Effect of Oxygen on the Self-formation of Carbonaceous Tribo-layer with Carbon Nitride Coatings under a Nitrogen Atmosphere

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• 作者：Naohiro Yamada ; Tomomi Watari ; Takanori Takeno ; Koshi Adachi
• 关键词：Carbon nitride ; Super ; low ; Oxygen ; Self ; formation ; Nanointerface
• 刊名：Tribology Letters
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：65
• 期：1
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Tribology, Corrosion and Coatings; Surfaces and Interfaces, Thin Films; Theoretical and Applied Mechanics; Physical Chemistry; Nanotechnology;
• 出版者：Springer US
• ISSN：1573-2711
• 卷排序：65

文摘

The ball-on-disk friction and wear tests of CN_X coatings (CN_X/CN_X) were conducted under a nitrogen atmosphere with controlled relative humidity (RH) (3.4–40.0%RH) and oxygen concentration (100–21 × 104 ppm) in this study. We found that the specific wear rate of CN_X coating on ball (W_b), which could give stable and low friction coefficient (<0.05), was below 3.0 × 10−8 mm3/Nm. Average friction coefficients (µ_a) and W_b of CN_X/CN_X increased (µ_a: 0.02–0.33, W_b: 1.6 × 10−8–2.4 × 10−7 mm3/Nm) with increasing oxygen concentration (230–211,000 ppm) as well as RH (4.7–21.1%RH) under a nitrogen atmosphere. However, the W_b remained low value below 2.3 × 10−8 mm3/Nm regardless of oxygen concentration (100–207,000 ppm) of a nitrogen atmosphere (3.4–3.9%RH) when CN_X-coated balls were slid against a hydrogenated CN_X (CN_X:H) coatings (CN_X/CN_X:H). Besides, the CN_X/CN_X:H achieved low and stable friction coefficient below 0.05 under a nitrogen atmosphere (10,000 ppmO₂) regardless of increasing RH up to 20%RH. Raman analysis indicated that the structure of carbon on the top surface of CN_X coating was changed from as-deposited CN_X coating in the case of low friction coefficient (<0.05). Furthermore, TOF-SIMS analysis provided the evidence that the carbon derived from CN_X-coated disk was considered to diffuse into the ball surface, and it mixed with the carbon derived from CN_X-coated ball on the wear scar, which formed the chemically bonded carbon tribo-layer. Low friction coefficient (<0.05) with CN_X coatings under a nitrogen atmosphere was achieved due to self-formation of the carbon tribo-layer.