CN112745116A

CN112745116A - Preparation method of high-corrosion-resistant composite piezoelectric ceramic material

Info

Publication number: CN112745116A
Application number: CN202110177686.1A
Authority: CN
Inventors: 汤柯
Original assignee: Individual
Current assignee: Multifield Technology Co ltd
Priority date: 2020-08-12
Filing date: 2020-08-12
Publication date: 2021-05-04
Anticipated expiration: 2040-08-12
Also published as: CN111908913B; CN111908913A; CN112723880B; CN112745116B; CN112723880A

Abstract

The invention discloses a preparation method of a high-corrosion-resistant composite piezoelectric ceramic material, which comprises the following steps: (1) weighing the following components: in stoichiometric ratio Ba_1‑xMg_xTi_1‑2ySb_yIn_yO₃Weighing; wherein x is 0.5-3 mol% and y is 0.2-3 mol%. (2) Primary molding: mixing the raw materials of the components, and performing ball milling, drying, granulation, extrusion forming, binder removal, sintering and other processes to obtain piezoelectric ceramics; (3) and (3) polarization treatment: soldering and magnetron sputtering silver electrodes on the upper surface and the lower surface of the preliminarily formed piezoelectric ceramic respectively to finally obtain the high-corrosion-resistance composite piezoelectric ceramic material. The preparation method has simple steps, and the BT-based ceramic is doped in a soft and hard mode, so that the piezoelectric constant d is ensured₃₃And also promote the machineA mechanical quality factor Qm and an electromechanical coupling coefficient Kp.

Description

Preparation method of high-corrosion-resistant composite piezoelectric ceramic material

Technical Field

The invention relates to the field of piezoelectric ceramics, in particular to a preparation method of a high-corrosion-resistant composite piezoelectric ceramic material.

Background

With the continuous development of piezoceramic materials in China, the requirements of people on piezoceramics are higher and higher, for example, a lead zirconate titanate (PZT) ceramic system has a higher piezoelectric constant d₃₃However, lead contained in PZT tends to cause environmental pollution when used or disposed of, and therefore development of lead-free piezoelectric ceramics is in a trend. And barium titanate (BaTiO)₃BT) ceramics do not cause much pollution, but the piezoelectric constant of BT-based ceramics prepared by the traditional method is generally equal to that of BT-based ceramicsOnly about 200 pC/N. Due to BaTiO₃The piezoelectric ceramic being ABO₃The A site ions of the perovskite ferroelectric can be replaced by Ca, Sr, La, Y and other elements, and the B site ions of the perovskite ferroelectric can be replaced by Zr, Sn, Nb, Ce and other elements, most of the prior art carries out modification on BT-based ceramics by doping, but the modification brings about side effects, such as the reduction of the flatness factor caused by the increase of the dielectric coefficient and the electromechanical coupling coefficient, and the mechanical quality factor Qm is particularly important in devices such as a filter, a resonant transducer and the like, so that the demand for obtaining ceramic materials with excellent performances is urgent.

Disclosure of Invention

The invention aims to provide a preparation method of a high-corrosion-resistance composite piezoelectric ceramic material, so as to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: the preparation method of the high-corrosion-resistance composite piezoelectric ceramic material comprises the following steps:

(1) weighing the following components: mixing the raw material BaCO₃、TiO₂、MgO、Sb₂O₅And In₂O₃In stoichiometric ratio of Ba_1-xMg_xTi_1- _2ySb_yIn_yO₃Weighing; wherein x is 0.5-3 mol% and y is 0.2-3 mol%;

using Mg²⁺For Ba²⁺Equivalent replacement can improve the piezoelectric constant d of the BT-based ceramic₃₃Using high valent ions Sb⁵⁺For Ti⁴⁺To be replaced by soft substituted, low valence ion In³⁺For Ti⁴⁺To be replaced by a hard substitute of the same amount of Sb⁵⁺And In³⁺Replacement of Ti⁴⁺The soft-hard implementation is realized, the mechanical quality factor Qm and the electromechanical coupling coefficient Kp are improved, and the piezoelectric constant d is not influenced₃₃。

