Industrial applications of piezoelectric ceramics
Piezoelectric ceramics are new high-tech inorganic non-metallic functional materials. With the continuous in-depth research and improvement of materials and processes, the application of piezoelectric ceramics technology is becoming more and more extensive. Piezoelectric materials have been widely used in the fields of sensors, actuators, transducers, non-destructive testing and communication technology as mechanical, electrical, sound, light and heat sensitive materials. With the development of high-tech, the application of piezoelectric ceramics will become wider and wider.
The base material is a key factor in determining product performance. At present, piezoelectric ceramic materials with high temperature resistance, high pressure resistance, high sensitivity and low loss are the recognized research and development directions of the global industry. Although there are many researches on lead-free piezoelectric ceramic materials, they have not yet reached the practical level. level, and cannot replace the existing lead-containing piezoelectric ceramics in the short term.
The advent of the era of mobile Internet and the emergence of the demand for small and ultra-thin terminal equipment, high reliability and low power consumption have provided a good opportunity for the application and development of piezoelectric ceramic products. Especially the laminated products can be made into piezoelectric receivers, speaker speakers, mobile phone back shell sound systems, screen vibration sound systems, MEMS microphones, piezoelectric high-frequency compensation transducers, etc. Traditional products are the best choice for mobile communication terminals. Thinner products are the trend of the future.
Piezoelectric ceramic devices are not only widely used in industrial and civilian products, but also have a large number of applications in the military. For example, piezoelectric ceramics are made into underwater acoustic transducers, which can be used as a pair of bright "eyes" for nuclear submarines, which can smoothly carry out underwater navigation, communication, reconnaissance of enemy ships, and cleaning of enemy mines. Piezoelectric fuzes can accurately ignite and detonate armor-piercing bombs and other lethal weapons; piezoelectric micro-displacement actuators are an indispensable key component in precision positioning systems; piezoelectric gyroscopes made of piezoelectric ceramics are indispensable in aerospace. The missing "helmsman" and so on.
Piezoelectric ceramics are used in a wide range of applications. Some of the main applications are listed below:
(1) Electroacoustic transducer
Electroacoustic transducers are mainly used in various alarms, bone conduction microphones, receivers, piezoelectric speakers, etc.
The alarm can be used for all kinds of home appliance alarms, smoke alarms, car burglar alarms, fire protection, personal safety alarms, etc. The bone conduction microphone converts the voice signal of the vibration of the ear bones into electrical signals, so as to convert the voice signal into an electrical signal. A new generation of anti-noise transmitters transmitted to the receiving end, such Bluetooth headsets are currently available in Japan; piezoelectric receivers and speakers have the characteristics of ultra-thin and low power consumption.
Electroacoustic transducers used in general alarms have not yet replaced products, and still have a large market, while high-sound pressure alarms in special environments will have a larger increase in alarms; With the development of power consumption, piezoelectric receivers and speakers will become the best choices for portable terminals, and have good market prospects.
(2) Ultrasonic transducer
Ultrasonic transducers are suitable for ultrasonic motors, ultrasonic atomization, sonar, ultrasonic cleaning, ultrasonic welding, ultrasonic beauty, ultrasonic processing, ultrasonic breeding, telemetry and remote control, traffic monitoring, ranging, leak detection, flow and heat detection, robotic imaging Information collection, etc.
There are currently no alternative products for ultrasonic transducers, and its application market is developing steadily. In particular, the northern heating will implement metering and charging, so the heat sensor will have a large market.
(3) Underwater acoustic transducer
In naval battles, the most difficult thing to deal with is submarines, which can submerge in the sea for a long time and attack ports and ships unknowingly, causing great headaches for the enemy. How to find enemy submarines? You can't rely on your eyes, nor can you use radar, because electromagnetic waves will attenuate sharply in seawater and cannot transmit signals effectively. The detection of submarines relies on sonar—underwater ears. Piezoelectric ceramics is the material for making sonar. It emits ultrasonic waves, which are reflected back when encountering submarines. After being received and processed, the azimuth and distance of enemy submarines can be measured. This is an indispensable application of national defense technology, and its development lies in increasing the transmitting power and improving the receiving sensitivity, so that the detection distance can be fully improved.
