Silver Molybdate-Decorated Nanocomposites of Tin Diselenide for Improved Tribological Activity

The tin diselenide (SnSe₂) nanosheets were prepared using the solvothermal method as an additive to enhance the wear and friction-reducing and load-carrying capacity of paraffin oil (PO). To further enhance the lubrication characteristics of SnSe₂ nanosheets (NSs), Ag₂MoO₄ nanoparticles (NPs) were incorporated through the in situ method. The separately prepared SnSe₂ nanosheets, Ag₂MoO₄ nanoparticles, and their nanocomposites (SnSe₂/Ag₂MoO₄) were characterized by p-XRD, FTIR, Raman, HR-SEM, EDX, TEM/HR-TEM, and XPS. The decoration of Ag₂MoO₄ nanoparticles onto SnSe₂ nanosheets hindered the process of restacking and decreased their tendency to agglomerate in the base lube, resulting in enhancement of the lubrication performances of (SnSe₂/Ag₂MoO₄) nanocomposites compared to their individual components. These results are evident through the examination of tribological characteristics, as determined by the ASTM D4172 and ASTM D5183 test standards. The enhanced tribo-activity of the nanocomposite provides evidence of a synergistic effect between SnSe₂ nanosheets and Ag₂MoO₄ nanoparticles. The prepared additives exhibited improvement in their tribological behaviors in PO using a four-ball tester machine, and their antiwear and seizure load were found in the following sequence: PO < SnSe₂ < Ag₂WO₄ < Ag₂MoO₄ < SnSe₂/Ag₂MoO₄. After the lubrication test, SEM and AFM techniques were utilized to examine the morphology of the worn surfaces, validating the above results. The EDX and XPS of the matting surfaces tested with the SnSe₂/Ag₂MoO₄ nanocomposite confirm the presence of elemental composition and Ag₂O, SnO₂, SeO₂, MoO₃, and Fe₂O₃ in the tribofilm, respectively, which are responsible for the improvement in the tribo-activities. The possible mechanism has also been displayed.