Titanium dioxide filler capable of improving dielectric property of ceramic and preparation method of titanium dioxide filler

Abstract

The invention relates to the field of titanium dioxide, and provides a preparation method of a titanium dioxide filler for improving the dielectric property of ceramic in order to solve the problem that the dielectric property of a product is not improved well when existing titanium dioxide is used as a functional filler of ceramic, the preparation method of the titanium dioxide filler for improving the dielectric property of the ceramic comprises the following steps: S100, under a heating condition, adding a doped ion solution into a precursor solution of titanium dioxide to obtain gel; the doped ion solution comprises Mo < 6 + > and Sn < 2 + >; the molar ratio of Mo < 6 + > to Ti < 4 + > is (10-30): (1-2), and the molar ratio of Sn < 2 + > to Ti < 4 + > is (10-20): (2-3); and S200, calcining the gel to obtain the titanium dioxide filler. The crystal form change of anatase type titanium dioxide in the early stage of sintering is utilized, so that the possibility of occurrence of ceramic microcracks is reduced; volume shrinkage is prevented from being intensified under the condition of high-temperature sintering, so that the possibility of structural defects of the ceramic is increased under the same process condition; the titanium dioxide prepared by a titanium dioxide doping process can promote the conversion of the titanium dioxide into rutile type titanium dioxide.

Description

Technical Field

[0001] The present invention relates to the field of titanium dioxide, and more particularly, to a titanium dioxide filler for improving the dielectric properties of ceramics and a preparation method thereof. Background Art

[0002] Dielectric ceramics are an important type of electronic ceramics with excellent insulation and dielectric properties, and are widely used in the fields of electronics, communication, etc. Rutile titanium dioxide has a relatively high dielectric constant. When it is added to a ceramic system with a low dielectric constant, it can improve the dielectric constant of the ceramic to a certain extent. However, the difference in the thermal expansion coefficients between titanium dioxide and ceramic raw materials easily leads to structural defects during the ceramic sintering process, thereby affecting the overall dielectric properties of the ceramic. The dispersion and compatibility of titanium dioxide in the matrix also affect the dielectric properties of the final product. Summary of the Invention

[0003] The purpose of the present invention is to provide a titanium dioxide filler for improving the dielectric properties of ceramics and a preparation method thereof, so as to solve the problem that when existing titanium dioxide is used as a functional filler for ceramics, due to the difference in the thermal expansion coefficient between it and the raw materials, structural defects easily occur during the sintering process, and the improvement of the dielectric properties of the product is not good.

[0004] The embodiments of the present invention are realized through the following technical solutions:

[0005] A preparation method of a titanium dioxide filler for improving the dielectric properties of ceramics, comprising:

[0006] S100. Under heating conditions, a doping ion solution is added to the precursor solution of titanium dioxide to obtain a gel; the doping ion solution includes: Mo 6+ and Sn 2+ ; the molar ratio of Mo 6+ to Ti 4+ is (10 - 30):(1 - 2), and the molar ratio of Sn 2+ to Ti 4 + is (10 - 20):(2 - 3);

[0007] S200. The gel is prepared into a titanium dioxide filler through a calcination process.

[0008] The concentration of the precursor solution can be selected as 18wt% - 25wt%; the solvent of the precursor solution can be deionized water or alcohol, such as ethanol or n-octanol.

[0009] High-dielectric ceramics play an important role in electronic components such as capacitors and filters. Utilizing their high dielectric constant characteristics, the size of components can be reduced, the energy storage density and response speed can be improved, meeting the requirements of miniaturization and integration of modern electronic devices. High-dielectric ceramics can also be used as potential energy storage materials, with advantages such as high energy storage density and fast charge and discharge speed, and are expected to play an important role in future energy storage systems. The property that high-dielectric ceramics are sensitive to electric field changes makes them an important material for sensors, capable of detecting and converting electric field changes into measurable signals. However, the production cost of high-dielectric ceramics is relatively high. When the usage scenario does not require an overly high dielectric constant, or even does not need to reach the dielectric constant of rutile ceramics, a certain amount of high-dielectric functional fillers can be added to relatively inexpensive raw materials, and on the premise of ensuring that the production cost will not increase significantly, the dielectric constant of the ceramics can be increased to a certain extent.

