Low Friction Achieved Using Repulsive Van Der Waals Forces: A Nanotribology Study With Colloid Probe AFM

2005 ◽  
Author(s):  
A. A. Feiler ◽  
L. Bergstro¨m ◽  
M. W. Rutland
Keyword(s):  
Friction Coefficient ◽  
Bearing Capacity ◽  
Atomic Force Microscope ◽  
Contact Surface ◽  
Van Der Waals ◽  
Surface Force ◽  
Low Friction ◽  
Load Bearing Capacity ◽  
Atomic Force ◽  
Almost All

We show that extremely low friction can be achieved with the use of a divergent, pre-contact “surface force” — the repulsive, so called van der Waals force. In almost all cases this force is attractive, but for certain combinations of materials it manifests repulsively and at short separations (of the order of molecular distances) the load bearing capacity provided by the force is large. We have used the Atomic Force Microscope (AFM) in colloid probe mode to measure the friction between sub-microscopic contacts in the presence of such a force and have achieved a friction coefficient of the order of 0.0002.

scholarly journals Constructing a biomimetic robust bi-layered hydrophilic lubrication coating on surface of silicone elastomer

Friction ◽  
2021 ◽  
Author(s):  
Luyao Gao ◽  
Xiaoduo Zhao ◽  
Shuanhong Ma ◽  
Zhengfeng Ma ◽  
Meirong Cai ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Composite Layer ◽  
High Load ◽  
Silicone Elastomer ◽  
Aqueous Lubrication ◽  
Low Friction ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Lubrication Performance ◽  
Wide Range

AbstractSilicone elastomers-based materials have been extensively involved in the field of biomedical devices, while their use is extremely restricted due to the poor surface lubricity and inherent hydrophobicity. This paper describes a novel strategy for generating a robust layered soft matter lubrication coating on the surface of the polydimethylsiloxane (PDMS) silicone elastomer, by entangling thick polyzwitterionic polyelectrolyte brush of poly (sulfobetaine methacrylate) (PSBMA) into the sub-surface of the initiator-embedded stiff hydrogel coating layer of P(AAm-co-AA-co-HEMA-Br)/Fe, to achieve a unified low friction and high load-bearing properties. Meanwhile, the stiff hydrogel layer with controllable thickness is covalently anchored on the surface of PDMS by adding iron powder to provide catalytic sites through surface catalytically initiated radical polymerization (SCIRP) method and provides high load-bearing capacity, while the topmost brush/hydrogel composite layer is highly effective for aqueous lubrication. Their synergy effects are capable of attaining low friction coefficient (COFs) under wide range of loaded condition in water environment with steel ball as sliding pair. Furthermore, the influence of mechanical modulus of the stiff hydrogel layer on the lubrication performance of layered coating is investigated, for which the COF is the lowest only when the modulus of the stiff hydrogel layer well matches the PDMS substrate. Surprisingly, the COF of the modified PDMS could remain low friction (COF < 0.05) stably after encountering 50,000 sliding cycles under 10 N load. Finally, the surface wear characterizations prove the robustness of the layered lubricating coating. This work provides a new route for engineering lubricious silicon elastomer with low friction, high load-bearing capacity, and considerable durability.

Heat Transfer Spectroscopy and “Heat Transfer-Distance” Curves

2008 ◽  
Author(s):  
Arvind Narayanaswamy ◽  
Sheng Shen ◽  
Gang Chen
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Atomic Force Microscope ◽  
Near Field ◽  
Surface Force ◽  
Casimir Forces ◽  
Distance Curve ◽  
Transfer Distance ◽  
Atomic Force ◽  
Order Of Magnitude

Thermal radiative transfer between objects as well as near-field forces such as van der Waals or Casimir forces have their origins in the fluctuations of the electrodynamic field. Near-field radiative transfer between two objects can be enhanced by a few order of magnitude compared to the far-field radiative transfer that can be described by Planck’s theory of blackbody radiation and Kirchoff’s laws. Despite this common origin, experimental techniques of measuring near-field forces (using the surface force apparatus and the atomic force microscope) are more sophisticated than techniques of measuring near-field radiative transfer. In this work, we present an ultra-sensitive experimental technique of measuring near-field using a bi-material atomic force microscope cantilever as the thermal sensor. Just as measurements of near-field forces results in a “force distance curve”, measurement of near-field radiative transfer results in a “heat transfer-distance” curve. Results from the measurement of near-field radiative transfer will be presented.

