阅读说明：本技术 一种微波介质陶瓷材料及其制备方法 (Microwave dielectric ceramic material and preparation method thereof ) 是由 张军志 杨和成 罗超 于 2020-06-28 设计创作，主要内容包括：本发明提供一种微波介质陶瓷材料,涉及信息功能材料领域。该陶瓷材料包括主材与改性添加物。主材的化学式为Mg<Sub>2-3x</Sub>Ca<Sub>x</Sub>TiO<Sub>4-2x</Sub>·yCaSiO<Sub>3</Sub>,其中0.01≤x≤0.50,0.00<y≤0.20；所述主材在所述微波介质陶瓷材料中所占的质量分数为99.2～99.8wt％；所述改性添加物在所述微波介质陶瓷材料中所占的质量分数为0.2～0.8wt％。改性添加物选自BaCO<Sub>3</Sub>、SrCO<Sub>3</Sub>、ZnO、MnCO<Sub>3</Sub>、Sb<Sub>2</Sub>O<Sub>3</Sub>、SiO<Sub>2</Sub>和MnO<Sub>2</Sub>中的一种或几种。本发明的陶瓷介质材料是一种无铅环保型材料,采用固相合成方法合成Mg<Sub>2-3x</Sub>Ca<Sub>x</Sub>TiO<Sub>4-2x</Sub>与CaSiO<Sub>3</Sub>作为主材的成分,掺杂改性添加物,经过合理设计配方,优化合成工艺,制备出粉体平均粒径为0.4-1.0um,利用该粉体制作电子陶瓷器件可在1300～1380℃的温度范围内烧结成瓷,其介电常数ε介于18～23之间,品质因数Qf值≥40000GHz,温度系数τf(-40～85℃)：±10ppm/℃。(The invention provides a microwave dielectric ceramic material, and relates to the field of information functional materials. The ceramic material comprises a main material and a modified additive. The main material has a chemical formula of Mg 2‑3x Ca x TiO 4‑2x ·yCaSiO 3 Wherein x is more than or equal to 0.01 and less than or equal to 0.50 and 0.00<y is less than or equal to 0.20; the mass fraction of the main material in the microwave dielectric ceramic material is 99.2-99.8 wt%; the mass fraction of the modified additive in the microwave dielectric ceramic material is 0.2-0.8 wt%. The modifying additive is selected from BaCO 3 、SrCO 3 、ZnO、MnCO 3 、Sb 2 O 3 、SiO 2 And MnO 2 One or more of them. The ceramic dielectric material is a lead-free environment-friendly material, and Mg is synthesized by adopting a solid-phase synthesis method 2‑3x Ca x TiO 4‑2x With CaSiO 3 As the main material, modified additive is doped and reasonably designedThe method optimizes the synthesis process, the average particle size of the prepared powder is 0.4-1.0um, the electronic ceramic device manufactured by the powder can be sintered into ceramic within the temperature range of 1300-1380 ℃, the dielectric constant is 18-23, the quality factor Qf value is more than or equal to 40000GHz, and the temperature coefficient tau f (-40-85 ℃): 10 ppm/DEG C.)

1. A microwave dielectric ceramic material comprises a main material and a modified additive, and is characterized in that: the main material has a chemical formula of Mg_2-3xCa_xTiO_4-2x·yCaSiO₃Wherein x is more than or equal to 0.01 and less than or equal to0.50，0.00<y is less than or equal to 0.20; the mass fraction of the main material in the microwave dielectric ceramic material is 99.2-99.8 wt%; the mass fraction of the modified additive in the microwave dielectric ceramic material is 0.2-0.8 wt%.

2. A microwave dielectric ceramic material according to claim 1, wherein: the modifying additive is selected from BaCO₃、SrCO₃、ZnO、MnCO₃、Sb₂O₃、SiO₂And MnO₂One or more than one mixture.

3. A microwave dielectric ceramic material as claimed in claim 2, wherein the mass fraction of each of the modifying additives in the microwave dielectric ceramic material is: BaCO₃0 to 0.35% of SrCO₃0 to 0.2% of ZnO, 0 to 0.2% of MnCO₃0 to 0.4% of Sb₂O₃0 to 0.3% of SiO₂0 to 0.1% of MnO₂0 to 0.3%.

