阅读说明：本技术 一种掺杂改性钪酸铋-钛酸铅-铁酸铋三元体系压电陶瓷及其偶极子发射换能器 (Doped modified bismuth scandate-lead titanate-bismuth ferrite ternary system piezoelectric ceramic and dipole transmitting transducer thereof ) 是由 杨长红 黄世峰 冯超 钱进 张晓芳 林秀娟 刘芬 程新 于 2020-12-18 设计创作，主要内容包括：本发明公开了一种掺杂改性钪酸铋-钛酸铅-铁酸铋三元体系的压电陶瓷,该陶瓷的化学通式为,其中0.30≤x≤0.33,0.05≤y≤0.10,0.02≤a≤0.05,0.01≤b≤0.03,0.01≤c≤0.03,采用金属氧化物为原料,通过固相反应法制备该压电陶瓷。本发明还公开了基于该压电陶瓷的偶极子发射换能器,换能器在空气中的谐振频率约为2～3kHz,可耐200℃的高温及50MPa的高静水压。(The invention discloses a piezoelectric ceramic doped with a modified bismuth scandate-lead titanate-bismuth ferrite ternary system, which has a chemical general formula Wherein x is more than or equal to 0.30 and less than or equal to 0.33, y is more than or equal to 0.05 and less than or equal to 0.10, a is more than or equal to 0.02 and less than or equal to 0.05, b is more than or equal to 0.01 and less than or equal to 0.03, and c is more than or equal to 0.01 and less than or equal to 0.03, and the piezoelectric ceramic is prepared by a solid-phase reaction method by using metal. The invention also discloses a dipole transmitting transducer based on the piezoelectric ceramic, wherein the resonant frequency of the transducer in the air is about 2-3 kHz, and the transducer can resist the high temperature of 200 ℃ and the high hydrostatic pressure of 50 MPa.)

1. The piezoelectric ceramic doped with the modified bismuth scandate-lead titanate-bismuth ferrite ternary system is characterized by having the chemical formula:wherein x is more than or equal to 0.30 and less than or equal to 0.33, y is more than or equal to 0.05 and less than or equal to 0.10, a is more than or equal to 0.02 and less than or equal to 0.05, b is more than or equal to 0.01 and less than or equal to 0.03, and c is more than or equal to 0.01 and less than or equal to 0.03.

2. A method for producing a piezoelectric ceramic according to claim 1, comprising the steps of:

(1) weighing raw materials according to the stoichiometric ratio of chemical composition, wherein the raw materials are oxides of Bi, Sc, Pb, Ti, La, Fe, Ga and Mn, and uniformly mixing by wet ball milling;

(2) drying and pre-sintering the ball-milled mixture;

(3) grinding and sieving the pre-sintered powder, adding an adhesive for granulation, performing compression molding, and performing degumming treatment to obtain a ceramic biscuit;

(4) sintering the ceramic biscuit at high temperature to obtain a ceramic wafer;

(5) silver is coated on the ceramic wafer after sintering, and sintering is carried out;

(6) and (4) performing electric polarization on the silver-coated ceramic chip.

3. The preparation method according to claim 2, wherein in the step (1), in order to compensate for volatilization of the Bi and Pb elements, the Bi and Pb oxides are respectively in excess of 3-5% and 5-10%, and ethanol is added during wet ball milling mixing, wherein the adding amount of the ethanol is 25mL/10g of the mixture.

4. The preparation method according to claim 2, wherein the drying temperature in the step (2) is 60-70 ℃, the pre-sintering temperature is 800 ℃, and the pre-sintering time is 2 hours.

5. The preparation method according to claim 2, wherein the pre-sintered powder in the step (3) is ground and sieved by a 60-mesh sieve, the adhesive is PVA aqueous solution or paraffin with the content of 5%, the degumming temperature is 500-600 ℃, the time is 2-4h, and the size of the ceramic biscuit is 20mm in length, 10mm in width and 1.2mm in thickness.

