Tribology of 2D Nanomaterials: A Review

Abstract

The exfoliation of graphene has opened a new frontier in material science with a focus on 2D materials. The unique thermal, physical and chemical properties of these materials have made them one of the choicest candidates in novel mechanical and nano-electronic devices. Notably, 2D materials such as graphene, MoS2, WS2, h-BN and black phosphorus have shown outstanding lowest frictional coefficients and wear rates, making them attractive materials for high-performance nano-lubricants and lubricating applications. The objective of this work is to provide a comprehensive overview of the most recent developments in the tribological potentials of 2D materials. At first, the essential physical, wear and frictional characteristics of the 2D materials including their production techniques are discussed. Subsequently, the experimental explorations and theoretical simulations of the most common 2D materials are reviewed in regards to their tribological applications such as their use as solid lubricants and surface lubricant nano-additives. The effects of micro/nano textures on friction behavior are also reviewed. Finally, the current challenges in tribological applications of 2D materials and their prospects are discussed.

Dialkyl Dithiophosphate-Functionalized Ti3C2Tx MXene Nanosheets as Effective Lubricant Additives for Antiwear and Friction Reduction

“…The relative movement of the contact surfaces provides shear stress for the as-prepared Ti 3 C 2 T x . In addition, the easy relative slip between the layers of the interlayer in the multilayer 2D DDP-Ti 3 C 2 T x nanosheets forms a sliding system with frictional contact. , The friction in the sliding system is much lower, resulting in effective lubrication. Furthermore, Ti 3 C 2 T x nanosheets can be easily destroyed under the condition of higher loads, forming smaller nanofragments, and the damaged Ti 3 C 2 T x fragments fill into the depression of the friction pair, which makes the friction pair surface smoother, reduces the roughness of the contact surface, and decreases wear volume .…”

Rheological Properties of Engine Oil with Nano-Additives Based on MoS2 Materials

“…where N [rev/s] is the rotation speed of the inner cylinder (rotor), and M [N•m] is the torque applied to the rotor. Equation ( 12) follows from Equation (8) and ω i = 2πN, while Equation ( 13) follows from the general torque formula. The inner and outer radiuses of the measuring gap were r i = 14.36 mm and r e = 14.46 mm, and the length of the measuring gap L = 15.00 mm has to be corrected by c L = 1.104 to account for the gap end effects.…”

“…MoS 2 is also characterized by good thermal stability and corrosion resistance. Due to its unique properties, MoS 2 finds various applications on the friction material market, such as solid lubricants and additives of lubricating oils and greases [6][7][8]. In order to enhance the tribological and rheological behavior, multiple types of MoS 2 materials have recently appeared.…”

Role of Interfacial Bonding in Tribochemical Wear

“…For instance, Li et al (2017) found that the wear resistance decreasing at higher RH conditions was found for the MoS 2 and MoS 2 /Ti composite coatings ( Figure 1E ). It has been widely accepted that the lubricity loss of MoS 2 in humid environments is mainly attributed to the chemical oxidation of MoS 2 layers activated by water vapor, which results in the formation of MoO 3 with worse frictional profiles ( Windom et al, 2011 ; Curry et al, 2017 ; Uzoma et al, 2020 ). Other studies focus on the enhanced molecular interactions of water with the layers as the fundamental mechanism behind the observed loss of MoS 2 lubricant properties ( Levita et al, 2016 ; Levita and Righi, 2017 ).…”