Preparation method of potassium-sodium niobate leadless piezoelectric ceramic based on high-temperature melting process

Abstract

The invention discloses a preparation method of potassium-sodium niobate leadless piezoelectric ceramic based on a high-temperature melting process. The preparation method comprises the following steps: weighing potassium carbonate, sodium carbonate, polyvinyl alcohol and niobium pentoxide to obtain a first material; putting the proportioned first material into an agate ball-milling tank to form slurry, and sealing the ball-milling tank; ball-milling the prepared slurry on a planetary ball mill; pre-sintering the ball-milled slurry to obtain a second material; the second material is dried and then ground, and sieved powder is taken for granulation; and putting the mixed powder into an alumina crucible, and then putting the alumina crucible into a high-temperature furnace for high-temperature melting to obtain the potassium-sodium niobate leadless piezoelectric ceramic. According to the invention, by accurately controlling the ratio of different component raw materials and preparation process parameters and systematically researching the interaction of the factors, the piezoelectric property of the material is optimized, the density of the lead-free piezoelectric ceramic is improved, the design and development of a new material are promoted, the production efficiency is improved, and the stability and reliability of the material in practical application are enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric ceramics, and particularly relates to a preparation method of sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process. Background Art

[0002] Piezoelectric ceramics are a kind of functional ceramic materials with piezoelectric effects, which are widely used in the fields of electronics, machinery, chemical engineering, medical treatment, etc. Traditional piezoelectric ceramic materials usually contain lead, which can cause harm to the environment and human health. Therefore, it is of great significance to develop lead-free piezoelectric ceramic materials.

[0003] In the prior art, Chinese Patent Application No. CN202410871982.5 discloses a large-strain piezoelectric ceramic material and a preparation method thereof. By using the melting-water quenching method and adding a special glass component to the PZT-based piezoelectric ceramics for modification, while optimizing the microstructure of the ceramic material, the strain of the material is significantly improved. Similar melting methods have not been seen in the application of the sodium potassium niobate (KNN) material system. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a preparation method of sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0005] A preparation method of sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process, comprising:

[0006] S1. Put potassium carbonate, sodium carbonate, polyvinyl alcohol and niobium pentoxide in an oven at 80 - 120 °C for heat preservation for 2 - 4 h to remove the moisture in the raw materials; weigh the first material according to the stoichiometric ratio of the formula of potassium carbonate, sodium carbonate, polyvinyl alcohol and niobium pentoxide;

[0007] S2. Put the proportioned first material into an agate ball milling tank, add deionized water and zirconia agate balls of different sizes according to the ratio of raw materials: agate balls: deionized water of 1:3:3 to form a slurry and seal the ball milling tank;

[0008] S3. Ball mill the prepared slurry on a planetary ball mill for 2 - 4 h;

[0009] S4. Dry the ball-milled slurry at 180 °C for 2 h to obtain a powder, grind the powder and pre-burn it at 850 °C for 3 - 6 h to obtain the second material;

[0010] S5. Dry the second material and then grind it, take the sieved powder for granulation, wherein, the granulation is: put 5% of polyvinyl alcohol into the ball-milled powder to make the binder evenly disperse in the powder to obtain a mixed powder;

[0011] S6. Place the mixed powder in an alumina crucible and then put it into a high-temperature furnace. Perform two-stage gradient heating at a heating rate of 5 - 10 °C / min: in the first stage, heat from room temperature to 850 °C at a heating rate of 10 °C / min and pre-burn for 1 - 2 hours; in the second stage, heat to the high-temperature melting zone of 1250 - 1400 °C at a heating rate of 5 °C / min and perform dynamic heat preservation for 1 - 4 h to obtain sodium potassium niobate lead-free piezoelectric ceramics.

[0012] In a specific embodiment, the first material: potassium carbonate 15 - 25 wt%, sodium carbonate 10 - 20 wt%, niobium pentoxide 77 - 78 wt% and polyvinyl alcohol 3 wt%.

[0013] In a specific embodiment, in step S2, during the mixing process, the usage amount of deionized water is controlled at 18 - 20% of the weight of the raw materials.

