scholarly journals Polyethylene glycol derived carbon quantum dots nanofluids: An excellent lubricant for diamond-like carbon film/bearing steel contact

Friction ◽  
2021 ◽  
Author(s):  
Fu Wang ◽  
Lunlin Shang ◽  
Guangan Zhang ◽  
Zhaofeng Wang
Keyword(s):  
Quantum Dots ◽  
Polyethylene Glycol ◽  
Friction Coefficient ◽  
Carbon Film ◽  
Carbon Quantum Dots ◽  
Bearing Steel ◽  
Carbon Films ◽  
Diamond Like Carbon ◽  
Low Friction ◽  
Diamond Like Carbon Film

AbstractPolyethylene glycol derived carbon quantum dots nanofluids were synthesized via a slow thermal oxidation process. The size of carbon quantum dots was ca. 2 nm and had a decreasing trend with the increase of oxidation time. When used as lubricant in a diamond-like carbon film/bearing steel interface, the nanofluids achieved an ultra-low friction coefficient (μ ≈ 0.02), much lower than that of original polyethylene glycol (μ = 0.12). The worn surface analyses revealed that the nanofluids could effectively inhibit the tribo-oxidation of steel counterpart that occurred under original polyethylene glycol lubrication, and hence reduced the abrasion component of friction. Especially, the poly-hydroxyl carbon dots and oxidized polyethylene glycol species in nanofluids induced a hydroxyl-rich sliding interface via their tribochemical reactions with friction surfaces, which promoted the adsorption of polyethylene glycol molecules on sliding surfaces. Along with the mild corrosion wear of steel counterface, this shifted the boundary lubrication to a mixed/film lubrication regime, thereby achieving an ultra-low friction coefficient. The above results suggest that the polyethylene glycol derived carbon quantum dots nanofluids should be a quite excellent candidate lubricant for solid-liquid synergy lubrication based on diamond-like carbon films.

scholarly journals Robust low friction performance of graphene sheets embedded carbon films coated orthodontic stainless steel archwires

Friction ◽  
2021 ◽  
Author(s):  
Zonglin Pan ◽  
Qinzhao Zhou ◽  
Pengfei Wang ◽  
Dongfeng Diao
Keyword(s):  
Stainless Steel ◽  
Friction Coefficient ◽  
Orthodontic Treatment ◽  
Artificial Saliva ◽  
Carbon Film ◽  
Carbon Films ◽  
Graphene Sheets ◽  
Substrate Bias ◽  
Low Friction ◽  
Substrate Bias Voltage

AbstractReducing the friction force between the commercial archwire and bracket during the orthodontic treatment in general dental practice has attracted worldwide interest. An investigation on the friction and wear behaviors of the uncoated and carbon film coated stainless steel archwires running against stainless steel brackets was systematically conducted. The carbon films were prepared at substrate bias voltages from +5 to +50 V using an electron cyclotron resonance plasma sputtering system. With increasing substrate bias voltage, local microstructures of the carbon films evolved from amorphous carbon to graphene nanocrystallites. Both static and stable friction coefficients of the archwire-bracket contacts sliding in dry and wet (artificial saliva) conditions decreased with the deposition of carbon films on the archwires. Low friction coefficient of 0.12 was achieved in artificial saliva environment for the graphene sheets embedded carbon (GSEC) film coated archwire. Deterioration of the friction behavior of the GSEC film coated archwire occurred after immersion of the archwire in artificial saliva solution for different periods before friction test. However, moderate friction coefficient of less than 0.30 sustained after 30 days immersion periods. The low friction mechanism is clarified to be the formation of salivary adsorbed layer and graphene sheets containing tribofilm on the contact interfaces. The robust low friction and low wear performances of the GSEC film coated archwires make them good candidates for clinical orthodontic treatment applications.

scholarly journals Multiscale frictional behaviors of sp2 nanocrystallited carbon films with different ion irradiation densities

Friction ◽  
2020 ◽  
Author(s):  
Zelong Hu ◽  
Xue Fan ◽  
Cheng Chen
Keyword(s):  
Friction Coefficient ◽  
Contact Pressure ◽  
Electron Cyclotron Resonance ◽  
Ion Irradiation ◽  
Carbon Film ◽  
High Hardness ◽  
Carbon Films ◽  
Real Contact Area ◽  
Low Friction ◽  
Plasma Sputtering

Abstract sp2 nanocrystallited carbon films with large nanocrystallite sizes, smooth surfaces, and relative high hardness were prepared with different ion irradiation densities regulated with the substrate magnetic coil current in an electron cyclotron resonance plasma sputtering system. Their multiscale frictional behaviors were investigated with macro pin-on-disk tribo-tests and micro nanoscratch tests. The results revealed that, at an ion irradiation density of 16 mA/cm2, sp2 nanocrystallited carbon film exhibits the lowest friction coefficient and good wear resistant properties at both the macroscale and microscale. The film sliding against a Si3N4 ball under a contact pressure of 0.57 GPa exhibited a low friction coefficient of 0.09 and a long wear life at the macroscale. Furthermore, the film sliding against a diamond tip under a contact pressure of 4.9 GPa exhibited a stable low friction coefficient of 0.08 with a shallow scratch depth at the microscale. It is suggested that sp2 nanocrystallites affect the frictional behaviors in the cases described differently. At the macroscale, the contact interface via the small real contact area and the sp2 nanocrystallited transfer layer dominated the frictional behavior, while the sp2 nanocrystallited structure in the film with low shear strength and high plastic resistivity, as well as the smooth surface morphology, decided the steady low nanoscratch properties at the microscale. These findings expand multiscale tribological applications of sp2 nanocrystallited carbon films.

