scholarly journals MoDTC Tribochemistry in Steel/Steel and Steel/Diamond-Like-Carbon Systems Lubricated With Model Lubricants and Fully Formulated Engine Oils

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Cayetano Espejo ◽  
Benoît Thiébaut ◽  
Frédéric Jarnias ◽  
Chun Wang ◽  
Anne Neville ◽  
...  
Keyword(s):  
Friction And Wear ◽  
Friction Reduction ◽  
Diamond Like Carbon ◽  
Additive Package ◽  
Friction Behavior ◽  
Engine Oils ◽  
Steel Surfaces ◽  
Friction Performance ◽  
Underlying Mechanisms ◽  
First Time

This work focuses on the tribochemistry of molybdenum dithiocarbamate (MoDTC) oil additive to improve friction behavior of diamond-like-carbon (DLC) coated systems lubricated in boundary regime. Raman microscopy has been used to investigate surface tribolayers formed on coated (hydrogenated a-C:H and non-hydrogenated ta-C) and steel surfaces when lubricated with model lubricants and commercial engine oils. The effect of the additive package and the type of DLC played a crucial role in the development and composition of the tribolayer and the friction performance. The additive package contained in the fully formulated (FF) oils limited the friction reduction capabilities of MoDTC additive for every material pair. Accelerated a-C:H coating wear related to MoDTC tribochemistry was found. For the first time, it has been shown that a distinctive MoS2-containing tribolayer can be formed on the ta-C surface, leading to a coefficient of friction lower than 0.04. The underlying mechanisms of MoDTC/surface interactions and their effect on friction and wear are discussed.

Effect of Texturing on the Friction Characteristic of Carbide and Steel Material by Grinding Process

2017 ◽  
Vol 887 ◽  
pp. 83-88
Author(s):  
Asma Perveen ◽  
Feng Liu
Keyword(s):  
Steel Surface ◽  
Friction Reduction ◽  
Grinding Wheel ◽  
Friction Behavior ◽  
Friction Characteristic ◽  
Frictional Properties ◽  
Steel Material ◽  
Steel Surfaces ◽  
Grooved Wheel

In this paper, friction behavior of textured carbide and steel surface has been studied in order to investigate the effect of different patterns. Several simple textures have been fabricated using straight groove grinding wheel. By microstructuring, various spacing and height of the structure, we investigate the role of topography in terms of friction characteristic. The change of friction behavior has been tailored by grinding operation using straight grooved wheel and evaluated in terms of friction. Friction values were measured by Tribometer. Frictional properties of textured carbide and steel surfaces were assessed with the help of parallel steel slider with 2000g normal force under dry condition using four different sliding speeds. It is found from the experiment that except 30° and 90° angle patterns, rest of the patterns on carbide surfaces show friction reduction which is roughly from 0.15 to 0.13. On the other hand, similar textured patterns can reduce the COF from 0.17 to 0.13 in case of steel surface.

scholarly journals Interplay of mechanics and chemistry governs wear of diamond-like carbon coatings interacting with ZDDP-additivated lubricants

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Valentin R. Salinas Ruiz ◽  
Takuya Kuwahara ◽  
Jules Galipaud ◽  
Karine Masenelli-Varlot ◽  
Mohamed Ben Hassine ◽  
...  
Keyword(s):  
Friction And Wear ◽  
Contact Stiffness ◽  
Diamond Like Carbon ◽  
Tribological Behaviour ◽  
Mechanical Mixing ◽  
Carbon Coatings ◽  
Engine Oils ◽  
Tetrahedral Amorphous Carbon ◽  
Wear Reduction ◽  
Low Wear

