Clarification of relationship between friction coefficient and transformed layer of CNx coating by in-situ spectroscopic analysis

Nishimura, Hidenori; Umehara, Noritsugu; Kousaka, Hiroyuki; Tokoroyama, Takayuki

doi:10.1016/j.triboint.2014.12.015

Cited by 27 publications

(5 citation statements)

References 7 publications

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“…In these reports, the ultralow coefficient of friction was attributed to the softness of the transfer layer compared to that of the original film. Although the transfer layer been reported to be a graphite-like material, softer than the original film 29) , it is unlikely that this layer is sufficiently fluid to exhibit an ultralow coefficient of friction.…”

Section: Effects and Physical Properties Of The Transfer Layermentioning

confidence: 99%

Eight Phenomena to Explain the Frictional Properties of Carbon-Based Thin Films

KANDA

2023

Journal of the Surface Finishing Society of Japan

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Section: Effects and Physical Properties Of The Transfer Layermentioning

confidence: 99%

Eight Phenomena to Explain the Frictional Properties of Carbon-Based Thin Films

KANDA

2023

Journal of the Surface Finishing Society of Japan

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“…In this study, we employed in situ re ectance spectroscopy to measure the tribo lm thickness and estimate its composition based on optical properties. In situ re ectance spectroscopy has proven effective in elucidating the friction mechanism of nm-scaled transformed layers of DLC coatings [36][37][38][39][40], oil lm structure of two-phase lubricants [41], he adsorption of ester in boundary lubrication regimes [42],…”

Section: Introductionmentioning

confidence: 99%

The Effect of Carbon Structure of DLC Coatings on Friction Characteristics of MoDTC-derived Tribofilm by Using an in situ reflectance spectroscopy

Hashizume,

Yamamoto,

Chen

et al. 2023

Preprint

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In this paper, we prepared 6 types of DLC coatings with varying carbon structures (amorphous ta-C coating and GNC coatings that include nano graphite crystals) and different doped Ta amounts to study friction characteristics. Results from the friction test with MoDTC-added lubricant revealed that DLC coatings with a higher ID/IG ratio exhibited a lower friction coefficient. Furthermore, in situ observations using a reflectance spectroscopy showed that the tribofilm formed on the DLC coatings with a higher ID/IG ratio maintained a higher MoS2 / (MoS2 + MoO3) ratio. This ratio strongly correlated with its friction coefficient. From the measurement of a work function of each DLC coating, the DLC coatings with a higher ID/IG ratio had a higher work function, which indicated to include larger amount of the defect of graphite structure. This active defect of graphite structure was considered to enhance the friction reduction effect of MoDTC. The findings of this paper suggest a material design concept for a DLC coating that amplifies the effects of lubricant additives in reducing friction.

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“…al. clarified the low friction mechanism of a CNx coating and an a-C:H coating by using in situ reflectance spectroscopy [27,28]. In their research, they measured thickness and optical properties (refractive index n and extinction coefficient k) of nm-scaled transformed layer of each coating.…”

Section: Introductionmentioning

confidence: 99%

In situ Observation of the Formation of MoDTC-Derived Tribofilm on a Bearing Steel with Different Surface Roughness by Using a Reflectance Spectroscopy and its Effects on Friction

Hashizume

Tokoroyama

Umehara

et al. 2023

Preprint

Self Cite

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In this paper, the formation of MoDTC-derived tribofilm and effects of its characteristics on friction reduction was evaluated. To consider a transition of the tribofilm during friction, in situ observation of the tribofilm was conducted by using a reflectance spectroscopy, and then thickness and composition of the tribofilm was calculated. As a result, the rough specimen (\({R}_{a}=12.7 \text{n}\text{m}\)) showed a smaller friction coefficient and kept a larger volume fraction of MoS2 compared with the smooth specimen (\({R}_{a}=2.6 \text{n}\text{m}\)). In addition, we estimated a transition of a shear strength of the tribofilm formed on both specimens by using the in situ observed composition and contact state. From the estimation, it was indicated that the shear strength of the tribofilm determined the friction properties, and the direct contact of the asperities which was notable to the rough specimen encouraged a generation of a low-shear tribofilm.

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Clarification of relationship between friction coefficient and transformed layer of CNx coating by in-situ spectroscopic analysis

Cited by 27 publications

References 7 publications

Eight Phenomena to Explain the Frictional Properties of Carbon-Based Thin Films

Eight Phenomena to Explain the Frictional Properties of Carbon-Based Thin Films

The Effect of Carbon Structure of DLC Coatings on Friction Characteristics of MoDTC-derived Tribofilm by Using an in situ reflectance spectroscopy

In situ Observation of the Formation of MoDTC-Derived Tribofilm on a Bearing Steel with Different Surface Roughness by Using a Reflectance Spectroscopy and its Effects on Friction

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