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

Figure 7

Zeta potential variation of nanofluids. (a) Lubricants with 10-hour ball-milled MWCNTs immediately after preparation, (b) lubricant with 10-hour ball-milled MWCNTs after 60 days, (c) lubricant with 20-hour ball-milled MWCNTs immediately after preparation, (d) lubricant with 20-hour ball-milled MWCNTs after 60 days.

(a)

(b)

(c)

(d)