The principle of piezoceramics is that when pressure or tension is applied to the ceramic plate, an opposite polarity charge is generated at the two ends of the ceramic plate and an electric current is generated through the circuit. This effect is called the piezoelectric effect. If a transducer made of this type of piezoelectric ceramic is put into water, the sound waves will induce a charge at the ends of the transducer, which is the receiver of the sound wave. In addition, the piezoelectric effect is reversible. If an alternating electric field is applied to a piezocervite chip, the chip gets thinner and thicker from time to time, vibrating and emitting sound waves. Therefore, the problem of ultrasonic transmitter is solved.
Piezoelectric ceramic transducers are made of two materials: magnetostrictive metals and piezoelectric ceramics. The purpose of this paper is to design transducers for high power mechanical ultrasonic machining, so only piezoelectric ceramic transducers are discussed. As a kind of energy transmission network, piezoelectric ceramic transducer has the problem of energy conversion efficiency. The conversion efficiency is related to the transducer material, vibration form, structure of mechanical vibration system (including supporting mechanism) and the choice of working frequency. Therefore, in the design of ultrasonic transducers, various factors such as acoustic impedance, frequency response, impedance matching, acoustic structure, vibration mode and conversion material should be considered, as well as how to design and coordinate these factors to achieve the best value of electroacoustic conversion.
Piezoelectric ceramic transducer (PZT) is a kind of electronic ceramic material with piezoelectric characteristics. The main difference between PZT and typical PZT crystal without ferroelectric composition is that the crystal phase of PZT is ferroelectric grain. Because ceramics are polycrystalline aggregates with randomly oriented grains, the spontaneous polarization vector of each ferroelectric grain is also disoriented. Show the macro piezoelectric properties in order to make the ceramic, piezoelectric ceramic must after the burn in strong polarization in direct current field, transverse through multiple electrodes, thus the original disordered orientation polarization vector of preferred orientation in the direction of the electric field, electric field after eliminating, polarization of piezoelectric ceramic after processing will keep certain macroscopic residual polarization, so that the ceramic has a certain pressure.