Effect of piezoelectric phase on the density of 1 - 3 type piezoelectric composites

Since the its density of general piezoelectric material piezoelectric ceramics is often much higher than that of the non-piezoelectric phase (usually Polymer) the density of the material, so when the volume fraction of the piezoelectric phase increases, the density of the composite tends to the volume fraction of the piezoelectric phase.

The sound velocity of the l-3 composite material increases with the increasing of the volume fraction of the Pzt disc piezoelectric ceramic. However, when the volume fraction is small (less than 30%), the growth trend gradually decreases; when the piezoelectric phase volume fraction is greater than 80%, the growth trend gradually increases. When the piezoelectric phase volume fraction changes between 30% and 80%, the sound velocity of the composite material increases linearly. This is due to the need to overcome the large mass load as the volume fraction increases. The speed of sound is also just beginning to increase, but due to the action of the polymer, it finally begins to decline. Then it began to increase again.

The acoustic impedance is the product of the sound velocity and the density of the piezoelectric materials cost. It can be seen that when the volume fraction of piezoelectric phase is smaller than 80%, the acoustic impedance.which basically maintains a good linear trend; when the piezoelectric phase volume fraction is greater. 80% acoustic impedance growth trend becomes larger.

Effect of piezoelectric phase section is aspect ratio of composite.

In general, for a l-3 type piezoelectric composite of the same polymer, as long as the functional material .The PzT material has the same volume fraction, regardless of how the columns are arranged in the polymer, The relative dielectric constant of piezoelectric quartz transducer is relatively constant. However, studies have shown that when the piezoelectric phase cross section When it is square, its hydrostatic pressure is constant . sensitivity value of hydrostatic pressure is basically along with the piezoelectric phase.The aspect ratio of the section decreases and increases, and when the aspect ratio is greater than a certain value.The trend began to stabilize. Therefore, it is generally required that the cross-sectional column of the l-3type piezoelectric composite has an aspect ratio ,That is, the cross section is square.

Effect of width to thickness ratio

Medical ultrasonic transducers generally use the thickness stretching vibration mode of piezoelectric materials, it is generally piezoelectric phase.The small column has a square cross section. In terms of structure, in the thickness direction vibration mode, in order to suppress as much as possible.The other vibration modes (such as the radial high-order vibration mode) interfere with the thickness vibration mode and are guaranteed .A certain directivity of its width to thickness ratio should be less piezoelectric sensor acoustic pickups.

Preparation of 1 -3 Type Piezoelectric Composites

There are generally two methods for the preparation of a 1 type piezoelectric composite material,it is alignment perfusion method and cutting filling method.The process of the perfusion method is cutting the piezoelectric ceramic material, piezoelectric ceramic is an appropriate size. piezoelectric ceramic piece is arranged on the fixed bracket, and the fixed bracket is placed in the plastic drum,Filling the composite under vacuum solidifies at the high or low temperature, cutting off excess polymer and grinding to the right thickness with electrodes can be polarized.