Effect of Plasma-Treated Nano-Al2O3 on DC Insulation Properties of Epoxy Nanocomposites at Cryogenic Temperature

This article presents the effect of dielectric barrier discharge (DBD) plasma treated nano-Al
₂
O
₃
particles on the dc insulation properties of epoxy resin (EP) nanocomposites at cryogenic temperature.The surface of the nano-Al
₂
O
₃
particles was treated by a designed DBD plasma setup. The pure EP, 3 wt% untreated EP/nano-Al
₂
O
₃
composite, and plasma-treated EP/Al
₂
O
₃
nanocomposites with 3, 5, and 10 wt% were prepared by a physical mixture and casting method. The scanning electron microscopy and energy dispersive X-ray spectroscopy were used to investigate the dispersion of the nano-Al
₂
O
₃
and elemental composition, respectively. The insulation properties such as DC breakdown strength, surface potential decay (SPD), dc conductivity and thermally stimulated depolarized current were measured under a cryogenic environment using cryogenic thermostat. The obtained results showed that under the cryogenic environment, the dc breakdown strength of the EP was evidently enhanced by the addition of the plasma treated nano-Al
₂
O
₃
up to 5 wt%, but that was decreased for 10 wt%. The dc conductivity and SPD rate were reduced with the addition of the plasma treated nano-Al
₂
O
₃
up to 5 wt%. It was found that the plasma-treated EP/Al
₂
O
₃
nanocomposites had a deeper energy level and higher trap density compared to the pure EP. It was elucidated that the enhanced dc insulation properties of the plasma-treated EP/Al
₂
O
₃
nanocomposites was attributed to the reduced charge carrier mobility and stronger chemical bonds in the materials.