Additives for Industrial Lubricant Applications

Understanding the true interfacial mechanisms involved in the growth of tribofilms generated by Zinc Dialkyl Dithiophosphate (ZDDP) is important because it is the most widely used antiwear additive and there is legislative pressure to find efficient environmentally-friendly replacements. The main focus of this study is to investigate the durability of the ZDDP tribofilm and correlate it to the chemical and physical properties of the glassy polyphosphates.A novel experimental method has been developed to study the effect of lubricant temperature and contact load on tribofilm growth and durability. Results show that physical parameters such as temperature and pressure significantly influence the tribofilm durability. XPS analyses were carried out before suspending the test and after changing the oil to assess the difference in chemical structure of the tribofilm before and after stopping the test. The chemical analyses suggest that there are different chemical properties across the thickness of the tribofilm and these determine the durability characteristics.

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“…There are also different mechanisms in which the additives react with the surface to form the tribofilm [2].…”

Section: Boundary Lubricationmentioning

confidence: 99%

A new insight into the interfacial mechanisms of the tribofilm formed by zinc dialkyl dithiophosphate

Parsaeian

Ghanbarzadeh

Eijk

et al. 2017

Applied Surface Science

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“…Most sulfurized species are compatible with other additives used in the formulation and in some cases, such as combination with aminic antioxidants or ZDDP's, they are synergistic, which makes them attractive for usage in fully formulated lubricants. A number of studies demonstrating synergism of sulfur based additives with other lubricant components for enhanced AW/EP performance have been done in past [5,9,10]. Sulfur species decomposes under external influences such as heat and/or pressure leading to the formation of polar species or surface active radicals containing sulfur that combines with iron on the interacting surface to form an intermediate layer of iron sulfide, also known as a sacrificial tribofilm.…”

Section: Introductionmentioning

confidence: 99%

“…Sulfur species decomposes under external influences such as heat and/or pressure leading to the formation of polar species or surface active radicals containing sulfur that combines with iron on the interacting surface to form an intermediate layer of iron sulfide, also known as a sacrificial tribofilm. This film decreases the rate of surface wear and accelerates the smoothening of the surface [5,9]. In recent studies, it was also found that EP activity of the formulation is proportional to the amount of sulfur present [5].…”

Section: Introductionmentioning

confidence: 99%

“…The term 'sulfur carriers' has been accepted in the industry and summarizes a class of sulfur based additives that provide anti-wear and extreme-pressure properties when used in automotive oils, greases and other metalworking fluids [5]. Commonly used class of sulfur carriers in greases are sulfurized olefins/esters, dithiocarbamates, thiadiazoles, dithiophosphates etc.…”

Section: Introductionmentioning

confidence: 99%

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Wear and Friction of Greases Containing Organic and Inorganic Sulfur Carriers

2017

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Lithium based grease formulations are the most common lubricants used in industry today. Sulfur containing additives play a key role in improving wear and friction performance of these greases. The current study is focused on developing an understanding of characteristics of chemical bonding between sulfur carriers (MoS2, WS2 , MoDTC and organo tungstate ) and the interacting surfaces and evaluates their effect as anti-wear and anti-friction agents. ASTM D2266 and spectrum loading tests with varying loads while keeping other tests parameters constant were performed on the grease blends to understand effects of cyclic loading on tribochemical degradation of sulfur carriers. Tribofilms formed on the wear surface were analyzed using surface characterization techniques like SEM, EDS and Stereo Optical Microscopes. Wear scar diameter (WSD) and coefficient of friction (COF) were reported for the tests performed. This research aims to gain better insight on the atomic coordination or oxidation states of sulfur atom in additives and their correlation with anti-wear and extreme pressure performance when blended in greases.

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“…Shahnazar et al [5], based on Rudnick works [6,7], presented a well-documented classification of nano additives in lubricants, those based on carbon being classified in four main allotropic classes: zero-dimensional (fullerene), one-dimensional (nanotubes, nanowires, nanorodes), two-dimensional (graphene), three-dimensional (graphite, nanosized diamonds). Graphite has been used as micro particles in lubricants but adding it at nano level could enhance the friction and wear performance of the tribosystem.…”

Section: Introductionmentioning

confidence: 99%

Nano graphite as additive in soybean oil

Cristea

Dima

et al. 2017

MATEC Web Conf.

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Abstract. Vegetable oil-based lubricants have several disadvantages as compared to mineral and synthetic ones, including low viscosity that not encourage the generation of a continuous film when the tribosystem runs, consequently, implying a mixt or boundary. This is why the additivation of such oils is of great interests for researchers, producers and users. This paper presents results of testing the soybean oil additivated with nano graphite (0.25%wt, 0.50%wt and 1%wt) on a four ball machine. The friction coefficient is slightly increased for the additivated lubricants, but no evident dependency on concentration and test conditions was noticed. Supplementary tests will give the opportunity of a statistical approach of this parameter. Any concentration of nano graphite makes the wear parameter (wear scar diameter) to slightly increase as compared to the values obtained for the non-additivated soybean oil. The increase of the nano graphite concentration in this vegetable oil does not influence significantly the wear parameter, meaning that, at least for the tested regime, this is not an efficient anti-wear additive.

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Additives for Industrial Lubricant Applications

Cited by 72 publications

References 0 publications

A new insight into the interfacial mechanisms of the tribofilm formed by zinc dialkyl dithiophosphate

A new insight into the interfacial mechanisms of the tribofilm formed by zinc dialkyl dithiophosphate

Wear and Friction of Greases Containing Organic and Inorganic Sulfur Carriers

Nano graphite as additive in soybean oil

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