OPTICAL PROPERTIES OF THE RAPID ANNEALED OXYGEN-DOPED DIAMOND-LIKE CARBON FILM

2019 ◽  
Vol 26 (01) ◽  
pp. 1850129 ◽  
Author(s):  
YI-MIN LU ◽  
GUO-JUN HUANG ◽  
YAN-LONG GUO ◽  
SHU-YUN WANG
Keyword(s):  
Infrared Spectra ◽  
Carbon Film ◽  
Carbon Films ◽  
Laser Deposition ◽  
Diamond Like Carbon ◽  
Infrared Band ◽  
Rapid Annealing ◽  
Diamond Like Carbon Film ◽  
Average Transmission ◽  
The Right

The amorphous oxygen-doped diamond-like carbon films were prepared by pulsed laser deposition. Compared with the pure diamond-like carbon film, there were much less graphite clusters on the surfaces of the oxygen-doped diamond-like carbon films, and the average transmission of the oxygen-doped diamond-like carbon films in the medium infrared band increased. However, some new absorption peaks in the infrared spectra of the oxygen-doped diamond-like carbon film were generated. Rapid annealing was experimented to remove the absorption peaks. XPS analysis showed that the fractions of the C–O and C=O bonds that generated the new absorption peaks were reduced more than the fractions of [Formula: see text] bonds by rapid annealing at 400[Formula: see text]C, and the absorption peaks in the medium infrared spectra decreased. It indicated that rapid annealing at right temperature during the right time could reduce greatly the absorption in the medium infrared band of oxygen-doped diamond-like carbon films.

Field emission from diamond-like carbon films and fabrication of gated diamond-like carbon film emitter

1998 ◽  
Vol 73 (1-4) ◽  
pp. 17-22 ◽  
Author(s):  
Sunup Lee ◽  
Bokeon Chung ◽  
Tae-Young Ko ◽  
D Jeon ◽  
Kwang-Ryeol Lee ◽  
...  
Keyword(s):  
Field Emission ◽  
Carbon Film ◽  
Carbon Films ◽  
Diamond Like Carbon ◽  
Diamond Like Carbon Film

Sliding velocity dependency of the friction coefficient of Si-containing diamond-like carbon film under oil lubricated condition

2011 ◽  
Vol 44 (11) ◽  
pp. 1296-1303 ◽  
Author(s):  
Takeshi Yamaguchi ◽  
Junji Ando ◽  
Takuya Tsuda ◽  
Naoko Takahashi ◽  
Mamoru Tohyama ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Carbon Film ◽  
Diamond Like Carbon ◽  
Sliding Velocity ◽  
Diamond Like Carbon Film

scholarly journals Key Role of Transfer Layer in Load Dependence of Friction on Hydrogenated Diamond-Like Carbon Films in Humid Air and Vacuum

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1550 ◽  
Author(s):  
Yunhai Liu ◽  
Lei Chen ◽  
Bin Zhang ◽  
Zhongyue Cao ◽  
Pengfei Shi ◽  
...  
Keyword(s):  
Applied Load ◽  
Carbon Films ◽  
Diamond Like Carbon ◽  
Low Friction ◽  
Transfer Layer ◽  
Humid Air ◽  
Friction Mechanism ◽  
Sharp Drop ◽  
Practical Applications ◽  
Load Dependence

The friction of hydrogenated diamond-like carbon (H-DLC) films was evaluated under the controlled environments of humid air and vacuum by varying the applied load. In humid air, there is a threshold applied load below which no obvious friction drop occurs and above which the friction decreases to a relatively low level following the running-in process. By contrast, superlubricity can be realized at low applied loads but easily fails at high applied loads under vacuum conditions. Further analysis indicates that the graphitization of the sliding H-DLC surface has a negligible contribution to the sharp drop of friction during the running-in process under both humid air and vacuum conditions. The low friction in humid air and the superlow friction in vacuum are mainly attributed to the formation and stability of the transfer layer on the counterface, which depend on the load and surrounding environment. These results can help us understand the low-friction mechanism of H-DLC film and define optimized working conditions in practical applications, in which the transfer layer can be maintained for a long time under low applied load conditions in vacuum, whereas a high load can benefit the formation of the transfer layer in humid air.

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