Next Article in Journal
Inducing Crystallinity of Metal Thin Films with Weak Magnetic Fields without Thermal Annealing
Previous Article in Journal
Tracing Phase Transformation and Lattice Evolution in a TRIP Sheet Steel under High-Temperature Annealing by Real-Time In Situ Neutron Diffraction
Article Menu
Issue 9 (September) cover image

Export Article

Open AccessArticle
Crystals 2018, 8(9), 361; https://doi.org/10.3390/cryst8090361

Molecular Dynamics Investigation of Graphene Nanoplate Diffusion Behavior in Poly-α-Olefin Lubricating Oil

1,2,3
,
2
,
3
and
1,2,*
1
MIIT Key Laboratory of Aerospace Bearing Technology and Equipment, Harbin Institute of Technology, Harbin 150001, China
2
School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
3
Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA
*
Author to whom correspondence should be addressed.
Received: 27 June 2018 / Revised: 27 August 2018 / Accepted: 9 September 2018 / Published: 13 September 2018
(This article belongs to the Section Crystal Engineering)
Full-Text   |   PDF [3300 KB, uploaded 13 September 2018]   |  

Abstract

Graphene as a type of novel additive significantly enhanced the tribological performance of blended lubricating oil. However, the dispersibility of graphene with long-term stability in lubricating oil is still a challenge. Chemical modification for graphene, rather than using surfactants, provided a better method to improve the dispersibility of graphene in lubricants. In this study, the equilibrium molecular dynamics (EMD) simulations were carried out to investigate the diffusion behavior of graphene nanoplates in poly-α-olefin (PAO) lubricating oil. The effects of graphene-size, edge-functionalization, temperature, and pressure on the diffusion coefficient were studied. In order to understand the influence of edge-functionalization, three different functional groups were grafted to the edge of graphene nanoplates: COOH, COON(CH3)2, CONH(CH2)8CH3 (termed GO, MG, and AG, respectively). The EMD simulations results demonstrated that the relationships between diffusion coefficient and graphene-size and number of functional groups were linear while the temperature and pressure had a nonlinear influence on the diffusion coefficient. It was found that the larger dimension and more functional groups provided the lower diffusion coefficient. AG with eight CONH(CH2)8CH3 groups exhibited the lowest diffusion coefficient. Furthermore, the experimental results and radial distribution function for graphene-PAO illustrated that the diffusion coefficient reflected the dispersibility of nanoparticles in nanofluids to some degree. To our best knowledge, this study is the first time the diffusion behavior of graphene in PAO lubricating oil was investigated using EMD simulations. View Full-Text
Keywords: graphene; molecular dynamics simulations; lubricating oil; diffusion coefficient graphene; molecular dynamics simulations; lubricating oil; diffusion coefficient
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
SciFeed

Share & Cite This Article

MDPI and ACS Style

Wu, L.; Song, B.; Keer, L.M.; Gu, L. Molecular Dynamics Investigation of Graphene Nanoplate Diffusion Behavior in Poly-α-Olefin Lubricating Oil. Crystals 2018, 8, 361.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Crystals EISSN 2073-4352 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top