Views: 3 Author: Site Editor Publish Time: 2018-11-20 Origin: Site
(1) Positive piezoelectric effect
If a pressure F is parallel to the direction of polarization which is applied to the ceramic sheet, the ceramic sheet is compressed, the polarization is reduced, and the free charge of piezoelectric ceramics originally absorbed is released, and a discharge phenomenon occurs. When F is removed, the piezo ceramic sheet returns to its original state, the polarization intensity becomes larger, and some free charges are adsorbed, and charging phenomenon occurs. This phenomenon of mechanical power transformation, or the conversion of mechanical energy into electrical energy is called the positive piezoelectric effect. (2) About inverse piezoelectric effect, If an electric field of the same direction as the polarization is applied to the ceramic sheet. The polarization is increased and the piezo ceramic sheet is elongated and deformed. Otherwise, the deformation is shortened. This phenomenon of conversion from electricity to mechanical motion, or from electrical energy to mechanical energy is called the inverse piezoelectric effect.
The piezoelectric principle of soft materials piezo disc crystal lies in the existence of spontaneous polarization and ferroelectric domains in piezoelectric ceramic structures; the polarization state (including domain state) is changed by external action (applied force or electric field), and energy conversion is realized to exhibit pressure of electrical effect.
The manufacturing process of sensitive piezoelectric ceramics are to obtain piezoelectric ceramics with good performance, and it is necessary to master its manufacturing process. The change in process conditions has a great influence on the piezoelectric properties. Therefore, we must understand the inherent laws of piezoelectric ceramics, design a reasonable production process, and strictly control its operation process.
Drying is to not affect the accuracy of the ingredients, and the water-containing raw materials must be dried and dehydrated. It is usually dried in an electric drying oven. The temperature is 110~120°C, and the time is not less than 4 hours until there is no moisture. Chemical analysis is the production of piezoelectric ring crystal in large quantities. The quality of each batch of purchased raw materials may vary depending on the manufacturer or batch of the manufacturer . Therefore, the purity or impurities should be sampled and tested to determine the particle size to ensure the performance of the piezoelectric ceramic.
There are usually two methods for formulating Pzt ceramic transducer materials: 1) Calculating the formulation ratio from the weight ratio of raw materials 1 Write the chemical formula of the formulation,molecular formula, purity and molecular weight (mol mass) of the raw materials used. Calculating the number of moles of xi as the raw material in the amount required for each raw material, Mi is its mol mass, xiMi is its mass, Pi is its purity, total mass of formula; W is the total amount of ingredients. This method is suitable for the case where the additive is given in weight percent in the formulation. Calculating the formula from the molar ratio of raw materials 1 Writing the chemical formula of the formula.2.Writing the molecular formula, purity, and molecular weight (mol mass) of the used (i=1, 2,...,n) 3 Use the following formula to calculate the amount of each raw material required. (2) where X is the total number of moles of the ingredients, the others are the same as above. This method is relatively simple to calculate, especially when the additive is given in mol percentage in the formulation. (2) Weighing calculation, weighing must meet the following requirements.
1.The weighing balance of electronic transducer piezo ceramics must have a certain precision. In mass production, the 0.1% gram precision balance is used for the bulk material and the 0.01% gram precision balance for the small material. Calibrate the zero point before weighing.Weighing requires both small error and fast speed to reduce the error caused by the raw material absorbing moisture in the air. Weighing and feeding according to the order of large material, small material and large material to ensure the uniformity of small materials in mixing. Strictly prevent all raw materials from being miscalculated, misjudged, or misplaced, and must be carefully checked and strictly checked.
2.Mixing and crushing:
