Figure 7

Suspension stability of the lubricating oils with rGO concentration (a) 0.2 and (b) 1.0 mg.mL−1 as determined by ultraviolet–visible light (UV– VIS) spectrophotometry.
Suspension stability of the lubricating oils with rGO concentration (a) 0.2 and (b) 1.0 mg.mL−1 as determined by ultraviolet–visible light (UV– VIS) spectrophotometry.