-DLC film with the Mo transition layer exhibited an internal stress of approximately 1.85 GPa, significantly lower than 2.18 GPa observed in the Mo-DLC film without the transition layer. This reduction in internal stress could be attributed to the Mo transition layer, which served to buffer the mismatch in mechanical properties between the film and the substrate. The film-substrate adhesion strength was also markedly improved, increasing from 100 mN of the film without the transition layer to 210 mN of the film with the transition layer, representing an increase of 110%. In addition to the improvement in mechanical properties, the Mo-DLC/Mo films demonstrated excellent wear resistance and environmental adaptability. The wear rates in both air and methanol were significantly lower than those of the Mo-DLC film without the transition layer, with values measured at 4.6×10−8 mm³/N.m and 5.8×10−8 mm³/(N.m), respectively. This indicated that the Mo-DLC/Mo films were not only more resistant to wear but also more consistent in their performance across different environments, making them well-suited for use in methanol-fueled engines. To sum up, by reducing internal stress and improving film-substrate adhesion, the Mo transition layer enables the Mo-DLC/Mo films to achieve outstanding friction and wear performance in methanol-based environments. The research findings provide a solid theoretical foundation and practical guidance for the preparation of low-stress DLC films, which can be invaluable for their application in the methanol internal combustion engine industry. |
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