[0010] Since titanium dioxide has a relatively high dielectric constant, it can be used as a functional filler in dielectric ceramics. Of course, the addition of titanium dioxide can also effectively improve the mechanical properties of ceramics. Ceramic raw materials generally mainly include silica, alumina, zirconia, barium carbonate, magnesium oxide, and organic matrices, etc. When adding inorganic fillers, the difference in thermal expansion coefficients between them and each component needs to be considered to avoid problems such as apparent quality defects in the product during the sintering process and large dielectric losses caused by low compatibility of inorganic fillers. Based on this, the usage amount of inorganic fillers will also be restricted. In addition, the firing process of ceramics is a densification process, which is not only accompanied by changes in the volume of raw material particles but also accompanied by the filling of pores in the green body. During the firing process of ceramics, the volume usually shrinks. The sintering process of ceramics generally includes a preheating stage, an oxidation stage, and a firing stage. The temperature in the oxidation stage is about 950°C, and the temperature in the firing stage of high-performance ceramics is generally above 1200°C, and can be as high as above 2000°C. The thermal expansion coefficient of silica decreases with the increase in temperature during the firing process and becomes basically stable when the temperature exceeds 1200°C. Commonly used titanium dioxide is mainly in the anatase type and rutile type. Among them, the thermal expansion coefficient of the rutile type is less than that of the anatase type. However, regardless of whether titanium dioxide is in the anatase type or rutile type, its thermal expansion coefficient is higher than that of common raw materials such as silica. Therefore, the applicant considered how to reduce the thermal expansion difference between titanium dioxide and other raw materials during the ceramic firing process and reduce the internal stress in the green body.

[0011] Although rutile titanium dioxide has higher stability, dielectric constant and a smaller coefficient of thermal expansion compared to anatase titanium dioxide, and theoretically mixing rutile titanium dioxide into the raw materials for firing should be more advantageous for improving product performance and ensuring appearance quality. However, the applicant hopes to utilize the shrinkage during the transformation of anatase titanium dioxide to rutile titanium dioxide to improve the sintering process of the ceramic. In the initial stage of sintering, especially during the heating period, the volume of the ceramic will expand to a certain extent. After heating to a high enough temperature, the disappearance of pores and the filling of voids start to cause significant volume shrinkage of the ceramic. The applicant hopes that the titanium dioxide can undergo a crystal form transformation in the early stage of sintering, and then compensate for the stress generated by space extrusion during expansion through the shrinkage of the titanium dioxide to a certain extent, which can reduce the possibility of the ceramic developing fine cracks. Furthermore, the amount of titanium dioxide used can be increased to a certain extent, thereby increasing the dielectric constant of the ceramic. In addition, since the crystal form transformation of the titanium dioxide is completed in the early stage of sintering, the overall shrinkage rate of the ceramic volume will not be accelerated due to the shrinkage of the titanium dioxide in the later stage of sintering, and thus the possibility of cracks appearing in the later stage of sintering will also be reduced, expanding the process parameter range. Currently, the volume shrinkage of most ceramics during sintering occurs after 1000°C. The temperature at which anatase titanium dioxide begins to transform into rutile is around 800°C. However, during the sintering process, the time from 800°C to 1000°C is short, and it is difficult for the crystal form to completely transform at temperatures between 800°C and 1000°C. Therefore, the applicant hopes to lower the temperature at which anatase titanium dioxide transforms into rutile. The applicant promoted the transformation of anatase titanium dioxide to rutile through a doping process. At the same time, in order to control the transformation and prevent it from transforming too quickly during the heating stage, resulting in too rapid volume changes and ultimately microcracks, the applicant controlled the doping amount through experiments. In addition, excessive doping may lead to out-of-control grain growth and an increase in structural defects, which not only affects the dielectric constant but also the mechanical properties and chemical stability of the product.

