The augmentation of lubricant oil properties is key to protecting engines, bearings, and machine parts from damage due to friction and wear and minimizing energy lost in countering friction. The tribological and rheological properties of the lubricants are of utmost importance to prevent wear under unembellished conditions. The marginal addition of particulate and filamentous nanofillers enhances these properties, making the lubricant oil stable under severe operating conditions. This research explores the improvement in SAE 5w-30 base oil performance after the addition of multiwalled carbon nanotubes (MWCNTs) in six marginal compositions, namely, Base, 0.02, 0.04, 0.06, 0.08, and 0.10 weight percentage. The effect of the addition of MWCNTs on flash and pour points, thermal conductivity, kinematic viscosity, friction coefficients, and wear are investigated and reported. X-ray diffraction and transmission electron microscopy are used to characterize the MWCNTs. The purity, crystallinity, size, shape, and orientation of the MWCNTs are confirmed by XRD and TEM characterization. Pour points and flash points increase by adding MWCNTs but inconsistency is observed after the 0.06 wt.% composition. The thermal conductivity and kinematic viscosity increase significantly and consistently. The friction coefficient and wear scar diameter reduce to 0.06 wt.% MWCNTs and then the trend is reversed due to agglomeration and inhomogeneity. A composition of 0.06 wt.% is identified as the optimum considering all the investigated properties. This composition ensures the stability of the tribo-film and hydrodynamic lubrication.

The current study aims to explore the tensile fracture mechanism and thermo-mechanical efficiency of polyamide-6 (PA6) reinforced with titanium dioxide (TiO₂) and multiwalled carbon nanotubes (MWCNTs). The uniform dispersion of the MWCNTs and appreciable interfacing between PA6, TiO₂, and MWCNTs were revealed in the fractography figures. The crystallization temperature and degree of crystallinity have been enhanced by the addition of nanoparticles to the PA6 matrix. Young’s modulus, tensile strength, and Charpy impact strength improved proportionally concerning reinforcement content. The essential work of fracture (EWF) method was applied to evaluate the toughening and fracture behavior of PA6 hybrid systems. Considerable improvement (+60.6%) in the EWF of PA6–TiO₂–MWCNT nanocomposites was observed at 4 wt.% CNT and 2 wt.% TiO₂. Limiting oxygen index (LOI) findings demonstrate that a polymer with a combination containing titanium dioxide and multiwalled carbon nanotubes has a highly substantial retardant influence. As a result, the TiO₂–CNT combination acts as a synergist filler, offering versatile PA6 composite products.

This study demonstrates the dual functionality of solvate ionic liquids (SILs) comprising lithium bis(trifluoromethanesulfonyl)imide ([LiTFSI]) coordinated with triethylene glycol dimethyl ether ([Li(G3)][TFSI]) or tetraethylene glycol dimethyl ether ([Li(G4)][TFSI]) as both high‐performance lubricants and effective corrosion inhibitors at polymer–steel interfaces. Tribological testing of polyamide 6 (PA6), polyphenylene sulfide (PPS), and their carbon–fiber (CF) composites revealed that SIL lubrication reduced the coefficient of friction by ∼60% compared to dry sliding, reaching steady‐state values as low as 0.04–0.05 for PPS lubricated with [Li(G4)][TFSI]. Dry PPS/CF composites exhibited elevated CoF up to ∼0.60, underscoring the benefit of SIL retention and tribofilm formation. SEM examination of stainless‐steel surfaces following 24‐h immersion confirmed that both [Li(G3)][TFSI] and [Li(G4)][TFSI] were noncorrosive, in contrast to severe pitting observed in 1 M HCl. Corrosion weight‐loss measurements in 1 M HCl further demonstrated clear inhibition behavior, with only 100 ppm of [Li(G3)][TFSI] (∼68.5 μL/L) reducing corrosion‐product weight loss by 63% compared to 54% for 100 ppm [Li(G4)][TFSI] (∼71.4 μL/L). Complementary electroimpedance spectroscopy analysis revealed distinct interfacial responses for the two SILs, [Li(G3)][TFSI] ( R _ct = 366 Ω, interface inhibition effect of ∼40%) and [Li(G4)][TFSI] ( R _ct = 308 Ω, interface inhibition effect of ∼28%), indicating a more pronounced modification of the steel–electrolyte interface.