6. The preparation method according to claim 2, wherein the temperature of the high-temperature sintering in the step (4) is 1050 ℃ and the sintering time is 2 h.

7. The method according to claim 2, wherein the sintering temperature of silver in step (5) is 560 ℃ and the time is 0.5 h.

8. The production method according to claim 2, wherein the electric polarization in the step (6) is carried out in silicone oil, the polarization field strength is 4.5-5kV/mm, the polarization temperature is 80 ℃, and the polarization time is 0.5 h.

9. A dipole transmitting transducer, characterized by comprising the piezoelectric ceramic of claim 1 or the piezoelectric ceramic (2) prepared by the preparation method of claims 2-8, a copper sheet (1), a stainless steel skeleton (3) and a high-temperature lead (4).

10. A dipole transmitting transducer according to claim 9, wherein the piezoelectric vibrator is formed by bonding an elongated piezoelectric ceramic sheet with a copper sheet having a length of 40mm and a width of 10mm, the high temperature leads are connected to upper and lower electrode surfaces of the piezoelectric ceramic sheet, respectively, and four piezoelectric vibrators for bending vibration surround a rectangular parallelepiped frame, each piezoelectric vibrator occupying one side surface of the rectangular parallelepiped frame, both ends in a length direction thereof being in a nested state.

Technical Field

The invention belongs to the field of piezoelectric ceramic-based transducers, and particularly relates to a piezoelectric ceramic doped with a modified bismuth scandate-lead titanate-bismuth ferrite ternary system and a dipole transmitting transducer thereof.

Background

The complex environment of the deep sea oil field puts higher requirements on oil gas detection equipment. Due to the influence of geothermal heat, the downhole temperature gradually increases as the drilling depth increases. For example, the average temperature gradient of the drilling well in the deep water area of the south sea is 3.91 +/-0.74/100 m (Petroleum institute, 2009, 30(1): 27-32), when the depth of the oil well exceeds 5000m, the downhole temperature exceeds the high temperature of 200 ℃. Meanwhile, the pressure is increased by 1MPa every time the sea depth is increased by 100m, and when the depth exceeds 5000m, the pressure exceeds 50 atmospheric pressures. The advanced sound wave testing technology can improve the detection capability and depth of oil and gas resources, and the deep sea oil and gas exploration well operation needs a piezoelectric transducer resistant to high temperature and high pressure. The acoustic logging transducer developed by Shanghai silicate of Chinese academy of sciences in China can not only meet the requirements on acoustic characteristics, but also can stably work at high temperature of 180 ℃ (http:// www.sic.cas.cn/glbm/kjfzb/sdhzc/xmzs/201202/t20120220_3442478. html). The 1-3 type PZT/polymer piezoelectric composite material transducer prepared by Chenqiu Ying et al, university of Chinese academy of sciences has stable working temperature up to 150 ℃ (Chenqiu Ying. research of high temperature resistant piezoelectric composite material ultrasonic transducer, university of Chinese academy of sciences.2014.). 0.9PbTiO prepared by Zhonghong et al of Shandong university₃-0.1Pb(Sn_1/3Nb_2/3)O₃The piezoelectric ceramic transducer has stable performance and better repeatability (functional material and device declaration, 2002, 8(4): 418-420 ℃) at the oil well depth of 5250m (the ground temperature is about 166 ℃). The utility model discloses a dipole transmitting transducer granted by China oil and gas group companyThe environmental conditions of the device meet 175 ℃ and 140MPa (ZL 200620119171.7). Therefore, the working temperature of the currently researched and developed transducer for logging is still lower than 200 ℃, and with the development of ocean oil and gas towards deep water, the demand for the transducer with stable performance under high temperature and high pressure and without failure is more urgent.

