The Effect of Fe3O4 Nanoparticle Size on Electrical Properties of Nanofluid Impregnated Paper and Trapping Analysis

Abstract

This paper systematically studies the effect of Fe3O4 nanoparticle size on the insulation performance of nanofluid impregnated paper. Three kinds of Fe3O4 nanoparticles with different sizes and their nanofluid impregnated papers were prepared. Environmental scanning electron microscopy (ESEM) and infrared spectroscopy were used to analyze the combination of Fe3O4 nanoparticles and nanofluid impregnated paper. The effect of nanoparticle size on breakdown voltage and several dielectric characteristics, e.g., permittivity, dielectric loss, of the nanofluid impregnated paper were comparatively investigated. Studies show that the Fe3O4 nanoparticles were bound to impregnated paper fibers by O–H bonds, while the relative permittivity and dielectric loss of the nanofluid impregnated papers were increased. Meanwhile, the increase of trap depth, caused by the nanoparticles, can trap the electric charge and improve the breakdown strength. The test results show that the direct current (DC) and alternating current (AC) breakdown voltages of nanofluid impregnated paper increased by 9.1% and 10.0% compared to FR3 nanofluid impregnated paper, respectively.

Mineral and Ester Nanofluids as Dielectric Cooling Liquid for Power Transformers

“…Top-down methods involve the reduction of the particle sizes of a pre-existing bulk material by grinding, or vaporization-condensation; in bottom-up methods, nanoparticles are created by a chemical reaction or the physical interactions of precursors, atom by atom, as in coprecipitation or solvothermal techniques. Although the bottom-up methods are more complex, they are more versatile, since the rate of addition of reagents to the solution and its concentration [ 145 , 146 ], together with the time of reaction [ 21 , 55 , 66 , 108 , 146 ] or temperature [ 147 ], affects the mean size and composition of the nanoparticles, and can be used to control them [ 109 , 139 ]. By reducing the reaction time or concentration of the reagents, smaller particles are produced, although the dependence of size on time was not seen in all of the studies [ 23 ].…”

“…This procedure, based on pH changes, was followed in many works [ 107 , 145 , 149 , 150 , 151 , 152 , 153 , 154 , 155 ], including those specific to thermal-dielectric nanofluids with transformer oils [ 8 , 20 , 34 , 58 , 96 , 123 , 124 , 156 ]. Alternative methods used the reaction of iron precursors in alcoholic-organic solutions [ 23 , 55 , 139 , 146 , 157 ], and again there were examples in thermal-dielectric research [ 7 , 19 , 21 , 55 , 66 , 108 , 109 ].…”

“…The abundance of the different phases depends on the concentration of the reactants, the temperature, and the presence of an oxidant or inert atmosphere. If magnetite is preferred over the other phases, a 2/1 mol ratio of ferric/ferrous salts is commonly used [ 8 , 20 , 34 , 137 , 149 , 150 , 152 , 154 , 155 , 156 , 157 , 158 ], (or even lower, [ 107 ]); nitrogen environments are also used [ 55 , 107 , 108 , 153 ] to offset the oxidation of ferrous cations during the reaction. In other cases, the production of maghemite was promoted by the addition of oxidants, or by bubbling a heated solution with oxygen [ 20 , 158 ].…”

“…The reaction temperature varies depending on the production method and the reactions that are involved in it, ranging from the rated temperature to approximately 1000 °C. According to the literature, oxides can be synthesized by co-precipitation at room temperature [ 8 , 149 , 152 , 153 , 157 ] or at approximately 100 °C [ 7 , 19 , 20 , 34 , 107 , 123 , 124 , 137 , 145 , 151 , 154 , 155 ], or by the decomposition or solvothermal way at approximately 200 °C [ 23 , 101 , 146 , 159 ], 300 °C, [ 21 , 55 , 139 ], or even above 500 °C, [ 3 , 65 , 160 ]. Sometimes, the complete synthesis process is subdivided into several steps, each at a different temperature [ 7 , 19 , 21 , 55 , 66 , 108 , 109 ].…”

“…These can be included either as reagents during the synthesis of particles [ 8 , 21 , 25 , 55 , 59 , 65 , 66 , 107 , 108 , 109 , 133 , 139 , 156 , 157 ], added to nanoparticles [ 7 , 19 , 34 , 51 , 57 , 58 , 61 , 66 , 70 , 73 , 85 , 91 , 96 , 113 , 124 , 137 , 148 , 149 , 151 , 152 , 153 , 158 ], or at both times [ 107 ]; they can be in a aqueous solution [ 20 , 25 , 67 , 107 , 123 , 124 ], organic solvent [ 7 , 19 , 21 , 51 , 59 , 61 , <...…”