Surfactant Effects on Dispersion Characteristics of Copper-Based Nanofluids: A Dynamic Light Scattering Study

Abstract

We present a study of powder agglomeration and thermal conductivity in copper-based nanofluids. Synthesis of the copper powders was achieved by the use of three different surfactants (polyvinylpyrrolidone, oleic acid, and cetyl trimethylammonium bromide). After careful determination of morphology and purity, we systematically and rigorously compared all three of the surfactants for the production of viable copper-based nanofluids using dynamic light scattering. Our results show that the use of surfactants during synthesis of copper nanopowders has important consequences on the dispersion of the powders in a base fluid. The oleic-acid-prepared powders consisted of small particles of ∼100 nm that did not change with the addition of dispersant. The CTAB-prepared powders exhibited the best dispersion characteristics, as they formed small particles of approximately 80 nm in the presence of SDBS. The thermal conductivity enhancement in our nanofluids exhibited a linear relationship with powder loading for an average particle size of ∼100 nm and similar particle size distributions that range from ∼50 to 650 nm, but independent of crystallite size and with all other factors maintained constant (surface area, surface additives, levels of oxidation) such that a 0.55 vol % loading results in a thermal conductivity enhancement of 22% over water and a 1.0 vol % loading results in a thermal conductivity enhancement of 48% over water. This study is the first to decouple the effect of a carefully characterized particle size distribution using dynamic light scattering versus crystallite size from X-ray line broadening on the thermal conductivity enhancement of a nanofluid.

Selective synthesis of copper microsheets and ultralong microwires via a surfactant assisted hydrothermal process

“…The bands at 1472 and 1462 cm -1 (curve 2) were attributed to the CH 2 scissoring mode of vibration. Copper nanosheets bands at 2924, 2854, 1474 and 1464 cm -1 (curve 2) assigned to C-H stretching and C-H bending, respectively [24][25][26] indicated presence of CTAB on the surface of copper nanosheets.…”

Mechanisms of pore formation in high-temperature carbides: Case study of TaC prepared by spark plasma sintering

“…TaC 1Àx (henceforth referred to as TaC) was produced by methods we previously developed [41][42][43] to generate powders with average crystallite size of 25 nm from X-ray line broadening, average particle (aggregate) size of 73 nm from dynamic light scattering [44][45][46][47][48][49][50][51][52][53][54][55][56][57], a C/Ta compound ratio of 0.94 (i.e. powders of composition TaC 0.94 ), an oxygen content of $6.1-7.9 wt.%, and a free carbon content of $2.4 wt.% [43].…”

Optical and structural properties of Er2O3–ErOOH powder grown by chemical bath

“…The O-H stretching mode is observed at 3611 cm À 1 , a typical position for a metal hydroxide. There are nine O-H stretching modes observed for two carbonate-containing materials [8], suggesting an analogous formula to Y 4 O(OH) 9 (NO) 3 , in which Y is replaced by Er 3þ and NO À 3 is replaced by CO 2 À 3 , taking into proper account the required charge balance (see Eqs. (1) and (2) the O-H vibrational regions in the two carbonate-containing compounds are practically identical.…”