Superlubricity with Graphitization in Ti-Doped DLC/Steel Tribopair: Response on Humidity and Temperature

Kim, Jae-Il; Lee, Wooyoung; Tokoroyama, Takayuki; Umehara, Noritsugu

doi:10.1021/acsami.3c01704

Cited by 14 publications

(6 citation statements)

References 131 publications

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“…This transition has been discussed as the main reason for the excellent frictional properties of DLC. 56,57 Figure S5 shows the evolution of sp 3 to sp 2 ratio in our multilayer coatings, demonstrating a weak dependence of DLC bond transition as a function of bilayer thickness. This observation suggests that the variation of scratch hardness can be mainly associated with the thickness of the WC layers rather than DLC ones.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

Interface Amorphization Controls Maximum Wear Resistance of Multinanolayer DLC/WC Coatings

Ma,

Nemati,

Kim

et al. 2024

ACS Appl. Mater. Interfaces

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Multilayer coatings offer significant advantages in protecting materials’ surfaces by shielding the underlying materials hierarchically from damage and wear. The layering morphology and structure of multilayer coatings directly affect their wear resistance capacity. Using a systematic set of experiments and molecular dynamics (MD) simulations, we studied the effect of layering thickness on the macroscale wear response of DLC/WC multinanolayer coatings. Our study revealed the existence of a critical bilayer thickness where maximum scratch hardness and wear resistance can be achieved. Our large-scale MD simulations showed that reducing the WC layer thickness to a certain limit increases the scratch hardness due to the confinement of dislocation motion. However, when the thickness of the WC layers falls below 2 nm, the deformation mechanism transitions from the interface-induced dislocation confinement to the interface-mediated amorphization of WC layers, reducing the scratch hardness of the coating. This finding offers a procedure for optimizing the macroscale wear performance of multinanolayer coatings.

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Section: ■ Results and Discussionmentioning

confidence: 98%

Interface Amorphization Controls Maximum Wear Resistance of Multinanolayer DLC/WC Coatings

Ma,

Nemati,

Kim

et al. 2024

ACS Appl. Mater. Interfaces

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“…Environmental Adaptability: How a material responds to changes in its environment is key to its potential for superlubricity. A study conducted by Kim et al [ 19 ] demonstrated that the friction between Ti-doped DLC and steel surfaces could transition to superlubricity under specific humidity and temperature conditions. The researchers discovered that the increased presence of water molecules in a humid environment could form a lubricating layer between the surfaces, significantly reducing friction.…”

Section: Materials Science In Superlubricitymentioning

confidence: 99%

“…Thus, precise control and consideration of these environmental parameters are necessary for achieving and maintaining the desired superlubric behavior in practical applications. For example, Kim et al [ 19 ] highlighted how superlubricity in titanium-doped diamond-like carbon on a steel tribopair could be accomplished under specific humidity and temperature settings. To achieve a superlubric sliding regime, numerous solutions focus on mitigating frictional energy dissipation mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Superlubricity of Materials: Progress, Potential, and Challenges

et al. 2023

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This review paper provides a comprehensive overview of the phenomenon of superlubricity, its associated material characteristics, and its potential applications. Superlubricity, the state of near-zero friction between two surfaces, presents significant potential for enhancing the efficiency of mechanical systems, thus attracting significant attention in both academic and industrial realms. We explore the atomic/molecular structures that enable this characteristic and discuss notable superlubric materials, including graphite, diamond-like carbon, and advanced engineering composites. The review further elaborates on the methods of achieving superlubricity at both nanoscale and macroscale levels, highlighting the influence of environmental conditions. We also discuss superlubricity’s applications, ranging from mechanical systems to energy conservation and biomedical applications. Despite the promising potential, the realization of superlubricity is laden with challenges. We address these technical difficulties, specifically those related to achieving and maintaining superlubricity, and the issues encountered in scaling up for industrial applications. The paper also underscores the sustainability concerns associated with superlubricity and proposes potential solutions. We conclude with a discussion of the possible future research directions and the impact of technological innovations in this field. This review thus provides a valuable resource for researchers and industry professionals engaged in the development and application of superlubric materials.

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“…Superlubricants can be broadly classified into two categories: solid and liquid . For the former, typical ones include molybdenum disulfide, graphene, diamond-like carbon films, and multiwalled carbon nanotubes. − However, solid superlubricity materials usually require specific conditions (e.g., vacuum/inert gas atmosphere, incommensurate contact, micrometer size, and absolute surface rigidity) to achieve superlubricity, whereas the liquid ones easily achieve macroscopic superlubricity on routinely flat surfaces under atmospheric conditions such as aqueous phosphoric acid solutions . As a result, liquid superlubricants have a much greater potential than solid superlubricants to meet the real-world requirements of a wide range of applications and are compatible with most existing lubrication systems.…”

Section: Introductionmentioning

confidence: 99%

Competition-Induced Macroscopic Superlubricity of Ionic Liquid Analogues by Hydroxyl Ligands Revealed by in Situ Raman

Liang,

Xia,

Liu

et al. 2024

Langmuir

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High load-bearing capacity is one of the crucial indicators for liquid superlubricants to move toward practicality. However, some of the current emerging systems not only have low contact pressures but also are highly susceptible to further degradation due to water adsorption and even superlubricity failure. Herein, a novel choline chloride-based ionic liquid analogues (ILAs) of a superlubricant with triethanolamine (TEOA) as the H-bond donor is reported for the first time; it obtains an ultralow coefficient of friction (0.005) and high loadbearing capacity (360 MPa, more than 2 times that of similar systems) due to adsorption of a small amount of water (<5 wt %) from the air. In situ Raman combined with 1 H NMR and FTIR techniques reveals that adsorbed water competes with the hydroxyl group of TEOA for coordination with Cl − , leading to the conversion of some strong H-bonds to weak H-bonds in ILAs; the localized strong H-bonds and weak H-bonds endow the ILAs with high load-bearing capacity and the formation of ultralow shearresistance sliding interfaces, respectively, under the shear motion. This study proposes a strategy to modulate the interactions between liquid species using adsorbed water from air as a competing ligand, which provides new insights into the design of ILAbased macroscopic liquid superlubricants with a high load-bearing capacity.

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Superlubricity with Graphitization in Ti-Doped DLC/Steel Tribopair: Response on Humidity and Temperature

Cited by 14 publications

References 131 publications

Interface Amorphization Controls Maximum Wear Resistance of Multinanolayer DLC/WC Coatings

Interface Amorphization Controls Maximum Wear Resistance of Multinanolayer DLC/WC Coatings

Superlubricity of Materials: Progress, Potential, and Challenges

Competition-Induced Macroscopic Superlubricity of Ionic Liquid Analogues by Hydroxyl Ligands Revealed by in Situ Raman

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