Reduction in EHL Friction by a DLC Coating

Bobach, Lars; Bartel, Dirk; Beilicke, Ronny; Mayer, Josef; Michaelis, Klaus; Stahl, Karsten; Bachmann, Svenja; Schnagl, J.; Ziegele, H.

doi:10.1007/s11249-015-0594-2

Cited by 28 publications

(34 citation statements)

References 20 publications

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“…A comparable effect of DLC coatings on friction reduction was demonstrated for ZrC g on hydrodynamic plain bearings for automobile crankshaft train using a motor‐driven engine test bench . Similar findings were obtained in EHL contacts using different hydrogenated (a‐C:H) and non‐hydrogenated DLC (ta‐C) coatings by both, experiments and simulations by Björling et al, Habchi, and Bobach et al…”

Section: Introductionsupporting

confidence: 73%

“…A comparable effect of DLC coatings on friction reduction was demonstrated for ZrC g on hydrodynamic plain bearings for automobile crankshaft train using a motor-driven engine test bench. 2 Similar findings were obtained in EHL contacts using different hydrogenated (a-C:H) and non-hydrogenated DLC (ta-C) coatings by both, experiments and simulations by Björling et al, [13][14][15] Habchi, [16][17][18] and Bobach et al 19,20 In current scientific discussion, different approaches are discussed to analyse the decisive effects of coatings on fluid friction in EHL contacts. One approach focuses on the poorer wetting behavior of DLC coatings compared with steel surfaces which leads to a "slipping effect" and thus to reduced friction due to reduced shear stress.…”

Section: Introductionsupporting

confidence: 57%

“…Hence, the fluid temperature in the EHL contact rises, which in turn results in a decrease of the effective lubricant viscosity η and hence shear stress and fluid friction . Besides experimental results of tribological tests indicating this theory, also simulations by Habchi and Bobach et al show similar results.…”

Section: Introductionmentioning

confidence: 61%

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A contribution to the thermal effects of DLC coatings on fluid friction in EHL contacts

Bobzin

Brögelmann

Kalscheuer

et al. 2018

Lubrication Science

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Diamond‐like carbon (DLC) coatings are commonly used to reduce boundary and mixed friction in tribological contacts. Recent works at the FZG efficiency gear test rig show that the application of the DLC coating ZrCg (a‐C:H:Zr) on gear flanks reduces the mean coefficient of friction in fluid film lubrication regime by up to 39% compared with uncoated gear flanks. A common explanation is the lower heat dissipation of DLC coatings resulting in higher EHL contact temperatures, hence in lower effective lubricant viscosity in the EHL contact. To gain a deeper understanding, discrete ZrxC1−x coatings were deposited on AISI 5115 using physical vapour deposition technology and thermophysical properties were directly measured. The tribological behavior of the coatings was investigated at the FZG twin‐disc test rig by using mineral gear oil. The results clearly prove the strong influence of the thermophysical properties of the DLC coatings on fluid friction in highly loaded EHL contacts.

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Section: Introductionsupporting

confidence: 73%

Section: Introductionsupporting

confidence: 57%

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A contribution to the thermal effects of DLC coatings on fluid friction in EHL contacts

Bobzin

Brögelmann

Kalscheuer

et al. 2018

Lubrication Science

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“…As the Carreau-Yasuda model does not limit the shear stress, it has been truncated numerically based on a linear pressure dependency of the limiting shear stress. Based on the Eyring model, Bobach et al [11] obtain very strong correlation between TEHL simulation results and measured friction curves from the FZG twin disk test rig. Based on the same TEHL simulation model and a combined Eyring and simplified Bair/Winer model, Beilicke et al [10] again achieve very strong correlation between simulated and measured friction curves.…”

Section: Introductionmentioning

confidence: 99%

Limiting Shear Stress Formulation for Tehl Simulation

Lohner¹,

Michaelis²,

Stahl³

2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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“…The first one originates from the lower surface energy of the DLC coatings, and with this the associated poorer wetting that induces solid‐liquid slip and thus reduces the viscous friction . The other involves the lower thermal conductivity of DLC coatings compared to a steel surface that induces a temperature rise in the contact and thus a viscosity decrease, which in turn reduces the viscous friction …”

Section: Introductionmentioning

confidence: 99%

High‐speed optical imaging of liquid film flow and liquid macro‐slip over free surfaces with different surface energies

Bizjan

Širok

Kalin

2017

Lubrication Science

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High‐speed optical imaging is introduced as a visualization method to investigate the film‐flow properties of liquids with different surface tensions and viscosities (water, poly‐alpha‐olefin oil, and glycerol) over free rotating surfaces with different surface energies and polarities (steel, and two different diamond‐like‐carbon ‐ DLC coatings, i.e. DLC, and F‐DLC). It was found that the polar surface energy strongly influences the structural dynamics of the liquid film's flow and the film's slip. Namely, a decrease in the polar surface energy results in a less stable film with de‐wetting areas and breakups into streams, as well as in a larger amount of film slip, which was most clearly expressed by the F‐DLC. It was also found that the combination of a high surface tension and a low viscosity provides the largest amount of liquid slip, with the most obvious breakup of the liquid film being observed with water, which clearly exhibits these properties.

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Reduction in EHL Friction by a DLC Coating

Cited by 28 publications

References 20 publications

A contribution to the thermal effects of DLC coatings on fluid friction in EHL contacts

A contribution to the thermal effects of DLC coatings on fluid friction in EHL contacts

Limiting Shear Stress Formulation for Tehl Simulation

High‐speed optical imaging of liquid film flow and liquid macro‐slip over free surfaces with different surface energies

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