[0014] In a specific embodiment, in step S3, the mixing time is controlled at 2 - 4 hours, and the rotation speed of the ball mill is controlled at 300 - 400 r / min.

[0015] In a specific embodiment, in step S4, the mixed slurry is dried; the drying process uses an oven or a vacuum drying oven, and the temperature is controlled at 180 °C.

[0016] In a specific embodiment, in step S5, a sieve with 120 - 200 meshes is used for screening, and the middle part of the slurry is taken for tabletting, so that the pressure is controlled at 20 MPa and the time is controlled at 180 s - 200 s.

[0017] In a specific embodiment, in step S6, the sintering temperature is controlled at 1350 °C; the dynamic heat preservation time is controlled at 2 hours.

[0018] Advantages of the present invention:

[0019] A method for preparing sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process according to the present invention precisely controls the ratio of different component raw materials and the preparation process parameters, systematically studies the interaction of these factors, optimizes the piezoelectric properties of the material, improves the density of the lead-free piezoelectric ceramics, promotes the design and development of new materials, improves production efficiency, and enhances the stability and reliability of the material in practical applications.

[0020] The following will further describe the present invention in detail with reference to the drawings and embodiments. Description of the Drawings

[0021] Figure 1It is a performance comparison diagram of Examples 1-4 of a preparation method of sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process provided by an embodiment of the present invention. Detailed implementation manners

[0022] The following further describes the present invention in detail with reference to specific embodiments, but the implementation manners of the present invention are not limited thereto.

[0023] Example 1

[0024] A preparation method of sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process includes:

[0025] S1. Put potassium carbonate, sodium carbonate, polyvinyl alcohol and niobium pentoxide in a drying oven at 120 °C for heat preservation for 2-4 h to remove the moisture in the raw materials; weigh the first material according to the formula stoichiometric ratio of potassium carbonate, sodium carbonate, polyvinyl alcohol and niobium pentoxide.

[0026] S2. Put the prepared first material into an agate ball milling tank, add deionized water and zirconia agate balls of different sizes according to the ratio of raw materials: agate balls: deionized water of 1:3:3 to form a slurry and seal the ball milling tank.

[0027] S3. Ball mill the prepared slurry on a planetary ball mill for 2-4 h.

[0028] S4. Dry the ball-milled slurry at 180 °C for 2 h to obtain a powder, grind the powder and pre-burn it at 850 °C for 3-6 h to obtain a second material. The purpose of the drying treatment is to remove the moisture in the raw materials so as not to affect the preparation process and the performance of the ceramics.

[0029] S5. Grind the second material after drying, and granulate the sieved powder. Among them, the granulation is: put 5% of polyvinyl alcohol into the ball-milled powder to make the binder evenly disperse in the powder to obtain a mixed powder.

[0030] S6. Place the mixed powder in an alumina crucible and then put it into a high-temperature furnace, and perform two-stage gradient heating at a heating rate of 5-10 °C / min: in the first stage, heat from room temperature to 850 °C at a heating rate of 10 °C / min and pre-burn for 1-2 hours; in the second stage, heat to 1250 °C high-temperature melting zone at a heating rate of 5 °C / min and perform dynamic heat preservation for 1.5 h to obtain sodium potassium niobate lead-free piezoelectric ceramics. The sintering process is particularly crucial because it will affect the piezoelectric properties, dielectric loss and environmental friendliness of the material. Compared with the traditional sintering process, the melting method is an alternative, avoiding the limitations of high-temperature solid-phase sintering, improving the material density and optimizing the performance. During the sintering process, the particles are connected to each other through mechanisms such as diffusion, surface energy reduction and atom / ion migration, reducing pores and improving the density and mechanical strength of the material.

[0031] In a specific embodiment, the first material: potassium carbonate 20 wt%, sodium carbonate 15 wt%, niobium pentoxide 77 wt% and polyvinyl alcohol 3 wt%.

[0032] In a specific embodiment, in the step S2, during the mixing process, the usage amount of deionized water is controlled at 18 - 20% of the weight of the raw materials.

[0033] In a specific embodiment, in the step S3, the mixing time is controlled at 4 hours, and the rotation speed of the ball mill is controlled at 400 r / min.

