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 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 Properties of Diamond-Like Carbon Coatings

2014 ◽  
Vol 874 ◽  
pp. 9-15 ◽  
Author(s):  
Monika Madej
Keyword(s):  
Tribological Properties ◽  
Cross Sections ◽  
Chemical Vapor ◽  
Substrate Material ◽  
Diamond Like Carbon ◽  
Linear Wear ◽  
Tribological Behaviour ◽  
Carbon Coatings ◽  
Coated Metal ◽  
Composition And Structure

The aim of the study was to analyze the superhard anti-wear diamond-like carbon coatings produced by Plasma Assisted Chemical Vapor Deposition (PACVD) and Physical Vapour Deposition (PVD). The a-C:H and a-C:H:W coatings were deposited on steel elements operating under friction conditions. The analysis involved comparing the tribological properties of coated metal elements with those of uncoated elements. It was essential to analyze how the coating composition and structure influence the tribological behaviour of elements under dry and lubrication friction conditions. The coating structure was analyzed by observing the topography of the surface and the cross-sections using an atomic force microscope (AFM) and a scanning electron microscope (SEM). The results were employed to determine the elemental composition and thickness of the coatings. The tribological tests were performed applying a ball-on-disc tribometer and using a pin-on-plate tribometer. The tribological properties were analyzed also in a micro scale using a microtribometer. Compared with the substrate material - steel, the diamond-like carbon coatings showed lower linear wear, lower friction coefficient and higher hardness.

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.

Interactions of Diamond-Like Carbon Coatings with Fully Formulated Engine Oils

2014 ◽  
Vol 57 (3) ◽  
pp. 503-514 ◽  
Author(s):  
A. Gangopadhyay ◽  
R. J. Zdrodowski ◽  
S. J. Simko
Keyword(s):  
Diamond Like Carbon ◽  
Carbon Coatings ◽  
Engine Oils

scholarly journals Tribological Performance of Si-Doped Hydrogenated Diamond-Like Carbon Coatings in Different Biodiesel

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Annett Dorner-Reisel ◽  
Zeynep Burcu Kavaklioglu ◽  
Stefan Svoboda ◽  
Jürgen Engemann
Keyword(s):  
Methyl Ester ◽  
Biodiesel Production ◽  
Diamond Like Carbon ◽  
Tribological Behaviour ◽  
Carbon Coatings ◽  
Wear Rates ◽  
Si Doped ◽  
Silicon Doped ◽  
Polar Functional Groups

In this paper, two kinds of different biodiesel were tested in terms of their impact on wear resistance of Si-DLC coated 100Cr6 flat worn by an oscillating 100Cr6 ball. The knowledge about the tribological behaviour of different types of biodiesel is rare. Rape and soybean are two of the most common natural sources for biodiesel production. Also, if the quality of biodiesel seems to be similar and, according to the demands, biodiesel from different natural origin could affect changes in the tribological behaviour. Although, soybean methyl ester (SME) gives the best results at room temperature wear tests, 150°C SME reaches wear rates of Si-DLC flat against 100Cr6 ball almost double as high as rapeseed methyl ester (RME). It is evident that, with increasing fraction of oxidation stabilizer C23H32O2, the wear rate increases. For silicon doped hydrogenated diamond-like carbon is especially suitable, for use in biodiesels, where certain fraction of humidity, dissociated water, or polar functional groups may present.

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