|History of piezoelectric ceramics
Piezoelectric ceramic is a functional ceramic material that can transform mechanical energy and electrical energy into one another. The piezoelectric effect is a positive piezoelectric effect when the medium is subjected to mechanical pressure, even if the pressure is small as the sound wave vibration is small, the shape changes such as compression or elongation can be generated, causing the dielectric surface to live. Conversely, if the electric field is applied, the medium will produce mechanical deformation, which is called inverse piezoelectric effect.
In 1880, the French Curie brothers discovered the "piezoelectric effect". In 1942, the piezoelectric ceramic barium titanate was made in the United States, the former Soviet Union and Japan. In 1947, the barium titanate pickup - piezoelectric ceramic device was born. In the early 50s, another kind of piezoelectric ceramic material, which was much better than barium titanate, was successfully developed. Since then, the development of piezoelectric ceramics has entered a new stage. From 60s to 70s, piezoelectric ceramics were constantly improved and perfected. For example, the ternary and quaternary piezoelectric ceramics based on lead zirconate titanate have emerged as the times require. These materials are excellent in performance, simple in manufacture, low in cost and wide in application.
Since the late 80s, the relaxor ferroelectric ceramic materials have been developed. On this basis, the single crystal material of the relaxor ferroelectrics has been developed successfully, which lays a foundation for the three-dimensional ultrasonic imaging. At present, nanotechnology has been applied to piezoelectric materials manufacturing technology has made new breakthroughs.
At present, the world is vigorously developing lead-free piezoelectric ceramics to protect the environment and pursue health. It is expected to form industrial production after 2008.
Application of piezoelectric ceramics
The piezoelectric igniter, movable X-ray power supply and projectile detonating device can be manufactured by utilizing the characteristics of piezoelectric ceramics which convert external force into electric energy。 Using two piezoelectric ceramic pillars 3 mm in diameter and 5 mm in height instead of ordinary flint, a gas electronic lighter can be made that can be continuously lighted tens of thousands of times。 Using piezoelectric ceramics to convert electrical energy into ultrasonic vibration, it can be used to explore the position and shape of underwater fish, nondestructive testing of metal, ultrasonic cleaning, ultrasonic medical treatment, and all kinds of ultrasonic cutter, welding device and soldering iron, plastic and even metal processing。
The sensitivity of a piezoelectric ceramic to the external force makes it even sensitive to the disturbance of the wings to the air over a dozen meters outside and converts extremely weak mechanical vibration into an electrical signal. This characteristic of piezoelectric ceramics can be used in sonar system, weather detection, telemetry environmental protection, household appliances and so on.
Submarine diving into the deep sea is equipped with sonar systems called underwater scouts. It is an indispensable equipment for underwater navigation, communication, reconnaissance of enemy ships, and the cleaning of enemy cloth mines. It is also a powerful tool for developing marine resources. It can detect the fish and explore the topography and geomorphology of the seabed. In this sonar system, there are a pair of bright "eyes" - piezoelectric ceramic underwater transducer. When the acoustic signal emitted by the acoustic transducer meets a target, the reflection signal is generated, which is received by another receiver of the receiver type underwater acoustic transducer, and the target is found. At present, piezoelectric ceramics are one of the better materials for making underwater acoustic transducers.
In medicine, the doctor puts the piezoelectric ceramic probe into the body's inspection site, sends out ultrasonic wave after electricity, and sends the echo after the body meets the human body. Then the echo is received and the doctor can understand the internal condition of the human body.
In industry, there are piezoelectric ceramic elements in the geological detector, which can be used to judge the geological condition of the stratum and find out the underground mineral deposits. There is a transformer in the TV set - voltage and ceramic transformer. It is smaller in volume and less in weight. The efficiency can reach 60% to 80%. It can withstand the high pressure of 30 thousand volts. It keeps the voltage stable and completely eliminates the defects of the fuzzy distortion of the TV image.
In the aerospace field, piezoelectric gyros made by piezoelectric ceramics are the rudders of spacecrafts and satellites that fly in space. Depending on the "rudder", the spacecraft and satellites can ensure their established position and route. The small and exquisite piezoelectric gyroscope has high sensitivity and good reliability.
A toy made of piezoceramic buzzer in the belly of a toy puppy produces a realistic and interesting voice.
Piezoelectric ceramics are more and more widely used in automobiles. A simple piezoceramic actuator is installed in the brake piston of the car to apply the "jitter" frequency to the support plate of the internal brake, which effectively inhibits the vibration of the sharp noise, and thus can be used in the condition of temperature and humidity change and the normal wear of the brake system.
Piezoelectric ceramics can also be used as piezoelectric ceramic detonation sensors, ultrasonic sensors and accelerometers. Piezoelectric ceramics are currently in the forefront of the development of fuel injectors for automotive fuel systems.
With the development of high and new technology, the application of piezoelectric ceramics will be more and more extensive. In addition to the high-tech field, it is more for people's daily life to create better life for people.