High-performance composite piezoelectric ceramic and preparation method thereof

Abstract

This invention relates to the field of piezoelectric ceramics technology, and more specifically, to a high-performance composite piezoelectric ceramic and its preparation method. A method for preparing a high-performance composite piezoelectric ceramic includes the following steps: mixing and ball-milling a matrix ceramic powder with a β-Si3N4 whisker dispersion; subsequently drying, adding a binder, granulating, and pressing to obtain a green body; heating and debinding the green body and sintering to obtain a piezoelectric ceramic sample; and polishing, silvering, and polarizing the piezoelectric ceramic sample to obtain the high-performance composite piezoelectric ceramic. Introducing β-Si3N4 whiskers into the high-performance composite piezoelectric ceramic is beneficial to improving its mechanical quality factor. In the matrix ceramic powder, through the composite doping of MgO and Sm2O3, MgO and Sm2O3 can produce a synergistic reinforcement effect, increasing the piezoelectric constant of the high-performance composite piezoelectric ceramic.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric ceramics technology, and more specifically, to a high-performance composite piezoelectric ceramic and its preparation method. Background Technology

[0002] Piezoelectric ceramics, as an important class of functional ceramic materials, are widely used in sensors, transducers, actuators, ultrasonic medical equipment, and precision actuators. Among them, lead-based perovskite piezoelectric ceramics, such as the PZT system, have long dominated the piezoelectric device market due to their high piezoelectric constant, good dielectric properties, and high electromechanical coupling coefficient. However, with the development of modern electronic devices towards high power, high frequency, miniaturization, and integration, traditional PZT ceramics have gradually revealed a series of performance bottlenecks in practical applications. Especially under high-power operating conditions, problems such as low mechanical quality factor, high energy loss, and decreased reliability are becoming increasingly prominent, seriously restricting their further expansion in high-end fields.

[0003] Therefore, in order to meet the ever-increasing performance requirements of modern industry for electronic devices, it is urgent to improve the overall performance of piezoelectric ceramics, especially to achieve the joint optimization of high voltage constant and high mechanical quality factor. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a high-performance composite piezoelectric ceramic and its preparation method.

[0005] A method for preparing a high-performance composite piezoelectric ceramic includes the following steps: The matrix ceramic powder and β-Si3N4 whisker dispersion were added to a ball mill and ball milled for 6-12 hours to obtain a mixed slurry. After the mixed slurry is dried, a mixed powder is obtained. A binder is added to the mixed powder, and the amount of binder added is 5-8% of the mass of the mixed powder. After granulation and pressing, a green body is obtained. Under nitrogen protection and PbO atmosphere, the temperature is raised to 450-550℃ at a heating rate of 3-5℃ / min, allowing the green body to be debonded for 0.5-2h. Then, the temperature is raised to 1200-1230℃ at a heating rate of 5-10℃ / min, and sintered for 1-3h to obtain piezoelectric ceramic samples. After polishing, silvering, and polarization, high-performance composite piezoelectric ceramics were obtained from the piezoelectric ceramic samples. The general chemical formula of the matrix ceramic powder is: Pb n Sr m (Mn) 1 / 3 Sb 2 / 3 ) z Zr y Tix O3+a%MgO-b%Sm2O3; n, m, x, y, z represent the mole fractions of the corresponding elements, n+m=1, x+y+z=1, where 0.965≤n≤0.982, 0.018≤m≤0.035, 0.45≤x≤0.55, 0.4≤y≤0.5, 0.04≤z≤0.1; a% and b% represent the percentage of Pb in the corresponding material. n Sr m (Mn) 1 / 3 Sb 2 / 3 ) z Zr y Ti x The mass percentage of O3, where 0.2≤a≤0.6 and 0.3≤b≤0.7.

[0006] Furthermore, the preparation steps of the matrix ceramic powder are as follows: Using Pb3O4, SrCO3, MnO2, Sb2O3, TiO2, ZrO2, MgO, and Sm2O3 as raw materials, according to Pb n Sr m (Mn) 1 / 3 Sb 2 / 3 ) z Zr y Ti x The mixture of O3+a%MgO-b%Sm2O3 was homogenized and kept at 850-900℃ for 2-4 hours to obtain the matrix ceramic powder.

