In Situ Green Synthesis of the New Sandwichlike Nanostructure of Mn₃O₄/Graphene as Lubricant Additives

Abstract

Nanoparticles and two-dimensional (2D) nanosheets are well-investigated as lubricant additives, which can significantly reduce frictional energy consumption. However, the tribological properties of the additives will deteriorate because of the occurrence of aggregation in the lubricant and the difficulty in entering the frictional contact area. In the present work, the new sandwichlike nanostructure of Mn3O4 nanoparticles and graphene nanosheets (Mn3O4@G) has been developed by an in situ green synthesis method; i.e., the impurities of Mn2+ ions in crude graphite oxide as the precursor are directly transferred into Mn3O4 precipitate between the graphene sheets. The graphene has a lamellar structure without folds and wrinkles, and the Mn3O4 nanoparticles are not only uniformly anchored on the graphene surfaces but also intercalated in the layers of the graphene nanosheets. The Mn3O4@G exhibits excellent tribological properties and high stability because of a synergistic lubrication effect between the graphene nanosheets and the Mn3O4 nanoparticles. Even at an ultralow concentration (0.075 wt %) and a high temperature of 125 °C, the friction coefficient and the wear depth have been reduced by 75% and 97% compared with base oil, respectively. The synthesis method and the Mn3O4@G nanocomposite have significant potential in various tribological applications for saving energy.

Improvement of the lubrication properties of grease with Mn3O4/graphene (Mn3O4#G) nanocomposite additive

“…26.152° illustrates that a small amount of MnO(OH) exists in Mn 3 O 4 #G, which is consistent with our previous results [44]. Figure 4 shows SEM and TEM images of the micromorphology of Mn 3 O 4 #G. From Fig.…”

“…According to our previous study, the load conditions (1 GPa) considerably affect the COF and wear of compound grease [44]. However, we must verify this result at higher load conditions.…”

“…The Mn 3 O 4 #G nanocomposite was used as an additive in the lubricating oil, and its tribological properties were investigated at a low speed (2.4 mm/s) and low load (1 GPa). The results indicated that Mn 3 O 4 #G can considerably improve the lubrication performance of oil [44]. However, the contact stress of actual machines under the engineering working conditions is much higher [45].…”

Influence of a carbon-based tribofilm induced by the friction temperature on the tribological properties of impregnated graphite sliding against a cemented carbide

“…The XPS spectrum of the C1s also shows the presence of the oxygencontaining functional groups of C=O (287.25 eV) and C-O (284.58 eV), which are probably due to the resin shown in Fig. 2(b) [26,27]. The experimental parameters used in this study are given in Table 2.…”

Nanolubricant additives: A review

“…It is easy to control the shape and distribution density of nanoparticles on nanocomposites. Especially, Zhao et al [81] prepared Mn 3 O 4 @G nanocomposites via in situ green methods and investigated their tribological properties as shown in Fig. 4.…”