(2) Primary molding: mixing the raw materials of all the components, and then carrying out primary ball milling, drying and primary sintering to obtain pre-sintered piezoelectric ceramic powder; performing secondary ball milling and drying on the pre-sintered piezoelectric ceramic powder, adding a binder, grinding and granulating, performing extrusion forming, discharging glue, and performing secondary sintering to obtain piezoelectric ceramic;

(3) and (3) polarization treatment: soldering a layer of metallic tin on the upper surface and the lower surface of the preliminarily formed piezoelectric ceramic respectively, compacting, carrying out magnetron sputtering on a layer of silver electrode, polarizing for 20-30 min in oil at the temperature of 75-85 ℃, and obtaining the high-corrosion-resistant composite piezoelectric ceramic material at the polarization electric field of 2500-.

The tin soldering layer of the metallic tin is used for effectively filling micro-pores on the surface of the preliminarily formed piezoelectric ceramic, so that the silver electrode subjected to magnetron sputtering is fully connected with the piezoelectric ceramic, and the contact resistance is reduced.

Preferably, x + y is 0.7 to 6 mol%.

Under the condition that the total doping amount is less than 0.7-6 mol%, the perovskite structure of BT ceramic is not changed, the simultaneously occurring lattice distortion increases the free energy, reduces the electric domain steering activation energy, and is more beneficial to the full deflection and retention of the electric domain during polarization treatment, thereby improving the piezoelectric constant d of the ceramic₃₃Dielectric coefficient epsilon and electromechanical coupling coefficient Kp; if the doping amount is too large, grain boundary segregation occurs, and the crystal structure of the perovskite structure is changed, thereby affecting the piezoelectric performance of the ceramic.

Preferably, the time of the primary ball milling and the time of the secondary ball milling are respectively 12-14 h and 6-8 h, the rotating speed is 400-450 r/min, and the ball milling media are water and agate balls.

Preferably, the drying temperature is 70-80 ℃ and the drying time is 3-6 h.

Preferably, the temperature of the primary sintering is increased to 800-900 ℃ at the temperature increasing rate of 80-90 ℃/h, and the temperature is kept for 3-4 h.

Preferably, the binder is an aqueous solution of PVA at a concentration of 4 to 8 wt%.

Preferably, the pressure for extrusion molding is 120-140 MPa.

Preferably, the temperature of the gel is raised to 450-500 ℃ at the temperature raising rate of 40-50 ℃/h, and the temperature is maintained for 50-60 min.

The binder removal is to remove the organic binder in the green body before the green body is fired so as to ensure the requirements of the shape, the size and the quality of the product; the temperature rising rate should be controlled at 40-50 deg.C/h, and the slow temperature rising rate is to ensure that the crystal structure is not damaged by deformation, cracks and other defects.

Preferably, the temperature of the secondary sintering is raised to 1200-1300 ℃ at a heating rate of 105-115 ℃/h, and the temperature is maintained for 110-130 min.

The excessive high temperature rise rate is not beneficial to the elimination of pores during the sintering of the ceramic, and further the compactness is influenced, and the slow temperature rise rate of 80-90 ℃/h can effectively avoid the cracking problem and the breakdown problem caused by the polarization treatment in the sintering process.

The invention also provides the high-corrosion-resistance composite piezoelectric ceramic material prepared by the method.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention adopts Mg²⁺For Ba²⁺Equivalent replacement is carried out to improve the piezoelectric constant d of BT-based ceramic₃₃While using the same amount of Sb⁵⁺And In³⁺Replacement of Ti⁴⁺Realizes the combination of hardness and hardness, and ensures the piezoelectric constant d₃₃Can not be excessively reduced, the mechanical quality factor Qm and the electromechanical coupling coefficient Kp of the composite piezoelectric ceramic are improved, and the mechanical quality factor Qm low caused by doping high-valence ions and the piezoelectric constant d caused by doping low-valence ions in the prior art are improved₃₃Low and poor anti-aging stability.