[0007] Furthermore, the preparation steps of the β-Si3N4 whisker dispersion are as follows: Add β-Si3N4 whiskers to deionized water and ultrasonically disperse for 20-30 minutes. After uniform dispersion, prepare a β-Si3N4 whisker dispersion with a mass fraction of 3-6%.

[0008] Furthermore, the mass ratio of the matrix ceramic powder to the β-Si3N4 whisker dispersion is (1~1.5):1.

[0009] Furthermore, the diameter of the β-Si3N4 whiskers is 0.2–1 μm and the length is 10–20 μm.

[0010] Furthermore, the adhesive is PVA.

[0011] Furthermore, the polarization operation steps are as follows: The piezoelectric ceramic sample with silver electrode was placed in silicone oil at 110–130°C, and a DC electric field of 2.5–3.5 kV / mm was applied for polarization for 30–60 min, and then cooled to room temperature.

[0012] A high-performance composite piezoelectric ceramic is prepared by the above-mentioned method for preparing a high-performance composite piezoelectric ceramic.

[0013] Compared with the prior art, the present invention has at least the following advantages: 1. In this invention, by introducing β-Si3N4 whiskers into the high-performance composite piezoelectric ceramic, the needle-shaped β-Si3N4 whiskers can be randomly and uniformly distributed in the matrix of the high-performance composite piezoelectric ceramic, allowing the β-Si3N4 whiskers to act as "stress-bearing units." This forms a high-modulus, high-strength β-Si3N4 whisker network in the matrix of the high-performance composite piezoelectric ceramic. When the high-performance composite piezoelectric ceramic is subjected to external force, the load borne by the high-performance composite piezoelectric ceramic matrix is ​​transferred to the matrix through the whisker-matrix interface. On β-Si3N4 whiskers, stress concentration in the matrix is ​​reduced. Furthermore, when cracks encounter the high-strength, high-modulus β-Si3N4 whisker network during crack propagation, the cracks are forced to change direction because they cannot pass through directly. They propagate along the whisker / matrix interface or around the whiskers, making the crack path tortuous. This significantly increases the effective surface area and energy required for crack propagation, hinders further crack opening, reduces crack propagation inside the matrix, thereby reducing the additional mechanical energy loss caused by crack opening and closing, and improving the mechanical quality factor of the composite piezoelectric ceramic.

