| 引用本文: | 程勇,王振玉,王振东,毕健浩男,张美琪,柯培玲,汪爱英.Cr掺杂对MoN涂层力学及摩擦学性能的影响[J].中国表面工程,2024,37(6):297~310 |
| CHENG Yong,WANG Zhenyu,WANG Zhendong,BIJIAN Haonan,ZHANG Meiqi,KE Peiling,WANG Aiying.Effect of Cr Doping on Mechanical and Tribological Properties of MoN Coatings[J].China Surface Engineering,2024,37(6):297~310 |
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| Cr掺杂对MoN涂层力学及摩擦学性能的影响 |
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程勇1，2，王振玉2，王振东2，毕健浩男2，张美琪1，2，柯培玲2，汪爱英2
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1.宁波大学材料科学与化学工程学院 宁波 315211 ； 2.中国科学院宁波材料技术与工程研究所海洋关键材料重点实验室 宁波 315201
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| 摘要: |
| 优异的力学和摩擦学性能使 MoN 涂层在箔片空气轴承防护上应用潜力较大，但 MoO3在 500 ℃以上环境下的强挥发性严重影响了其服役寿命。Cr 元素掺杂在提高 MoN 涂层抗氧化性能方面优势显著，然而 Cr 元素掺杂对 MoN 涂层的力学性能、组织结构和中高温摩擦学性能的影响尚不明确。使用高功率脉冲磁控溅射（HiPIMS）复合直流磁控溅射（DCMS）技术在不同基体表面制备系列不同 Cr 元素含量的 MoCrN 涂层，利用 SEM、XRD、EDS、纳米压痕设备、维氏压痕、划痕仪、应力仪、拉曼光谱仪和摩擦试验机对涂层的微观结构、物相组成、力学性能与摩擦学性能进行系统研究。结果表明，MoN 涂层由单一 Mo2N 相组成，MoCrN 涂层由 Mo2N 与 CrN 构成。随 Cr 元素掺杂含量的增加，Mo2N 含量降低及压应力下降，导致涂层硬度与韧性单调降低，结合力先增加后下降。其中，Cr 元素掺杂含量为 10.4at.%的样品具有最高的结合力，相较于纯 MoN 涂层提高了 29 N。摩擦学试验发现，随 Cr 元素掺杂含量的增加，由于涂层强韧性降低、鳞片状摩擦层的消失以及摩擦产物的变化，室温摩擦因数和磨损率单调增加；当 Cr 元素掺杂含量为 19.9at.%时，因显著提升了 MoN 涂层抗氧化性能，涂层在 550 ℃下的耐磨性能最佳。研究结果详细对比分析不同 Cr 元素掺杂含量对 MoCrN 涂层力学性能及摩擦学性能的作用规律，揭示了相关影响机制，可为提高 MoN 涂层综合性能提供参考。 |
| 关键词: MoCrN 涂层 高功率脉冲磁控溅射(HiPIMS) 微观组织 力学性能 摩擦学性能 |
| DOI：10.11933/j.issn.1007-9289.20231228006 |
| 分类号:TG178 |
| 基金项目:国家自然科学基金（U22A20111，52171090）；宁波市科技计划项目（2023QL049，2022Z011，2023Z022） |
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| Effect of Cr Doping on Mechanical and Tribological Properties of MoN Coatings |
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CHENG Yong1，2，WANG Zhenyu2，WANG Zhendong2，BIJIAN Haonan2，ZHANG Meiqi1，2，KE Peiling2，WANG Aiying2
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1.School of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211 , China ；2.Key Laboratory of Advanced Marine Materials, Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences, Ningbo 315201 , China
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| Abstract: |
| Foil air bearings are supported by a layer of air or inert gas during operation, providing several advantages, such as low resistance, wide applicability, energy efficiency, and emission reduction. Thus, they hold great potential for high-temperature and high-speed applications. However, during startup and stopping, there is physical contact between the shaft and foil, which leads to friction and wear. To mitigate this, advanced surface coating technology can be employed to apply solid lubricant coatings to shafts and foils, effectively reducing friction and wear and extending service life. MoN coatings possess excellent mechanical and tribological properties, making them a promising option for foil-air bearings. However, MoO3, which exhibits high volatility above 500 ℃, limits the application of MoN coatings at high temperatures. However, Cr, as a high-temperature-stabilizing element, generates Cr2O3 oxide, which exhibits lubricating effects at both room and high temperatures. Moreover, it formed a dense oxide layer that enhanced the high-temperature oxidation resistance of the coating, thereby reducing wear. This theoretical feasibility suggests that Cr doping can improve the mechanical and tribological properties of MoN coatings. However, the effects of Cr doping on the mechanical properties, organizational structure, and tribological properties of MoN coatings, particularly at medium