The maximum operating temperature of the piezoelectric transducer is determined primarily by the maximum limit operating temperature of the piezoelectric element when the operating temperature of the piezoelectric material exceeds the curie temperature (T _C) The piezoelectric effect will be lost. In order to ensure that the piezoelectric material and the device can stably and normally work under the high-temperature extreme environment, the service temperature of the piezoelectric material is often limited to be the service temperature of the piezoelectric materialT _CHalf (0.5)T _C). With Pb (Zr, Ti) O₃(T _CThe relaxation ferroelectrics represented by the temperature of =320-350 ℃) dominate the global piezoelectric transducer market once because of the excellent piezoelectric performance. However, the PZT piezoelectric solid solution has low working temperature, large mechanical brittleness and high lead content. Bismuth scandate-lead titanate (BiScO)₃-PbTiO₃) Solid solutions have piezoelectric properties comparable to those of PZT piezoelectric solid solutions (d ₃₃=460pC/N) and relatively highT _C(450 ℃ C.). However, BiScO₃-PbTiO₃Solid solutions have large dielectric losses and continued operation at high temperatures and frequencies results in significant energy losses. And bismuth ferrite (BiFeO)₃) High temperature piezoceramic materials, typically having a high Curie temperature ofT _C=825 deg.C), but relatively small piezoelectric constant ((C)d ₃₃=27pC/N) limits its applications.

Disclosure of Invention

The invention aims to provide a composite material with high strengthT _CCeramics with excellent piezoelectric property and dielectric property and preparation of dipole transmitting transducer. In order to realize the purpose, the invention constructs the bismuth scandate-lead titanate-bismuth ferrite ternary system solid solution ceramic and realizes high contentT _CHigh piezoelectric constant at 470-500 deg.Cd ₃₃>230pC/N and significantly reduced dielectric loss tan delta =1.0% -1.2%, and a pair is prepared based on the solid solution ceramicThe polar transmitting transducer can resist high temperature of 200 ℃ and high hydrostatic pressure of 50 MPa.

The invention is realized by the following technical scheme:

a bismuth scandate-lead titanate-bismuth ferrite ternary system piezoelectric ceramic has a chemical formula as follows:wherein x is more than or equal to 0.30 and less than or equal to 0.33, y is more than or equal to 0.05 and less than or equal to 0.10, a is more than or equal to 0.02 and less than or equal to 0.05, b is more than or equal to 0.01 and less than or equal to 0.03, and c is more than or equal to 0.01 and less than or equal to 0.03.

The preparation method of the bismuth scandate-lead titanate-bismuth ferrite ternary system piezoelectric ceramic specifically comprises the following steps:

(1) weighing raw materials according to the stoichiometric ratio of chemical composition, wherein the raw materials are oxides of Bi, Sc, Pb, Ti, La, Fe, Ga and Mn, and uniformly mixing by wet ball milling;

(2) drying and pre-sintering the ball-milled mixture;

(3) grinding and sieving the pre-sintered powder, adding an adhesive for granulation, performing compression molding, and performing degumming treatment to obtain a ceramic biscuit;

(4) sintering the ceramic biscuit at high temperature to obtain a ceramic wafer;

(5) silver is coated on the ceramic wafer after sintering, and sintering is carried out;

(6) and (4) performing electric polarization on the silver-coated ceramic chip.

In the step (1), in order to compensate for volatilization of Bi and Pb elements, the Bi and Pb oxides are respectively excessive by 3-5% and 5-10%, and the wet ball milling mixing is to add ethanol, wherein the adding amount of the ethanol is 25mL/10g of the mixture.

In the step (2), the drying temperature is 60-70 ℃, the presintering temperature is 800 ℃, and the presintering time is 2 hours.

And (3) grinding the pre-sintered powder in the step (3) and sieving the powder by a 60-mesh sieve, wherein the adhesive is 5% PVA aqueous solution or paraffin, the adhesive removing temperature is 500-600 ℃, the time is 2-4h, and the size of the ceramic biscuit is 20mm in length, 10mm in width and 1.2mm in thickness.

The temperature of the high-temperature sintering in the step (4) is 1050 ℃, and the sintering time is 2 h.