4. A method for preparing a microwave dielectric ceramic material as claimed in any one of claims 1 to 3, comprising the following steps:

s1, Synthesis of Mg_2-3xCa_xTiO_4-2x: putting magnesium hydroxide, calcium carbonate and titanium dioxide into a ball mill according to a ratio, adding water, uniformly mixing, carrying out wet ball milling, calcining at the temperature of 1050-1300 ℃ for 2-4 hours in air atmosphere to obtain Mg_2-3xCa_xTiO_4-2x(ii) a The specific surface area of the magnesium hydroxide is more than 7.0m²The specific surface area of the titanium dioxide is more than 5.0m²/g；

S2, Synthesis of CaSiO₃: proportionally placing calcium carbonate and silicon dioxide in a ball mill, adding water, uniformly mixing, carrying out wet ball milling, calcining at 1050-1100 ℃ for 1-2 hours in air atmosphere to obtain CaSiO₃；

S3, mixing the Mg obtained in the step S1_2-3xCa_xTiO_4-2xCaSiO obtained in step S2₃And the modified additives are put into a ball mill together according to the formula requirements, water is added for wet ball milling, homogenization treatment is carried out, and then the ball-milled materials are dried to obtain the microwave dielectric ceramic material in a powder state.

5. The preparation method according to claim 4, wherein in step S3, the particle size of the ball-milled material is 0.4-1.0 um.

6. The method of claim 4, further comprising the steps of:

s4, adding an adhesive, a plasticizer, a dispersing agent and the like into the microwave dielectric ceramic material in a powder state, performing ball milling for 1-2 hours to obtain slurry, drying to obtain powder, and pressing the powder into a green body;

s5, removing glue: placing the green body in a temperature range of 500-650 ℃, and preserving heat for 16-32 hours to obtain a green body;

s6, sintering: keeping the blank subjected to the binder removal at 1300-1380 ℃ for 3-5 hours in an air atmosphere;

s7, annealing: and after sintering, keeping the temperature for 1-2 hours at 950-1050 ℃ to obtain the formed microwave dielectric ceramic material.

7. The method according to claim 6, wherein the binder is polyvinyl alcohol, the plasticizer is polyethylene glycol, and the dispersant is ammonium carboxylate.

8. The method according to claim 6, wherein in the step S5, the temperature rising rate is less than 10 ℃/hr.

9. The method according to claim 6, wherein the sintering process of step S6 has a temperature rise rate of 150 ℃ to 200 ℃/hr.

10. The preparation method of claim 6, wherein the formed microwave dielectric ceramic material is obtained, and has a warm dielectric constant of 18-23 and a temperature coefficient τ f (-40-85 ℃): +/-10 ppm/deg.C, and Qf value greater than or equal to 40000 GHz.

Technical Field

The invention relates to the field of information functional materials, in particular to a microwave dielectric ceramic material with medium and low dielectric constants and a preparation method thereof.

Background

Microwave dielectric ceramic materialIs a novel functional ceramic material which is rapidly developed in recent years. It has the characteristics of low dielectric loss, high dielectric constant, stable dielectric constant temperature coefficient tau f and the like. The material is a core basic material of a novel microwave circuit and a device including a dielectric resonator, a filter, an oscillator, a duplexer, an antenna, a dielectric substrate and the like, and has wide application in modern microwave communication and satellite navigation systems and equipment. In recent years, microwave devices have been rapidly developed in a direction of miniaturization, integration, and low power consumption, especially, mass production and low price for civil use, and thus a large number of microwave dielectric ceramic materials suitable for various microwave frequency bands have been developed. However, the dielectric constant of the existing microwave dielectric ceramic material is higher, and the microwave dielectric ceramic material is general>23, or dielectric constant<23 but temperature coefficient τ f>+ -10 ppm/DEG C, the performance is unstable. For example, magnesium metatitanate (MgO. TiO) having an ilmenite structure₂) The microwave dielectric ceramic material is an important microwave dielectric ceramic material due to relatively cheap raw materials and excellent microwave performance, but the high-temperature coefficient is-50 ppm/DEG C, so that the practical application of the microwave dielectric ceramic material is influenced.

Disclosure of Invention

The invention aims to provide a microwave dielectric ceramic material and a preparation method thereof, which are used for solving the problems of high dielectric constant and unstable performance of the conventional microwave dielectric ceramic material.

The invention adopts the following scheme to achieve the aim.

The invention provides a microwave dielectric ceramic material, which comprises a main material and a modified additive, wherein the chemical formula of the main material is Mg_2-3xCa_xTiO_4-2x·yCaSiO₃Wherein x is more than or equal to 0.01 and less than or equal to 0.50 and 0.00<y is less than or equal to 0.20; the mass fraction of the main material in the microwave dielectric ceramic material is 99.2-99.8 wt%; the mass fraction of the modified additive in the microwave dielectric ceramic material is 0.2-0.8 wt%.

Preferably, the modifying additive is selected from BaCO₃、SrCO₃、ZnO、MnCO₃、Sb₂O₃、SiO₂And MnO₂One or more than one mixture.

Preference is given toAnd the mass fraction range of each modified additive in the microwave dielectric ceramic material is as follows: BaCO₃0 to 0.35% of SrCO₃0 to 0.2% of ZnO, 0 to 0.2% of MnCO₃0 to 0.4% of Sb₂O₃0 to 0.3% of SiO₂0 to 0.1% of MnO₂0 to 0.3%.

The invention also provides a preparation method of the microwave dielectric ceramic material, which comprises the following steps:

s1, Synthesis of Mg_2-3xCa_xTiO_4-2x: putting magnesium hydroxide, calcium carbonate and titanium dioxide into a ball mill according to a ratio, adding water, uniformly mixing, carrying out wet ball milling, calcining at the temperature of 1050-1300 ℃ for 2-4 hours in air atmosphere to obtain Mg_2-3xCa_xTiO_4-2x(ii) a The specific surface area of the magnesium hydroxide is more than 7.0m²The specific surface area of the titanium dioxide is more than 5.0m²/g；

S2, Synthesis of CaSiO₃: proportionally placing calcium carbonate and silicon dioxide in a ball mill, adding water, uniformly mixing, carrying out wet ball milling, calcining at 1050-1100 ℃ for 1-2 hours in air atmosphere to obtain CaSiO₃；

S3, mixing the Mg obtained in the step S1_2-3xCa_xTiO_4-2xCaSiO obtained in step S2₃And the modified additives are put into a ball mill together according to the formula requirements, water is added for wet ball milling, homogenization treatment is carried out, and then the ball-milled materials are dried to obtain the microwave dielectric ceramic material in a powder state.

Further, in step S3, the particle size of the ball-milled material is 0.4-1.0 um.

Further, the preparation method also comprises the following steps:

s4, adding an adhesive, a plasticizer, a dispersing agent and the like into the microwave dielectric ceramic material in a powder state, performing ball milling for 1-2 hours to obtain slurry, drying to obtain powder, and pressing the powder into a green body;

s5, removing glue: placing the green body in a temperature range of 500-650 ℃, and preserving heat for 16-32 hours to obtain a green body;

s6, sintering: keeping the blank subjected to the binder removal at 1300-1380 ℃ for 3-5 hours in an air atmosphere;

s7, annealing: and after sintering, keeping the temperature for 1-2 hours at 950-1050 ℃ to obtain the formed microwave dielectric ceramic material.

Preferably, the adhesive is polyvinyl alcohol, the plasticizer is polyethylene glycol, and the dispersant is carboxylic acid ammonium salt.

Preferably, in the glue discharging process of the step S5, the temperature rising speed is less than 10 ℃/hour.

Preferably, in the sintering process of step S6, the temperature rise rate is 150 to 200 ℃/hr.

The formed microwave dielectric ceramic material has a temperature dielectric constant of 18-23 and a temperature coefficient tau f (-40-85 ℃): +/-10 ppm/deg.C, and Qf value greater than or equal to 40000 GHz.

Magnesium metatitanate (MgO. TiO) having ilmenite structure₂) The high temperature coefficient of (2) is-50 ppm/DEG C, and the temperature coefficient can be adjusted by compounding with other materials with positive temperature coefficients according to a mixing rule. By predoping Ca, it can be mixed with TiO₂Formation of CaTiO₃. And CaTiO₃Is a twisted orthogonal perovskite structure, has the dielectric constant of 170 at room temperature, has a very high positive temperature coefficient of 800 ppm/DEG C, can realize the adjustment of a high-temperature coefficient, and synthesizes CaSiO for realizing sintering at a lower temperature₃，CaSiO₃Besides being a low-dielectric-constant ceramic material with good performance, the ceramic material is also a cosolvent. Mixing Mg_2-3xCa_xTiO_4-2xWith CaSiO₃The ceramic material which is sintered at 1300-1380 ℃ and has microwave performance can be obtained by compounding the two according to a certain proportion. The ceramic material can form a ceramic material with a room temperature dielectric constant of 18-23, a Qf value of more than or equal to 40000GHz and a temperature coefficient tau f (-40-85 ℃): 10 ppm/DEG C.

The invention has the beneficial effects that: mixing Mg_2-3xCa_xTiO_4-2x、CaSiO₃And compounding with modified additivesThe prepared microwave dielectric ceramic material has good material uniformity and meets the requirements of microwave devices. The microwave dielectric ceramic material with microwave performance is obtained after the powder is sintered at 1300-1380 ℃. The ceramic material can form a ceramic material with a room temperature dielectric constant of 18-23, a Qf value of more than or equal to 40000GHz and a temperature coefficient tau f (-40-85 ℃): +/-10 ppm/DEG C, and can meet the microwave performance requirement of the microwave device.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The invention provides a microwave dielectric ceramic material, which comprises a main material and a modified additive, wherein the chemical formula of the main material is Mg_2-3xCa_xTiO_4-2x·yCaSiO₃Wherein x is more than or equal to 0.01 and less than or equal to 0.50 and 0.00<y is less than or equal to 0.20; the mass fraction of the main material in the microwave dielectric ceramic material is 99.2-99.8 wt%; the mass fraction of the modified additive in the microwave dielectric ceramic material is 0.2-0.8 wt%.

