A molecular dynamics study on the tribological behavior of molybdenum disulfide with grain boundary defects during scrat
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ISSN 2223-7690 CN 10-1237/TH
RESEARCH ARTICLE
A molecular dynamics study on the tribological behavior of molybdenum disulfide with grain boundary defects during scratching processes Boyu WEI1, Ning KONG1,*, Jie ZHANG1, Hongbo LI1, Zhenjun HONG1, Hongtao ZHU2, Yuan ZHUANG3, Bo WANG3 1
School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China
2
School of Mechanical, Materials & Mechatronics Engineering, University of Wollongong, Wollongong, NSW 2522, Australia
3
Beijing Institute of Spacecraft System Engineering, Beijing 100094, China
Received: 14 June 2020 / Revised: 26 August 2020 / Accepted: 28 September 2020
© The author(s) 2020. Abstract: The effect of grain boundary (GB) defects on the tribological properties of MoS2 has been investigated by molecular dynamics (MD) simulations. The GB defects‐containing MoS2 during scratching process shows a lower critical breaking load than that of indentation process, owing to the combined effect of pushing and interlocking actions between the tip and MoS 2 atoms. The wear resistance of MoS2 with GB defects is relevant to the misorientation angle due to the accumulation of long MoS bonds around the GBs. Weakening the adhesion strength between the MoS 2 and substrate is an efficient way to improve the wear resistance of MoS 2 with low‐angle GBs. Keywords: MoS2; grain boundary; tribological behavior; molecular dynamics; misorientation angle
1 Introduction In recent years, two‐dimensional (2D) transition metal dichalcogenides (TMDCs) have caused great attentions due to their excellent physical, mechanical and tribology properties [1−5]. As a representative of TMDCs, MoS2 has a layered hexagonal crystal structure, which consists of one metal Mo layer and two S layers [6]. Due to its strong covalent bonding in molecular layer [7], single‐layer MoS2 (SL‐MoS2) shows extraordinary mechanical properties, such as the high effective in‐plane Young’s modulus [6, 8] and low bending modulus [9]. The weak van der Waals interactions in the interlayer of MoS2 make shear more easily, which is the main reason for the low friction of MoS 2 [10−12]. Base on the excellent mechanical and tribological properties, MoS2 is commonly used
as solid lubricant [13] and wear resistant coating [14], and is utilized as an additive in lubricating oils [13]. Due to the monolayer thickness, SL‐MoS 2 and thin film MoS2 present a number of potential applications to serve as lubricant materials in microelectromechanical systems (MEMS) [10, 11]. Under specific conditions, SL‐MoS2 and thin film MoS2 even show a lower friction than graphene [15, 16]. Moreover, the super‐lubricity phenomena are observed in MoS2–MoS2 [17] and MoS2–Sb [18] contacts as well. SL‐MoS2 with high‐quality and large‐area is required to achieve the applicati
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