Effects of Surface Roughness on Behaviors of Lubricant Molecules in Ultra-Thin Film Lubrication

Tetsuya Okumura, Joichi Sugimura, Yuji Yamamoto

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Molecular dynamics (MD) simulation is conducted in order to study effects of atomic scale roughness on sliding surfaces on the ultra-thin film lubrication. The model lubricants are hydrocarbons including n-hexane, cyclohexane and n-hexadecane, which are confined and sheared by iron surfaces having transverse roughness. Velocity distribution and shear force computed in MD simulations are compared with those obtained through the conventional hydrodynamic (HD) lubrication theory. Although some similarity is seen in velocity distributions in MD and HD results, the MD simulation reveals roughness effects that are quite different from those derived in the continuum HD approach. Atomic surface roughness affects formation and breakdown of layered structures, movement of bridging molecules between the layers, and slip between the molecules and that between the molecules and the solid surface. When surfaces have roughness, particularly when both stationary and moving surfaces have roughness, disturbances caused in molecular movement are far greater, resulting in higher traction coefficient than in the case when surfaces are atomically flat. All these effects depend on surface asperity shape and molecular structure of lubricants.

Original languageEnglish
Pages (from-to)836-846
Number of pages11
JournalToraibarojisuto/Journal of Japanese Society of Tribologists
Volume48
Issue number10
Publication statusPublished - 2003

Fingerprint

Ultrathin films
lubricants
lubrication
Lubrication
Lubricants
surface roughness
Surface roughness
molecular dynamics
Molecules
roughness
Molecular dynamics
hydrodynamics
thin films
molecules
Hydrodynamics
velocity distribution
Velocity distribution
simulation
traction
Computer simulation

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering

Cite this

Effects of Surface Roughness on Behaviors of Lubricant Molecules in Ultra-Thin Film Lubrication. / Okumura, Tetsuya; Sugimura, Joichi; Yamamoto, Yuji.

In: Toraibarojisuto/Journal of Japanese Society of Tribologists, Vol. 48, No. 10, 2003, p. 836-846.

Research output: Contribution to journalArticle

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