[0012] Preferably, the precursor solution of the titanium dioxide includes one or more of tetrabutyl titanate solution, titanyl sulfate solution, tetraisopropyl titanate solution, and titanium tetrachloride solution.

[0013] Preferably, the temperature of the reaction system in S100 is 60°C - 80°C, and the pH value is 7.5 - 9.

[0014] The pH value can be adjusted using ammonia water. Appropriate system temperature and pH value are beneficial for metal ions to enter the titanium dioxide lattice, the completion of the hydrolysis of the precursor solution, and the stability of the hydrolysis products.

[0015] Preferably, S200 includes:

[0016] A100. The gel is calcined to obtain a pre-product;

[0017] After the pre-product is coated with a film layer through a coating process, a titanium dioxide filler is obtained; the volatilization temperature or decomposition temperature of the film layer is 300°C - 600°C.

[0018] Since anatase titanium dioxide will also expand to a certain extent before transforming into rutile and its expansion coefficient is greater than that of conventional ceramic raw materials, it may cause product structure defects and finally affect the dielectric properties of the product. Therefore, in the present invention, a film layer is coated on the titanium dioxide to limit the expansion of the titanium dioxide through the film layer, and the film layer space released by the decomposition or volatilization of the film layer can also provide expansion space for the titanium dioxide. Therefore, the temperature at which the film layer is damaged in the present invention is less than the crystal form transformation temperature of anatase titanium dioxide.

[0019] Preferably, the coating process includes: taking 1 to 4 parts by weight of triethanolamine, 1.5 to 5 parts by weight of coupling agent, and 80 to 100 parts by weight of pre-product, mixing and reacting them, and then drying to obtain the titanium dioxide filler.

[0020] During the early ceramic forming process, in order to ensure the stability of the shape, the dispersibility of titanium dioxide can be improved by selecting the film layer material, and the bonding degree between titanium dioxide and the organic binder can be improved during the forming process. The stability of the film layer can be improved through the coupling agent, and then the decomposition temperature can be increased, and the decomposition temperature can be adjusted to 400°C - 600°C.

[0021] Preferably, the reaction temperature of the coating process is 65°C - 85°C, and the reaction time is 0.8 h - 2 h.

[0022] By adjusting the raw material dosage, reaction temperature, and reaction time, the film layer thickness can be controlled so that the film layer will not be too large, avoiding excessive increase in the voids of the formed embryo, too high volume shrinkage rate of the product after high-temperature sintering, and extension of the time for the densification process. If the film layer thickness is too small, it is difficult to adapt to the expansion process before the transformation of anatase titanium dioxide. Through the applicant's experiments, the product performance after adopting the parameters of the present invention is relatively excellent.

[0023] Preferably, the coupling agent includes one or more of isostearoyl titanate isopropyl ester, GR-501, and KH570.

[0024] Through experiments, it is obtained that the product performance prepared by using isostearoyl titanate isopropyl ester is good.

[0025] Preferably, the S100 includes:

[0026] Dissolve phosphomolybdic acid in ethanol to obtain solution A;

[0027] Dissolve tin tetrachloride in ethanol to obtain solution B;

[0028] Under heating conditions, solution A and solution B are added to the precursor solution of titanium dioxide, and after mixing for 10 min - 30 min under an ultrasonic environment, it is left standing at room temperature for 8 h - 12 h to obtain a gel; the ultrasonic frequency is 20 KHz - 30 KHz.

[0029] Preferably, after solution B is added to the precursor solution of titanium dioxide at one time, solution A is gradually added.

[0030] The applicant found during the doping experiment that when both solution A and solution B are added to the precursor solution at one time or gradually, the doping amount of Sn 4+ is limited. The applicant conjectures that the reason is that there is a competitive relationship between the two ions during the doping process.

