Important Life Lessons Piezo Plates And Blocks Taught Us

Piezoelectric ceramic transducers in the work of the destruction of the main mechanisms are the following types of insulation breakdown, piezoelectric ceramic of compressive strength is with the signal frequency and different thickness, for the electrode exposed to the edge of the oscillator, Without proper insulation, it is easy to cause edge discharge and damage to the vibrator, therefore, the electrical model piezoelectric discs should be coated with insulating resin to protect it. There are two commonly used methods,The first method is to coat thepiezoelectric ceramic discs transducer PZT with the horn and the back cover after clamping, the advantage of which is that is to the positioning of the mold and the assembly accuracy, the plastic jacket and the horn, electric ceramic, dry lid then close, the appearance is beautiful. The disadvantage is due to the injection molding temperature is high, it is easy to make the piezoelectric ceramic thermal depolarization, and requires large batches that small cost is too high,the second method that coat and horn of piezoelectric ceramic, which is back cover with adhesive dry connection, which is commonly used epoxy resin and poly-phthalid that is unitary system of adhesive, the adhesive curing at room temperature for about 2h4.The advantage of electrical model ultrasonic piezoelectric ceramic is that the assembly process is simple, free from batch restrictions, low cost, the entire assembly process at room temperature to prevent injection molding piezoelectric ceramics easy to depolarization defects. The disadvantage is the assembly accuracy and appearance of a bit less.Taking into account the second method is more appropriate. Stress damage Transducer vibrators of piezoelectric ceramic plate PZT chip are under stress during use. The piezoelectric ceramic has a compressive strength of 5.0×10.8 Pa, and its tensile strength is only about 8.0×10 -7 Pa. About transducer vibration, because the acceleration of piezo plate working crystal is too large, about the acceleration of 8.5 X 10 times the internal stress, if it exceeds this limit, the occurrence of stress damaged. If the stress is only caused by the electrostatic field, then the electrostatic field caused by stress damage is about 1.0 ~ 1.5 times the polarization voltage, that is 2.0 ~ 3.0 kv /mm; if the AC electric field, The reason of piezo element voltage for the dry resonance of amplitude will increase, in order to avoid causing stress damage, the effective value of the electric field can only be about 300vmm. The best resonant electric field of this transducer is 75 ~ 150 nrm.