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Synthesis and Characterisation of a Nanoalloy for Thermal Applications
Abstract
Metal oxide nano particles are potentially useful for heat transfer applications because of their chemical and physical properties. In this present study an attempt has been made to synthesize Fe2O3–Al2O3–CuO nano-composites by Co-precipitation method. The chemical, physical and thermal properties of the synthesized nano-particles were examined by Scanning Electron Microscopy, Energy Dispersive X-Ray Analyser, Fourier transform infrared spectroscopy and Thermo gravimetric Analyser. The properties of nano-alloy were studied along with those of the constituent nano-particles to estimate potential benefits of using this nano-composite for heat transfer applications. Energy Dispersive X-Ray analysis of metallic nano-alloy annealed at 500 °C revealed the presence of copper (Cu), aluminium (Al), iron (Fe), oxide(O) elements in metallic nano-alloy and data indicated that nano-particles were nearly stoichiometric. The molecules of metallic nano-alloy were found to be spiral in shape with size distribution of 200 nm. FTIR also confirms the presence of aluminium oxide, copper oxide and iron oxide in synthesized nano-alloy sample. Thermal analysis of the nano-alloy shows that there is significant increase in heat transfer characteristic of nano-fluid made of water with 0.4 wt% nano-alloy. It was observed that heat transfer characteristics increased with increase in concentration of nano-alloy in base fluid.
Today’s widespread activities in nanoscience and technology are actually rooted in the ideas of some leading scientists of the last century. Among them, the foremost name was
Richard P. Feynman. He delivered a legendary talk entitled “there is plenty of room at the
bottom” in the Annual general body meeting of the American Physical society on December 29, 1959 [1] at California Institute of Technology. In that talk he discussed about the ideas of manipulating and controlling things at the atomic scale. In this famous lecture the great scientist uttered also these famous words “the principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom”. He also envisioned building circuits having sizes few nanometers that can be used as elements in more powerful computers. In that time these ideas were regarded ‘too speculative’. But nearly twenty years later from this prophetic talk, many inventions and discoveries began to appear justifying Feynman’s time ahead ideas. Soon the technology advisors and predictors realized the importance of these discoveries and declared that a new revolution is imminent namely nanotechnology, just as in the past we experienced industrial revolution and information revolution. Drexler expanded Feynman’s ideas and definition in a stimulating and lateral thinking way in his book, ‘Engines of Creation, the Coming Age of Nanotechnology’ [2]. We can quote Drexler to have some ideas about nanotechnology: “Nanotechnology is the principle of manipulation atom by atom, through
control of the structure of matter at the molecular level. It entails the ability to build molecular systems with atom-by-atom precision, yielding a variety of nanomachines.”
In recognition with this reality National Science and Technology Council (NSTC) of USA
created an integrating working group on nanoscience, engineering and technology in 1998. Then in the year 2001 they announced the National Nanotechnology Initiative (NNI) programme with a large amount of fund in the budgetary provisions [3]. The major objective of this initiative was to create a common platform for the academia, industries and also private sector for working on this new technology. Following this example, most of the advanced countries in the world and many developing countries including China and India invested heavily on research and development in this new field of science and technology.
The Pr ³⁺ :LaF 3 (C Pr = 3, 7, 12, 20, 30%) nanoparticles were characterized by means of high-resolution transmission electron microscopy, X-ray diffraction, optical spectroscopy, energy dispersive X-ray spectroscopy, dynamic light scattering, and MTT assay. It was revealed that the average diameter of all the NPs is around 14–18 nm. The hydrodynamic radius of the Pr ³⁺ :LaF 3 (C Pr = 7%) nanoparticles strongly depends on the medium. It was revealed that hydrodynamic radii of the Pr ³⁺ :LaF 3 (C Pr = 7%) nanoparticles in water, DMEM, and RPMI-1640 biological mediums were 18 ± 5, 41 ± 6, and 186 ± 8 nm, respectively. The Pr ³⁺ :LaF 3 (C Pr = 7%) nanoparticles were nontoxic at micromolar concentrations toward COLO-320 cell line. The lifetime curves were fitted biexponentially, and for the Pr ³⁺ :LaF 3 (C Pr = 7%) NPs, the luminescence lifetimes of Pr ³⁺ ions were 480 ± 2 and 53 ± 5 nanosec.