The temperature for sintering by silver in the step (5) is 560 ℃, and the time is 0.5 h.

In the step (6), electric polarization is carried out in silicone oil, the polarization field strength is 4.5-5kV/mm, the polarization temperature is 80 ℃, and the polarization time is 0.5 h.

A dipole transmitting transducer comprises the piezoelectric ceramic, a copper sheet, a stainless steel framework and a high-temperature lead.

The long strip-shaped piezoelectric vibrator is formed by bonding a long strip-shaped piezoelectric ceramic piece and a copper sheet, and the high-temperature lead is respectively connected with the upper electrode surface and the lower electrode surface of the piezoelectric ceramic piece.

The four bar-shaped vibrators of bending vibration surround the cuboid framework, each piezoelectric vibrator occupies one side face of the cuboid framework, and two ends of each piezoelectric vibrator in the length direction are in an embedded state.

The transducer is of an overflow structure and is not limited by external pressure.

Advantageous effects

The piezoelectric ceramic prepared by the invention has high Curie temperatureT _C=470 ℃ -500 ℃), excellent piezoelectric property (d ₃₃>230pC/N) and low dielectric loss (tan delta =1.0% -1.2%), so that the piezoelectric ceramic can be applied to a high-temperature environment of 200 ℃, and the dipole transmitting transducer prepared based on the piezoelectric ceramic can meet the survey of deep sea oil fields of 200 ℃, thereby providing a feasible transducer for the exploration of deep sea oil and gas resources.

Drawings

FIG. 1 shows 0.33Bi_0.991La_0.009ScO₃-0.62PbTiO₃-0.05Bi_0.999La_0.001Fe_0.95Ga_0.05O₃XRD pattern of 1mol% Mn.

FIG. 2 shows 0.33Bi_0.991La_0.009ScO₃-0.62PbTiO₃-0.05Bi_0.999La_0.001Fe_0.95Ga_0.05O₃1mol% Mnd ^* ₃₃Graph of change with temperature.

FIG. 3 shows 0.33Bi_0.991La_0.009ScO₃-0.62PbTiO₃-0.05Bi_0.999La_0.001Fe_0.95Ga_0.05O₃-dielectric thermogram of 1mol% Mn.

Fig. 4 shows a dipole transmitting transducer with a single piezoelectric vibrator.

Fig. 5 is a schematic diagram of a dipole transmitting transducer.

FIG. 6(a) shows the variation of the impedance spectrum of the transducer with temperature, and (b) shows the variation of the resonant frequency with temperature.

Fig. 7 shows the impedance spectrum of the transducer before and after high temperature.

In the figure: 1-copper sheet; 2-BS-PT-BF ceramic plate; 3-high temperature lead; 4-stainless steel skeleton.

Detailed Description

The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.

Example 1

Preparation of Bi of chemical composition 0.33_0.991La_0.009ScO₃-0.62PbTiO₃-0.05Bi_0.999La_0.001Fe_0.95Ga_0.05O₃-1mol% Mn piezoelectric ceramic.

With analytically pure starting material Bi₂O₃、Sc₂O₃、PbO、TiO₂、La₂O₃、Fe₂O₃、Ga₂O₃、MnO₂Proportioning according to a stoichiometric ratio, wherein Bi and Pb oxides are respectively 3% and 10% in excess, the amount of added ethanol is 25mL, and the mixture is put into a ball milling tank for ball milling for 24 hours and is uniformly mixed; after being uniformly mixed, the mixture is put into a drying oven and dried at 60 ℃; grinding the dried mixture and sieving the ground mixture by a 60-mesh sieve; presintering for 2h at the temperature of 800 ℃; and adding 0.5ml of aqueous solution of VA into the pre-sintered material, grinding and sieving by a 100-mesh sieve to complete granulation. Pressing the granulated pre-sintered material into a long sheet with the length of 20mm, the width of 10mm and the thickness of 1.2mm by using a tablet press, and carrying out degumming at the temperature of 600 ℃ to obtain a ceramic biscuit, wherein the degumming time is 2 hours; then sintering the biscuit at 1050 ℃ for 2h to obtain a ceramic wafer; bakingPolishing two sides of the bonded ceramic wafer, and burning silver by an Ag electrode; applying a direct current electric field of 4.5kV/mm in silicone oil at 80 ℃ and keeping for 0.5h to obtain 0.33Bi_0.991La_0.009ScO₃-0.62PbTiO₃-0.05Bi_0.999La_0.001Fe_0.95Ga_0.05O₃-1mol% Mn of the finished piezoelectric ceramic; the properties of the ceramics are as follows:T _C =500℃，d ₃₃=270pC/N，tanδ=1.0%。

