Subproject C8
Polarization Determination of Integrated Piezoceramics as Part of Process Control and Non-destructive Device Evaluation
Project Managers:
Prof. Dr.-Ing. habil Gerald GerlachTechnische Universität Dresden
Fakultät Elektrotechnik und Informationstechnik
Institut für Festkörperelektronik
Professur für Ferstkörperelektronik (IFE)
01062 Dresden
Telephon: +49-(0)351 / 463 32077
Telefax: +49-(0)351 / 463 32320
E-Mail: gerald.gerlach@tu-dresden.de
Dr. rer. nat Andreas Schönecker
Fraunhofer-Institut für Keramische Technologien und Systeme IKTS
Winterbergstraße 28
01277 Dresden
Telephon: +49-(0)351 / 2553 508
Telefax: +49-(0)351 / 2554 136
E-Mail: andreas.schoenecker@ikts.fraunhofer.de
Objetctive
The investigation is aimed at the creation of a non-destructive and in-situ method allowing for the dermination of the polarisation distribution in piezoceramic elements integrated in composite structures. The approach uses thermal waves with different penetration depths defined by the modulation frequency. The spectrum of generated pyroelectric current and the phase shift between the thermal wave and the pyroelectric current as well as the time dependence of the pyroelectric current will be measured ans used for the reconstruction of the depth profile of polarisation by a mathematical procedure. Additionally, the method aneables the analysis of structural defects like parasitic layers and delaminations at the interface to the piezoceramic.
Tasks of the second funding phase
The following tasks will be investigated in the second funding phase
AP 1. Design and prepartation of test samples
| Composite samples with integrated piezoelectric elements are designed and prepared based on LTCC multilayer ceramic, thermoplastic fibre composites and metal sheets. The samples are transferred to the other work groups for basic measurements. |
AP 2. Design and building a new LIMM-measuring set-up
| The LIMM measurement system generates defined thermal waves and measures the induced pyroelectric current. A new set-up will be developed and introduced. |
AP 3/4. Identification of thermal and thermo-mechanical materials data and reconstruction of polarization profiles
| The reconstruction of the polarization profile requieres a 1-dimensional layer model, which requires realistic input data of thermal conductivity, heat capacity, thermal expansion coefficients. These data will be measured. Based on that, the polarization profiles of the integrated piezoelectric elements will be calculated. |
AP 5. Derivation of stored, total polarization of integrated piezoceramic elements
| The whole amount of bonded polarization charge is measured by heating the piezoceramic element above Curie-temperature. This measurement is destructive, but should allow a consistent consideration of charge storing at polarization and charge release during processing and operation (degradation). |
AP 6. Use of integrated resistance heater to control the polarization status of integrated piezoceramics
| Thermal waves will be generated by an integrated heating element. The pyroelectric effect is used to control the remaining polarization in correlation with processing and functional operation. |