Copper oxide nanoparticles were prepared by modified sol-gel technique using sodium dodecyl sulphate as a surfactant. Effect of calcination temperature on particle size, band-gap, crystallinity and morphology of the nanoparticles were studied with the help of particle size analysis, UV-Spectroscopy, powder X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) studies. Prepared nanoparticles will be tested for their activity towards gas sensing.
Sample preparation is an important step in chemical analysis process. The present article gives an overview about the co-precipitation as a technique for sample preparation for trace element analysis. Co-precipitation steps, mechanism, advantages, disadvantages and some applications have been discussed.
We have tested modified hydrolysis method for the preparation of α-Fe2O3 nanoparticles. The particles after synthesis were applied for a series of physicochemical techniques. Iron chloride was used as a precursor material. The particle size distribution was determined using zeta sizer and scanning electron microscopy. The surface area and the morphology of the particles vary by changing the concentration of the precursor material. The size of nanoparticles varies from 10 to 90 nm. The particles having size of 23 ± 1 nm were separated out from the solution and their size remains almost the same even after one month. Energy dispersive X-ray analysis (EDX) of Fe2O3 nanoparticles confirms the purity of the desired material. The weight loss of the particles with respect to the temperature was studied by thermogravimetric and differential thermogravimetric (TG/DTG) analysis. X-ray diffraction (XRD) has been employed to study the crystallinity of the particles.
Low thermal conductivity is a primary limitation in the development of energy-efficient heat transfer fluids that are required in many industrial applications. In this paper we propose that an innovative new class of heat transfer fluids can be engineered by suspending metallic nanoparticles in conventional heat transfer fluids. The resulting {open_quotes}nanofluids{close_quotes} are expected to exhibit high thermal conductivities compared to those of currently used heat transfer fluids, and they represent the best hope for enhancement of heat transfer. The results of a theoretical study of the thermal conductivity of nanofluids with copper nanophase materials are presented, the potential benefits of the fluids are estimated, and it is shown that one of the benefits of nanofluids will be dramatic reductions in heat exchanger pumping power.
An experimental system is built to investigate convective heat transfer and flow characteristics of the nanofluid in a tube.
Both the convective heat transfer coefficient and friction factor of Cu-water nanofluid for the laminar and turbulent flow
are measured. The effects of such factors as the volume fraction of suspended nanoparticles and the Reynolds number on the
heat transfer and flow characteristics are discussed in detail. The experimental results show that the suspended nanoparticles
remarkably increase the convective heat transfer coefficient of the base fluid and show that the friction factor of the sample
nanofluid with the low volume fraction of nanoparticles is almost not changed. Compared with the base fluid, for example,
the convective heat transfer coefficient is increased about 60% for the nanofluid with 2.0 vol% Cu nanoparticles at the same
Reynolds number. Considering the factors affecting the convective heat transfer coefficient of the nanofluid, a new convective
heat transfer correlation for nanofluid under single-phase flows in tubes is established. Comparison between the experimental
data and the calculated results indicate that the correlation describes correctly the energy transport of the nanofluid.
In this present study, the thermal conductivity of Al2O3/water, CuO/water and Al2O3 – CuO/water hybrid nanofluid were investigated experimentally. The two step method was adopted to prepare the hybrid nanofluid. Three different volume concentrations of nanofluids (0.05, 0.1 & 0.2%) were prepared by dispersing Al2O3 and CuO nanoparticles in water. The properties of single and hybrid nanofluids were measured by varying the temperature from 20℃ to 60°C. The obtained results demonstrate that the thermal conductivity of nanofluids are the function of volume concentration and temperature. Also the experimental results showed that a maximum of 9.8 % enhancement of thermal conductivity was observed for 0.2% particle volume concentration. The experimental thermal conductivity values were compared with the theoretical thermal conductivity values.
