Alkyl-Functionalized Boron Nitride Nanosheets as Lubricant Additives

Abstract

Inorganic boron nitride (BN) nanosheets with excellent oil solubility were essential to replacing the traditional sulfur/ phosphate-containing additives because of their long practical services. However, serious agglomerated BN nanosheets without proper modification hamper their application in lubricant as green oil additives. Here, we developed a simple and robust method for fabricating highly oil-dispersed ultrathin alkyl-functionalized BN nanosheets via a ball-milling process combined with surface modification. Such a chemical-assisted exfoliation process endows ultrathin BN nanosheets with a superior dispersion ability in nonpolar lubricant. Because of the ultrathin structure and good compatibility, the resulting BN nanosheets significantly display great antifriction and antiwear performance as oil additives, as well as reduced surface pitting. As a result, about 45% friction reduction and 89% wear reduction, together with 2.67 times load capacity improvement, were achieved with the help of BN nanosheets in lubricant. High lubrication performance could be attributed to the continuous delivery of BN nanosheets to the contact region and the chemical formation of a protecting boron-based tribofilm. The present work highlights the significance of designing welldispersed functional 2D nanosheets as green additives for boosting lubrication performance as well as reducing surface pitting.

Effect of copper oxide@boron nitride nanosheet hybrid nanocomposite on tribological properties of paraffin liquid

“…The dramatical peak narrowing at 26.7° can be attributed to the sonic effect during the preparation of BNNS nano sheet, which means the obtain of few-layered structure compared to the raw h-BN. And the weaken of the intensity for CuO@BNNS maybe resulted from the surface modified with nano f-CuO [13]. Meanwhile, the peak at 32.6°, 35.6°, 38.8°, 49.02° in pattern of CuO@BNNS are totally aligned with peaks in pattern of f-CuO.…”

“…With the similar layered structure to graphene, h-BN maintaining lots of excellent properties, such as hearresistant property, electrical insulation and low interlaminar shear stress, has been studied on tribological properties in different areas [8][9][10][11][12][13][14][15][16][17][18]. As the traditional lubricant additive, h-BN can improve the tribological properties of lubricant composites [8][9][10][11][12][13] or oil [14][15][16][17][18]. Based on the results [14][15][16][17][18], the functionalized h-BN presents obviously friction-reduction and wear-resistance compared to the h-BN without any surface treatment.…”

Alkali-Assisted Hydrothermal Exfoliation and Surfactant-Driven Functionalization of h-BN Nanosheets for Lubrication Enhancement

“…Such a dispersion decreased the friction and improved the antiwear and load-bearing capacity by forming a protective tribo thin film. 26 The chemically exfoliated h-BN nanosheets (h-BNNSs) functionalized with 4-carboxyphenylboronic acid showed good dispersibility in 150 N lube base oil for 5 days. 11 The chemical modification of exfoliated h-BNNSs via a silane coupler extended their dispersibility for 7 days in liquid paraffin.…”

“…However, the poor dispersion stability of the h -BN nanomaterials in liquid lubricants because of their incompatibility with non-polar hydrocarbon lube oil has been a major challenge to effectively utilize the inherent tribological properties of h -BN for the development of new-generation liquid lubricants. Surface functionalization of h -BN nanomaterials with variable surfactants, dispersants, chemical functionalities, polymers, and so forth, based on chemical and physical interactions, has shown great potential in improving the dispersibility of h -BN nanosheets in lubricating media. − The surfactant-assisted exfoliation of 2D nanomaterials were used to stabilize the nanosheets against their re-aggregation in liquid media . The alkyl-functionalized h -BN nanosheets, prepared by a ball-milling process in the presence of polyisobutylene succinimide and oleic acid, showed a good dispersibility in non-polar lubricants.…”

“…The alkyl-functionalized h -BN nanosheets, prepared by a ball-milling process in the presence of polyisobutylene succinimide and oleic acid, showed a good dispersibility in non-polar lubricants. Such a dispersion decreased the friction and improved the antiwear and load-bearing capacity by forming a protective tribo thin film . The chemically exfoliated h -BN nanosheets ( h -BNNSs) functionalized with 4-carboxyphenylboronic acid showed good dispersibility in 150 N lube base oil for 5 days .…”