Influence of wetting and thermophysical properties of diamond-like carbon coatings on the frictional behavior in automobile gearboxes under elasto-hydrodynamic lubrication

Bobzin, Kirsten; Brögelmann, Tobias; Stahl, Karsten; Stemplinger, J.-P.; Mayer, Josef; Hinterstoißer, Michael

doi:10.1016/j.surfcoat.2015.06.087

Cited by 38 publications

(34 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…DLC coatings possess a very low thermal conductivity of λ DLC = 1–5 W/m K which can lead to a significant thermal insulating effect in highly loaded EHL contacts. 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%

“…In order to reduce frictional losses, chromium‐based nitride hard coatings and diamond‐like carbon (DLC) coatings are deposited on tappets, crankshaft bearings, piston rings, valve lifters, gear wheels, etc. . Regarding passenger car fuel energy consumption, the corresponding losses can be divided into thermal energy losses due to exhaust (33%), cooling (29%) and the mechanical power that has to be split up into air drag (5%) and frictional losses (33%) .…”

Section: Introductionmentioning

confidence: 99%

“…The surface properties of the gear flanks influence the solid and fluid friction in elastohydrodynamic lubrication (EHL) contacts. The properties of DLC coatings differ by process variations of plasma enhanced chemical vapour deposition and physical vapour deposition . DLC coatings offer a great potential to reduce frictional losses and wear of components leading to extended lifetimes of automotive components .…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, numerous studies analysed the tribological behavior of coatings in boundary and mixed friction and increased the understanding of its friction and wear mechanisms . A DLC coating that offers great potential for friction reduction is graded zirconium carbide coating ZrC g that was tested in several automobile applications like crankshaft bearings, gears, and bucket tappets showing reduced frictional losses in comparison to uncoated steel samples . Various experiments have been carried out in boundary, mixed, and fluid film lubrication.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

Bobzin

Brögelmann

Kalscheuer

et al. 2018

Lubrication Science

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Bobzin

Brögelmann

Kalscheuer

et al. 2018

Lubrication Science

Self Cite

View full text Add to dashboard Cite

show abstract

“…In order to get higher power densities and fatigue lives of gears, advanced technologies, such as case hardening [2] and shot peening [3], have been developed to augment the service lives or reduce the friction and wear. Among these technologies, coating is an effective method that has been widely used in many industrial fields [4,5].…”

Section: Introductionmentioning

confidence: 99%

Tribological behavior of coated spur gear pairs with tooth surface roughness

Liu

Zhu

et al. 2018

Friction

View full text Add to dashboard Cite

Abstract:Coating is an effective way to reduce friction and wear and to improve the contact-fatigue lives of gear components, which further guarantees a longer service life and better reliability of industrial machinery. The fact that the influence coefficient linking the tractions and stress components could not be expressed explicitly increases the difficulty of coated solids contact analysis. The complicated tribological behavior between tooth surfaces influenced by lubrication and surface roughness further adds difficulty to the coated gear pair contact problems. A numerical elastohydrodynamic lubricated (EHL) contact model of a coated gear pair is proposed by considering the coupled effects of gear kinematics, coating properties, lubrication, and surface roughness. The frequency response function and the discrete convolute, fast Fourier transformation (DC-FFT) method are combined to calculate the surface deformation and the subsurface stress fields at each meshing position along the line of action (LOA). The Ree-Eyring fluid is assumed to incorporate the non-Newtonian effect, which is represented in the generalized Reynolds equation. Influences of the ratio between the Young's modulus of the coating and the substrate on the contact performance, such as pressure, film thickness, tooth friction coefficient, and subsurface stress field, are studied. The effect of the root mean square (RMS) value of the tooth surface roughness is studied by introducing the roughness data, deterministically measured by an optical profiler.

show abstract

Formation mechanisms of zinc, molybdenum, sulfur and phosphorus containing reaction layers on a diamond‐like carbon (DLC) coating

Bobzin

Brögelmann

Kalscheuer

et al. 2020

Materialwissenschaft Werkst

View full text Add to dashboard Cite

Diamond‐like carbon (DLC) coatings are nowadays successfully applied on industrial components like pistons, piston rings and bearings in lubricated tribological contacts due to friction and wear reducing effects. In contradiction thereto, todays lubricants and additives are designed for tribological steel/steel contacts, whereby the knowledge on tribochemical layer formation on steel surfaces is comprehensive in contrast to the physical‐chemical interactions between diamond‐like carbon coatings, lubricants and additives. Therefore the formation mechanisms of zinc, molybdenum, sulfur and phosphorus containing reaction layers on a zirconium modified diamond‐like carbon coating a‐C : H : Zr (ZrCg) in lubricated tribological contacts were analyzed by means of pin‐on‐disc (PoD) tribometer by varying the distances from s = 200 m–3,000 m under boundary and mixed friction conditions at T = 90 °C and a contact pressure p = 1,300 MPa regarding the application of diamond‐like carbon coatings on gears. The base lubricant poly‐alpha‐olefin (PAO) was formulated using the anti‐wear (AW) and extreme pressure (EP) additive zinc dialkyldithiophosphate (ZnDTP) and the friction modifier (FM) additive molybdenum dialkyldithiophosphate (MoDTP). The chemical composition of the tribochemical reaction layers by means of and Raman spectroscopy and x‐ray photoelectron spectroscopy (XPS) as well as for the thickness differ significantly by varying the additivation.

show abstract

Influence of wetting and thermophysical properties of diamond-like carbon coatings on the frictional behavior in automobile gearboxes under elasto-hydrodynamic lubrication

Cited by 38 publications

References 59 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

Tribological behavior of coated spur gear pairs with tooth surface roughness

Formation mechanisms of zinc, molybdenum, sulfur and phosphorus containing reaction layers on a diamond‐like carbon (DLC) coating

Contact Info

Product

Resources

About