[0014] 2. In the matrix ceramic powder of the present invention, MgO and Sm2O3 are used as composite dopants, and Sm2O3 dissociates to generate Sm 3+ Due to the ionic radius and the Pb at the A site 2+ 、Sr 2+ It exhibits excellent matching properties, preferentially occupies A-sites and forms donor-type doping, and the resulting excess positive charge generates Pb. 2+ Vacancies achieve charge compensation; MgO dissociation produces Mg 2+ Due to the ionic radius and the B-site Zr 4+ Ti 4+ With high matching, it preferentially occupies B sites and forms acceptor doping. The excess negative charge generated is compensated by generating oxygen vacancies. In this way, the composite doping of MgO and Sm2O3 can form donor-acceptor defect pairs. The uniformly distributed donor-acceptor defect pairs can suppress the excessive aggregation of single-type defects through electrostatic interaction, avoiding strong agglomeration and pinning of domain walls. Compared with the local enrichment of defects caused by single doping, this uniform defect distribution can weaken the pinning and binding strength of domain walls, reducing the turning resistance of domain walls under external electric fields. This preserves the turning ability of domain walls to achieve full polarization, while avoiding performance degradation caused by excessive migration of domain walls, thereby improving the piezoelectric constant of high-performance composite piezoelectric ceramics. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1 A method for preparing high-performance composite piezoelectric ceramics specifically includes the following steps: S1: Using Pb3O4, SrCO3, MnO2, Sb2O3, TiO2, ZrO2, MgO, and Sm2O3 as raw materials, according to Pb 0.974 Sr 0.026 (Mn) 1 / 3 Sb 2 / 3 ) 0.05 Zr 0.45 Ti 0.5 The mixture of O3, 0.4%MgO, and 0.5%Sm2O3 was thoroughly mixed and kept at 875℃ for 3 hours to obtain the matrix ceramic powder. S2: Add β-Si3N4 whiskers with a diameter range of 0.2-1 μm and a length range of 10-20 μm to deionized water, and ultrasonically disperse for 25 min. After uniform dispersion, a β-Si3N4 whisker dispersion with a mass fraction of 4.5% is obtained. S3: Add the matrix ceramic powder and β-Si3N4 whisker dispersion into a ball mill and ball mill for 9 hours. The mass ratio of the matrix ceramic powder to the β-Si3N4 whisker dispersion is 1.25:1 to obtain a mixed slurry. S4: After the mixed slurry is dried, a mixed powder is obtained. PVA is added to the mixed powder at a rate of 6.5% of the mass of the mixed powder. After granulation and pressing, a green body is obtained. S5: Under nitrogen protection and PbO atmosphere, the temperature was raised to 500℃ at a heating rate of 4℃ / min, and the green body was debonded for 1.25h. Then, the temperature was raised to 1215℃ at a heating rate of 7.5℃ / min and sintered for 2h to obtain the piezoelectric ceramic sample. S6: After polishing and silvering the piezoelectric ceramic sample, the piezoelectric ceramic sample with silver electrodes is placed in silicone oil at 120°C, a DC electric field of 3kV / mm is applied, polarized for 45 minutes, and then cooled to room temperature to obtain a high-performance composite piezoelectric ceramic.

[0017] Example 2 A method for preparing high-performance composite piezoelectric ceramics specifically includes the following steps: S1: Using Pb3O4, SrCO3, MnO2, Sb2O3, TiO2, ZrO2, MgO, and Sm2O3 as raw materials, according to Pb 0.982 Sr 0.018 (Mn) 1 / 3 Sb 2 / 3 ) 0.05 Zr 0.4 Ti 0.55 The mixture of O3, 0.6%MgO, and 0.7%Sm2O3 was thoroughly mixed and kept at 900℃ for 4 hours to obtain the matrix ceramic powder. S2: Add β-Si3N4 whiskers with a diameter range of 0.2-1μm and a length range of 10-20μm to deionized water, and ultrasonically disperse for 30 min. After uniform dispersion, a β-Si3N4 whisker dispersion with a mass fraction of 6% is obtained. S3: Add the matrix ceramic powder and β-Si3N4 whisker dispersion into a ball mill and ball mill for 12 hours. The mass ratio of the matrix ceramic powder to the β-Si3N4 whisker dispersion is 1.5:1 to obtain a mixed slurry. S4: After the mixed slurry is dried, a mixed powder is obtained. PVA is added to the mixed powder at a rate of 8% of the mass of the mixed powder. After granulation and pressing, a green body is obtained. S5: Under nitrogen protection and PbO atmosphere, the temperature was increased to 550℃ at a heating rate of 5℃ / min to remove the binder in the green body for 2 hours, and then increased to 1230℃ at a heating rate of 10℃ / min and sintered for 3 hours to obtain the piezoelectric ceramic sample. S6: After polishing and silvering the piezoelectric ceramic sample, the piezoelectric ceramic sample with silver electrodes is placed in silicone oil at 130℃, a DC electric field of 3.5kV / mm is applied, polarized for 60min, and then cooled to room temperature to obtain a high-performance composite piezoelectric ceramic.

