Effect of Size of Multiwalled Carbon Nanotubes Dispersed in Gear Oils for Improvement of Tribological Properties

Figure 6

Zeta potential variation of nanofluids during 60 days. (a) Lubricants with long MWCNTs immediately after preparation, (b) lubricant with long MWCNTs after 60 days, (c) lubricant with 5-hour ball-milled MWCNTs immediately after preparation, (d) lubricant with 5-hour ball-milled MWCNTs after 60 days.

(a)

(b)

(c)

(d)