AbstractFriction and wear reduction by diamond-like carbon (DLC) in automotive applications can be affected by zinc-dialkyldithiophosphate (ZDDP), which is widely used in engine oils. Our experiments show that DLC’s tribological behaviour in ZDDP-additivated oils can be optimised by tailoring its stiffness, surface nano-topography and hydrogen content. An optimal combination of ultralow friction and negligible wear is achieved using hydrogen-free tetrahedral amorphous carbon (ta-C) with moderate hardness. Softer coatings exhibit similarly low wear and thin ZDDP-derived patchy tribofilms but higher friction. Conversely, harder ta-Cs undergo severe wear and sub-surface sulphur contamination. Contact-mechanics and quantum-chemical simulations reveal that shear combined with the high local contact pressure caused by the contact stiffness and average surface slope of hard ta-Cs favour ZDDP fragmentation and sulphur release. In absence of hydrogen, this is followed by local surface cold welding and sub-surface mechanical mixing of sulphur resulting in a decrease of yield stress and wear.

scholarly journals Reduction of Wall Friction of Fine Powders by Use of Wall Surface Coatings

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 427
Author(s):  
Christof Lanzerstorfer ◽  
Christian Forsich ◽  
Daniel Heim
Keyword(s):  
Carbon Coating ◽  
Friction Reduction ◽  
Surface Coatings ◽  
Wall Friction ◽  
Wall Material ◽  
Diamond Like Carbon ◽  
Ring Shear ◽  
First Results ◽  
First Time ◽  
Ultra High Molecular Weight

In this study, the possibilities for the reduction of powder wall friction by different types of surface coatings on the wall material were investigated. Two conventional coatings, an ultra-high molecular weight polyethylene plate and an anti-friction varnish, were tested, together with a diamond-like carbon coating. It is the first time a diamond-like carbon coating has been researched with respect to powder wall friction reduction. The wall friction angles were measured with a ring-shear tester. The results showed that the conventional coatings did not really reduce wall friction in comparison to structural steel. In comparison to the stainless steel they even increased it. In contrast, the diamond-like carbon coating reduced wall friction significantly. These first results are very promising. However, more detailed investigations are required.

scholarly journals On the Microstructural, Mechanical and Tribological Properties of Mo-Se-C Coatings and Their Potential for Friction Reduction against Rubber

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1336
Author(s):  
Jorge Caessa ◽  
Todor Vuchkov ◽  
Talha Bin Yaqub ◽  
Albano Cavaleiro
Keyword(s):  
Carbon Content ◽  
Friction And Wear ◽  
Current Mode ◽  
Friction Reduction ◽  
Transition Metal Dichalcogenide ◽  
Butadiene Rubber ◽  
Wear Rates ◽  
Mechanical And Tribological Properties ◽  
The Coefficient Of Friction ◽  
Pin On Disk

Friction and wear contribute to high energetic losses that reduce the efficiency of mechanical systems. However, carbon alloyed transition metal dichalcogenide (TMD-C) coatings possess low friction coefficients in diverse environments and can self-adapt to various sliding conditions. Hence, in this investigation, a semi-industrial magnetron sputtering device, operated in direct current mode (DC), is utilized to deposit several molybdenum-selenium-carbon (Mo-Se-C) coatings with a carbon content up to 60 atomic % (at. %). Then, the carbon content influence on the final properties of the films is analysed using several structural, mechanical and tribological characterization techniques. With an increasing carbon content in the Mo-Se-C films, lower Se/Mo ratio, porosity and roughness appeared, while the hardness and compactness increased. Pin-on-disk (POD) experiments performed in humid air disclosed that the Mo-Se-C vs. nitrile butadiene rubber (NBR) friction is higher than Mo-Se-C vs. steel friction, and the coefficient of friction (CoF) is higher at 25 °C than at 200 °C, for both steel and NBR countersurfaces. In terms of wear, the Mo-Se-C coatings with 51 at. % C showed the lowest specific wear rates of all carbon content films when sliding against steel. The study shows the potential of TMD-based coatings for friction and wear reduction sliding against rubber.

scholarly journals Tribological Behaviour of Graphene Nanoplatelets as Additive in Pongamia Oil

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 732
Author(s):  
Yeoh Jun Jie Jason ◽  
Heoy Geok How ◽  
Yew Heng Teoh ◽  
Farooq Sher ◽  
Hun Guan Chuah ◽  
...  
Keyword(s):  
Friction And Wear ◽  
Graphene Nanoplatelets ◽  
Friction Reduction ◽  
Engine Oil ◽  
Protective Film ◽  
Tribological Behaviour ◽  
Wear Reduction ◽  
Pongamia Oil ◽  
Interacting Surfaces ◽  
Worn Surface

