Effects of transverse atomic steps on bilayer lubricating films of simple hydrocarbons

Joichi Sugimura, T. Okumura, Y. Yamamoto

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Molecular dynamics (MD) simulations were conducted in order to study the dynamic behavior and traction of bilayer lubricating films of n-hexane, cyclohexane, and n-hexadecane. Lubricants were confined between bcc iron surfaces with and without transverse grooves of mono-atomic depth. Once the system equilibrated statically, one of the solid surfaces was moved to shear the film. The results demonstrated that the traction coefficient was governed by structures of the films, which depended on the molecular structures of the lubricants and on the atomic scale geometry of the solid surfaces. Traction was high when interfacial slip between lubricant layers and solid walls occurred. Evolution of the layered structure by gradual rearrangement of the molecules and resulting slip between the lubricant layers, caused significant reduction in the traction coefficient. The atomic steps enhanced the molecular rearrangement of n-hexadecane, while they retarded or inhibited those of n-hexane and cyclohexane resulting in a relatively higher traction coefficient for stepped surfaces. Molecular orientation of the normal alkanes under shear is described by the orientational order parameter, which has a strong correlation with the traction coefficient. The steady state traction coefficient of all the three simple hydrocarbons was highest when both of the surfaces had steps, and lowest when both of the surfaces were flat.

Original languageEnglish
Pages (from-to)117-131
Number of pages15
JournalTribology Letters
Volume25
Issue number2
DOIs
Publication statusPublished - Feb 1 2007

Fingerprint

traction
Hydrocarbons
hydrocarbons
lubricants
Lubricants
coefficients
Cyclohexane
Hexane
solid surfaces
cyclohexane
slip
Alkanes
shear
Molecular orientation
Paraffins
Molecular structure
Molecular dynamics
grooves
alkanes
Iron

All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Mechanical Engineering
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

Cite this

Effects of transverse atomic steps on bilayer lubricating films of simple hydrocarbons. / Sugimura, Joichi; Okumura, T.; Yamamoto, Y.

In: Tribology Letters, Vol. 25, No. 2, 01.02.2007, p. 117-131.

Research output: Contribution to journalArticle

@article{6c17f342aabf4d62a63784202dea6644,
title = "Effects of transverse atomic steps on bilayer lubricating films of simple hydrocarbons",
abstract = "Molecular dynamics (MD) simulations were conducted in order to study the dynamic behavior and traction of bilayer lubricating films of n-hexane, cyclohexane, and n-hexadecane. Lubricants were confined between bcc iron surfaces with and without transverse grooves of mono-atomic depth. Once the system equilibrated statically, one of the solid surfaces was moved to shear the film. The results demonstrated that the traction coefficient was governed by structures of the films, which depended on the molecular structures of the lubricants and on the atomic scale geometry of the solid surfaces. Traction was high when interfacial slip between lubricant layers and solid walls occurred. Evolution of the layered structure by gradual rearrangement of the molecules and resulting slip between the lubricant layers, caused significant reduction in the traction coefficient. The atomic steps enhanced the molecular rearrangement of n-hexadecane, while they retarded or inhibited those of n-hexane and cyclohexane resulting in a relatively higher traction coefficient for stepped surfaces. Molecular orientation of the normal alkanes under shear is described by the orientational order parameter, which has a strong correlation with the traction coefficient. The steady state traction coefficient of all the three simple hydrocarbons was highest when both of the surfaces had steps, and lowest when both of the surfaces were flat.",
author = "Joichi Sugimura and T. Okumura and Y. Yamamoto",
year = "2007",
month = "2",
day = "1",
doi = "10.1007/s11249-006-9126-4",
language = "English",
volume = "25",
pages = "117--131",
journal = "Tribology Letters",
issn = "1023-8883",
publisher = "Springer New York",
number = "2",

}

TY - JOUR

T1 - Effects of transverse atomic steps on bilayer lubricating films of simple hydrocarbons

AU - Sugimura, Joichi

AU - Okumura, T.

AU - Yamamoto, Y.

PY - 2007/2/1

Y1 - 2007/2/1

N2 - Molecular dynamics (MD) simulations were conducted in order to study the dynamic behavior and traction of bilayer lubricating films of n-hexane, cyclohexane, and n-hexadecane. Lubricants were confined between bcc iron surfaces with and without transverse grooves of mono-atomic depth. Once the system equilibrated statically, one of the solid surfaces was moved to shear the film. The results demonstrated that the traction coefficient was governed by structures of the films, which depended on the molecular structures of the lubricants and on the atomic scale geometry of the solid surfaces. Traction was high when interfacial slip between lubricant layers and solid walls occurred. Evolution of the layered structure by gradual rearrangement of the molecules and resulting slip between the lubricant layers, caused significant reduction in the traction coefficient. The atomic steps enhanced the molecular rearrangement of n-hexadecane, while they retarded or inhibited those of n-hexane and cyclohexane resulting in a relatively higher traction coefficient for stepped surfaces. Molecular orientation of the normal alkanes under shear is described by the orientational order parameter, which has a strong correlation with the traction coefficient. The steady state traction coefficient of all the three simple hydrocarbons was highest when both of the surfaces had steps, and lowest when both of the surfaces were flat.

AB - Molecular dynamics (MD) simulations were conducted in order to study the dynamic behavior and traction of bilayer lubricating films of n-hexane, cyclohexane, and n-hexadecane. Lubricants were confined between bcc iron surfaces with and without transverse grooves of mono-atomic depth. Once the system equilibrated statically, one of the solid surfaces was moved to shear the film. The results demonstrated that the traction coefficient was governed by structures of the films, which depended on the molecular structures of the lubricants and on the atomic scale geometry of the solid surfaces. Traction was high when interfacial slip between lubricant layers and solid walls occurred. Evolution of the layered structure by gradual rearrangement of the molecules and resulting slip between the lubricant layers, caused significant reduction in the traction coefficient. The atomic steps enhanced the molecular rearrangement of n-hexadecane, while they retarded or inhibited those of n-hexane and cyclohexane resulting in a relatively higher traction coefficient for stepped surfaces. Molecular orientation of the normal alkanes under shear is described by the orientational order parameter, which has a strong correlation with the traction coefficient. The steady state traction coefficient of all the three simple hydrocarbons was highest when both of the surfaces had steps, and lowest when both of the surfaces were flat.

UR - http://www.scopus.com/inward/record.url?scp=33846539203&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33846539203&partnerID=8YFLogxK

U2 - 10.1007/s11249-006-9126-4

DO - 10.1007/s11249-006-9126-4

M3 - Article

VL - 25

SP - 117

EP - 131

JO - Tribology Letters

JF - Tribology Letters

SN - 1023-8883

IS - 2

ER -