[0018] Example 3 A method for preparing high-performance composite piezoelectric ceramics specifically includes the following steps: S1: Using Pb3O4, SrCO3, MnO2, Sb2O3, TiO2, ZrO2, MgO, and Sm2O3 as raw materials, according to Pb 0.965 Sr 0.035 (Mn) 1 / 3 Sb 2 / 3 ) 0.1 Zr 0.45 Ti 0.45 The mixture of O3, 0.2%MgO, and 0.3%Sm2O3 was thoroughly mixed and kept at 850℃ for 2 hours to obtain the matrix ceramic powder. S2: Add β-Si3N4 whiskers with a diameter range of 0.2-1μm and a length range of 10-20μm to deionized water, and ultrasonically disperse for 20 min. After uniform dispersion, a β-Si3N4 whisker dispersion with a mass fraction of 3% is obtained. S3: Add the matrix ceramic powder and β-Si3N4 whisker dispersion into a ball mill and ball mill for 6 hours. The mass ratio of the matrix ceramic powder to the β-Si3N4 whisker dispersion is 1:1 to obtain a mixed slurry. S4: After the mixed slurry is dried, a mixed powder is obtained. PVA is added to the mixed powder at a rate of 5% of the mass of the mixed powder. After granulation and pressing, a green body is obtained. S5: Under nitrogen protection and PbO atmosphere, the temperature was raised to 450℃ at a heating rate of 3℃ / min to remove the binder from the green body for 0.5h, and then raised to 1200℃ at a heating rate of 5℃ / min and sintered for 1h to obtain the piezoelectric ceramic sample. S6: After polishing and silvering the piezoelectric ceramic sample, the piezoelectric ceramic sample with silver electrodes is placed in silicone oil at 110℃, a DC electric field of 2.5kV / mm is applied, polarized for 30min, and then cooled to room temperature to obtain a high-performance composite piezoelectric ceramic.

[0019] Comparative Example 1 Compared with Example 1, the difference of Comparative Example 1 is that steps S2-S3 are removed, the matrix ceramic powder of step S1 is added to a ball mill, and deionized water and zirconium balls are used as media for ball milling for 9 hours to obtain a matrix ceramic slurry. The mixed slurry in step S4 is replaced with the matrix ceramic slurry, and the other steps remain unchanged to prepare a high-performance composite piezoelectric ceramic, which is referred to as Comparative Example 1.

[0020] According to GB / T 11320-1989, the mechanical quality factors of the high-performance piezoelectric ceramics prepared in Examples 1-3 and Comparative Example 1 were tested, and the test results are shown in Table 1.

[0021] Table 1:

[0022] As shown in Table 1, the mechanical quality factor (Qm) of the high-performance piezoelectric ceramics in Examples 1-3 is ≥1195, which is significantly better than the mechanical quality factor test results of the high-performance piezoelectric ceramic in Comparative Example 1. This indicates that the introduction of β-Si3N4 whiskers into the high-performance composite piezoelectric ceramic is beneficial to enhancing the mechanical strength and stiffness of the high-performance composite piezoelectric ceramic and improving its mechanical quality factor.

[0023] Comparative Example 2 Compared with Example 1, Comparative Example 2 differs in that, in step S1, Pb3O4, SrCO3, MnO2, Sb2O3, TiO2, ZrO2, and MgO are used as raw materials, according to Pb 0.974 Sr 0.026 (Mn) 1 / 3 Sb 2 / 3 ) 0.05 Zr 0.45 Ti 0.5 The O3 + 0.9% MgO were mixed and kept at 875℃ for 3 hours to obtain the matrix ceramic powder. The remaining steps remained unchanged to prepare a high-performance composite piezoelectric ceramic, which was designated as Comparative Example 2.

[0024] Comparative Example 3 Compared with Example 1, Comparative Example 3 differs in that, in step S1, Pb3O4, SrCO3, MnO2, Sb2O3, TiO2, ZrO2, and Sm2O3 are used as raw materials, according to Pb 0.974 Sr 0.026 (Mn) 1 / 3 Sb 2 / 3 ) 0.05 Zr 0.45 Ti 0.5 The mixture of O3 and 0.9% Sm2O3 was thoroughly mixed and kept at 875℃ for 3 hours to obtain the matrix ceramic powder. The remaining steps remained unchanged to prepare a high-performance composite piezoelectric ceramic, which was designated as Comparative Example 3.

[0025] According to GB / T 11309-1989, the piezoelectric constants of the high-performance piezoelectric ceramics prepared in Examples 1-3 and Comparative Examples 2-3 were tested, and the test results are shown in Table 2.

