A1.3 - Detection of Coatings and Measurement of Coating Thickness on Technical Substrates using Surface Acoustic Waves in a Waveguide Configuration
- Event
- SENSOR+TEST Conferences 2009
2009-05-26 - 2009-05-28
Congress Center Nürnberg - Band
- Proceedings SENSOR 2009, Volume I
- Chapter
- A1 - Microacoustic Sensors
- Author(s)
- G. Lindner, M. Schmitt, K. Schmidt, H. Faustmann, S. Krempel, J. Schubert - Coburg University of Applied Sciences, Coburg, Germany
- Pages
- 36 - 40
- DOI
- 10.5162/sensor09/v1/a1.3
- ISBN
- 978-3-9810993-4-8
- Price
- free
Abstract
Surface acoustic waves turned out to be very sensitive to deposition layers on their propagation path on the solid substrate, which both influence the propagation velocity of the waves and their amplitude. In our approach, Lamb waves are excited on arbitrary technical substrates like metals, glass or plastics with a thickness of not more than the acoustic wavelength via interdigital piezoelectric transducers attached to the backside of the substrate. The performance of this approach was demonstrated with simple delay lines made of thin glass plates and with acoustic waveguides formed by parallel glass plates or a plastic tube, which will be covered by plastic films of different thicknesses on the inner surface. This concept allows an on-line monitoring of coverage layer formation on the inner wall of a liquid-filled conduit and the measurement of the layer thickness from outside. A sensitivity in the order of 1 ns time shift of the receiver signal per μm layer thickness has been achieved so far, which depends, however, on the type of material both of the substrate and the deposition layer.