and high temperatures, remain insufficiently explored and warrant further investigation. MoCrN coatings with varying Cr contents were prepared by high-power impulse magnetron sputtering (HiPIMS) combined with direct magnetron sputtering (DCMS) on different substrate surfaces. The coatings are investigated using various techniques such as SEM, XRD, EDS, nanoindentation equipment, Vickers indentation, scratching instrument, stress meter, step meter, Raman spectrometer, and tribological testing machine to analyze their microstructure, phase composition, mechanical properties, and tribological properties. The findings reveal that all coatings exhibit columnar crystal structure growth, good coating-matrix combination, and a defect-free dense surface. The pure MoN coating consisted of the Mo2N phase, whereas introducing Cr led to the appearance of the CrN phase in the coating. The MoCrN coating consisted of CrN and Mo2N phases with a shift in preferential orientation from the (200) face to the (111) face. In terms of mechanical properties, the hardness gradually decreases from 22.28±0.7 GPa to 11.66±1.18 GPa due to reduced compressive stress and the lower hardness CrN phase. The toughness also decreases with increasing Cr doping. The bonding force initially increased and then decreased, with the highest bonding force of 137 N observed for the coating with a Cr content of 10.4at.%, surpassing the pure MoN coating. Tribological property results indicate that at room temperature, the factor of friction of the coating increases monotonically from 0.38 for the pure MoN coating to 0.63 for the 19.9at. % Cr coating. This increase is attributed to the decrease in the mechanical properties, decrease in the generation of the oxide of the Magnéli phase of Mo, and loosening of the friction layer inside the wear marks with increasing Cr content. Additionally, the wear rate also increases monotonically from 2.59×10?7 mm?3 ·N?1 ·m?1 to 4.95× 10?7 mm?3 ·N?1 ·m?1 , indicating that Cr doping is unfavorable to the room temperature tribological performance of MoN coatings. However, it is important to note that the wear rate is generally low. In the environment of 550 ℃, the friction factor of the coating increases from 0.37 to 0.72 at 10.4at.% Cr due to the generation of globular oxide particles and the disappearance of a continuous smooth oxide enamel layer. Subsequently, with the reduction of oxide particles and the reappearance of a relatively continuous oxide enamel layer, the factor of friction slightly decreases to 0.63 at 19.9at.% Cr. Similar to the factor of friction, the wear rate initially increased with increasing Cr content and then sharply decreased at a Cr content of 19.9at.%. Compared with pure MoN coatings, MoCrN coatings with a Cr content of 19.9at.% exhibit higher friction factor. However, owing to the improvement in the oxidation resistance, the wear rate was reduced by approximately three times compared to that of pure MoN coatings, making them more resistant to high-temperature wear. A comparative analysis of the microstructure, mechanical properties, and tribological properties of the MoCrN coatings with different Cr contents was conducted to elucidate the mechanism of Cr doping. This study provides valuable insights into enhancing the tribological properties of MoN coatings. |
| Key words: MoCrN coating high power inpulse magnetron sputtering (HiPIMS) microstructure mechanical properties tribological properties |
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