[0026] Table 2:

[0027] As shown in Table 2, the piezoelectric constants (d) of the high-performance piezoelectric ceramics in Examples 1-3 are... 33 The piezoelectric constants of the composite piezoelectric ceramics are all ≥342, which are better than those of the high-performance piezoelectric ceramics in Comparative Examples 2-3. This indicates that, compared with single doping of MgO or Sm2O3, composite doping of MgO and Sm2O3 can produce a synergistic enhancement effect and improve the piezoelectric constant of high-performance composite piezoelectric ceramics.

[0028] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-performance composite piezoelectric ceramic, characterized in that, Includes the following steps: The matrix ceramic powder and β-Si3N4 whisker dispersion were added to a ball mill and ball milled for 6-12 hours to obtain a mixed slurry. After the mixed slurry is dried, a mixed powder is obtained. A binder is added to the mixed powder, and the amount of binder added is 5-8% of the mass of the mixed powder. After granulation and pressing, a green body is obtained. Under nitrogen protection and PbO atmosphere, the temperature is raised to 450-550℃ at a heating rate of 3-5℃ / min, allowing the green body to be debonded for 0.5-2h. Then, the temperature is raised to 1200-1230℃ at a heating rate of 5-10℃ / min, and sintered for 1-3h to obtain piezoelectric ceramic samples. After polishing, silvering, and polarization, the piezoelectric ceramic samples were used to obtain high-performance composite piezoelectric ceramics. The general chemical formula of the matrix ceramic powder is: Pb n Sr m (Mn 1 / 3 Sb 2 / 3 ) z Zr y Ti x O3+a%MgO-b%Sm2O3; n, m, x, y, z represent the mole fractions of the corresponding elements, n+m=1, x+y+z=1, where 0.965≤n≤0.982, 0.018≤m≤0.035, 0.45≤x≤0.55, 0.4≤y≤0.5, 0.04≤z≤0.1; a% and b% represent the percentage of Pb in the corresponding material. n Sr m (Mn) 1 / 3 Sb 2 / 3 ) z Zr y Ti x The mass percentage of O3, where 0.2≤a≤0.6 and 0.3≤b≤0.

7.

2. The method for preparing a high-performance composite piezoelectric ceramic according to claim 1, characterized in that, The preparation steps of the matrix ceramic powder are as follows: Using Pb3O4, SrCO3, MnO2, Sb2O3, TiO2, ZrO2, MgO, and Sm2O3 as raw materials, according to Pb n Sr m (Mn) 1 / 3 Sb 2 / 3 ) z Zr y Ti x The mixture of O3+a%MgO-b%Sm2O3 was homogenized and kept at 850-900℃ for 2-4 hours to obtain the matrix ceramic powder.

3. The method for preparing a high-performance composite piezoelectric ceramic according to claim 1, characterized in that, The preparation steps of β-Si3N4 whisker dispersion are as follows: Add β-Si3N4 whiskers to deionized water and ultrasonically disperse for 20-30 minutes. After uniform dispersion, prepare a β-Si3N4 whisker dispersion with a mass fraction of 3-6%.

4. The method for preparing a high-performance composite piezoelectric ceramic according to claim 3, characterized in that, The mass ratio of the matrix ceramic powder to the β-Si3N4 whisker dispersion is (1~1.5):

1.

5. The method for preparing a high-performance composite piezoelectric ceramic according to claim 3, characterized in that, The diameter of β-Si3N4 whiskers is 0.2–1 μm and the length is 10–20 μm.

6. The method for preparing a high-performance composite piezoelectric ceramic according to claim 1, characterized in that, The adhesive is PVA.

7. The method for preparing a high-performance composite piezoelectric ceramic according to claim 1, characterized in that, The steps for polarization are as follows: The piezoelectric ceramic sample with silver electrode was placed in silicone oil at 110–130°C, and a DC electric field of 2.5–3.5 kV / mm was applied for polarization for 30–60 min, and then cooled to room temperature.

8. A high-performance composite piezoelectric ceramic, characterized in that, It is prepared by the preparation method of any one of claims 1-7.

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