Fabrication of Al2O3 Nano-Structure Functional Film on a Cellulose Insulation Polymer Surface and Its Space Charge Suppression Effect

Abstract

Cellulose insulation polymer (paper/pressboard) has been widely used in high voltage direct current (HVDC) transformers. One of the most challenging issues in the insulation material used for HVDC equipment is the space charge accumulation. Effective ways to suppress the space charge injection/accumulation in insulation material is currently a popular research topic. In this study, an aluminium oxide functional film was deposited on a cellulose insulation pressboard surface using reactive radio frequency (RF) magnetron sputtering. The sputtered thin film was characterized by the scanning electron microscopy/energy dispersive spectrometer (SEM/EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The influence of the deposited functional film on the dielectric properties and the space charge injection/accumulation behaviour was investigated. A preliminary exploration of the space charge suppression effect is discussed. SEM/EDS, XPS, and XRD results show that the nano-structured Al 2 O 3 film with amorphous phase was successfully fabricated onto the fibre surface. The cellulose insulation pressboard surface sputtered by Al 2 O 3 film has lower permittivity, conductivity, and dissipation factor values in the lower frequency (<10 3 Hz) region. The oil-impregnated sputtered pressboard presents an apparent space-charge suppression effect. Compared with the pressboard sputtered with Al 2 O 3 film for 90 min, the pressboard sputtered with Al 2 O 3 film for 60 min had a better space charge suppression effect. Ultra-small Al 2 O 3 particles (<10 nm) grew on the surface of the larger nanoparticles. The nano-structured Al 2 O 3 film sputtered on the fibre surface could act as a functional barrier layer for suppression of the charge injection and accumulation. This study offers a new perspective in favour of the application of insulation pressboard with a nano-structured function surface against space charge injection/accumulation in HVDC equipment.

Structural and optical study of Fe3+‐doped Al2O3 nanocrystals prepared by new sol gel precursors

“…By plotting the maximum curve slope and its intercept with the energy axis (F(R) = 0), the energy band gap value was calculated. The results showed that band gaps of 4, 3.87, 3.62, and 3.42 eV were obtained for pure and doped samples at 0, 1, 3, and 5% impurities, respectively, which it is smaller than compared to the results obtained by other researchers (E g = 7 eV) . The reason for the decrease in energy band gap following increase in the doping percentage can be adduced to the sp‐d interactions of the energy band of the d electrons of the Fe 3+ dopant band and the band electrons in Al 2 O 3 .…”

CuS‐functionalized cellulose based aerogel as biocatalyst for removal of organic dye

“…Carbon XPS spectrum was characterized as shown in Figure (c) where typical sp2 hybrid and sp3 hybrid structures of C 1s gave peaks at 284.05 and 285.8 eV. Another peak at 288.4 eV corresponds to groups containing oxygen on surface of carboxyl groups, respectively . Oxygen O 1s as shown in Figure (d), has a major peak at 531.2 and shoulder at 532.3 eV that is attributed to the oxygen in hydroxyl groups…”

Alumina/nano-graphite composite as a new nanosorbent for the selective adsorption, preconcentration, and determination of chromium in water samples by EDXRF

“…The diffractogram does not contain discrete patterns which could expose the presence of crystalline entities, including Al 2 O 3 . The absence of peaks for Al 2 O 3 phase is due to the amorphous texture [ 26 ]. Instead, a plain background is recorded, with high low-angle intensity decreasing at higher theta angles.…”