[0034] In a specific embodiment, in the step S4, the mixed slurry is dried; the drying treatment is carried out using an oven or a vacuum drying oven, and the temperature is controlled at 180°C.

[0035] In a specific embodiment, in the step S5, a sieve with 120 - 200 meshes is used for screening, and the middle part of the slurry is taken for tabletting, so that the pressure is controlled at 20 MPa and the time is controlled at 180 s - 200 s.

[0036] Example Two

[0037] A method for preparing sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process, comprising:

[0038] S1. Potassium carbonate, sodium carbonate, polyvinyl alcohol and niobium pentoxide are placed in a drying oven at 120°C for heat preservation for 2 - 4 h to remove the moisture in the raw materials; the first material is weighed according to the stoichiometric ratio of the formula of potassium carbonate, sodium carbonate, polyvinyl alcohol and niobium pentoxide.

[0039] S2. The prepared first material is put into an agate ball milling tank, and deionized water and zirconia agate balls of different sizes are added according to the ratio of raw materials: agate balls: deionized water of 1:3:3 to form a slurry, and the ball milling tank is sealed.

[0040] S3. The prepared slurry is ball milled on a planetary ball mill for 2 - 4 h.

[0041] S4. The ball milled slurry is dried at 180°C for 2 h to obtain a powder, and after the powder is ground, it is pre-sintered at 850°C for 3 - 6 h to obtain a second material.

[0042] S5. After the second material is dried, it is ground again, and the sieved powder is granulated. Among them, the granulation is as follows: 5% of polyvinyl alcohol is put into the ball milled powder, so that the binder is evenly dispersed in the powder to obtain a mixed powder.

[0043] S6. Place the mixed powder in an alumina crucible and then put it into a high-temperature furnace. Perform two-stage gradient heating at a heating rate of 5-10 °C / min: in the first stage, heat from room temperature to 850 °C at a heating rate of 10 °C / min and pre-burn for 1-2 hours; in the second stage, heat to the high-temperature melting zone of 1300 °C at a heating rate of 5 °C / min and perform dynamic heat preservation for 2 h to obtain sodium-potassium niobate lead-free piezoelectric ceramics.

[0044] In a specific embodiment, the first material: potassium carbonate 16 wt%, sodium carbonate 19 wt%, niobium pentoxide 78 wt% and polyvinyl alcohol 3 wt%.

[0045] In a specific embodiment, in the step S2, during the mixing process, the usage amount of deionized water is controlled at 18-20% of the weight of the raw materials.

[0046] In a specific embodiment, in the step S3, the mixing time is controlled at 4 hours and the rotation speed of the ball mill is controlled at 300 r / min.

[0047] In a specific embodiment, in the step S4, the mixed slurry is dried; the drying treatment is carried out using an oven or a vacuum drying oven, and the temperature is controlled at 180 °C.

[0048] In a specific embodiment, in the step S5, a sieve with 120 mesh - 200 mesh is used for screening, and the middle part of the slurry is taken for tabletting, so that the pressure is controlled at 20 MPa and the time is controlled at 180 s - 200 s.

[0049] Example 3

[0050] A method for preparing sodium-potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process, comprising:

[0051] S1. Place potassium carbonate, sodium carbonate, polyvinyl alcohol and niobium pentoxide in a drying oven at 120 °C for heat preservation for 2-4 h to remove the moisture in the raw materials; weigh the first material according to the stoichiometric ratio of the formula of potassium carbonate, sodium carbonate, polyvinyl alcohol and niobium pentoxide;

[0052] S2. Put the proportioned first material into an agate ball mill tank, add deionized water and zirconia agate balls of different sizes according to the ratio of raw materials: agate balls: deionized water of 1:3:3 to form a slurry and seal the ball mill tank;

[0053] S3. Ball mill the prepared slurry on a planetary ball mill for 2-4 h;

[0054] S4. Dry the ball-milled slurry at 180 °C for 2 h to obtain a powder, grind the powder and pre-burn it at 850 °C for 3-6 h to obtain the second material;

[0055] S5. After drying the second material, grind it, and take the sieved powder for granulation. Among them, the granulation is as follows: put 5% polyvinyl alcohol into the ball-milled powder to make the binder evenly dispersed in the powder to obtain a mixed powder.