(2) In the prior art, the electrode prepared by a magnetron sputtering method alone can only be deposited on the surface of ceramic but cannot go deep into micropores, the problem of point contact or surface contact among silver particles is caused by a conductive silver paste coating method, and both the silver particles and the piezoelectric ceramic generate contact resistance.

(3) According to the invention, the piezoelectric ceramic is prepared by adopting a mode of two-step slow temperature rise of glue removal and secondary sintering, so that organic matters and air holes can be effectively removed, and the density of the piezoelectric ceramic is improved. Meanwhile, the high hardness and the hydrophobicity of the piezoelectric ceramic are improved due to the compact combination of the multi-component raw materials, and the corrosion problem caused by the absorption of acid and alkali liquor is avoided.

(4) BaCO used in the invention₃、TiO₂The materials such as MgO and the like have wide sources and are economical, the preparation method of the invention is simple and mild, and the prepared composite piezoelectric ceramic material has uniform performance.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example one

The invention provides a preparation method of a high-corrosion-resistant composite piezoelectric ceramic material, which comprises the following steps:

(1) weighing the following components: mixing the raw material BaCO₃、TiO₂、MgO、Sb₂O₅And In₂O₃In stoichiometric ratio of Ba_1-xMg_xTi_1- _2ySb_yIn_yO₃Weighing; wherein x is 0.5 mol% and y is 0.2 mol%;

(3) and (3) polarization treatment: soldering a layer of metallic tin on the upper surface and the lower surface of the preliminarily formed piezoelectric ceramic respectively, compacting, carrying out magnetron sputtering on a layer of silver electrode, and polarizing in oil at 75 ℃ for 20 min, wherein the polarizing electric field is 2500V/mm, thus finally obtaining the high-corrosion-resistance composite piezoelectric ceramic material.

Wherein said x + y is 0.7 mol%; the time of the primary ball milling and the time of the secondary ball milling are respectively 12 hours and 6 hours, the rotating speed is 400 r/min, and the ball milling media are water and agate balls; the drying temperature is 70 ℃ and the drying time is 3 hours; the primary sintering is carried out by heating to 800 ℃ at a heating rate of 80 ℃/h and preserving heat for 3 h; the adhesive is PVA aqueous solution with the concentration of 4 wt%; the pressure intensity of the extrusion forming is 120 Mpa; the temperature of the binder removal is increased to 450 ℃ at the heating rate of 40 ℃/h, and the temperature is kept for 50 min; the secondary sintering is carried out by heating to 1200 ℃ at a heating rate of 105 ℃/h and preserving the heat for 110 min.

Example two

(1) weighing the following components: mixing the raw material BaCO₃、TiO₂、MgO、Sb₂O₅And In₂O₃In stoichiometric ratio of Ba_1-xMg_xTi_1- _2ySb_yIn_yO₃Weighing; wherein x is 3 mol% and y is 3 mol%;

(3) and (3) polarization treatment: soldering a layer of metallic tin on the upper surface and the lower surface of the preliminarily formed piezoelectric ceramic respectively, compacting, carrying out magnetron sputtering on a layer of silver electrode, and polarizing in oil at 85 ℃ for 30 min, wherein the polarizing electric field is 4000V/mm, thereby finally obtaining the high-corrosion-resistance composite piezoelectric ceramic material.

Wherein said x + y is 6 mol%; the time of the primary ball milling and the time of the secondary ball milling are 14 h and 8 h respectively, the rotating speed is 450 r/min, and the ball milling media are water and agate balls; the drying temperature is 80 ℃ and the drying time is 6 hours; the primary sintering is carried out by heating to 900 ℃ at the heating rate of 90 ℃/h and preserving heat for 4 h; the adhesive is PVA aqueous solution with the concentration of 8 wt%; the pressure intensity of the extrusion forming is 140 Mpa; the temperature of the binder removal is raised to 500 ℃ at the heating rate of 50 ℃/h, and the temperature is kept for 60 min; the secondary sintering is carried out by heating to 1300 ℃ at the heating rate of 115 ℃/h and preserving the heat for 130 min.