[0031] The present invention has at least the following beneficial effects:

[0032] The present invention utilizes the crystal form change of anatase titanium dioxide in the early stage of sintering to reduce the possibility of ceramic microcracks; anatase titanium dioxide can complete the transformation to rutile type before high-temperature sintering, avoiding exacerbating shrinkage in the case of a high volume shrinkage rate during high-temperature sintering, which increases the possibility of ceramic structural defects under the same process conditions; the titanium dioxide prepared by the doping process of titanium dioxide can promote its transformation to rutile titanium dioxide; after covering a film layer on the outer surface of titanium dioxide through a coating process, the film layer can limit the expansion of titanium dioxide at low temperature, reducing the possibility of structural defects caused by the difference in thermal expansion of raw materials; the film layer volatilizes or decomposes before the crystal form transformation of titanium dioxide, so that the released film layer space can be used for the expansion of titanium dioxide or the surrounding matrix, reducing internal stress; the presence of the film layer can also increase the dispersibility of titanium dioxide and the compatibility with the matrix, thereby increasing the dielectric properties of the product. Specific embodiments

[0033] To make the objectives, method solutions, and advantages of the embodiments of the present invention clearer, the method solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0034] Embodiment 1: A preparation method of a titanium dioxide filler for improving the dielectric properties of ceramics, comprising:

[0035] S100. Under heating conditions, a doping ion solution is added to the precursor solution of titanium dioxide to obtain a gel; the doping ion solution includes: Mo 6+ and Sn 4+ ; the molar ratio of Mo 6+ to Ti 4+ is 10:1, and the molar ratio of Sn 2+ to Ti 4+The molar ratio is 10:2; the temperature of the reaction system in S100 is 60 °C, and the pH value is 7.5; the solute of the titanium dioxide precursor solution is titanium tetrachloride, the solvent is ethanol, and the concentration of titanium tetrachloride is 20 wt%.

[0036] S100 includes:

[0037] Dissolve phosphomolybdic acid in ethanol to obtain solution A;

[0038] Dissolve tin tetrachloride in ethanol to obtain solution B;

[0039] Under heating conditions, add solution A and solution B to the titanium dioxide precursor solution at one time, mix them in an ultrasonic environment for 10 min, and then let it stand at room temperature for 8 h to obtain a gel; the ultrasonic frequency is 20 KHz.

[0040] S200. The gel is calcined to obtain a titanium dioxide filler. The calcination temperature is 450 °C, and the calcination time is 1.5 h.

[0041] Example 2: A preparation method of a titanium dioxide filler for improving the dielectric properties of ceramics, including:

[0042] S100. Under heating conditions, add a doping ion solution to the titanium dioxide precursor solution to obtain a gel; the doping ion solution includes: Mo 6+ and Sn 4+ ; the molar ratio of Mo 6+ to Ti 4+ is 30:2, and the molar ratio of Sn 2+ to Ti 4+ is 20:3; the temperature of the reaction system in S100 is 80 °C, and the pH value is 9; the solute of the titanium dioxide precursor solution is titanium tetrachloride, the solvent is ethanol, and the concentration of titanium tetrachloride is 20 wt%.

[0043] S100 includes:

[0044] Dissolve phosphomolybdic acid in ethanol to obtain solution A;

[0045] Dissolve tin tetrachloride in ethanol to obtain solution B;

[0046] Under heating conditions, add solution A and solution B to the titanium dioxide precursor solution at one time, mix them in an ultrasonic environment for 30 min, and then let it stand at room temperature for 12 h to obtain a gel; the ultrasonic frequency is 30 KHz.

[0047] S200. The gel is calcined to obtain a titanium dioxide filler. The calcination temperature is 450 °C, and the calcination time is 1.5 h.

[0048] Example 3: A preparation method of titanium dioxide filler for improving ceramic dielectric properties, comprising:

[0049] S100. Under heating conditions, a doping ion solution is added to the precursor solution of titanium dioxide to obtain a gel; the doping ion solution includes: Mo 6+ and Sn 4+ ; the molar ratio of Mo 6+ to Ti 4+ is 20:1.4, and the molar ratio of Sn 2+ to Ti 4+ is 16:2.5; the temperature of the reaction system in S100 is 72 °C, and the pH value is 8.3; the solute of the precursor solution of titanium dioxide is titanium tetrachloride, the solvent is ethanol, and the concentration of titanium tetrachloride is 20 wt%.

[0050] The S100 includes:

[0051] Dissolve phosphomolybdic acid in ethanol to obtain solution A;

[0052] Dissolve tin tetrachloride in ethanol to obtain solution B;

[0053] Under heating conditions, add solution A and solution B to the precursor solution of titanium dioxide at one time, and mix for 20 min in an ultrasonic environment, then stand at room temperature for 10 h to obtain a gel; the ultrasonic frequency is 25 KHz.

[0054] S200. The gel is prepared into a titanium dioxide filler through a calcination process. The calcination temperature is 450 °C, and the calcination time is 1.5 h.

[0055] Example 4: A preparation method of titanium dioxide filler for improving ceramic dielectric properties, comprising:

[0056] S100. Under heating conditions, a doping ion solution is added to the precursor solution of titanium dioxide to obtain a gel; the doping ion solution includes: Mo 6+ and Sn 4+ ; the molar ratio of Mo 6+ to Ti 4+ is 20:1.4, and the molar ratio of Sn 2+ to Ti 4+ is 16:2.5; the temperature of the reaction system in S100 is 72 °C, and the pH value is 8.3; the solute of the precursor solution of titanium dioxide is titanium tetrachloride, the solvent is ethanol, and the concentration of titanium tetrachloride is 20 wt%.

[0057] The S100 includes:

[0058] Dissolve phosphomolybdic acid in ethanol to obtain solution A;

[0059] Dissolve tin tetrachloride in ethanol to obtain solution B;

[0060] Under heating conditions, add solution B to the precursor solution of titanium dioxide at one time, and then add solution A of 25 vt% every 5 minutes. During this period, the system is in an ultrasonic environment. After 20 minutes, let it stand at room temperature for 10 h to obtain a gel; the ultrasonic frequency is 25 KHz.

[0061] S200. The gel is calcined to obtain titanium dioxide filler. The calcination temperature is 450 °C and the calcination time is 1.5 h.

[0062] Blank example: The difference from Example 3 is that no doping ion solution is added in step S100.

[0063] Preparation method of experimental samples: Ceramic powder and binder PVA are wet ball-milled and mixed for 30 hours to obtain a slurry, and the dosage of the binder is 4% of the powder. After the slurry is pressed into a blank, sintering is started. Sintering process: First preheat at 300 °C for 1 h, then raise the temperature to 1000 °C at a rate of 80 °C / h, hold for 1 h, and then raise the temperature to 1300 °C at a rate of 60 °C / h and hold for 5 h. The ceramic powder includes 70 wt% alumina powder, 10 wt% magnesia powder, 1 wt% silica and the balance titanium dioxide filler.

[0064] Experiment 1: The titanium dioxide fillers prepared by the preparation methods provided in Examples 1-4 and the blank example are used for the preparation of experimental samples, and then the dielectric constant of the prepared samples is tested with reference to the standard of GB / T5594.4-2015. Test conditions: 1 MHz, 25 °C, thickness 5 mm. Take the average value after testing 5 times for each group, and the test results are shown in Table 1.

[0065] Table 1

[0066] Example 1 Example 2 Example 3 Example 4 Blank Example Dielectric Constant 16.6 17.4 18.7 24.3 11.0

[0067] From the data comparison between Examples 1-3 and the blank example in Table 1, it can be seen that the titanium dioxide filler prepared after doping titanium dioxide can effectively improve the dielectric constant of ceramics.

[0068] From the data comparison between Example 3 and Example 4 in Table 1, it can be seen that the way of adding solution A and solution B to the precursor solution affects the effect of the titanium dioxide filler in improving the dielectric constant of ceramics.

[0069] Example 5: A preparation method of a titanium dioxide filler for improving the dielectric properties of ceramics, including:

[0070] S100. Under heating conditions, add a doping ion solution to the precursor solution of titanium dioxide to obtain a gel; the doping ion solution includes: Mo 6+ and Sn 4+ ; the Mo6+ The molar ratio with Ti 4+ is 20:1.4, and the Sn 2+ The molar ratio with Ti 4+ is 16:2.5; the temperature of the reaction system in S100 is 72 °C and the pH value is 8.3; the solute of the precursor solution of titanium dioxide is titanium tetrachloride, the solvent is ethanol, and the concentration of titanium tetrachloride is 20 wt%.

[0071] S100 includes:

[0072] Dissolve phosphomolybdic acid in ethanol to obtain solution A;

[0073] Dissolve tin tetrachloride in ethanol to obtain solution B;

[0074] Under heating conditions, add solution B to the precursor solution of titanium dioxide at one time, and then add 25 vt% of solution A every 5 minutes. During this period, the system is in an ultrasonic environment. After 20 min, let it stand at room temperature for 10 h to obtain a gel; the ultrasonic frequency is 25 KHz.

[0075] S200. The gel is calcined to obtain a pre-product. The calcination temperature is 450 °C and the calcination time is 1.5 h. After the pre-product is coated with a film layer through a coating process, a titanium dioxide filler is obtained; the coating process includes: by weight, mix 1 part of triethanolamine, 1.5 parts of isopropyl triisostearoyl titanate, 80 parts of the pre-product and 100 parts of deionized water, react, separate, wash with water, and dry to obtain the titanium dioxide filler. The reaction temperature is 65 °C and the reaction time is 0.8 h.

[0076] Example 6: A preparation method of a titanium dioxide filler for improving the dielectric properties of ceramics, including:

[0077] S100. Under heating conditions, add a doping ion solution to the precursor solution of titanium dioxide to obtain a gel; the doping ion solution includes: Mo 6+ and Sn 4+ ; the molar ratio of Mo 6+ with Ti 4+ is 20:1.4, and the molar ratio of Sn 2+ with Ti 4+ is 16:2.5; the temperature of the reaction system in S100 is 72 °C and the pH value is 8.3; the solute of the precursor solution of titanium dioxide is titanium tetrachloride, the solvent is ethanol, and the concentration of titanium tetrachloride is 20 wt%.

[0078] S100 includes:

[0079] Dissolve phosphomolybdic acid in ethanol to obtain solution A;

[0080] Dissolve tin tetrachloride in ethanol to obtain solution B;

[0081] Under heating conditions, add solution B to the precursor solution of titanium dioxide at one time, and then add 25 vt% of solution A every 5 minutes. During this period, the system is in an ultrasonic environment. After 20 minutes, let it stand at room temperature for 10 h to obtain a gel; the ultrasonic frequency is 25 KHz.

[0082] S200. The gel is calcined to obtain a pre-product. The calcination temperature is 450 °C and the calcination time is 1.5 h. After the pre-product is coated with a film layer through a coating process, titanium dioxide filler is obtained; the coating process includes: by weight, mix 4 parts of triethanol, 5 parts of isopropyl triisostearoyl titanate, 100 parts of the pre-product and 100 parts of deionized water, react, separate, wash with water and dry to obtain titanium dioxide filler. The reaction temperature is 85 °C and the reaction time is 2 h.

[0083] Example 7: A preparation method of titanium dioxide filler for improving the dielectric properties of ceramics, including:

[0084] S100. Under heating conditions, add a doping ion solution to the precursor solution of titanium dioxide to obtain a gel; the doping ion solution includes: Mo 6+ and Sn 4+ ; the molar ratio of Mo 6+ to Ti 4+ is 20:1.4, and the molar ratio of Sn 2+ to Ti 4+ is 16:2.5; the temperature of the reaction system in S100 is 72 °C and the pH value is 8.3; the solute of the precursor solution of titanium dioxide is titanium tetrachloride, the solvent is ethanol, and the concentration of titanium tetrachloride is 20 wt%.