[0056] S6. Place the mixed powder in an alumina crucible and then put it into a high-temperature furnace, and perform two-stage gradient heating at a heating rate of 5-10 °C / min: in the first stage, heat from room temperature to 850 °C at a heating rate of 10 °C / min and pre-burn for 1-2 hours; in the second stage, heat to the high-temperature melting zone of 1350 °C at a heating rate of 5 °C / min and perform dynamic heat preservation for 2.5 h to obtain sodium-potassium niobate lead-free piezoelectric ceramics.

[0057] In a specific embodiment, the first material: potassium carbonate 24 wt%, sodium carbonate 12 wt%, niobium pentoxide 77 wt% and polyvinyl alcohol 3 wt%.

[0058] In a specific embodiment, in the S2 step, during the mixing process, the usage amount of deionized water is controlled at 18-20% of the weight of the raw materials.

[0059] In a specific embodiment, in the S3 step, the mixing time is controlled at 4 hours, and the rotation speed of the ball mill is controlled at 300 r / min.

[0060] In a specific embodiment, in the S4 step, the mixed slurry is dried; the drying treatment is carried out using an oven or a vacuum drying oven, and the temperature is controlled at 180 °C.

[0061] In a specific embodiment, in the S5 step, take a sieve with 120-200 meshes for screening, and take the middle part of the slurry for tabletting, so that the pressure is controlled at 20 MPa and the time is controlled at 180 s-200 s.

[0062] Example 4

[0063] A method for preparing sodium-potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process, comprising:

[0064] S1. Place potassium carbonate, sodium carbonate, polyvinyl alcohol and niobium pentoxide in a drying oven at 120 °C for heat preservation for 2-4 h to remove the moisture in the raw materials; weigh according to the stoichiometric ratio of the formula of potassium carbonate, sodium carbonate, polyvinyl alcohol and niobium pentoxide to obtain the first material.

[0065] S2. Put the prepared first material into an agate ball mill tank, add deionized water and zirconia agate balls of different sizes according to the ratio of raw materials: agate balls: deionized water of 1:3:3 to form a slurry and seal the ball mill tank.

[0066] S3. Ball mill the prepared slurry on a planetary ball mill for 2 - 4 h;

[0067] S4. Dry the ball - milled slurry at 180 °C for 2 h to obtain a powder. After grinding the powder, pre - sinter it at 850 °C for 3 - 6 h to obtain the second material;

[0068] S5. After drying the second material, grind it again. Take the sieved powder for granulation. Among them, the granulation is as follows: put 5% polyvinyl alcohol into the ball - milled powder, and make the binder evenly disperse in the powder to obtain a mixed powder;

[0069] S6. Place the mixed powder in an alumina crucible and then put it into a high - temperature furnace. Perform two - stage gradient heating at a heating rate of 5 - 10 °C / min: in the first stage, heat from room temperature to 850 °C at a heating rate of 10 °C / min and pre - sinter for 1 - 2 hours; in the second stage, heat to the 1400 °C high - temperature melting zone at a heating rate of 5 °C / min and perform dynamic heat preservation for 3 h to obtain sodium potassium niobate lead - free piezoelectric ceramics.

[0070] In a specific embodiment, the first material: potassium carbonate 16 wt%, sodium carbonate 19 wt%, niobium pentoxide 78 wt% and polyvinyl alcohol 3 wt%.

[0071] In a specific embodiment, in the S2 step, during the mixing process, the usage amount of deionized water is controlled at 18 - 20% of the weight of the raw materials.

[0072] In a specific embodiment, in the S3 step, the mixing time is controlled at 4 hours, and the rotation speed of the ball mill is controlled at 300 r / min.

[0073] In a specific embodiment, in the S4 step, perform a drying treatment on the mixed slurry; the drying treatment uses an oven or a vacuum drying oven, and the temperature is controlled at 180 °C.

[0074] In a specific embodiment, in the S5 step, use a 120 - mesh to 200 - mesh sieve for screening, and take the middle part of the slurry for tabletting, so that the pressure is controlled at 20 MPa and the time is controlled at 180 s - 200 s.