EXAMPLE III

(1) weighing the following components: mixing the raw material BaCO₃、TiO₂、MgO、Sb₂O₅And In₂O₃In stoichiometric ratio of Ba_1-xMg_xTi_1- _2ySb_yIn_yO₃Weighing; wherein x is 2 mol% and y is 1 mol%;

(3) and (3) polarization treatment: soldering a layer of metallic tin on the upper surface and the lower surface of the preliminarily formed piezoelectric ceramic respectively, compacting, carrying out magnetron sputtering on a layer of silver electrode, and polarizing in oil at the temperature of 80 ℃ for 25 min, wherein the polarizing electric field is 3000V/mm, thereby finally obtaining the high-corrosion-resistance composite piezoelectric ceramic material.

Wherein said x + y is 3 mol%; the time of the primary ball milling and the time of the secondary ball milling are respectively 13 h and 7 h, the rotating speed is 420 r/min, and the ball milling media are water and agate balls; the drying temperature is 75 ℃, and the drying time is 4 hours; the primary sintering is carried out at the temperature rise rate of 85 ℃/h to 850 ℃ and the heat preservation time is 3.5 h; the adhesive is a PVA aqueous solution with the concentration of 6 wt%; the pressure intensity of the extrusion forming is 130 Mpa; the temperature of the discharged glue is increased to 480 ℃ at the heating rate of 45 ℃/h, and the heat is preserved for 55 min; the secondary sintering is carried out by heating to 1250 ℃ at the heating rate of 110 ℃/h and preserving the heat for 120 min.

In order to detect the performance of each composite piezoelectric ceramic material, the invention respectively tests the piezoelectric constant d of each composite piezoelectric ceramic material₃₃Dielectric coefficient epsilon, electromechanical coupling coefficient Kp and mechanical quality factor Qm. Cutting the prepared composite piezoelectric ceramic material into a rectangle with the size of 10 mm multiplied by 2 mm multiplied by 1 mm, determining the frequency dependence of the impedance of the ceramic sample by using an impedance analyzer, and calculating the piezoelectric constant d from the observed resonance frequency and antiresonance frequency₃₃Dielectric coefficient epsilon, and mechanical quality factor Qm. Piezoelectric constant d₃₃The larger the piezoelectric performance, the larger the mechanical quality factor Qm, and the smaller the loss of the ceramic at the time of resonance vibration. The composite piezoelectric ceramic is cut into a wafer with the diameter of 10 mm and the thickness of 2 mm, and then a dielectric temperature spectrometer is used for automatically measuring the dielectric coefficient epsilon of the material.

Through comparative experiments on the three groups of examples, the composite piezoelectric ceramic material with excellent performance and high corrosion resistance can be prepared by each group of examples. Wherein, the piezoelectric constant d of the composite piezoelectric ceramic material with high corrosion resistance prepared in the first embodiment₃₃389 pC/N, dielectric coefficient epsilon 2487, electromechanical coupling coefficient Kp 41%, mechanical quality factor Qm 334; piezoelectric constant d of the high corrosion resistant composite piezoelectric ceramic material prepared in example two₃₃393 pC/N, a dielectric coefficient epsilon of 2271, an electromechanical coupling coefficient Kp of 39 percent and a mechanical quality factor Qm of 312; piezoelectric constant d of the high corrosion resistant composite piezoelectric ceramic material prepared in example three₃₃410 pC/N, a dielectric coefficient ε 2418, an electromechanical coupling coefficient Kp of 38%, and a mechanical quality factor Qm of 326. It can be seen that the piezoelectric constant d of the high corrosion resistant composite piezoelectric ceramic material prepared by the invention₃₃The mechanical quality factor Qm can reach 310 while keeping over 380 pC/N, wherein the three effects of the embodiment are the best.

