Wear performance of PAO4, ZDDP, and ZnS NPs at the different concentrations at 100 °C.
| Lubricant | Wear volume (×107 μm3) | Steady-state COFa | ||
|---|---|---|---|---|
| Flat | Ball | Total | ||
| Neat PAO4 | 196 ± 40.50 | 0.75 ± 0.06 | 196.75 ± 40.50 | 0.136 |
| PAO4 + 0.8% ZDDP | 9.24 ± 0.32 | 0.05 ± 0.01 | 9.27 ± 0.32 | 0.104 |
| PAO4 + 1% ZnS NPs | 3.33 ± 0.58 | 0.08 ± 0.01 | 3.41 ± 0.58 | 0.085 |
| PAO4 + 0.50% ZnS NPs | 3.20 ± 0.23 | 0.16 ± 0.10 | 3.36 ± 0.23 | 0.090 |
| PAO4 + 0.25% ZnS NPs | 48.60 | 0.86 | 49.46 | 0.130 |
a
Steady-state COF determined by averaging the COF data of last 200 m.