Q: What is a piezoelectric ceramic chip?A: Piezoelectric ceramic chip is the core component of the vibrating liquid level switch. It makes the meter probe vibrate at the resonance frequency and receive the signal. Through the processing and analysis of the intelligent circuit unit, it outputs a switch signal to judge the existence of the material.The quality of piezoelectric ceramics is directly related to the service life of the vibrating liquid level switch. If a piezoelectric material with poor temperature characteristics is selected at a higher operating temperature, the vibration of the level switch will be quickly weakened, and misoperation will often occur, or the piezoelectric ceramic may be damaged, and the vibration switch will fail, making it impossible to detect or judge the existence of the material , Thereby affecting normal production.Since the quality of piezoelectric ceramics has such a great influence on the level switch in a high-temperature environment, what factors should be considered when choosing piezoelectric ceramics for high-temperature vibrating level switches?As we all know, as a new type of functional ceramic material, piezoelectric ceramics have piezoelectric effect and can convert mechanical energy and electrical energy into each other.The reason why piezoelectric ceramics have positive and negative piezoelectric effects is that they have spontaneous polarization behavior. After these spontaneous polarizations are artificially polarized and arranged forcibly, residual polarization still exists in the ceramics.If the polarization intensity can be changed under the action of the external environment (such as pressure or electric field), the ceramic will have a piezoelectric effect.Based on this, the performance parameters of piezoelectric ceramics usually include dielectric constant, piezoelectric constant D, electromechanical coupling coefficient kp, quality factor Qm, Curie temperature* (Tc), etc.*The Curie temperature, also called the magnetic transition point, refers to the temperature at which the spontaneous magnetization in a magnetic material drops to zero, and it is also the critical point at which ferromagnetic or ferrimagnetic materials transform into paramagnetic materials.Therefore, the above parameters should be considered when selecting piezoelectric ceramics for high-temperature vibration level switches.First of all, temperature has the greatest impact on the performance of piezoelectric ceramics. Piezoelectric ceramics have a limit temperature, which is the Curie temperature mentioned above. When the temperature reaches this limit temperature, the piezoelectric ceramic will lose its piezoelectric properties.In addition, as the temperature increases, some electrical parameters of the piezoelectric material will be further reduced, affecting the output sensitivity of the sensor and worsening the low-frequency response of the sensor.The safe working temperature of piezoelectric ceramics is generally between 0 and 1/2 Curie temperature. However, due to the complex application conditions of liquid level switches, especially under high temperature conditions, the performance requirements of piezoelectric ceramic materials are higher.Therefore, in the selection of piezoelectric ceramics that work in harsh environments such as high temperatures, in order to obtain a wider operating temperature range, piezoelectric materials with a higher Curie temperature and better thermal stability should be selected as much as possible.Secondly, the dielectric constant, piezoelectric constant and electromechanical coupling coefficient of piezoelectric ceramics should be as large as possible.
Finally, in order to improve the temperature stability and time stability of the material, piezoelectric materials containing “variable” additives should also be selected, so that the material has both “soft” and “hard” properties, and has stronger stability. After in-depth research on the application of piezoelectric ceramics and many high-temperature tests, Huikeda engineers chose piezoelectric devices suitable for high-temperature working conditions, which provided reliable guarantee for the stable operation of Vacorda vibrating liquid level switches under high-temperature working conditions. . The stable performance of Huikeda instruments in practice has also been praised by users.
Post time: 21-09-21