Piezoceramic
As a piezoelectric ceramic such are ceramic materials referred to, which show the action of a deformation by an external force a charge separation. That is, if the material z. B. is pressurized and so deformed that electrically charged areas form either on the top or bottom or on opposite lateral surfaces. This is known as the direct piezoelectric effect. Conversely, a deformation can be caused by applying an electrical voltage and the resultant charge formation. This is known as the inverse piezoelectric effect.
The piezoelectric effect was discovered in 1880 by Pierre and Jacques Curie in quartz and Rochelle salt crystals; it is caused by the displacement of ions in the crystals. This effect is very small with natural materials, so improved ceramics, such as. B. lead zirconate titanate (PZT) developed, which is used today in piezo technology.
Applications
Piezo ceramics are used today in wide areas of technology. One of the best-known is probably the quartz oscillator as a clock in a quartz watch . One of the main applications for piezo ceramics is the manufacture of piezo actuators for fuel injection systems . Since 2000, around 10 million vehicles around the world have been equipped with such piezo injection systems. The advantage of such injection systems: very precise fuel metering and short response times. Up to now, actuators of this type have largely been used in diesel injection systems.
Otherwise piezoceramics are also used as transducers to generate ultrasound (for example in an ultrasonic cleaning device ) and in piezo loudspeakers to generate audible tones with high frequencies. Piezoceramics are also used as pickup systems for stringed instruments. The strings lie on the crystal and deform it when the string is struck or bowed. The resulting electricity is absorbed and fed to the amplifier.
Their property of charge separation during deformation is also used in piezoelectric sensors to measure mechanical parameters such as forces and accelerations. The problem here is that the charge degrades over time, which is why piezoceramic force gauges can only be used for short-term measurements.
Individual evidence
- ↑ Dagmar Hülsenberg: Ceramics. How an old material becomes ultra-modern . In: acatech, TU Ilmenau (ed.): Technology in focus. Data, facts, background . Springer Vieweg, Berlin, Heidelberg, Ilmenau 2014, ISBN 978-3-642-53882-7 .