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Aqueous lubrication in nature is attracting increasing attention in the tribological fields for reducing friction energy consumption and improving anti-wear durability. Generally, adding nanolubricant additives is one of the most important strategies to effectively enhance the interface performance under boundary lubrication via the formation of a protective tribofilm on rubbing surfaces. However, the adsorbed tribofilms are unstable and are prone to failure during friction, and the interaction mechanism between the tribofilms and frictional interfaces is partly disclosed. In this study, inspired by mussels, an in situ-assembled polydopamine (PDA) tribofilm is achieved with PDA nanoparticles as aqueous lubricant additives, which shows excellent lubrication properties. The coefficient of friction is interface-independent and is reduced by as much as 83%. The results show that the PDA tribofilm can not only form chemical bonding with metal interfaces but also present a synergistic lubrication effect with the upper ceramic surface. Especially, a self-repairing effect of the PAD tribofilm is observed, by which the ultrastable lubricating properties can be achieved during friction, and thus, the friction and wear can be effectively controlled. This work provides an effective method for improving the interface stability of friction pairs under aqueous lubrication and also shows great meaning for industrial applications.

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 Mn 3 O 4 nanoparticles and graphene nanosheets (Mn 3 O 4 @G) has been developed by an in situ green synthesis method; i.e., the impurities of Mn 2+ ions in crude graphite oxide as the precursor are directly transferred into Mn 3 O 4 precipitate between the graphene sheets. The graphene has a lamellar structure without folds and wrinkles, and the Mn 3 O 4 nanoparticles are not only uniformly anchored on the graphene surfaces but also intercalated in the layers of the graphene nanosheets. The Mn 3 O 4 @G exhibits excellent tribological properties and high stability because of a synergistic lubrication effect between the graphene nanosheets and the Mn 3 O 4 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 Mn 3 O 4 @G nanocomposite have significant potential in various tribological applications for saving energy.

An ultrathin layer is investigated for its potential application of replacing conventional diffusion barriers and promoting interface adhesion for nanoelectric circuits with porous ultralow dielectrics. The porous ultralow dielectric (k ≈ 2.5) substrate is silanized by 3-aminopropyltrimethoxysilane (APTMS) to form the nanoadhesive layer by performing oxygen plasma modification and tailoring the silanization conditions appropriately. The high primary amine content is obtained in favor of strong interaction between amino groups and copper. And the results of leakage current measurements of metal-oxide-semiconductor capacitor structure demonstrate that the aminosilanization nanoadhesive layer can block copper diffusion effectively and guarantee the performance of devices. Furthermore, the results of four-point bending tests indicate that the nanoadhesive layer with monolayer structure can provide the satisfactory interface toughness up to 6.7 ± 0.5 J/m(2) for Cu/ultralow-k interface. Additionally, an annealing-enhanced interface toughness effect occurs because of the formation of Cu-N bonding and siloxane bridges below 500 °C. However, the interface is weakened on account of the oxidization of amines and copper as well as the breaking of Cu-N bonding above 500 °C. It is also found that APTMS nanoadhesive layer with multilayer structure provides relatively low interface toughness compared with monolayer structure, which is mainly correlated to the breaking of interlayer hydrogen bonding.