Combined Effect of Textured Patterns and Graphene Flake Additives on Tribological Behavior under Boundary Lubrication

Abstract

A ball-on-plate wear test was employed to investigate the effectiveness of graphene (GP) nanoparticles dispersed in a synthetic-oil-based lubricant in reducing wear. The effect by area ratio of elliptically shaped dimple textures and elevated temperatures were also explored. Pure PAO4 based oil and a mixture of this oil with 0.01 wt% GP were compared as lubricants. At pit area ratio of 5%, GP-base oil effectively reduced friction and wear, especially at 60 and 100°C. Under pure PAO4 oil lubrication, the untextured surfaces gained low friction coefficients (COFs) and wear rates under 60 and 100°C. With increasing laser—texture area ratio, the COF and wear rate decreased at 25 and 150°C but increased at 60 and 100°C. Under the GP-based oil lubrication, the textured surface with 5% area ratio achieved the lowest COF among those of the area ratios tested at all test temperatures. Meanwhile, the textured surface with 20% area ratio obtained the highest COF among those of the area ratios. With the joint action of GP and texture, the textured surface with 10% area ratio exhibited the best anti-wear performance among all of the textured surfaces at all test temperatures.

Highly Exfoliated Reduced Graphite Oxide Powders as Efficient Lubricant Oil Additives

“…The curve of PAO‐6 containing 0.5 wt% tRGO or heRGO‐4 is below that of pure PAO‐6 and it is stable in the whole testing process, implying that either tRGO or heRGO‐4 has antifriction effect. The average COF of PAO‐6 containing 0.5 wt% tRGO was tested to be about 0.109 ± 0.025, reducing the COF by about 27.8% (Figure c), and this value is comparable to those of previously reported other graphene‐based additives in similar lubricant systems (Table S2, Supporting Information). It is amazing to us that the average COF of PAO‐6 with 0.5 wt% heRGO‐4 additive was found to be only 0.084 ± 0.005, reducing the COF of PAO‐6 by about 44.3% (Figure c).…”

Inorganic nanomaterial lubricant additives for base fluids, to improve tribological performance: Recent developments

“…The use of dispersants is another effective method for enhancing the dispersion stability of graphene in base oils. Cai et al [78] used Span-80 (C 24 H 44 O 6 ) as a dispersant, to improve the dispersion stability of graphene in PAO4. Three days later, the PAO4 supplemented with 0.05 wt% graphene and 1 wt% Span-80 was darker and more turbid than when 0.05 wt% graphene was added.…”

Nano Diesel Soot Particles Reduce Wear and Friction Performance Using an Oil Additive on a Laser Textured Surface

“…As displayed in Figure 15f, the ratio of D and G peaks on the worn surface is considerably higher than those of the worn dimple, thereby indicated that the micro-dimple could protect the DS particles and the DS additives on the textured surfaces undergo more significant graphitization than that of original DS during friction, probably attributed to that the large amount of graphitized wear debris entrapped in the micro-dimples according to Ferrari and Robertson's three-stage model for the Raman spectra of disordered and amorphous carbon [28]. When the ball is sliding through the dimples, the additives in the dimples would be rolling or sliding in the dimples to decrease friction [29,30]. The ratio of D and G peaks in the smooth surface is similar to the original DS particles, which prove that the dimples could collect the unbroken additives.…”