This study investigated the tribological behaviour of Pongamia oil (PO) and 15W–40 mineral engine oil (MO) with and without the addition of graphene nanoplatelets (GNPs). The friction and wear characteristics were evaluated in four-ball anti-wear tests according to the ASTM D4172 standard. The morphology of worn surfaces and the lubrication mechanism of GNPs were investigated via SEM and EDS. This study also focuses on the tribological effect of GNP concentration at various concentrations. The addition of 0.05 wt % GNPs in PO and MO exhibits the lowest friction and wear with 17.5% and 12.24% friction reduction, respectively, and 11.96% and 5.14% wear reduction, respectively. Through SEM and EDS surface analysis, the surface enhancement on the worn surface by the polishing effect of GNPs was confirmed. The deposition of GNPs on the friction surface and the formation of a protective film prevent the interacting surfaces from rubbing, resulting in friction and wear reduction.

Tribological effects of laser surface texturing and residual stress

2018 ◽  
Vol 70 (1) ◽  
pp. 126-132 ◽  
Author(s):  
Shuwen Wang ◽  
Feiyan Yan ◽  
Ao Chen
Keyword(s):  
Residual Stress ◽  
Wear Resistance ◽  
Friction And Wear ◽  
Surface Texturing ◽  
Laser Surface ◽  
Friction Reduction ◽  
Laser Surface Texturing ◽  
Wear Testing ◽  
Content Type ◽  
Surface Textures

Purpose The purpose of this paper is to investigate the tribological effects of laser surface texturing (LST) and residual stress on functional surfaces. Design/methodology/approach Three different surface textures (circular dimple, elliptical dimple and groove) with two different textured area ratios (10 and 20 per cent) are designed and fabricated by a Picosecond Nd YAG Laser machine. The friction and wear performance of textured specimens is tested using a UMT-2 friction and wear testing machine in mixed lubrication. Findings Test results show that elliptical dimples exhibit the best performance in wear resistance, circular dimples in friction reduction and grooves in stabilization of friction. The surfaces with larger textured area density exhibit better performance in both friction reduction and wear resistance. The improved performance of LST is the coupled effect of surface texture and residual stress. Originality/value The findings of this study may provide guidance for optimal design of functional surface textures in reciprocating sliding contacts under mixed or hydrodynamic lubrication, which can be used in automotive and other industrial applications.

Friction reduction in EHL contacts by surface microtexturing – tribological performance, manufacturing and tailored design

2019 ◽  
Vol 71 (8) ◽  
pp. 986-990 ◽  
Author(s):  
Stephan Tremmel ◽  
Max Marian ◽  
Michael Zahner ◽  
Sandro Wartzack ◽  
Marion Merklein
Keyword(s):  
Product Life Cycle ◽  
Structural Parameters ◽  
Surface Texturing ◽  
Friction Reduction ◽  
Forming Process ◽  
Friction Behavior ◽  
Holistic View ◽  
Content Type ◽  
Efficient Manufacturing ◽  
Tailored Design

Purpose This paper aims to derive tailor-made microtextures for elastohydrodynamically lubricated (EHL) contacts under consideration of manufacturing possibilities. Design/methodology/approach Component tests were used for the evaluation of the influence of surface texturing on the friction behavior in the cam/tappet contact. Furthermore, the manufacturing possibilities and limitations of a combined μEDM and micro-coining process and the feasibility of integration into a forming process were studied. Finally, a methodology based on transient EHL simulations and a meta-model of optimal prognosis was exemplarily used for microtexture optimization. Findings It was found that surface texturing in EHL contacts with high amount of sliding is promising. Moreover, the combination of μEDM and micro coining and the integration into established production processes allow the manufacturing of microtextures with desirable structural parameters and sufficient accuracy. Originality/value This paper gives a holistic view on surface microtexturing over several phases of the product life cycle, from the design, over efficient manufacturing to application-related testing.

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