Boundary Film Formation by Viscosity Index Improvers

Smeeth, Matthew; Spikes, H. A.; Günsel, Selda

doi:10.1080/10402009608983590

Cited by 115 publications

(71 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One promising technique is ultrathin-film interferometry [13,14], which directly measures film thicknesses down to 1 nm or less in rolling-sliding steel-on-silica contacts under high pressure. This technique was applied to examine the film forming properties of, for example, viscosity index improvers [15] and anti-wear agents [16].…”

Section: Introductionmentioning

confidence: 99%

Process of Boundary Film Formation from Fatty Acid Solution

Nakano

Spikes

2012

Tribology Online

View full text Add to dashboard Cite

Ultrathin-film interferometry was used to investigate the developing process of boundary films in a steel-on-silica contact lubricated by a solution of n-hexadecanoic acid dissolved in n-hexadecane. Immersion of the surfaces in the solution is not sufficient to initiate boundary film formation. However, upon a nominally pure rolling contact, boundary film formation is initiated, and, once initiated, the boundary film develops spontaneously. It is believed that the initial monolayer film adsorbed strongly on the solid surface induces subsequent molecular stacking from the solution. The developed boundary film can be partially destroyed by the rolling contact, although the nominally identical rolling contact acts as the trigger of boundary film formation. These findings reveal that the immobile boundary films to reduce friction of solids under high pressure result from the equilibrium of two competing processes: spontaneous development by molecular stacking and mechanical destruction by relative motion of the contact surfaces.

show abstract

Section: Introductionmentioning

confidence: 99%

Process of Boundary Film Formation from Fatty Acid Solution

Nakano

Spikes

2012

Tribology Online

View full text Add to dashboard Cite

show abstract

“…Except for the range where U is more than 2×10 −10 , the gradients of all the plots nearly equal to 0.67. That is, EHL theory seems to be applied down to 3 nm; Smeeth et al 8) has described that EHL theory is obeyed down to 1nm for a mineral oil. Figure 2 shows the Stribeck friction curve, which corresponds to Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Optical interferometry 4,5) has experimentally proved the above theoretical result. The ultra thin film interferometry technique developed by Johnston et al 6) has shown that the EHL film thickness equation is obeyed down to only a few nanometer 7,8) . This value is less than the roughness of conventional engineering surface.…”

Section: Introductionmentioning

confidence: 99%

Stribeck Friction Curve in Point EHL Contacts

Nishikawa

Kaneta

2006

Tribology Online

View full text Add to dashboard Cite

The ultra thin film interferometry and conventional optical interferometry techniques are used to measure the central film thickness and friction force as a function of the dimensionless speed parameter. Experiments were conducted in point contacts with a mineral bright stock oil and a disk-like chemical compound by changing the temperature, entrainment velocity and surface roughness at a fixed slide-roll ratio. It has been found that the friction coefficient curve, i.e., the relationship between the friction coefficient and the dimensionless speed parameter, changes depending on lubrication regimes, even when the relationship between the central film thickness and the dimensionless speed parameter obeys EHL theory.

show abstract

“…Different kinds of additives in the lubricants [37], e.g., sulfurous extreme pressure or anti wear additives, which are polar and known to adsorb to metallic surfaces, or copolymer-based viscosity index improvers [53] may conjugate to the nanoparticle surface and avoid nanoparticle growth. Further bulky engine additives in the liquid, which have no affinity to gold nanoparticles, can influence the barrierless diffusion of nanoparticles.…”

Section: Discussionmentioning

confidence: 99%

Colloidal Stability of Metal Nanoparticles in Engine Oil under Thermal and Mechanical Load

2017

View full text Add to dashboard Cite

Extended colloidal stability and high dispersion degree of nanolubricants are required to avoid nanoparticle deposition in combustion engines and to reduce friction and wear. The simple and rapid one-step technique of pulsed laser ablation in liquids is employed to synthesize precursor-free and highly dispersed gold nanoparticles in lubricants while the colloidal stability is measured by optical spectroscopy and transmission electron microscopy. A remarkable colloidal stability is determined under engine-like and ambient conditions for nine months in terms of constant primary particle size. In contrast to additive-free oils, almost no agglomeration is observed, which might be attributed to the attachment of engine oil additives or pyrolyzed/oxidized molecules to the nanoparticles preventing attractive nanoparticle interactions.

show abstract

Boundary Film Formation by Viscosity Index Improvers

Cited by 115 publications

References 17 publications

Process of Boundary Film Formation from Fatty Acid Solution

Process of Boundary Film Formation from Fatty Acid Solution

Stribeck Friction Curve in Point EHL Contacts

Colloidal Stability of Metal Nanoparticles in Engine Oil under Thermal and Mechanical Load

Contact Info

Product

Resources

About