| Because of excellent physical and chemical properties,TiO2 has shown great potential in improving the insulating properties of liquid dielectrics.There are a lot of research on the electrical properties of TiO2 modified transformer oil.But the research on the effect of TiO2 microscopic morphology and structure on transformer oil modification is not deep enough.There is still a lack of amorphous hollow structure TiO2 for transformer oil.Research on modification.For this reason,in this paper,by adjusting the reaction parameters of liquid phase synthesis,amorphous hollow TiO2 spheres with different sizes and wall thicknesses were prepared,the preparation method and regulation mechanism of hollow TiO2 were studied,and the effect of hollow TiO2 on transformer oil exchange and exchange was further studied.Modification of DC breakdown characteristics.Firstly,tetrabutyl titanate is used to synthesize solid amorphous titanium dioxide by solvothermal method and hydrolysis method.And hollow TiO2 spheres are prepared by self-templating method through surface protection etching.The effect of reaction temperature,time and concentration of hydrolyzing agent on the hollow structure of TiO2 and its regulation mechanism were studied.Hollow TiO2 spheres with average diameters of 1.0μm,701nm and 182nm were initially prepared.Secondly,the silica microspheres prepared by the liquid phase method were used as the hard template,and the TiO2 shell layer was deposited on the surface structure.The TiO2 hollow structure was prepared by chemically etching the silica with NaOH aqueous solution.By controlling the reaction parameters,the average wall thickness was obtained.Hollow structured TiO2 particles with adjustable wall thickness of 22nm,48nm and 71 nm.Thirdly,using the prepared hollow titanium dioxide spheres to modify transformer oil,the effect of particle concentration and hollow structure on the AC and DC breakdown strength of transformer oil was tested and analyzed.It was found that at the same concentration,hollow TiO2 spheres with a wall thickness of 22nm have the best effect on the AC breakdown voltage modification of transformer oil,hollow TiO2 fail to improve the DC breakdown strength of transformer oil,but the DC breakdown strength of transformer oil modified by wall-thickness of 48nm hollow TiO2 spheres is better than other particles,which provides a reference for subsequent optimization.By measuring the dielectric constant of hollow TiO2 spheres with different wall thicknesses and their modified oil samples,the results show that the crystal form and hollow structure of TiO2 spheres are the two main factors affecting the dielectric constant,and the amorphous structure significantly reduces the titanium dioxide.The orientation polarization of the TiO2 and the hollow structure further changes the interface polarization in the low frequency region,thus realizing the regulation of the dielectric properties of the modified transformer oil.Under the action of an AC electric field,the polarized particles not only help to capture and inhibit the transmission of electrons in the oil,but also weaken the electric field strength in the oil and improve the AC breakdown strength of the transformer oil.Compared with other particles,there are more hollow TiO2 spheres with a wall thickness of 22nm at the same concentration,so they have the best effect on the modification of AC breakdown strength.Under the action of a fixed-direction DC electric field,in addition to capturing electrons,hollow particles also contribute carriers as charged negative particles,increasing the conductance of the oil.Therefore,it is not conducive to improving the DC breakdown strength of transformer oil.In summary,this article synthesizes and regulates the crystal form and hollow TiO2 spheres,studies the influence of hollow TiO2 spheres on the AC and DC breakdown strength and dielectric properties of transformer oil,and provides guidance for optimizing transformer oil with comprehensive insulation properties. |
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