Study On Preparation Of TiO₂ Nanoparticles And Dispersibility In Transformer Oil

Transformer oil is an important insulation medium for the reliable operation of large power equipment such as transformer and so on.TiO2 nanoparticle plays a very important role in improving the breakdown strength,AC and lightning impulse breakdown strength and the resistance of thermal heat aging of transformer oil.Its dispersion in transformer oil is an important factor affecting the performance of transformer oil.In this paper,the effects of morphology,size and surface modification of nanoparticle on the dispersion in transformer oil are studied.By analyzing the surface modification of nano particles,the variation law of the dispersion is explainedHere we manufacture TiO2 nanoparticles by the Here we manufacture TiO2 nanoparticles by solvothermal method,condensation polymerization method and decomposition method.The crystal structure of the product was characterized by X ray diffraction.The size and morphology of the nanoparticles were characterized by transmission electron microscopy(TEM).The surface modification,chemical bonding and coating of the products were characterized by Fourier infrared analyzer and thermogravimetric analyzer.The effects of the reaction method,the amount of modifier,the ratio of the amount of solvent on the product size,morphology and surface modification were studied.The selective adsorption of the modifier on the grain surface of the titanium dioxide limits the growth direction and rate of the growth,and inhibits the rate of the reactionBy controlling the dosage and ratio of oleic acid,amine,laurylamine,the TiO2 nanoparticles,such as spherical,nanorod,rhombic shape,truncated rhombic shape and dog-bone-like nanorods can be obtained.The average size of spherical are 4.0nm～11.0nm.The average diameter of the nanorods is 8nm～10nm,and the length is 5nm～30nm.The reaction system of water vapor to replace water as a reactant or non water solvent reduces the reaction rate of the nucleation process,which provides the basis for controlling the morphology of TiO2 nanoparticles.TiO2 nanoparticles surface modification state,size and morphology are the main factors that affect the dispersion stability of the oil in the transformer.When the nanoparticle size is 3-4nm,the particle size of hexylamine modified nanofluid was nearly 50 times larger than that of oleic acid and amine modified.With the extension of time,the difference becomes greater.Compared with the spherical particles,the nanorod particle size of the oil is increased,which is related to its intrinsic morphology.Oleic acid modified nanofluid stay for 98 days without any precipitation,the size from the initial 33nm only increased 3nm,showing a good dispersion stability.The polar water molecules adsorbed on the surface of the nanoparticles can make the particles more easily agglomerated in the transformer oil and reduce the dispersion stability.In addition,oleic acid molecules with eighteen carbon chain adsorped on the surface of particles can increase the effective distance between particles,reduce the gravitational force between particles,play a role in steric hindrance.Thus,the spherical nanoparticles modified by oleic acid have good dispersion stability in transformer oil.