Surface analysis of epoxy nanocomposite insulator materials eroded by partial discharge

Tomonori Iizuka, Yuqing Zhou, Tomoaki Maekawa, Toshikatsu Tanaka, Kohei Tatsumi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Citations (Scopus)


Effects of the addition of nano filler particles in the improvement of epoxy resin insulating characteristics were investigated and it has been clarified that surface erosion resulting from partial discharge (PD) could be substantially suppressed by the addition of several percent of nano filler content to epoxy composites. One insulating performance improvement mechanism resulting from nano filler addition could be related to the deposition of filler particles on the eroded surface. However, no analysis reports on PD-related surface erosion have been identified to date. In this study, epoxy resin degradation and epoxy composite materials were quantitatively evaluated and eroded surfaces resulting from PD were analyzed by energy dispersive X-ray spectrometry (EDX) and auger electron spectroscopy (AES). To facilitate our experiments, neat epoxy resin specimens consisting of 3 wt% micro-SiO<inf>2</inf> composites and 3 wt% nano-SiO<inf>2</inf> composites, were prepared for use. Accelerated PD tests were performed with an applied voltage of 4 kV<inf>rms</inf> and a frequency of 600 Hz in an air atmosphere. In our experiments, erosion depths of all specimens were increased by lengthening the discharge time, and the addition of fillers to the epoxy resin suppressed the degree of the erosion, compared with the neat epoxy specimens. Out of these, nano filler composites were found to be particularly effective. The results of scanning electron microscopy (SEM) observation and EDX analysis of the eroded surfaces showed that the filler amounts deposited on the surface increased with lengthening discharge time in the composite specimens. After removing the deposited filler particles via ultrasonic cleaning, an increase in the SiO<inf>2</inf> surface concentration could still be detected for the nanocomposite materials via AES measurements. Through an analysis of AES depth profiles, the increased layer thickness of the SiO<inf>2</inf> surface contents was found to be from 10 to 20 nanometers. This indicates that that the surface resin was selectively sputtered during PD. From the above experimental results, it can be concluded that one of the major mechanisms related to improving insulating performance via filler additions was the surface covering provided by filler deposition during the PD. In the case of nano filler composites, the outermost surface was more effectively and densely covered with filler particles during the PD.

Original languageEnglish
Title of host publication2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2014
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages4
ISBN (Print)9781479975235
Publication statusPublished - 2014 Dec 22
Event2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2014 - Des Moines, United States
Duration: 2014 Oct 192014 Oct 22


Other2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2014
Country/TerritoryUnited States
CityDes Moines


  • AES analysis
  • EDX analysis
  • Nanocomposite Insulator Materials
  • Partial Discharge

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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