Comparative example 1: the difference from the third embodiment is that only Mg is doped²⁺For Ba²⁺Performing equivalent replacement to obtain the composite piezoelectricPiezoelectric constant d of ceramic material₃₃381 pC/N, a dielectric coefficient ε of 1893, an electromechanical coupling coefficient Kp of 32%, and a mechanical quality factor Qm of 117. The piezoelectric constant d of the BT-based ceramic can be further improved by only carrying out small-amount doping of equivalent ions₃₃However, the ceramic crystal structure lacking soft or hard substitution is almost unchanged, and the compactness of the ceramic basically keeps the characteristics of the original BT-based ceramic, so that the mechanical quality factor Qm is lower.

Comparative example 2: the difference from the third example is the absence of the higher valence ions Sb⁵⁺For Ti⁴⁺Soft substitution of (A), and the piezoelectric constant d of the prepared composite piezoelectric ceramic material₃₃235 pC/N, dielectric coefficient ε 1698, electromechanical coupling coefficient Kp 31%, and mechanical quality factor Qm 337. The lack of high valence ion pair Ti can be seen⁴⁺The replaced composite piezoelectric ceramic material contains Mg²⁺Doping to raise the piezoelectric constant d₃₃But a piezoelectric constant d after soft substitution by high valence ions₃₃And again, the mechanical quality factor Qm is only improved.

Comparative example 3: the difference from the third example is the lack of In as low-valent ion³⁺For Ti⁴⁺Hard substitution of (A), the piezoelectric constant d of the obtained composite piezoelectric ceramic material₃₃414 pC/N, a dielectric coefficient ε of 2474, an electromechanical coupling coefficient Kp of 38%, and a mechanical quality factor Qm of 109. The doping of equivalent ions and high valence ions can influence the piezoelectric constant d of the composite piezoelectric ceramic₃₃But the mechanical quality factor Qm of the ceramic material after softening is reduced, and the improvement effect is not substantial.

Comparative example 4: the difference from the third embodiment is that x + y is 20 mol%, and the piezoelectric constant d of the prepared composite piezoelectric ceramic material₃₃186 pC/N, a dielectric coefficient ε of 934, an electromechanical coupling coefficient Kp of 26%, and a mechanical quality factor Qm of 53. Appropriate equivalent ion substitution or soft or hard substitution can be modified on the basis of not changing the perovskite crystal structure, and once the crystal structure is damaged due to excessive impurities, the piezoelectric performance of the BT-based ceramic is reduced or even disappears.

Comparative example 5: same as in the third embodimentThe difference lies in that the electrode is prepared by using a conductive silver paste coating mode, and the prepared composite piezoelectric ceramic material has the piezoelectric constant d₃₃402 pC/N, a dielectric coefficient ε of 2359, an electromechanical coupling coefficient Kp of 32%, and a mechanical quality factor Qm of 287. Since insufficient connection between the electrode and the composite piezoelectric ceramic results in excessive contact resistance, insufficient polarization in a partial region during polarization treatment, and reduced polarization uniformity, the electromechanical coupling coefficient Kp and the mechanical quality factor Qm are both reduced.

Comparative example 6: the difference from the third embodiment is that the temperature rise rate of the secondary sintering is 200 ℃/h, and the piezoelectric constant d of the prepared composite piezoelectric ceramic material₃₃376 pC/N, a dielectric coefficient ε of 2127, an electromechanical coupling coefficient Kp of 33%, and a mechanical quality factor Qm of 265. Because the temperature rise rate is too fast, pores in the ceramic in the sintering process cannot be effectively eliminated, the compactness is greatly reduced, and the mechanical quality factor is reduced.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A preparation method of a high corrosion resistant composite piezoelectric ceramic material is characterized by comprising the following steps: the method comprises the following steps: