Lubricated PVD CrAlN and WC/C coatings for automotive applications

Bobzin, Kirsten; Bagcivan, Nazlim; Goebbels, N.; Yılmaz, Koray K.; Hoehn, Bernd-Robert; Michaelis, Klaus; Hochmann, Michael

doi:10.1016/j.surfcoat.2009.07.045

Cited by 57 publications

(38 citation statements)

References 17 publications

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“…The stringent emission legislation has pushed forward research and has accelerated the introduction of hard coatings such as DLC and nitride coatings [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

“…Application of DLC coatings in the automotive industry is seen as an alternative approach towards reducing the dependence on some high SAPS (Sulphated Ash, Phosphorus and Sulphur) additives [1,6]. This is due to their relative chemical inertness compared with ferrous surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, commercial lubricants comprise different additives and also depend on selected interfaces. Understanding of coating and additive interactions requires more fundamental research to understand how optimization of the entire system can be achieved [1,[6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…However, reported literature showed no superior performance over other metal-doped or non-doped DLCs [1,6,7,[9][10][11]. There are a number of possible reasons, i.e., different coating composition, hydrogenation, tribological and processing conditions, and the various additive packages used [1,7,11]. Most of the literature is on large scale experimental evaluations.…”

Section: Introductionmentioning

confidence: 99%

“…[1,2,[6][7][8][9][10][12][13][14]. Most of them suggest that the mechanisms are either by interactions with the carbon coating surfaces (GMO for example) [9,10,15], or chemical decomposition (MoDTC and ZDDP for example) [2,14], or formation of tribological films that claimed to have some superior structure or properties [7,13].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Effect of Lubricant Additives on the WDLC Coating Structure When Tested in Boundary Lubrication Regime

Yang

Neville

Brown³

et al. 2015

Tribol Lett

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“…The stringent emission legislation has pushed forward research and has accelerated the introduction of hard coatings such as DLC and nitride coatings [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of Lubricant Additives on the WDLC Coating Structure When Tested in Boundary Lubrication Regime

Yang

Neville

Brown³

et al. 2015

Tribol Lett

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Friction performance of MoDTP and ester‐containing lubricants between CKS piston ring and cast iron cylinder liner

Wang

Yang

et al. 2017

Lubrication Science

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The friction performance of MoDTP in the existence of ester was investigated. Tribological experiments were performed on reciprocating test rig between CKS piston ring and cast iron cylinder liner. Experimental results show that ester concentration is a key factor that influences the performance of MoDTP, the competitive effects between MoDTP and ester also vary with test temperature and load, and the "V" shape friction coefficient curve is caused by the change in friction surface states. During friction, when the surface roughness decreased and liner surface is covered by the friction layer, fresh metal is less likely to expose to lube oil, which reduces the activity of MoDTP in the existence of high concentration ester. | INTRODUCTIONEngine lube oil has been designed as a complex mixture, which is mainly composed of base oil and various functional additives. Among different additives, friction modifier (FM) is important for engine lube oil. FM is the component that reduces the friction coefficient on the friction surface. A better friction reduction performance will improve the energy efficiency and emission reduction performance.Basically, there are four main classes of FM additives applied to liquid lubricants, which are organic FMs, organic-molybdenum compounds, functionalized polymers, and dispersed nanoparticles.1 Among these additives, organic FMs (OFM) and organic-molybdenum compounds are most widely used in modern engine lube oil. Synthetic ester is typical OFM, which contain polar group and form adsorption film on friction surface. Different from OFM, organic-molybdenum compounds will form tribo-chemical film on the metal surface, reduce friction coefficient, and increase fuel economy. MoDTC/MoDTP have been used as FM for a long time.12,13 Significant friction reduction performance was shown in engine performance. Mistsuaki et al developed engine oil with excellent fuel economy performance. The low friction formulation contains molybdenum compound and phosphorus extreme-pressure agent. The fuel economy can improve up to 7% compared with commercial oil. 14 Grossiord et al studied the friction reduction mechanism of MoDTP; it is found that the MoDTP tribofilm is mainly composed of an amorphous phosphate glass containing flexible and highly dispersed MoS 2 single sheets. 15Martin et al investigated the friction reduction film formed by MoDTP in ultra high vacuum tribometer (UHV). 16Results indicate that molybdenum disulphide (MoS 2 ) contributes to the friction reduction performance, and the metal phosphate glass is responsible for the anti-wear action. The tribochemical reaction of MoDTP can be separated into 2 steps. Firstly, the phosphate reacted with iron oxide. Secondly, the nascent iron surface reacted with sulfide species, which decrease the friction coefficient. 17,18When MoDTP mixed with other additives, most studies focus on the performances in the presence of MoDTC, zinc dithiophosphate (ZnDTP an interesting phenomenon is found that the friction coefficient drops down first and is fol...

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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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Lubricated PVD CrAlN and WC/C coatings for automotive applications

Cited by 57 publications

References 17 publications

Effect of Lubricant Additives on the WDLC Coating Structure When Tested in Boundary Lubrication Regime

Effect of Lubricant Additives on the WDLC Coating Structure When Tested in Boundary Lubrication Regime

Friction performance of MoDTP and ester‐containing lubricants between CKS piston ring and cast iron cylinder liner

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

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