Study on Surface Roughness Based on Dynamic Minimum Thickness of Cut

2011 ◽  
Vol 88-89 ◽  
pp. 34-37
Author(s):  
Kuai Ji Cai
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Atomic Force Microscope ◽  
Surface Quality ◽  
Experimental Verification ◽  
Cutting Parameters ◽  
Minimum Thickness ◽  
Atomic Force ◽  
Relationship Of ◽  
The Relationship

The relationship of the friction coefficient and the MTC were discussed, and the MTC and its effects on surface roughness were a theoretical analysised and experimental verification by AFM (atomic force microscope). The results show that the theoretical MTC tends to be minimal value then before the adhering effect to reach remarkable. Appropriate adjustments cutting parameters, the cutting process can always micro-cutting phase to reach the steady-thin chip, and no plowing phenomenon. So the surface residues highly were reduced and higher surface quality was achieved.

Tribological study of low friction DLC:Ti and MoS2 thin films

2018 ◽  
Vol 1 (89) ◽  
pp. 13-18
Author(s):  
A. Paradecka ◽  
K. Lukaszkowicz
Keyword(s):  
Thin Films ◽  
Friction Coefficient ◽  
New Technologies ◽  
Scratch Test ◽  
Substrate Material ◽  
High Wear Resistance ◽  
Research Information ◽  
Low Friction ◽  
Atomic Force ◽  
Intensive Development

Purpose: The purpose of this article is to characterize and compare the microstructure and tribological properties of low friction DLC:Ti and MoS2 thin films deposited on the austenitic steel X6CrNiMoTi17-12-2 substrate. Design/methodology/approach: In the research, the samples of the DLC:Ti and MoS2 thin films deposited by PACVD technology and magnetron sputtering method respectively were used. Observations of topography were made using atomic force microscope (AFM). Adhesion of the coating to the substrate material was verified by the scratch test. The friction coefficient and wear rate of the coating were determined in the ball-on-disc test. Findings: AFM as well as adhesion and friction coefficient tests confirmed low friction nature of MoS2 and DLC:Ti coatings. During the research information on the behaviour of coatings under tribological load was obtained. The investigated coating reveals high wear resistance and good adhesion to the substrate. Practical implications: The area of testing of low-friction thin films is widely studied due to their practical application. Intensive development of new technologies requires the introduction of corresponding layers of both full protective functions and reducing friction. Originality/value: Growing area of low-friction coatings with specific properties requires thorough tribological and topographical research, which is closely related to these properties.

scholarly journals Nanoscale Measurement of Surface Roughness and the existing Surface Forces of Aluminum by AFM

2011 ◽  
Vol 2 ◽  
pp. 76-79
Author(s):  
Purna B Pun ◽  
Shobha K Lamichhane
Keyword(s):  
Surface Roughness ◽  
Atomic Force Microscope ◽  
Thermal Oxidation ◽  
Surface Force ◽  
Surface Forces ◽  
Crystal Defects ◽  
Surface Contamination ◽  
Thermal Agitation ◽  
Atomic Force ◽  
Aluminum Sample

The surface contamination affects Atomic Force Microscope (AFM) performance. Thermal agitation during mapping doping, thermal oxidation, annealing impurities and crystal defects promotes the roughness; various kinds of forces on the surface can be detected by the interaction between tip of cantilever and sample. This interaction not only help us to understand the characteristics and morphology of the sample but also useful to measure the surface force of the aluminum sample too.Key words: Atomic Force Microscope (AFM) performance; Thermal oxidation; Annealing impurities; Crystal defectsThe Himalayan Physics Vol.2, No.2, May, 2011Page: 76-79Uploaded Date: 1 August, 2011

Tilt of Atomic Force Microscope Cantilevers: Effect on Friction Measurements

2007 ◽  
Vol 353-358 ◽  
pp. 742-745
Author(s):  
Fei Wang ◽  
Xue Zeng Zhao
Keyword(s):  
Friction Coefficient ◽  
Atomic Force Microscope ◽  
Tilt Angle ◽  
Silicon Surface ◽  
Theoretical Study ◽  
Atomic Force ◽  
Afm Tips ◽  
Variation Range ◽  
Frictional Forces ◽  
Friction Measurements

The cantilevers of atomic force microscope (AFM) are mounted under a certain tilt angle, which is commonly assumed to have negligible effect on friction measurements in AFM. We present a theoretical study of the effect of the tilt angle on AFM based friction measurements. A method for correcting the friction coefficient between sample surfaces and AFM tips is also presented to minimize the effects of the tilt. The frictional forces between a silicon tip and a silicon surface at tilt angles ranging from 5 degrees to 25 degrees were measured. The results show that the measured friction coefficient increases with the tilt angle effectively, whereas the variation range of the corrected friction coefficient is within 10%.

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