الفهرس 
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Abstract
Recently, it has been demonstrated that colloidal nanoparticles have
many advantages and applications. These advantages are realized by
controlling and manipulating the force between the suspended
nanoparticles in the liquid. Nanofluids are dilute liquid suspentions of
nanoparticles smaller than 100 nm. In this study, water-base ceramic
nanofulids containing TiO2, Al2O3 and ZrO2 nanoparticles were prepared
using ultrasonication method. Different amounts of suitable dispersant
agent for each metal oxide nanofluids i.e. 0.1, 0.2, 0.3, 0.6, 1 and 1.5
wt.%, were tested to stabilize the prepared nanofluids. The stability of the
prepared nanofluids was verified using optical microscope, transmission
electron microscope and Zeta potential. After selecting the suitable
amount of dispersant, nanofluids having different volume fractions of
metal oxide nanoparticles were prepared e.g. 0.1, 0.15, 0.2, 0.5, 0.75
vol.%. The stabilized nanofluids were subjected for measuring
rheological behavior and electrical conductivity. The measured electrical
conductivity was correlated to the thermal conductivity according to
Wiedemann-Franz law. The results revealed that the electrical
conductivity increases with increasing particle concentration and
reducing particle size. The influence of surfactant is found to increase the
stability and decrease the electrical conductivity of the nanofluids by
increasing its viscosity. There is a rise in electrical conductivity of
nanofluids having low electrolyte concentration whereas a decrement is
observed in nanofluids having high electrolyte concentration due to
reduced surface conductance. Also, the rheological properties such as
viscosity of nanofluids increased firstly with increasing shear rate then