TY - CONF A1 - Bovtun, Viktor Petrovic A1 - Döring, Joachim A1 - Bartusch, Jürgen A1 - Beck, Uwe A1 - Erhard, Anton A1 - Yakimenko, Y. T1 - EMFIT Ferroelectret Film Transducers for Non-Contact Ultrasonic Testing T2 - 9th European Conference on NDT CY - Berlin, Germany DA - 2006-09-25 KW - Non-contact ultrasound KW - Ferroelectret film KW - Ultrasonic transducer PY - 2006 SN - 3-931381-86-2 SP - 1 EP - 10(?) PB - European Federation for Non-Destructive Testing CY - Berlin AN - OPUS4-14211 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gaal, Mate A1 - Döring, Joachim A1 - Bartusch, Jürgen A1 - Beck, Uwe A1 - Weise, Matthias A1 - Bovtun, Viktor Petrovic A1 - Brekow, Gerhard A1 - Kreutzbruck, Marc T1 - Parameter reproducibility of polypropylene ferroelectret transducers for air-coupled ultrasonic testing N2 - The extremely low acoustic impedance of polypropylene ferroelectret combined with its piezoelectric properties makes this material suitable for construction of aircoupled ultrasonic transducers for non-destructive testing. For the fabrication of transducers with a stable quality, the reproducibility of their key parameters is of interest. The reproducibility was evaluated by means of (i) impedance spectroscopy and (ii) pulse-echo measurements. (i) Impedance spectroscopy was applied to identify the resonance frequency, the coupling factor and the acoustic impedance of several nominally identical transducers. (ii) Pulse-echo measurements yielded the signal form of these transducers. The variation of the signal amplitude measured with pulseecho technique was about 10 dB. A part of this variation Comes from the deposition of transducer electrodes and another part from local variations of ferroelectret properties. The variation of the signal amplitude was caused by the observed variation of the coupling factor, which was also about 10 dB. The variation of the acoustic impedance was only about 1 dB, thus having no effect on the variation of the signal amplitude. These results indicate that the variability can be reduced by improving the control of electrode deposition and by optimizing the production technology affecting the reproducibility of material properties. T2 - 2011 IEEE International ultrasonics symposium (IUS) CY - Orlando, FL, USA DA - 18.10.2011 KW - Air-coupled ultrasonic transducers KW - Polypropylene ferroelectret KW - Reproducibility PY - 2011 IS - Abstract-ID 258 SP - 1 EP - 3 AN - OPUS4-26405 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Döring, Joachim A1 - Bovtun, Viktor Petrovic A1 - Bartusch, Jürgen A1 - Erhard, Anton T1 - Eigenschaften von Polypropylen- und PVDF-Folien für Luftschall-Anwendungen N2 - An Methoden zur luftgekoppelten Ultraschallprüfung wird seit einigen Jahren mit großer Intensität gearbeitet. Probleme bei der praktischen Realisierung entstehen vor allem durch die großen Unterschiede in der akustischen Impedanz von Wandlermaterial und Luft. Sie führen zu erheblichen Signaldämpfungen. Durch die Verwendung von Kunststoff-Folien z.B. aus porösem Polypropylen kann dieser Unterschied stark reduziert werden. Im Beitrag werden die akustischen Eigenschaften dieser Folien untersucht und im Hinblick auf ihre Eignung für die Luftultraschall-Technik analysiert. T2 - DACH-Jahrestagung 2004 - ZfP in Forschung, Entwicklung und Anwendung CY - Salzburg, Österreich DA - 2004-05-17 KW - Luftschall-ZfP KW - Ultraschall-Wandler PY - 2004 UR - http://www.ndt.net/article/dgzfp04/papers/p11/p11.htm SP - 1 EP - 4 CY - Salzburg, Österreich AN - OPUS4-19059 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -