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A porous piezoelectric ceramic and its manufacture method

An electric ceramic and pore pressure technology, which is applied in the manufacture/assembly of piezoelectric/electrostrictive devices, piezoelectric/electrostrictive/magnetostrictive devices, circuits, etc., can solve the problem of reducing the imaging resolution of transducers, The production process is complex and the production cost is high, and the effect of low production cost, simple preparation process and low cost is achieved.

Inactive Publication Date: 2008-10-22
TSINGHUA UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Such a large impedance mismatch leads to a large energy loss of the ultrasonic signal at the interface between the piezoelectric ceramic and human tissue or water, which seriously reduces the imaging resolution of the transducer
The 1-3 structure piezoelectric composite material composed of piezoelectric ceramics and polymers has a low acoustic impedance, which can improve the acoustic impedance matching of the transducer. It is also the most widely studied and most practical piezoelectric composite material. , but the manufacturing process of this type of composite material is complex and the production cost is high

Method used

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  • A porous piezoelectric ceramic and its manufacture method
  • A porous piezoelectric ceramic and its manufacture method
  • A porous piezoelectric ceramic and its manufacture method

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preparation example Construction

[0022] The invention provides a method for preparing porous piezoelectric ceramics with a gradient change in porosity, which is carried out according to the following steps:

[0023] 1) The piezoelectric ceramics and the pore-forming agent are prepared into mixed powders according to different volume ratios, and the pore-forming agent accounts for 0 to 50 vol% of the total volume of the mixed powder; in order to prepare a more uniform powder, when preparing the mixed powder, at least grind Half an hour; and adding several drops of polyvinyl alcohol aqueous solution with a content of 5wt% in the mixed powder as a binder to facilitate subsequent compression molding;

[0024] 2) Lay mixed powders of different proportions in the mold layer by layer in the order of gradient change;

[0025] 3) Under the pressure of 80-120MP, the powder in the mold is compression-molded with a tablet press machine;

[0026] 4) Put the molded sample into a latex sheath and immerse in the oil body, a...

Embodiment 1

[0031] Commercially available lead zirconate titanate (PZT) powder (Japan Sakai Chemical Industry Co., Ltd., Zr / Ti molar ratio is 0.516 / 0.484, average particle size is 0.97 microns) and polymethyl methacrylate (PMMA) powder (Japan Wako A chemical company with an average particle size of 34-76 microns and a density of 1.22 g / cm 3 , with a melting point of 160°C) as raw materials, respectively proportioning 3 kinds of mixed powders such as 10vol% PMMA, 30vol% PMMA, and 50vol% PMMA, and pure PZT powder and the above-mentioned 3 kinds of mixed powders, etc. The order of increasing content is placed in the mold. After compression molding, cold isostatic pressing, and heat preservation at 250°C, the porosity is 3.4% / 9.7% / 21.7% / 36.7%. Porous PZT piezoelectric ceramics, the microstructure of which is as follows image 3 shown. It can be seen from the figure that there are 4 layers of porous piezoelectric ceramics, the thickness of each layer is about 0.5 mm, and the total thickness ...

Embodiment 2

[0033] Commercially available PZT powder (Japan Sakai Chemical Industry Co., Zr / Ti molar ratio is 0.516 / 0.484, and the average particle diameter is 0.97 micron) and carbamide (Urea) powder (Sichuan Chemical General Plant, the average particle diameter is 0.85 micron) ~2.8mm, density 1.34g / cm 3, with a melting point of 132.7°C) as raw materials, respectively proportioning 3 kinds of mixed powders such as 10vol% Urea, 30vol% Urea, and 50vol% Urea. Die, cold isostatic pressing, heat preservation at 200°C, and sintering at 1200°C to prepare porous PZT piezoelectric ceramics with a gradient change of porosity of 6.3% / 21.7% / 32.8%. There are 3 layers in total, and the thickness of each layer is between About 0.33 mm, the total thickness is about 1.0 mm.

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Abstract

The invention relates to a porous piezoelectric ceramic and relative production. Wherein, it uses organic as holing agent to hole the piezoelectric ceramic; changing the content of holing agent from layer to layer to from the porous piezoelectric ceramic with composite and gradient changeable hole rates; the content of holing agent is 0-50vol%; the hole rate is 3-50%; the layers of product is 3-5, while the thickness of each layer is 0.2-0.5mm and the total thickness is 1-2mm. the invention has the advantages that it increases the hole rates along thickness direction, to obtain decreased sound resistance whose gradient change can avoid loss of electric signal at the interface between piezoelectric ceramic and human or water, to improve the resolution of heat exchanger. Compared with 1-3 structure piezoelectric composites, the invention has simple method and lower cost.

Description

technical field [0001] The invention belongs to the field of porous ceramics, and relates to a method for preparing porous piezoelectric ceramics with gradient porosity changes using organic matter as a pore-forming agent, especially including piezoelectric ceramic devices applied to medical imaging systems and underwater sonar detectors. Background technique [0002] An important aspect of piezoceramic applications are ultrasonic transducers for medical imaging or hydroacoustic transducers for underwater sonar detection. When the piezoelectric material is subjected to an external pulse electric field, due to the inverse piezoelectric effect, the piezoelectric material will deform and oscillate accordingly, and emit ultrasonic waves of the same frequency. Similarly, when the piezoelectric material receives ultrasonic waves from the outside, it is excited by the piezoelectric effect and generates a corresponding electrical signal. The acoustic impedance of piezoelectric cera...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L41/187H01L41/083H01L41/24C04B35/472C04B35/622C04B35/632H10N30/853H10N30/093H10N30/50
Inventor 李敬锋张海龙
Owner TSINGHUA UNIV