Exploring low friction of lubricated DLC coatings in no-wear conditions with a new relaxation tribometer

Majdoub, Fida; Belin, M.; Martin, Jean Michel; Perret-Liaudet, Joël; Kano, Makoto; Yoshida, Kentaro

doi:10.1016/j.triboint.2013.03.013

Cited by 11 publications

(7 citation statements)

References 12 publications

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“…The terms ω 0 γ h sin ϕ and ω 0 γ h cos ϕ (Appendix) must respectively be added to the right-hand sides of Eqs. (4) and (9). If the force modifies the envelope, the matrix L of Eq.…”

Section: Identification Of Force Strengthmentioning

confidence: 99%

See 1 more Smart Citation

Relaxation Tribometry: A Generic Method to Identify the Nature of Contact Forces

et al. 2019

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Recent years have witnessed the development of so-called relaxation tribometers, the free oscillation of which is altered by the presence of frictional stresses within the contact. So far, analysis of such oscillations has been restricted to the shape of their decaying envelope, to identify in particular solid or viscous friction components. Here, we present a more general expression of the forces possibly acting within the contact, and retain six possible, physically relevant terms. Two of them, which had never been proposed in the context of relaxation tribometry, only affect the oscillation frequency, not the amplitude of the signal. We demonstrate that each of those six terms has a unique signature in the time-evolution of the oscillation, which allows efficient identification of their respective weights in any experimental signal. We illustrate our methodology on a PDMS sphere/glass plate torsional contact.

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“…The terms ω 0 γ h sin ϕ and ω 0 γ h cos ϕ (Appendix) must respectively be added to the right-hand sides of Eqs. (4) and (9). If the force modifies the envelope, the matrix L of Eq.…”

Section: Identification Of Force Strengthmentioning

confidence: 99%

“…Recently, renewed interest for relaxation tribometry has emerged as a unique tool to measure low forces efficiently and accurately [9,10,11]. The reason is that the smaller the friction force, the smaller the decrement, the more measurable oscillations before rest and thus the more data available to estimate the force.…”

Section: Introductionmentioning

confidence: 99%

Relaxation Tribometry: A Generic Method to Identify the Nature of Contact Forces

et al. 2019

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“…In previous studies [14,15], the authors have reported how the relaxation tribometer technique was able to discriminate different contributions to friction: velocity-dependent and velocity-independent. Another result shows that the friction evolution depends on the velocity amplitude of the free oscillating response.…”

Section: Identification Of the Friction Lawmentioning

confidence: 99%

Friction Laws Determination of Random-Textured Surface of Microcrystalline Diamond Coatings, Using the Oscillating Tribometer Technique

2019

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Achieving low-friction and robust tribosystems is an open and challenging question to tribologists. In this study, we are considering the diamond films as candidates. Quantification of friction is obtained here using an original technique, so called the oscillating relaxation tribometry. It is based on the study of the oscillating motion of a free-damped 1-DOF mechanical oscillator, the sliding contact acting as a main source of mechanical dissipation ("relaxation"). Therefore, it is possible to determine friction value and its sliding speed dependency, i.e. a kind of "Stribeck curve" under non-stationary conditions. The interest of such "relaxation tribometer" is to characterize low friction with an unequalled sensitivity, and to directly obtain the "friction law" thanks to a robust and rapid experimental test. Polycrystalline diamond films are deposited by the Hot Filament CVD method on SiC substrate, which were partly polished and finished to gradient surface roughness with random-textured asperities. Stainless steel balls of 6.0 mm diameter are used as the rubbing counterface. The normal force is varied between 50 and 300 mN, leading respectively to a maximum Hertzian contact pressure of 0.30 and 0.71 GPa, respectively. Taking into account the experimental setup, the sliding speed is decaying as a damped pseudo-sine motion, the maximum sliding value being set to 0.16 m/s, progressively decaying to 0 when mechanical equilibrium is reached, within a typical duration of 5 s. First results are reported here, using this innovative friction characterization technique. The different contributions to friction of the surface roughness are analyzed and discussed. These results show the major interest of the use of this method to characterize the low-friction behavior of textured diamond films. These results are discussed and the high potential of such textured films in actual tribosystems is presented here.

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“…In previous studies [19,20], the authors had reported that the relaxation tribometer technique was able to discriminate between the different contributions to friction being, namely, velocity-dependent…”

Section: Identification Of the Friction Lawsmentioning

confidence: 99%

Low Friction, Lubricity, and Durability of Polymer Brush Coatings, Characterized Using the Relaxation Tribometer Technique †

et al. 2018

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Among the possible solutions for achieving low friction, polymer brushes that are grafted onto surfaces are good candidates. The tribological characterization of such layers becomes more difficult when the friction is lower: the signal-to-noise ratio of the friction force that is measured with conventional tribometers impedes the precise quantification. Therefore, we have applied a new technique that has been developed at the Laboratory of Tribology and System Dynamics (LTDS), called the 'oscillating relaxation tribometer'. The advantage of this original technique is that it characterizes low friction with unequalled sensitivity. The lower the friction, the better the precision, and it permits obtaining the 'friction law' directly from robust and rapid experimental tests. In this study, the samples that have been used are the ionic liquid-type polymer brushes (ILPBs) with different thicknesses, which have been grafted onto silicon wafers and steel coupons. The counter-face is a mirror-polished steel ball. We show that (i) a thick ILPB layer on silicon is very resistant to high contact pressure, up to 555 MPa; (ii) the friction behavior that is obtained is close to that of a Newtonian viscous one, even under maximum normal loads; (iii) poorer results are obtained for the thinner sample; and (iv) the repetition, up to 5000 oscillations on the same surface, does not affect the friction damping of the contact, which demonstrates that this film provides a favorable resistance to friction under severe contact conditions. In addition, the feasibility of grafting onto steel surfaces is demonstrated. The results are then discussed, with respect to friction and dissipation.

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Exploring low friction of lubricated DLC coatings in no-wear conditions with a new relaxation tribometer

Cited by 11 publications

References 12 publications

Relaxation Tribometry: A Generic Method to Identify the Nature of Contact Forces

Relaxation Tribometry: A Generic Method to Identify the Nature of Contact Forces

Friction Laws Determination of Random-Textured Surface of Microcrystalline Diamond Coatings, Using the Oscillating Tribometer Technique

Low Friction, Lubricity, and Durability of Polymer Brush Coatings, Characterized Using the Relaxation Tribometer Technique †

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