Tribological properties of lubricating oil with micro/nano-scale WS₂ particles

Figures & data

Figure 1. TEM with different magnifications of nano-WS₂.

Figure 2. (a,b) SEM of micro-WS₂ under different magnifications.

Table 1. Contents of WS2 and ionic liquid as lubricant additives.

Particle size	WS2/base oil (wt.%)				Ionic liquid
90 nm	0.5%	1%	1.5%	2%	Add
90 nm	0.5%	1%	1.5%	2%	Not add
2 µm	0.5%	1%	1.5%	2%	Add
2 µm	0.5%	1%	1.5%	2%	Not add

Figure 3. Friction coefficient of the sample oil with different WS₂ morphology, diverse concentrations of WS₂ and ionic liquid: (a) 2 µm; (b) 90 nm; (c) 2 µm + ionic liquid; (d) 90 nm + ionic liquid.

Figure 4. Comparison among the four optimum amounts of nano-WS₂ groups and base oil.

Figure 5. Contrast tests among base oil, nano-WS₂ + ionic liquid for 5400 s.

Figure 6. Optical micrographs of the typical wear scars on the bottom balls lubricated by the sample oil: (a) base oil; (b) 1%, 90 nm WS₂; (c) 1%, 90 nm WS₂ and ionic liquid; (d) 0.5% 2 µm WS₂ and ionic liquid; (e) 2% 2 µm WS₂.

Figure 7. Magnification of the optical micrographs of the wear scars: (a) base oil; (b) 1%, 90 nm WS₂; (c) 2% 2µm WS₂.

Table 2. Average WSD of steel balls with different lubricants.

Lubricants	Average value WSD (mm)	WSD lessen ratio
Base oil	0.452	/
1%, 90 nm WS2	0.400	11.51%
1%, 90 nm and ionic liquid	0.392	13.27%
0.5%, 2 µm WS2 and ionic liquid	0.412	8.85%
2% 2 µm WS2	0.432	4.42%