[0075] In order to verify the piezoelectric effect of the product, prepare lead - free piezoelectric ceramics according to the schemes of Examples 1 - 4 respectively, test the products, and obtain the performance comparison as Figure 1 shown, and specifically, refer to Table 1.

[0076] Table 1 Performance comparison table

[0077] Property Example 1 Example 2 Example 3 Example 4 <![CDATA[Piezoelectric coefficient d 33 (Unit: pC / N)]]> 386 396 426 410 <![CDATA[Density (unit: g / cm 3 )]]> 4.59 4.65 5.1 4.75

[0078] As can be seen from the above, when the preparation is carried out according to the solution of Embodiment 3, the piezoelectric properties of the obtained product are better, and its piezoelectric coefficient d33 reaches 426 pC / N.

[0079] A method for preparing sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process in this embodiment precisely controls the ratios of different component raw materials and the preparation process parameters, systematically studies the interactions of these factors, optimizes the piezoelectric properties of the materials, improves the density of the lead-free piezoelectric ceramics, promotes the design and development of new materials, improves production efficiency, and enhances the stability and reliability of the materials in practical applications.

[0080] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for preparing sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process, characterized in that, Including: S1. Place potassium carbonate, sodium carbonate, polyvinyl alcohol, and niobium pentoxide in an oven at 80 - 120°C for heat preservation for 2 - 4 h to remove the moisture in the raw materials; weigh according to the stoichiometric ratio of the formula of potassium carbonate, sodium carbonate, polyvinyl alcohol, and niobium pentoxide to obtain the first material. S2. Put the prepared first material into an agate ball milling tank, add deionized water and zirconia agate balls of different sizes according to the ratio of raw materials : agate balls : deionized water of 1 : 3 : 3 to form a slurry, and seal the ball milling tank. S3. Ball mill the prepared slurry on a planetary ball mill for 2 - 4 h. S4. Dry the ball milled slurry at 180°C for 2 h to obtain a powder, grind the powder, and pre - sinter it at 850°C for 3 - 6 h to obtain the second material. S5. After drying the second material, grind it again, take the sieved powder for granulation. Among them, the granulation is as follows: put 5% of polyvinyl alcohol into the ball milled powder to make the binder evenly disperse in the powder to obtain a mixed powder. S6. Place the mixed powder in an alumina crucible and then put it into a high - temperature furnace, and perform two - stage gradient heating at a heating rate of 5 - 10°C / min: in the first stage, heat from room temperature to 850°C at a heating rate of 10°C / min and pre - sinter for 1 - 2 h; in the second stage, heat to the high - temperature melting zone of 1250 - 1400°C at a heating rate of 5°C / min and perform dynamic heat preservation for 1 - 4 h to obtain sodium potassium niobate lead - free piezoelectric ceramics.

2. The method for preparing sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process according to claim 1, wherein, The first material: potassium carbonate 15 - 25 wt%, sodium carbonate 10 - 20 wt%, niobium pentoxide 77 - 78 wt%, and polyvinyl alcohol 3 wt%.

3. The method for preparing sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process according to claim 1, wherein In the step S2, during the mixing process, the usage amount of deionized water is controlled at 18 - 20% of the weight of the raw materials.

4. The method for preparing sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process according to claim 1, wherein In the step S3, the mixing time is controlled at 2 - 4 h, and the rotation speed of the ball mill is controlled at 300 - 400 r / min.

5. The method for preparing sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process according to claim 1, characterized in that, In the step S4, the mixed slurry is subjected to a drying treatment; the drying treatment uses an oven or a vacuum drying oven, and the temperature is controlled at 180°C.

6. The method for preparing sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process according to claim 1, characterized in that, In the step S5, take a sieve of 120 - 200 meshes for screening, and take the middle part of the slurry for tablet pressing, so that the pressure is controlled at 20 MPa and the time is controlled at 180 s - 200 s.

7. The method for preparing sodium potassium niobate lead-free piezoelectric ceramics based on a high-temperature melting process according to claim 1, characterized in that In the step S6, the sintering temperature is controlled at 1350°C; the dynamic heat preservation time is controlled at 2 h.

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