Author, Institution: Vaida Vaškelienė, Kaunas University of Technology
Science area, field of science: Technological Sciences, Measurement Engineering, T010
Scientific Supervisor: Assoc. Prof. Dr. Reimondas Šliteris (Kaunas University of Technology, Measurement Engineering, T010)
Dissertation Defense Board of Measurement Engineering Science Field:
Prof. Dr. Arminas Ragauskas (Kaunas University of Technology, Technological Sciences, Measurement Engineering, T010) – chairperson
Prof. Dr. Darius Plonis (Vilnius Gediminas Technical University, Technological Sciences, Electrical and Electronics Engineering, T001)
Prof. Dr. Renaldas Raišutis (Kaunas University of Technology, Technological Sciences, Measurement Engineering, T010)
Senior Researcher Dr. Vykintas Samaitis (Kaunas University of Technology, Technological Sciences, Measurement Engineering, T010)
Dr. Mindaugas Tamošiūnas (University of Latvia, Latvia, Technological Sciences, Measurement Engineering, T010)
Dissertation defense meeting will be at Rectorate Hall of Kaunas University of Technology (K. Donelaičio 73-402, Kaunas)
The doctoral dissertation is available at the library of Kaunas University of Technology (Gedimino 50, Kaunas) and on the internet: V. Vaškelienė el. dissertation (PDF)
Annotation: There is a growing worldwide demand for non-destructive testing of objects at 200–500 °C, but commercially available ultrasonic transducers are not suitable for prolonged measurements over a wide temperature range, because a delamination of the electrodes from the piezoceramic and deformation of other parts of the ultrasonic transducers is observed as the temperature changes. The lack of information in the scientific literature on the strength of adhesion between the electrode and the piezoelectric material has led to a qualitative and quantitative assessment of the adhesion of silver and nickel electrodes to the Pz27 piezoelectric material and the joining technology of the individual parts of the ultrasonic transducer in this thesis. A prototype ultrasonic transducer suitable for use in prolonged non-destructive thickness testing over temperature cycles from 25 °C to 200 °C has been developed and tested. Metallic coatings were used for bonding, protection of the electrode from damage during soldering, and for reducing the stresses in the multilayer structure due to temperature exposure, thus helping to avoid delamination of the electrode from the piezoceramic. This ultrasonic transducer has been validated by the Belgian Atomic Research Centre as suitable for non-destructive testing for the detection of a defect in the wall of a nuclear reactor under extreme conditions (temperature of 200 °C, prolonged measurements in a lead-bismuth alloy).
December 2 d. 10:00
Rectorate Hall at Kaunas University of Technology (K. Donelaičio 73-402, Kaunas)
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