Abstract
The design and fabrication of lithium niobate piezocomposite transducers aims to achieve high-temperature ultrasonic NDT measurements at 400ºC. In this paper, three aspects are investigated: exploring design parameters at room
temperature by a comparison of experimental and modelled results for lithium niobate piezocomposites with an epoxy matrix; high-temperature electromechanical testing of lithium niobate piezocomposites with a cement matrix; and fabrication and testing of a high-temperature transducer operating at 400ºC for defect detection.
The piezocomposites were made with a 1-3 structure using a y/36º-cut lithium niobate single-crystal material. The typical piezocomposite thickness was 1 mm, with a pillar width of 0.4-0.8 mm, a kerf width of 0.5 mm, a volume fraction
of lithium niobate of 30-40% and a pillar aspect ratio (pillar height to pillar width) ranging from 1 to 6. The operating frequency of the samples was between 1 MHz and 4 MHz.
The results of the lithium niobate piezocomposite with an epoxy matrix and pillar aspect ratios of 3, 4 and 6 indicated that a high coupling coefficient kt
should be achievable, even with a low pillar aspect ratio. The piezocomposite
material was heated in air to 400-500ºC over several thermal cycles and showed good stability of the electromechanical impedance spectrum. A 13 x 13 mm2
transducer with an operating frequency of 3 MHz was used to demonstrate the
detection of an artificial defect in a steel block using a high-temperature couplant on a hot plate at 400ºC.
temperature by a comparison of experimental and modelled results for lithium niobate piezocomposites with an epoxy matrix; high-temperature electromechanical testing of lithium niobate piezocomposites with a cement matrix; and fabrication and testing of a high-temperature transducer operating at 400ºC for defect detection.
The piezocomposites were made with a 1-3 structure using a y/36º-cut lithium niobate single-crystal material. The typical piezocomposite thickness was 1 mm, with a pillar width of 0.4-0.8 mm, a kerf width of 0.5 mm, a volume fraction
of lithium niobate of 30-40% and a pillar aspect ratio (pillar height to pillar width) ranging from 1 to 6. The operating frequency of the samples was between 1 MHz and 4 MHz.
The results of the lithium niobate piezocomposite with an epoxy matrix and pillar aspect ratios of 3, 4 and 6 indicated that a high coupling coefficient kt
should be achievable, even with a low pillar aspect ratio. The piezocomposite
material was heated in air to 400-500ºC over several thermal cycles and showed good stability of the electromechanical impedance spectrum. A 13 x 13 mm2
transducer with an operating frequency of 3 MHz was used to demonstrate the
detection of an artificial defect in a steel block using a high-temperature couplant on a hot plate at 400ºC.
| Original language | English |
|---|---|
| Pages (from-to) | 193-199 |
| Number of pages | 7 |
| Journal | Insight - Non-destructive Testing and Condition Monitoring |
| Volume | 57 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - Apr 2015 |