Modification of insulating oils and oil-based titanium dioxide nanofluids for transformers: a review

In the last decade, oil-based titanium dioxide nanofluids (TiO2 NFs) have gained immense interest due to their unique insulating properties and excellent thermal performance, which endow them with the potential for application in the field of modified insulating oils. A timely comparison, analysis and summary of recent advances in the preparation, characterization, and properties of different oil-based TiO2 NFs for oil-immersed power transformers will contribute to provide a useful reference for the subsequent development of such materials. Preparation methods are reviewed along with their merits and demerits. Characterization techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), optical microscopy (OM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy, thermally stimulated current (TSC), pulse electroacoustic technique (PEA), finite element analysis (FEA), fluorescence spectroscopy, Raman spectroscopy and zeta potential analysis are all applied to determine the crystal structure, particle size, surface function, surface charge and stability. Stabilization mechanisms are also discussed in detail. Some critical properties of oil-based TiO2 NFs under the application of different influencing factors such as base oils, crystal structure, size of nanoparticles, surface modifiers, mixing percentage, and aging environment are highlighted. Finally, the existing challenges and perspectives are presented for future research.

Automated summary

In the last decade, oil-based titanium dioxide nanofluids (TiO2 NFs) have gained significant attention for their unique insulating properties and excellent thermal performance, making them potential candidates for modified insulating oils in power transformers. This article provides a comprehensive review of the recent advances in the preparation, characterization, and properties of different oil-based TiO2 NFs. Various characterization techniques are employed to determine the crystal structure, particle size, surface function, surface charge, and stability of the nanofluids. The critical properties of oil-based TiO2 NFs under different influencing factors are highlighted, and the existing challenges and future perspectives are presented.