This article reports the surface modification of Ti-6Al-4V, which is widely used for mechanical engineering applications by laser texturing in order to enhance its tribological properties. Surface patterns with three different diametered dimples were prepared for Ti-6Al-4V. Two types of oil with different viscosities were evaluated as lubricants using a pin-disc tribometer. The results show that the textured surfaces exhibit lower friction coefficients and wear compared with the untextured surface. However, as the load increases, the effect of friction reduction for all the textured surfaces decreases when lubricated with lower viscosity oil. The beneficial effects of the dimples are more pronounced at higher speeds and loads when lubricated with higher viscosity oil. The influence of dimple sizes on lubricating-regime transitions is investigated in this study, and the mechanism for friction reduction is discussed.

Herein, to endow h-BN nanosheets with gelling ability, a diurea compound was decorated on the h-BN nanosheets via designed adsorption and in situ reaction processes. The prepared h-BN-based gelator, BTO, exhibited excellent dispersibility in non-polar liquid media, and the gelation of BTO dispersions could be readily triggered by ultrasonic treatments. The sol–gel transformation of the system was found to be highly reversible by stirring and sonication. Based on the investigation on the self-assembly behavior of BTO nanosheets in the liquid phase, it was proposed that a continuous and layered structure formed by BTO during sonication was the key factor for the gelling properties of these nanosheets. The viscoelasticity of the sonication-induced gel was studied using a rheometer. Tribological evaluations show that the prepared h-BN nanogel exhibits outstanding lubricating performances, and more importantly, it has been proved that the gel state of the h-BN nanosheets provides superior and more reliable lubricating performances than the corresponding dispersion state under certain conditions; this can be ascribed to the formation of a continuous and uniform structure of modified h-BN nanosheets during gelation. Thus, this study not only clarifies the key role of the assembly structure in the tribological performances of 2D nanomaterials, but also demonstrates the potential of gelation in improving the macroscopic friction reduction and wear resistance of 2D nanomaterials.