Kiyoko Murayama

Improving Epoxy-based Insulating Materials with Nano-fillers toward Practical Application

A primary concern in recent nanocomposite research is practical application. In this study, various kinds of epoxy-based nanocomposites were made and their properties evaluated to determine their applicability as insulating materials for heavy electric apparatuses. Experimental results demonstrated that nano-fillers enhance insulation breakdown properties in nanocomposites. Moreover, nano- and micro-filler combinations were adopted as an approach toward practical application of nanocomposite insulating materials. These nano- and micro- filler mixed composites had the same low thermal expansion as aluminum, and insulation breakdown properties superior to those of conventional insulating materials. Consequently, an aluminum conductor and a vacuum interrupter were molded by the nano- and micro-filler mixed composites for the first time in nanocomposite research.

Nano- and micro-filler combination enabling practical use of nanocomposite insulating materials

Recent interests concerning nanocomposites are shifting emphasis from fundamental research to application-oriented research. In this study, nano- and micro-filler mixed composites were made and evaluated toward practical use of nanocomposite insulating materials. Some kinds of the nano-filler/micro-filler combinations such as nano-layered silicate/micro-silica, nano-silica/micro-silica and nano-titania/micro-silica were compared from viewpoints of volume resistivitiy, relative permittivity, thermal expansion and insulation breakdown properties. Comprehensive consideration based on experimental results determined a candidate nano- and micro-filler mixed composites to make trial models. An aluminum conductor and a vacuum interrupter were molded from the nano- and micro-filler mixed composites for the first time in nanocomposite research.

Nano-clay and micro-silica mixed composites for insulating materials for environmentally-conscious switchgear

Nano-clay and micro-silica mixed composites were made for use as insulating materials for switchgear. Observation of nano-clay dispersion and measurements of insulation breakdown properties under a homogeneous electric field were conducted of these composites. Moreover, simulations were carried out to estimate the curing reaction and rheological behavior of the composite in an automatic pressure gelation system. Experimental results demonstrated that these composites have suitable material characteristics for practical use in switchgear.

Component models insulated with nanocomposite material for environmentally-friendly switchgear

Nano-clay and micro-silica mixed composites were made for use as insulating materials for environmentally-friendly switchgear. The thermal properties and V-t characteristics of these composites were evaluated under a homogeneous electric field. They were shown to have sufficient thermal and insulation breakdown properties as insulating materials for switchgear. In particular, their average insulation breakdown time was longer than that of conventional filled epoxy at 10 and 20 kV/mm. Moreover, we succeeded in making component models insulated with the composite for switchgear.

Application-oriented researches on nanocomposite insulating materials

In the past decade, the nanocomposite technology has made much progress rapidly. We also developed the epoxy-based nanocomposites which have the enhanced insulation properties. The advantages of the nanocomposite materials stimulate the efforts for practical use of them. Therefore, the applications of the nanocomposite materials are primary interests in current researches. In this paper, we briefly introduce the four kinds of the application-oriented researches on the nanocomposite insulating materials.