[0085] The S100 includes:

[0086] Dissolve phosphomolybdic acid in ethanol to obtain solution A;

[0087] Dissolve tin tetrachloride in ethanol to obtain solution B;

[0088] Under heating conditions, add solution B to the precursor solution of titanium dioxide at one time, and then add 25 vt% of solution A every 5 minutes. During this period, the system is in an ultrasonic environment. After 20 minutes, let it stand at room temperature for 10 h to obtain a gel; the ultrasonic frequency is 25 KHz.

[0089] S200. The gel is calcined to obtain a pre-product. The calcination temperature is 450 °C and the calcination time is 1.5 h. After the pre-product is coated with a film layer through a coating process, a titanium dioxide filler is obtained. The coating process includes: by weight, mixing 3 parts of triethanolamine, 3 parts of isopropyl triisostearoyl titanate, 90 parts of the pre-product, and 100 parts of deionized water, reacting, separating, washing with water, and drying to obtain the titanium dioxide filler. The reaction temperature is 80 °C and the reaction time is 1.5 h.

[0090] Comparative Example 1: The difference from Example 7 is that the doped ion solution does not contain Sn. 4+ .

[0091] Comparative Example 2: The difference from Example 7 is that the doped ion solution does not contain Mo. 6+ .

[0092] Comparative Example 3: The difference from Example 7 is that the amount of triethanolamine used is 0.5 part.

[0093] Comparative Example 4: The difference from Example 7 is that the reaction time of the coating process is 3 h.

[0094] Comparative Example 5: The difference from Example 7 is that there is no ultrasonic environment.

[0095] Comparative Example 6: The difference from Example 7 is that there is no standing for 10 h.

[0096] Comparative Example 7: The difference from Example 7 is that no coupling agent is used.

[0097] Test 2: The titanium dioxide fillers prepared by the preparation methods provided in Examples 4 - 7 and Comparative Examples 1 - 7 are used for the preparation of experimental samples, and then the dielectric constants of the prepared samples are tested with reference to the GB / T5594.4 - 2015 standard. The test conditions are: 1 MHz, 25 °C, and a thickness of 5 mm. The average value is taken after each group is tested 5 times, and the test results are shown in Table 2.

[0098] Table 2

[0099] Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Dielectric Constant 24.3 31.7 32.9 34.1 20.5 26.3 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Dielectric Constant 30.6 31.4 32.8 32.7 28.3

[0100] It can be seen from the comparison of the data of Example 5 and Example 4 in Table 2 that the addition of the coating process can effectively promote the titanium dioxide filler to increase the dielectric constant of the ceramic.

[0101] It can be seen from the results of Examples 5 - 7 that the titanium dioxide prepared with the process parameters provided in Example 7 has the best performance.

[0102] It can be seen from the comparison of Comparative Examples 1 - 2 and Example 7 that the use of Sn 4+ and Mo 6+ mixed doping can improve the applicability of the titanium dioxide filler during the ceramic sintering process.

[0103] It can be seen from the comparison between Comparative Examples 3-4 and Example 7 that the selection of coating raw materials and coating process parameters both affect the degree of improvement of the ceramic dielectric constant by the titanium dioxide filler.

[0104] It can be seen from the comparison between Comparative Examples 5-6 and Example 7 that both the ultrasonic environment and the standing process in the titanium dioxide doping process affect the degree of improvement of the ceramic dielectric constant by the titanium dioxide filler.

[0105] It can be seen from the comparison between Comparative Example 7 and Example 7 that the use of a coupling agent can promote the improvement of the ceramic dielectric constant by the titanium dioxide filler. The applicant conjectures that one of the reasons is that the thermal stability of triethanolamine is relatively low, the coating is damaged earlier, and the restriction on the expansion of titanium dioxide is weaker.