The modifying additive is selected from BaCO₃、SrCO₃、ZnO、MnCO₃、Sb₂O₃、SiO₂And MnO₂One or more than one mixture.

Preferably, the mass fraction of each modified additive in the microwave dielectric ceramic material is as follows: BaCO₃0 to 0.35% of SrCO₃0 to 0.2% of ZnO, 0 to 0.2% of MnCO₃0 to 0.4% of Sb₂O₃0 to 0.3% of SiO₂0 to 0.1% of MnO₂0 to 0.3%.

The invention also provides a preparation method of the microwave dielectric ceramic material, which comprises the following steps:

① preparation of Mg as one of the principal materials_2-3xCa_xTiO_4-2xPowder: weighing high-purity and superfine Mg (OH) with corresponding mass according to the proportion of each metal element in the compound₂、CaCO₃、TiO₂Placing the mixture into a ball mill, and taking the solid materials according to the mass ratio: water 1: (1.0-2.0), adding water, performing ball milling and mixing uniformly, performing sand milling treatment to reach a certain particle size, drying by using a spray drying tower or other methods, calcining for 2-4 hours in an air atmosphere furnace at the temperature of 1050-1300 ℃, and finally obtaining Mg_2-3xCa_xTiO_4-2xAnd (3) powder. Wherein, Mg (OH)₂Has a specific surface area of more than 7.0m²/g，TiO₂Has a specific surface area of more than 5.0m²/g。

② preparation of CaSiO as another component of the main material₃Powder: mixing high-purity, ultra-fine CaCO₃And SiO₂Weighing the materials according to a molar ratio of 1:1, placing the materials in a ball mill, and mixing the materials according to the mass ratio: deionized water 1: (1.0-2.0), adding water, ball-milling, uniformly mixing, drying by using a spray drying tower or other methods after reaching a certain particle size, calcining for 1-2 hours at 1050-1100 ℃ in an air atmosphere furnace to finally obtain CaSiO₃And (3) powder.

③ preparing formula powder by mixing ① and ② two main materials with various modified additives BaCO₃、MnCO₃、MnO₂、SrCO₃、ZnO、SiO₂、Sb₂O₃One or more of the microwave dielectric ceramic materials are weighed according to the formula of the microwave dielectric ceramic materials, placed in a ball mill and prepared into solid materials according to the mass ratio: water 1: (0.6-1.0) adding water for wet sanding, wherein the materials are required to be uniformly mixed, and the average particle size of the sanded powder is 0.40-1.0um measured by a laser particle sizer. And drying the mixture by using a spray drying tower or other methods after the ball milling is finished to obtain the powdery microwave dielectric ceramic material.

Further, the preparation method of the microwave dielectric ceramic material of the invention also comprises the following steps:

and fourthly, adding a proper amount of adhesive, plasticizer, dispersant and the like into the microwave dielectric ceramic material in the powder state, using zirconia balls as grinding media to perform ball milling for 1-2 hours in a ball milling tank to obtain slurry, and performing centrifugal spray drying to obtain spherical particle powder with good fluidity. In a preferred mode, the adhesive is polyvinyl alcohol, the plasticizer is polyethylene glycol, and the dispersant is ammonium carboxylate.

Pressing the spherical particle powder into a green device.

Sixthly, placing the green device in the temperature range of 500-650 ℃, preserving heat for 16-32 hours, removing organic matters in the green sheet, and requiring the temperature rise speed in the whole glue removing process to be less than 10 ℃/hour.

And (c) sintering: and sintering the green body after the binder removal in air, heating to 1300-1380 ℃ at a heating rate of 150-200 ℃/h, and keeping the temperature for 3-5 hours. The sintering temperature is preferably 1350 ℃. Sintering can move the grain boundary of the powder particles in the ceramic body, the air holes are gradually eliminated, and the body shrinks into a compact ceramic body with certain strength.

And eighthly, annealing treatment: and (3) after high-temperature sintering, keeping the furnace temperature within the range of 950-1050 ℃ for 1-2 hours to obtain the formed microwave dielectric ceramic material. Annealing can reduce the internal stress of the blank, refine crystal grains, close microcracks, improve the tissue structure of the material and improve the mechanical property of the ceramic.

Ninthly, testing the device: and performing microwave performance test at the frequency of 5-8GHz by adopting an Agilent network.

According to the test result: the formed microwave dielectric ceramic material has a temperature dielectric constant of 18-23 and a temperature coefficient tau f (-40-85 ℃): +/-10 ppm/deg.C, and Qf value greater than or equal to 40000 GHz.