Publication detail

Microstructure and Defects Evaluation of Varistors by Ultrasonic Waves in Low Frequency Range

TOFEL, P. ŠKARVADA, P. ŠIKULA, J. CSÉFALVAY, G.

Original Title

Microstructure and Defects Evaluation of Varistors by Ultrasonic Waves in Low Frequency Range

Type

journal article in Web of Science

Language

English

Original Abstract

Each material contains defects and in-homogeneities in a structure volume. It has influence on the properties of material (conductivity, mass density, mechanical properties). Interaction of the ultrasonic waves with defects or in-homogeneities in the solid state is not clear. Electro-ultrasonic spectroscopy can help to clarify this phenomenon. The electro-ultrasonic spectroscopy describes defects and un-homogeneities inside the sample structure. This method is quite different from electro-acoustic effect. Ultrasonic signal is in range from 20 kHz to 150 kHz. Ultrasonic signal changes geometry of the sample in elastic range only. The sizes of cracks are changing also in the sample volume. Conductivity near the area of cracks is strongly changing due to ultrasonic vibrations. It has influence on resistance of the sample which is changing along with a frequency of ultrasonic vibrations. The amplitude of the resistance change depends on the material, number of cracks, size of cracks and Eigen frequencies of the sample excited by ultrasonic wave. We applied the electro-ultrasonic spectroscopy on two types of varistors. It can be useful for understanding the relation between microstructure and mechanical properties of these types of varistors.

Keywords

Non-destructive testing, electro-ultrasonic spectroscopy, resistance change, crack geometry change, inhomogeneities

Authors

TOFEL, P.; ŠKARVADA, P.; ŠIKULA, J.; CSÉFALVAY, G.

RIV year

2014

Released

1. 1. 2014

Publisher

Trans Tech Publications

Location

Switzerland

ISBN

1013-9826

Periodical

Key Engineering Materials (print)

Year of study

465

Number

1

State

Swiss Confederation

Pages from

688

Pages to

691

Pages count

4

BibTex

@article{BUT110818,
  author="Pavel {Tofel} and Pavel {Škarvada} and Josef {Šikula} and Gabriel {Cséfalvay}",
  title="Microstructure and Defects Evaluation of Varistors by Ultrasonic Waves in Low Frequency Range",
  journal="Key Engineering Materials (print)",
  year="2014",
  volume="465",
  number="1",
  pages="688--691",
  doi="10.4028/www.scientific.net/KEM.592-593.688",
  issn="1013-9826"
}