Preparation method
The preparation method of piezoelectric composites is to uniformly decompose the inorganic piezoelectric material powder and mix into the thermoplastic high polymer, and then mix molding. Commonly used inorganic piezoelectric materials include piezoelectric ceramics such as lead zirconate titanate, PBTO 3 ; commonly used polymer matrix is PVDF and other fluororesizes.
Advantages
(1) The horizontal vibration is very weak, and the rechabrack is smaller;
(2) mechanical quality factor Q value low:
< P> (3) Bandwidth (80% ~ 100%);(4) The electromechanical coupling coefficient is large;
(5) high sensitivity, better signal-to-noise ratio PZT probe;
(6) in a large temperature range is stable;
(7) can process complicated probes, only simple cutting and filling technology; / p>
(8) sound speed, acoustic impedance, relative insulation constant and electromechanical coefficients are easy to change (due to these parameters);
(9) Easy to acoustic impedance Material matching (from water to steel);
(10) can be adjusted to adjust ultrasonic sensitivity by changes in ceramic volume.
Classification of piezoelectric material
piezoelectric material refers to a material having a piezoelectric effect, which means that the material generates a current under external force, or in turn to generate it under current. A functional material for power or deformation. It is widely used in transducers to achieve mutual conversion between mechanical energy and electrical energy. Since the fire brothers found in 1880, a variety of piezoelectric materials have been developed, which can be divided into five categories: 1 single crystal materials such as quartz, phosphoric acid, 2 ceramic materials, lead (PZT) ), Lead or the like of titanate; 3 polymer polymers such as polyvinyl chloride, 4 composite, such as PZT / polymer, etc., 5 glass ceramics, such as Tisro 3 , etc.. It can be seen from the above order that the piezoelectric material has undergone the process of developing a simple single crystal material present from the nature to the structure of the complicated composite material. The piezoelectric composite is made of a plurality of piezoelectric ceramics and polymers in a certain communication method, a certain volume mass ratio, and a certain spatial distribution, which can be used to increase the piezoelectric properties of the material.
0 -3 piezoelectric composite material
0-3 is the simplest piezoelectric composite, which is dispersed from discontinuous ceramic particles (0 dimension) The three-dimensional contact polymer matrix is formed. It has a lot of adaptability, can be made into thin slices, bats or wires, and even mold into the desired complex shape, but it is more difficult to poorer and performance is susceptible to various processes.
(1) 0-3 piezoelectric composite polarization is difficult to be due to polarization electric field intensity on the piezoelectric filler phase is much smaller than the external polarization electric field strength. In order to improve the polarization properties, conductive phases such as small amounts of carbon, germanium, and other substances can be added to the composite material to increase the conductivity of the polymer matrix, and other measures to improve piezoelectric ceramic phase resistivity can be used.
(2) An important parameter that is required to consider the piezoelectric phase is that the material is longer than C / A. C / A large piezoelectric phase can obtain a large spontaneous strain. The filled phase system is PZT, PBTIO 2 2 , (pb, bi) (Ti, Fe) O 3 , etc.
(3) Material performance is also closely related to the preparation method of the compound. High purity, uniform composites prepared by chemical methods have a significant effect on improved performance.