A kinetic study of interface reactions for an organic molybdenum compound as a lubricant additive

Sun, Yu; Jang, Seong-Cheol; Liu, Zheng; Tang, Kaluo; Wu, Dong

doi:10.1016/0301-679x(90)90060-3

Cited by 9 publications

(1 citation statement)

References 7 publications

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“…These studies lead to no clear correlation of the structural characteristics of the additives [24][25][26][27], the extent of surface reaction, the quantities and quality of chemisorbed films formed on the surface with regards to their antiwear and antifriction properties. Godfrey [35] has distinctly shown that iron sulfides or oxides do not posses properties such as low shear strength, plasticity, good basal cleavage and low melting point, which are considered to be important characteristics for low wear and friction properties under boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

Anti wear and anti friction characteristics of tribochemical films of alkyl octa-decenoates and their derivatives

Chibber

Chaudhary

Tyagi

et al. 2005

Lubrication Science

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The wear, friction and film forming characteristic of ethyl octadecenoate and methyl 12-hydroxy ocatadecenoates, their thio and thiopyrophosphoro derivatives have been studied on HFRR friction and wear machine. The structural characteristics of chemisorbed films formed on the iron surfaces by these derivatives have been investigated using various analytical techniques such FT-IR, Microreflectance Absorption and Proton Magnetic Resonance. It has been inferred that these films are primarily organic in nature. The constituents of these films are hydroxy alkyl and aryl ethers, unsaturated and condensed ring hydroxy ketones, aromatic hydroxy quinones and highly condensed aromatic structures chemically linked to iron sufaces through hydroxy, oxy, thia, oxyphosphoro and thiophosphoro moieties forming chelated and coordinated complexes.The antiwear and antifriction characteristic of alkyl octadecenoates increase with increasing polar linkages in the alkyl ocatadecenoate backbone. This is primarily due to the increase in number of sites amenable to chemisorption on the surfaces and consequently their reactivity. The antiwear and antifriction characteristic of derivatives of ethyl octadecenoates are inferior to the corresponding 12-hydroxy methyl octadecenoates derivatives. This can be attributed to increased reactivity of 12-hydroxy methyl octadecenoates derivatives at the surfaces due to an additional hydroxyl moiety. The films formed are highly condensed ring aromatic layered structures coordinating to iron atoms of the surface particularly in case of thiopyrophosphoro derivatives of methyl 12-hydroxy octadecenoates. These films, as a consequence, provide lower wear and friction characteristics as compared to other types of organic films. These studies have led to much clear evidence of the intimate relationship between the chemical structure of the additives and their film forming characteristics.

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Section: Introductionmentioning

confidence: 99%

Anti wear and anti friction characteristics of tribochemical films of alkyl octa-decenoates and their derivatives

Chibber

Chaudhary

Tyagi

et al. 2005

Lubrication Science

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Studies on the tribological behaviour of two oil‐soluble molybdenum compounds under reciprocating sliding conditions

Gondal

Sethuramiah

Prakash

1993

Lubrication Science

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The use of oil-soluble organo-molybdenum compounds in engine oils can help in fuel conservation by reducing engine friction and increase durability by improving wear characteristics. The tribological behaviour of molybdenum dialkyldithiophosphate (MoDDP) was studied with a SRV Optimol tester under reciprocating sliding conditions. The studies were conducted under nonconformal contact conditions on En-31 steel and conformal contact conditions on piston ring and liner materials. The results indicated that the frictional behaviour of these additives is shear sensitive. Shear sensitivity is influenced by materials, operating conditions and the interaction of MoDDP with additives present in the oil. MoDDP when used in base oil was found to increase the scuff resistance of ring and liner materials. The use of the additive reduced friction and wear (running in as well as normal) under nonconformal contact conditions, while under conformal contact conditions its effect was selective and limited. piston rings and valve train. Figure 2 9 shows the proportional contribution of the components' friction to the total frictional losses of a gasoline engine, and possible reductions. The top 30% of the stroke of the uppermost piston ring during the power stroke is under boundary-or mixed-lubrication regime conditions and 60% of the total frictional losses of piston rings are attributed to boundary regime. 9 In a mixed-film lubrication regime up to 50% reduction in friction is possible if friction modifiers are added to engine oils. But in actual practice much lower reductions are achieved, because of the dependence of the effectiveness of additives on operating conditions. 13 The present study was carried out on tribological behaviour of two different soluble molybdenum additives in base and engine oils under reciprocating sliding conditions on a SRV Optimol tester. The studies were conducted in non-conformal and conformal contacts. In nonconformal contact conditions tests were conducted with En-31 steel in point and line contact to study:• frictional behaviour • the influence of sliding velocity on friction (shear dependence), and • the wear behaviour of MoDDP additives. Figure 3. Friction force trace under different lubrication conditions. Conformal Contact: Ring and Liner MaterialThe requirements of the SRV tester are such that it accommodates the stationary part in the form of an 8 mm thick, 24 mm diameter disc, while the reciprocating part can be mounted on attachments for ball, roller or annular rings of specific dimensions. For present purposes, discs were cut from cylinder liner using a special tool, on a vertical drilling machine. A number of discs were obtained by shifting and rotating the liner. The curvature on the inner side was retained while the outer surface was accurately flattened by polishing it by mounting the discs on a specially designed plate.The piston-ring piece was to be mounted on the upper reciprocating part of the SRV so as to simulate contact. Since the liner discs were thinner, a roller of 17 mm dia...

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Some specific methods of organizing two-layer lubrication

Buyanovskii

Kuksenova

Rybakova

et al. 2000

Chem Technol Fuels Oils

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A kinetic study of interface reactions for an organic molybdenum compound as a lubricant additive

Cited by 9 publications

References 7 publications

Anti wear and anti friction characteristics of tribochemical films of alkyl octa-decenoates and their derivatives

Anti wear and anti friction characteristics of tribochemical films of alkyl octa-decenoates and their derivatives

Studies on the tribological behaviour of two oil‐soluble molybdenum compounds under reciprocating sliding conditions

Some specific methods of organizing two-layer lubrication

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