Iron oxide nanoparticle/Poly(ethylene terephthalate) (PET) nanowebs were obtained by electrospinning. To achieve superparamagnetic properties, iron oxide nanoparticles with diameters below 25 nm were used. Diameter distribution of iron oxide nanoparticles was measured by a particle size analyzer. Iron oxide nanoparticles were added into 16 wt % PET solution in the ratio of 5, 10, and 15 wt % to PET. The morphology of iron oxide nanoparticle/PET nanowebs was observed using field emission‐scanning electron microscopy (FE‐SEM) and transmission electron microscopy (TEM). The nanofiber diameter increased as increasing iron oxide nanoparticle concentration. The superparamagnetic behavior of iron oxide nanoparticle/PET nanofiber was confirmed using superconducting quantum interference device (SQUID). The degree of crystallinity of iron oxide nanoparticle/PET nanowebs was calculated from a differential scanning calorimeter (DSC) results. The change of flexural rigidity and tensile properties of electrospun iron oxide nanoparticle/PET nanowebs with the external magnetic field were examined ISO 9073‐7 testing method, universal testing machine and an appropriate magnet. Also, the elastic modulus of iron oxide nanoparticle/PET nanofiber was measured using nanoindentation. With applying magnetic field, the improvement in mechanical properties of field‐responsive magnetic nanofibers and nanowebs was confirmed. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Divided and ultra-divided systems such as colloidal and nanoparticle
dispersions are generally unstable with regard to the size and number of their
constituents because the solid-solution interfacial tension, acting as a driving
force, leads to a reduction of the surface area to minimise the dispersion free
enthalpy. Such phenomenon known as surface energy minimisation induces an
increase in average particle size as a result of the decrease of the surface area at
constant volume. For such a reason such dispersions are usually considered
thermodynamically unstable. However, they can be thermodynamically
stabilised if, by adsorption, the interfacial tension of the system becomes very
low. This phenomenon, well known for microemulsions, is for the first time
quantitatively modelled and demonstrated for transition metal oxide
nanoparticles. When the pH of precipitation is sufficiently far from the point of
zero charge and the ionic strength sufficiently high, the ripening of
nanoparticles is avoided and their size can be monitored over one order of
magnitude by tailoring solution pH and ionic strength. A model based on Gibbs
adsorption equation leads to an analytical expression of the water-oxide
interfacial tension as a function of the pH and the ionic strength of the
dispersion/precipitation medium. The stability condition, defined by a ‘zero’
interfacial tension, corresponds to the chemical and electrostatic saturation of
the water-oxide interface. In such a condition, the density of charged surface
groups reaches its maximum, the interfacial tension its minimum and further
adsorption forces the surface area to expand and consequently, the size of
nanoparticles to decrease. An excellent agreement was found between the
model prediction and the experimental results obtained from the aqueous
precipitation of magnetite (Fe3O4) nanoparticles in basic medium. A general
control of the metal oxide nanoparticle size when precipitated far from their
point-of-zero-charge is thus expected.
Indium tin oxide (ITO) nanoparticles with crystallite size of 12.6 nm and specific surface area of 45.7 m 2 ·g −1 were synthesized by co-precipitation method. The indium solution was obtained by dissolving metal indium in HNO 3 . The tin solution was obtained by dissolving metal tin in HNO 3 and followed by stabilizing with citric acid. The free of chlorine ions in the synthesis process brought several advantages: shortening the synthesis time, decreasing the particle agglomeration, decreasing the chlorine content in the ITO nanoparticles and improving the particle sinterability. This is the first time to report the synthesis of ITO nanoparticles free from chlorine contamination without using the expensive metal alkoxides as starting materials.
Both unmodified cupric oxide (CuO) nanoparticles and those functionalized with a bi-functional coupling agent methacryloxypropyl-trimethoxysilane (MPS) were used to fabricate vinyl-ester resin polymeric nanocomposites. The nanoparticle functionalization was observed to have a significant effect on the physical properties of the cupric oxide filled vinyl-ester resin nanocomposite. Thermal degradation study by thermo-gravimetric analysis (TGA) showed the increased thermo-stability in the functionalized-nanoparticle-filled vinyl-ester resin nanocomposites as compared with the unmodified-nanoparticle-filled counterparts. The more uniform particle dispersion and the chemical bond between nanoparticle and vinyl-ester resin were found to contribute to the increased thermal stability and enhanced tensile strength.
Study of the properties of iron oxide nanostructures (Chap. 17). In: Research in nanotechnology developments
- A Barrañón
Imad-ud-Din, Physical properties of a-Fe
- M Waseem
- S Munsif
- U Rashid
Fabrication and characterization of novel iron oxide/alumina nanomaterials for environmental applications
- A Mahapatra