Mechanisms of additive effectiveness

Hsu, Stephen M.; Pei, P.; Ku, C. S.; Lin, Rong-Yan; Hsu, SL

doi:10.1002/ls.3010010205

Cited by 11 publications

(5 citation statements)

References 13 publications

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“…The deleterious effect of the dispersant on the oxidation stability of the ZnDTPcontaining lubricant is clearly enhanced by calcium detergents [100] and, to a larger extent, magnesium detergents [39]. In summary, the additive interaction pattern is influenced by the type of dispersant and detergent, by the base stock composition and by the concentration ratio of the additives used in a formulation [101]. Organocopper salts: During the 1980s, the successful application of organocopper salts in passenger car engine oils was made possible by the eventual selection of a concentration of copper in the range 90-120 ppm.…”

Section: Antioxidant Technology For Passenger Car Engine Oilsmentioning

confidence: 99%

Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants

Aguilar

Mazzamaro

Rasberger

2009

Chemistry and Technology of Lubricants

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Thermally induced hydrocarbon oxidation is a self-accelerating autoxidation process and is divided into 'low'-, 30-120 • C, and 'high'-, >120 • C, temperature phases. The first has four stages -induction of radical chain reactions, propagation, branching and then termination. Mechanisms of these processes are described and discussed. Differences in hydrocarbon reactivity are related to molecular structure. For hydrocarbon oxidation >120 • C, the first stage is the same as low-temperature oxidation but with reduced selectivity and increased reactivity; second, the oxidation phase becomes diffusion controlled as hydrocarbon viscosities increase from progressive polycondensation of higher molecular weight products, causing varnish and sludge formation. Base oil oxidation stabilities depend upon their derivation, whether solvent neutral, hydrocracked or synthetic, and their response to antioxidant treatment. Lubricant oxidation control focuses on radical scavengers and hydroperoxide decomposers and their synergistic mixtures.Engine oils increasingly use phenolic and aminic antioxidants as radical scavengers with organometallic complex antioxidants. Sterically hindered phenols substituted at 2-and 6-positions by t-butyl groups are particularly effective, reacting successively with peroxy radicals to form stable cyclohexadieneone peroxides. Secondary amines as either two aryl or phenyl and naphthyl groups are very effective at eliminating four peroxy radicals per molecule. They are more effective by a ratio of 4:2 than the sterically hindered phenols below 120 • C. At higher temperatures a catalytic cycle is suggested as an extended stabilisation mechanism. Transition metal ions with two valence states, Fe 2+/3+ , Cu 1+/2+ , etc. as trace quantities of metal soaps catalyse/retard autoxidation according to concentration and/or combination of metals. They catalyse or inhibit oxidation by complexing and decomposing hydroperoxides or can also oxidise peroxy radicals and reduce alkyl radicals to inert products. Organomolybdenum complexes such as molybdenum dialkyldithiocarbamates, MDTC, are increasingly used to stabilise engine lubricants particularly because of synergy with other antioxidants such as alkylated diphenylamines. 107 R.M. Mortier et al. (eds.), Chemistry and Technology of Lubricants, 3rd edn.,

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Section: Antioxidant Technology For Passenger Car Engine Oilsmentioning

confidence: 99%

Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants

Aguilar

Mazzamaro

Rasberger

2009

Chemistry and Technology of Lubricants

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“…It is well-known that the formation of tribofilm is the main reason for anti-wear and friction reduction. While lots of mechanism work of film formation has been done with oil-based lubricant [21][22][23], little work has been done on water-based lubricants. The film formation of SDSAME is discussed here as an example.…”

Section: Film Formation Mechanismmentioning

confidence: 99%

Tribological properties and worn surface analysis generated by ashless and phosphorus-free additive in water-based lubricant

Ren

Yang

et al. 2008

Proceedings of the Institution of Mechanical Engineers, Part J:

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Two kinds of ashless and non-phosphorus water-based lubricant additives, dodecenyl succinic acid monoesters and sulphurized dodecenyl succinic acid monoesters, were synthesized from dodecenyl succinic anhydride. The anti-wear and friction-reducing properties of the synthesized additives were evaluated using a four-ball machine, and the worn surfaces were analysed by scanning electron microscopy and X-ray absorption near-edge structure (XANES) spectrocoscopy. The tribological results show that the two kinds of additives exhibit good anti-wear and friction reduction properties as well as or better than oleate, which is an important commercial lubricant additive. The XANES results indicate that the tribofilms mainly consist of adsorbed layers and tribochemical layers, and more sulphate and less sulphide in the films would result in lower friction coefficient. The XANES results also show that thriboheat has important influences on the tribofilms' formation. The mechanism of film formation is proposed.

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“…Bench oxidation tests for use on crankcase and transmission lubricants have been reviewed [79][80][81][82]. These offer advantages of low cost, repeatabil ity and flexibility over engine tests, and provide valuable information on the performance of basestocks and additives, but no bench test can be expected to correlate exactly with a fired engine test and this problem is made more difficult by the multiplicity of engine tests and the continuing changes in engine design and operating conditions.…”

Section: Bench Oxidation Tests Catalysis By Metals and Nitrogen Oxidesmentioning

confidence: 99%

“…Aromatic amines and hindered phenols perform well in the ASTM D-943 and ASTM D-2272 tests, whereas the performance of ZDDPs could be affected by hydrolysis, and these tests can give misleading results if applied to crankcase oils containing ZDDPs [79].…”

Section: Metal Catalysis In Transmission and Industrial Lubricantsmentioning

confidence: 99%

Lubricating Oil Oxidation and Stabilisation

Colclough¹

1993

Atmospheric Oxidation and Antioxidants

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Mechanisms of additive effectiveness

Cited by 11 publications

References 13 publications

Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants

Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants

Tribological properties and worn surface analysis generated by ashless and phosphorus-free additive in water-based lubricant

Lubricating Oil Oxidation and Stabilisation

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