(4) Piezoelectric vibration damping system
Piezoelectric vibration reduction systems can be divided into passive vibration reduction and active vibration reduction. Passive vibration reduction is to prepare a layer of resistance film on the surface of piezoelectric ceramics, piezoelectric ceramics convert vibration or noise into electrical energy, current is converted into heat energy through the resistance film, and the heat energy is exported through the heat conductor to play the role of vibration reduction and noise reduction; Active vibration reduction is to compound piezoelectric ceramics on the object to be vibration-reduced, convert its vibration waveform into a corresponding voltage signal, and perform reverse vibration through phase adjustment and amplification to the transducer coupled to the vibrating element, thereby Suppress vibration to achieve the purpose of vibration reduction. There are not many applications of this type at present, and most of them are still in the experimental stage, such as computer noise reduction and vibration reduction systems required by some military devices, etc., and will have good market prospects.
(5) Piezoelectric actuator
Piezoelectric ceramic actuating elements are divided into monolithic lateral expansion type, bending type, thickness laminated type, lateral laminated type, tube type, cymbal type, etc. They are widely used in aerospace, common rail injectors, high-speed intelligent valves, nanometer Positioning, micromachining, laser gyro micro-displacement compensation system, deformation control of deformable mirror, hard disk drive (magnetic head positioning), optical instrument (optical axis adjustment, focus adjustment), piezoelectric pump, knitting jacquard system, blind reader, etc. Piezoelectric actuators are technically difficult, and currently only a few companies in the world can do them. China has a slow start. At present, computer jacquard knitting machines have applied piezoelectric actuators in large quantities. , Pante Electric Ceramics has become one of the manufacturers that can manufacture a full range of piezoelectric actuators, and domestic applications are gradually taking shape, and it is expected to form a larger market in the future.
(6) Piezoelectric energy harvesting
Piezoelectric blankets (Japan has used piezoelectric blankets to power subway signs), piezoelectric shoes (place piezoelectric energy collection devices on the soles of the shoes to generate electricity when walking, which can be used for battery charging and shoe body heating, etc.), Muscle power generation (power supply for electronic devices implanted in the body), hybrid and full electric vehicle vibration energy harvesting (which can not only improve the vibration reduction effect, but also prolong the energy saving by feeding the collected electric energy into the battery), ocean wave power generation, etc. Piezoelectric ceramic energy harvester is used as a permanent power source for bioelectronic devices. This project has been reported, and domestic research institutions have begun to study it, which will save patients with implanted electrical devices from the pain of changing batteries; the recovery of automobile vibration energy is also It will become an indispensable part of all-electric and hybrid vehicles; my country has a long coastline, and wave power generation will also become the cleanest and lower-cost new energy source.
(7) Piezoelectric frequency device
Resonators, filters, traps, etc., made of the resonant characteristics of piezoelectric ceramics, are used for the generation and processing of frequency signals. Commonly used, frequency processing devices such as filters are rapidly decreasing, so its market is in a rapid shrinking stage.
(8) Piezoelectric transformer
Piezoelectric transformers are mainly used for small current, high voltage power supplies. The main application object of the original research and development was the backlight power supply of liquid crystal displays such as notebook computers, but now most of them have used LED backlights and no longer need high-voltage and low-current power supplies, so now only some small electric batons and negative ion generators are used. large application market.
(9) Piezoelectric detonation ignition element
The armor-piercing projectile fired by the anti-tank gun would immediately explode upon contact with the tank, shattering the tank. This is because the warhead is equipped with piezoelectric ceramics, which can convert the strong mechanical force when they collide into an instantaneous high voltage, and explode a spark to detonate the explosive. Now gas stoves and lighters are also made of piezoelectric ceramics. As long as you press the ignition button with your finger, the piezoelectric ceramics on the lighter can generate high voltage, form electric sparks and ignite the gas, and can be used for a long time. Therefore, piezoelectric lighters are not only easy to use, safe and reliable, but also have a long life. For example, a lighter made of lead titanate piezoelectric ceramics can be used more than 1 million times. At present, there is no better alternative product for detonating ignition components, and the application market is steadily rising.
