ZnSnO3 quantum dots-reinforced boron carbon nitride nanosheets for enhanced tribological performance

Abstract

Boron carbon nitride (BCN) nanosheets are much better for reducing friction and wear compared to graphitic carbon nitride (g-CN) with a similar structure. To further improve the tribological activity of BCN, an attempt has been made to decorate the nanosheets (NSs) with ZnSnO3 quantum dots (QDs) in the form of BCN/ZnSnO3 nanocomposites. The field-emission scanning electron microscopy (FE-SEM), high resolution-transmission electron microscopy (HR-TEM), and TEM imaging techniques showed that these QDs were spread throughout the BCN NSs. The prepared nanoadditives, including g-CN, BCN NSs, ZnSnO3 QDs, and their nanocomposites (g-CN/ZnSnO3, BCN/ZnSnO3) were analyzed using Fourier-transform infrared spectroscopy (FT-IR) and powder X-ray diffraction (p-XRD). X-ray photoelectron spectroscopy (XPS) helped to understand the chemical states of the elements in the BCN/ZnSnO3 nanocomposite. All the tribological tests were conducted as the ASTM standard utilizing a four-ball tester at an optimized concentration (0.03 % w/v) in paraffin oil (PO). The results demonstrated a significant decrease in friction and wear and enhanced load-bearing capability for the nanocomposites as compared to their individual components. The prepared nanocomposites demonstrated a 43.54 % reduction in mean wear scar diameter (MWD), a 62 % reduction in coefficient of friction (COF), and a 62.07 % lower power consumption compared to base oil (PO). Further examination of the worn surfaces via FE-SEM and atomic force microscopy (AFM) validated the tribological findings. The elemental composition of the in situ tribofilm formed on the lubricated surfaces was confirmed through Energy Dispersive X-ray (EDX) analysis, while XPS provided insights into the chemical states of the elements present in the tribofilm. The collaborative effect between the ZnSnO3 QDs and BCN NSs facilitated the enhanced performance of the nanocomposite. The study also explored the possible mechanisms behind this improved lubrication. © 2025 Elsevier B.V.