Piezoceramic Composites
Composite Tubes, Composite Hemispheres, Composite Focal Bowls, Composite Disks
Piezoceramic composites combine a piezoelectric ceramic part and a filling polymer, bringing together the advantages of both materials. The composite materials provide an alternative to well-known all-ceramic components. In addition to its excellent adaptability to specific shapes, the polymer part offers numerous advantages over all-ceramic parts, including the following: Composites are characterized by their easy adaption to surrounding media with different acoustic impedance. This enables a wide range of applications in the area of >> medical technology, for example, in high-intensity focused ultrasound (HIFU) applications or for diagnostic imaging, such as in >> industrial applications like flow rate metering or non-destructive measurement. Composites enable higher ultrasound sensitivity and resolution.
Specifications for Composites
PI Ceramic composites are manufactured using the Dice & Fill method with a 1-3 arrangement, cut to individual pins. The dimensions and >> material can be selected according to the customer-specific >> piezoceramic components and can be produced as a composite. The choice of filling polymer is epoxy resin for rigid composites or polyurethane for flexible composite structures. The composites from PI Ceramic are currently in the prototype stage.
Piezo composites use the d33 effect and are characterized by a restriction in radial deflection due to the polymer filling. This leads to a low-coupling thickness resonator. The pin dimension of the composite determines the capacitance (C). The working principle corresponds to all-ceramics with the same design.
| Resonant frequency (thickness) f [kHz] | Thickness TH (mm) | Pin dimension PIN (mm) | Piezoceramic share of volume (%) | Resonant impedance I (Ω) | Electrical capacitance C* (nF) | Dielectric loss factor tan δ (x10-3) | Coupling factor keff (%) |
|---|---|---|---|---|---|---|---|
| 400 | 4.0 | 1.0 x 1.0 | 83 | <30 | 1.6 | <20 | >55 |
| 600 | 2.6 | 0.5 x 0.5 | 69 | <15 | 2.1 | <20 | >60 |
| 1500 | 1.1 | 0.4 x 0.4 | 69 | <5 | 5.0 | <20 | >55 |
| 2000 | 0.7 | 0.3 x 0.3 | 64 | <3 | 6.5 | <20 | >55 |
*1000 kHz
Prototype specifications for a 1-3 epoxy resin composite disc with OD 25 mm, made of piezo material PIC255
Example impedance curve for a 1-3 epoxy resin composite disc with OD 25 mm x TH 1.1 mm, pin dimension 0.4 x 0.4 mm, volume share 69 % made of piezo material PIC255 compared to a piezo disc with OD 25 mm x TH 1.4 mm made of piezo material PIC255
Customized Versions on Request
PI Ceramic has in-depth expertise, from selecting suitable materials to developing and manufacturing composites according to desired specifications and applications. In addition to the selection of composites according to the piezo components, the following parameters can be customized:
- Material
- Design
- Layout of the pins
- Electrodes
Composites can be manufactured from soft to hard >> PZT, as well as in various arrangements. Hence, in addition to the 1-3 variant, individual pins, such as the ceramic rows in the 2-2 arrangement, are available.
Electrodes and Contacting of Composites
The electrodes are applied to the finished composites using a sputtering process. In addition to copper-nickel (CuNi), other compounds such as gold (Au) are also possible. Both full-surface electrodes for broadband applications, for example, and individual electrodes can be manufactured. If contacting is desired, stranded wires or flexible printed circuit boards (PCBs) are glued to the composites.
Applications of Piezoceramic Components
As sensors, actuators, and in ultrasonic transducers, piezoceramic composites can replace solid piezoceramics in many applications.
- Sensor devices
- Hydroacoustics
- Water metering
- Non-destructive testing