Plasma nanocoated carbon nanotubes for heat transfer nanofluids.
Multi-wall carbon nanotubes (CNTs) were plasma-treated using glow discharges of argon, oxygen and methane/oxygen mixtures and then dispersed into a base fluid of water. It was found that proper plasma treatments of CNTs using nanoscale plasma coatings significantly improve the dispersion and stabilize the suspension of CNTs in the base fluid. With 0.01 vol% addition of plasma-treated CNTs, a 25% initial increase in thermal conductivity was achieved and a stabilized 20% increase was observed with the resulting nanofluids after 5 days' settling. It should particularly be pointed out that such a large increase in thermal conductivity was achieved when plasma-treated CNTs were stably dispersed in water without adding any dispersing agents or surfactants. Surface modification of the CNTs was confirmed by Raman spectroscopy and ultra-thin (approximately 2 nm) plasma nanocoatings were noted on the treated CNT surfaces by transmission electron microscopy (TEM).
Kim
Young Jo
YJ
Center for Surface Science and Plasma Technology, Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, MO 65211, USA.
Ma
Hongbin
H
Yu
Qingsong
Q