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Talks and Poster Presentations (without Proceedings-Entry):

E. Kaniusas, H. Pfützner, L. Mehnen, J. Kosel, J. Tellez-Blanco, E Mulasalihovic, T Meydan, M Vazquez, M. Rohn, C Malvicino, B Marquardt:
"Applicability of magnetostrictive amorphous trilayers for thermal sensors";
Poster: 16th International Conference on Soft Magnetic Materials (SMM16), Düsseldorf, Germany; 09-09-2003 - 09-12-2003.



English abstract:
Earlier [1, 2] we reported about fundamental applications of bilayers as thermal sensors which consist of a magnetostrictive layer (ML) fixed on a nonmagnetic metal counter layer (CL). Increasing the temperature, different thermal expansion coefficients κ of ML (e.g. an Fe-based amorphous ribbon with κML = 12.10-6 / K) and CL (e.g. Al with κCL, Al = 24.10-6 / K) yield a curvature change of the bilayer and due to κCL > κML compressive stress of constant sign in the whole volume of ML. The corresponding change of the ML-permeability μ is registered by a pick-up coil. A distinct drawback of the bilayers as thermal sensors is their cross-sensitivity to bending.
As an alternative, we have mentioned in [1] the concept of a trilayer. The target of this study is to discuss the trilayer performance in a closer way. The trilayer is built up by an ML fixed between two CLs or a CL between two MLs, the symmetric arrangement eliminating the sensitivity to bending in a distinct way. For high thermal sensitivity, κCL and κML should by strongly different and the ML should be preferably expressed to compression since compressive stresses in the ML induce stronger changes of μ than tensile ones.
The above requirements for high thermal sensitivity can be met by using CLs with κCL<κML which is given for Invar alloys. On the other hand, most other CLs show κCL > κML . In order to attain compression in the ML, they can be used with pre-compression of the ML.
First sensor prototypes were prepared from 30 mm long and 3 mm wide trilayers exhibiting 30 μm ML thickness and 100 μm CLs thickness (Al, Invar alloys with κCL, IN = 3.10-6 / K). The layers were connected by means of agglutination, the thickness of the glue layer being 10-20 μm (κGL=100.10-6 / K). Preliminary results show sensitivity values up to 0.5 % change of μ per K, trilayers with Al as CL being better than with Invar alloys.
Acknowledgments: This work was performed within the EU project B-SENS
(No. G5RD-CT-2002-00690).
[1] E.Kaniusas, L.Mehnen, H.Pfützner: Magnetostrictive amorphous bilayers and trilayers for thermal sensors. J.Magn.Magn.Mater. 254-255, 624-626 (2003).
[2] E. Kaniusas, H. Pfützner, L. Mehnen, J. Kosel, J.C. Téllez-Blanco, E. Mulasalihovic, T. Meydan, M. Vázquez, M. Rohn, C. Malvicino, B. Marquardt: Optimisation of sensitivity and time constant of thermal sensors based on magnetoelastic amorphous bilayers. Submitted for Journal of Alloys and Compounds, (2003).

Created from the Publication Database of the Vienna University of Technology.