preparing a dipole transmitting transducer.

The prepared piezoelectric ceramic piece is adhered to a copper sheet through conductive adhesive, the ceramic piece is positioned in the middle of the copper sheet, and high-temperature leads are respectively led out from the upper electrode surface of the ceramic piece and the copper sheet to form a piezoelectric vibrator; fixing the four piezoelectric vibrators on four side surfaces of the stainless steel framework through insulating screws; the resonant frequency of the transducer in the air is about 2-3 kHz, the transducer can resist the high temperature of 200 ℃, and the transducer can resist the high hydrostatic pressure of 50MPa on a deep sea hydrostatic test device (sup-hd-10000).

Example 2:

preparation of 0.3Bi conforming to the chemical composition_0.992La_0.008ScO₃-0.6PbTiO₃-0.1Bi_0.998La_0.002Fe_0.95Ga_0.05O₃-1mol% Mn piezoelectric ceramic.

With analytically pure starting material Bi₂O₃、Sc₂O₃、PbO、TiO₂、La₂O₃、Fe₂O₃、Ga₂O₃、MnO₂Proportioning according to a stoichiometric ratio, wherein Bi and Pb oxides are respectively 5% and 5% in excess, adding 25mL of ethanol, and putting into a ball milling tank for ball milling for 24 hours to be uniformly mixed; after being uniformly mixed, the mixture is put into a drying oven and dried at 60 ℃; grinding the dried mixture and sieving the ground mixture by a 60-mesh sieve; presintering for 2h at the temperature of 800 ℃; and adding 0.5mL of PVA aqueous solution into the pre-sintered material, grinding and sieving by a 100-mesh sieve to complete granulation. Pressing the granulated pre-sintered material into a long sheet with the length of 20mm, the width of 10mm and the thickness of 1.2mm by using a tablet press, and carrying out degumming at the temperature of 600 ℃ to obtain a ceramic biscuit, wherein the degumming time is 2 hours; then sintering the biscuit at 1050 ℃ for 2h to obtain the potteryA tile; polishing two surfaces of the sintered ceramic wafer, and burning silver by an Ag electrode; applying a direct current electric field of 4.5kV/mm in silicone oil at 80 ℃ and keeping for 0.5h to obtain 0.3Bi_0.992La_0.008ScO₃-0.6PbTiO₃-0.1Bi_0.998La_0.002Fe_0.95Ga_0.05O₃-1mol% Mn of the finished piezoelectric ceramic; the properties of the ceramics are as follows:T _C =470℃，d ₃₃=238 pC/N，tanδ=1.2%。

preparing a dipole transmitting transducer.

The prepared piezoelectric ceramic piece is adhered to a copper sheet through conductive adhesive, the ceramic piece is positioned in the middle of the copper sheet, and high-temperature leads are respectively led out from the upper electrode surface of the ceramic piece and the copper sheet to form a piezoelectric vibrator; fixing the four piezoelectric vibrators on four side surfaces of the stainless steel framework through insulating screws; the resonant frequency of the transducer in the air is about 2-3 kHz, the transducer can resist the high temperature of 200 ℃, and the transducer can resist the high hydrostatic pressure of 50MPa on a deep sea hydrostatic test device (sup-hd-10000).

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.