[0106] Experiment 3: The titanium dioxide fillers prepared by the preparation methods provided in Examples 1-7 and Comparative Examples 1-7 were used to prepare experimental samples, and then the mechanical properties of the prepared samples were tested. The average value was taken after 5 tests for each group, and the test results are shown in Table 3.

[0107] Example 1 Example 2 Example 3 Example 4 Example 5 Flexural Strength 304.75 312.48 318.06 339.1 367.89 Fracture Toughness 4.72 4.78 4.81 5.07 5.43 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Comparative Example 3 Flexural Strength 370.04 378.13 319.72 332.08 341.37 Fracture Toughness 5.56 5.72 4.86 5.11 5.24 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Flexural Strength 339.72 350.64 361.27 336.83 Fracture Toughness 5.20 5.38 5.43 5.17

[0108] The unit of flexural strength is MPa, and the fracture toughness is MPa·m 1 / 2 .

[0109] It can be seen from the test results of Examples 1-7 in Table 1 that the ceramic samples prepared with the titanium dioxide filler provided by the present invention all have good mechanical properties.

[0110] It can be seen from the comparison between Comparative Examples 1-7 and Example 7 that the specific steps and process parameters of the doping process and the coating process both affect the mechanical properties of the ceramic samples prepared with the titanium dioxide filler provided by the present invention.

[0111] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of titanium dioxide filler for improving ceramic dielectric properties, characterized in that, Including: S100. Under heating conditions, a doping ion solution is added to the precursor solution of titanium dioxide to obtain a gel. The doped ion solution includes: Mo 6+ and Sn 4+ ; The molar ratio of the Mo 6+ to Ti 4+ is (10 - 30):(1 - 2), and the molar ratio of the Sn 2+ to Ti 4+ is (10 - 20):(2 - 3); S200. The gel is prepared into a titanium dioxide filler through a calcination process.

2. The preparation method according to claim 1, characterized in that, The precursor solution of titanium dioxide includes one or more of tetrabutyl titanate solution, titanyl sulfate solution, tetraisopropyl titanate solution, and titanium tetrachloride solution.

3. The preparation method according to claim 1, characterized in that, In S100, the temperature of the reaction system is 60°C - 80°C, and the pH value is 7.5 - 9.

4. The preparation method according to any one of claims 1 to 3, characterized in that, S200 includes: A100. A pre-product is obtained after the gel undergoes a calcination process. A200. After the pre-product is coated with a film layer through a coating process, a titanium dioxide filler is obtained; the volatilization temperature or decomposition temperature of the film layer is 300°C - 600°C.

5. The preparation method according to claim 4, characterized in that, The coating process includes: by weight, mixing 1 part - 4 parts of triethanolamine, 1.5 parts - 5 parts of coupling agent, and 80 parts - 100 parts of the pre-product, reacting, and then drying to obtain the titanium dioxide filler.

6. The preparation method according to claim 5, wherein The reaction temperature of the coating process is 65°C - 85°C, and the reaction time is 0.8 h - 2 h.

7. The preparation method according to claim 5, characterized in that, The coupling agent includes one or more of isostearoyl titanate isopropyl ester, KH560, and KH570.

8. The preparation method according to claim 4, characterized in that, S100 includes: Dissolving phosphomolybdic acid in ethanol to obtain solution A. Dissolving tin tetrachloride in ethanol to obtain solution B. Under heating conditions, adding solution A and solution B to the precursor solution of titanium dioxide, mixing in an ultrasonic environment for 10 min - 30 min, and then standing at room temperature for 8 h - 12 h to obtain a gel; the ultrasonic frequency is 20 KHz - 30 KHz.

9. The preparation method according to claim 8, characterized in that, Solution B is added to the precursor solution of titanium dioxide once, and then solution A is gradually added.

10. A titanium dioxide filler prepared by the preparation method according to any one of claims 1 - 9.