Preparation, characterization and tribological mechanism of nanofluids

Abstract

This article is focused on various synthetic methods and characterization techniquesof nanofluids. Factors enhancing the stability and lubrication mechanism have been delineated in detail as well.

A Review on Nanofluids: Fabrication, Stability, and Thermophysical Properties

“…The usual practice reported for inspecting the sample stability using a TEM device is by placing a drop of the asprepared nanofluid on a carbon coated copper grid and then monitoring the distribution of the nanoparticles on top of the copper grid when the basefluid is completely evaporated [23]. Total evaporation of the basefluid always results in aggregation of the nanoparticles.…”

“…These very highresolution microscopes tend to capture the digital image, known as the electron micrograph, of approximately 0.1 nm in size [23,69]. If clusters of nanoparticles are found within the obtained images, then sedimentation mechanism is most likely to occur (i.e., the nanofluid is considered unstable).…”

“…This is because the rise in temperature causes the bounds between the O ONa ＃( 3 (＃( 2 ) 5 ＃( 2 nanoparticles and the surfactant to be damaged and in some cases, it can chemically react into producing foams [148]. Additionally, excessive amount of surfactant affects the thermophysical properties of the nanofluid, where it increases the viscosity of the nanofluid and reduces its thermal conductivity [23,149].…”

“…The main disadvantage of the two-step approach is the large aggregation of particles that accompanies the process compared to the one-step method. Despite such disadvantages, this process is still the most popular route for producing nanofluids of large or small quantities and can be used to synthesise almost any kind of nanofluids [23].…”

“…Resistively heated crucible Liquid Cooling system Figure 7: Preparation of nanofluid using one-step vapour deposition method [23].…”