Three elements and principles for high-voltage polarization of piezoelectric ceramics by high-voltage polarization device

Three elements and principles for high-voltage polarization of piezoelectric ceramics by high-voltage polarization device

Three elements

1. Polarized electric field

Only under the action of the polarized electric field, the electric domain of piezoceramics transducer can be aligned along the direction of the electric field, so it is the main factor in the polarization condition. The higher the polarization electric field, the greater the effect of promoting the arrangement of electric domains, and the more sufficient the polarization. Therefore, for thicker products, the polarization electric field is reduced accordingly, and the polarization effect can be achieved by increasing the polarization temperature and prolonging the polarization time. The polarization temperature of the MPD high-voltage polarization device can reach 260°C, and the boost time, that is, the boost time of the high-voltage power supply, is generally above 3s, 5s (classic value); the test time depends on the voltage level, generally above 60S (at 4000V ), the higher the voltage, the longer the test time.

2. Polarization temperature

Under the conditions of constanpoling electric field and poling time, when the poling temperature of piezoceramics components is high, the domain alignment is easier and the poling effect is better. In practice, when selecting the polarization temperature, it is better to use a higher temperature, because increasing the polarization temperature can shorten the polarization time and improve the polarization efficiency.

3. Polarization time

Polarization time refers to the heat preservation and pressure holding time required for porcelain piezo ceramics crystals to change from one equilibrium state to another. If the time is long, the electrical domain turns to be fully aligned, and it is beneficial to the relaxation of stress during the polarization process.

Polarization principle

Considering comprehensively, the determination of the polarization conditions should be based on the principles of giving full play to the piezoelectric performance, improving the yield and saving time. For materials with different components, the polarization conditions of underwater piezo tubes should be optimized through experiments under the guidance of the polarization process principle. At present, the MPD high-voltage polarization device adopts intelligent monitoring, which can observe the polarization process and generate the polarization curve of the sample. The operation is simple and the test data can be obtained.

Test Method for Static Bending Strength of Piezoelectric Ceramic Materials April 18, 2016 08:36 Source: Jinan Zhongchuang Industrial Testing System Co., Ltd. >> Enter the company's booth Popularity: 497

scope:

This standard specifies the test principle, test conditions, samples, test equipment and devices and test procedures for the static bending strength of piezoelectric ceramic materials.

  This standard is suitable for measuring the static bending strength of piezoelectric ceramic materials at room temperature.

Test principle:

The bending strength test adopts the three-point bending method. The sample is positioned between an indenter and two supports, the relative movement of the piezoceramics transducer componets and the support causes the sample to bend, and the bending load is applied to the sample by the testing machine until the sample breaks, and the critical load when passing the break , the size of the fixture and the sample, and calculate the static bending strength of the sample according to formula (1).

       Bb=1.5FL/bh^2 

In the formula:

Bb——Numerical value of static bending strength

F——The value of the maximum pressure when the sample breaks

L—the value of the distance between the sample supports

b—the value of the width of the sample

h—the value of the height of the sample

Selection of testing machine:

1. The piezoceramics transducer material should be equipped with a speed regulating device, and its loading rate should be controlled within the range of 4N/s, and the test force can be added and unloaded smoothly without impact

2. The relative error of the test force indication value is ±1%, and the relative variation of the test force should not exceed ±1%.

3. The test force can be divided into different ranges.

Selection of testing machine fixtures:

a) The support and indenter should not produce plastic deformation during the test, and the elastic modulus of the material should not be less than 200 GPa

b) The radius of curvature of the support and the indenter and the test span are shown in Figure 3. The width of the fixture should be greater than the width of the sample, and the surface roughness (Ra) of the part in contact with the sample should not be greater than 1.6um

c) The measurement error of the fixture span should not be greater than 0. 05 mm.