阅读说明：本技术 一种复合陶瓷材料及其制备方法 (Composite ceramic material and preparation method thereof ) 是由 张海波 范鹏元 南博 李利松 肖建中 郭新 卢亚 张国军 于 2020-07-14 设计创作，主要内容包括：本发明公开一种复合陶瓷材料及其制备方法,该复合陶瓷材料由0.5(Bi<Sub>0.5</Sub>Na<Sub>0.5</Sub>)TiO<Sub>3</Sub>-0.5(Sr<Sub>0.7</Sub>Bi<Sub>0.2</Sub>)TiO<Sub>3</Sub>粉体和氮化硼颗粒按照化学式0.5(Bi<Sub>0.5</Sub>Na<Sub>0.5</Sub>)TiO<Sub>3</Sub>-0.5(Sr<Sub>0.7</Sub>Bi<Sub>0.2</Sub>)TiO<Sub>3</Sub>/BN所制成,所述0.5(Bi<Sub>0.5</Sub>Na<Sub>0.5</Sub>)TiO<Sub>3</Sub>-0.5(Sr<Sub>0.7</Sub>Bi<Sub>0.2</Sub>)TiO<Sub>3</Sub>粉体是由Bi<Sub>2</Sub>O<Sub>3</Sub>、Na<Sub>2</Sub>CO<Sub>3</Sub>、SrCO<Sub>3</Sub>、TiO<Sub>2</Sub>根据化学式0.5(Bi<Sub>0.5</Sub>Na<Sub>0.5</Sub>)TiO<Sub>3</Sub>-0.5(Sr<Sub>0.7</Sub>Bi<Sub>0.2</Sub>)TiO<Sub>3</Sub>进行配料后混合而成。本发明所制成的复合陶瓷材料兼具高储能密度和高储能效率,可用于制造大功率介电储能器件。(The invention discloses a composite ceramic material and a preparation method thereof, wherein the composite ceramic material is prepared from 0.5 (Bi) 0.5 Na 0.5 ）TiO 3 ‑0.5（Sr 0.7 Bi 0.2 ）TiO 3 The powder and boron nitride particles are according to the chemical formula 0.5 (Bi) 0.5 Na 0.5 ）TiO 3 ‑0.5（Sr 0.7 Bi 0.2 ）TiO 3 0.5 (Bi) of 0.5 Na 0.5 ）TiO 3 ‑0.5（Sr 0.7 Bi 0.2 ）TiO 3 The powder is made of Bi 2 O 3 、Na 2 CO 3 、SrCO 3 、TiO 2 According to chemical formula 0.5 (Bi) 0.5 Na 0.5 ）TiO 3 ‑0.5（Sr 0.7 Bi 0.2 ）TiO 3 The components are mixed to obtain the product. The inventionThe prepared composite ceramic material has high energy storage density and high energy storage efficiency, and can be used for manufacturing high-power dielectric energy storage devices.)

1. A composite ceramic material is characterized by comprising 0.5 (Bi)_0.5Na_0.5）TiO₃-0.5（Sr_0.7Bi_0.2）TiO₃The powder and boron nitride particles are according to the chemical formula 0.5 (Bi)_0.5Na_0.5）TiO₃-0.5（Sr_0.7Bi_0.2）TiO₃0.5 (Bi) of_0.5Na_0.5）TiO₃-0.5（Sr_0.7Bi_0.2）TiO₃The powder is made of Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂According to chemical formula 0.5 (Bi)_0.5Na_0.5）TiO₃-0.5（Sr_0.7Bi_0.2）TiO₃The components are mixed to obtain the product.

2. The composite ceramic material according to claim 1, wherein the boron nitride particles have an average particle size of 300nm, and the added mass fraction is 1wt% to 7wt% of the total mass of the material.

3. The preparation method of the composite ceramic material is characterized by comprising the following steps of:

(1) separately adding Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂According to chemical formula 0.5 (Bi)_0.5Na_0.5）TiO₃-0.5（Sr_0.7Bi_0.2）TiO₃After the materials are mixed, the materials are sequentially ball-milled, mixed and dried to form 0.5 (Bi)_0.5Na_0.5）TiO₃-0.5（Sr_0.7Bi_0.2）TiO₃Powder;

(2) 0.5 (Bi)_0.5Na_0.5）TiO₃-0.5（Sr_0.7Bi_0.2）TiO₃Putting the powder into a crucible, and pre-burning in an air atmosphere;

(3) 0.5 (Bi)_0.5Na_0.5）TiO₃-0.5（Sr_0.7Bi_0.2）TiO₃Granulating and sieving the pre-sintered powder, then putting the powder into a crucible, and carrying out high-temperature heat treatment in an air atmosphere;

(4) 0.5 (Bi) heat-treated at high temperature_0.5Na_0.5）TiO₃-0.5（Sr_0.7Bi_0.2）TiO₃Pouring the powder and the boron nitride particles into a ball milling tank, ball milling and drying;

(5) drying 0.5 (Bi)_0.5Na_0.5）TiO₃-0.5（Sr_0.7Bi_0.2）TiO₃And granulating and sieving the mixed powder with the boron nitride, pressing into a wafer, and sintering the wafer in a nitrogen-hydrogen mixed gas to obtain the composite ceramic material.

4. The method for preparing a composite ceramic material according to claim 3, wherein in the steps (1) and (4), the ball milling is performed under anhydrous ethanol, the drying temperature is 80 ℃, and in the step (4), the ball milling time is 3 hours.

5. The method of claim 3, wherein in the step (2), the pre-firing requirement is 0.5 (Bi)_0.5Na_0.5）TiO₃-0.5（Sr_0.7Bi_0.2）TiO₃The powder was burned in air at 850 ℃ for 3 hours.

6. The method for preparing a composite ceramic material according to claim 3, wherein in the step (3), 0.5 (Bi) is added_0.5Na_0.5）TiO₃-0.5（Sr_0.7Bi_0.2）TiO₃The powder is heat treated at 1000 deg.c for 1 hr.

7. The method for preparing a composite ceramic material according to claim 3, wherein in the step (5), the pressure for pressing the wafer is 100-150 MPa.

8. The method of claim 3, wherein in step (5), the wafer is a green wafer having a diameter of 10mm and a thickness of about 1 mm.

9. The method for preparing a composite ceramic material according to claim 3, wherein in the step (5), the volume ratio of the nitrogen gas to the hydrogen gas of the nitrogen-hydrogen mixed gas is 95:5, the air flow rate is 0.5L/min.

10. The preparation method of the composite ceramic material as claimed in claim 3, wherein in the step (5), the sintering requirement is that the wafer is sintered in the nitrogen-hydrogen mixed gas at 1120-1180 ℃ for 3 hours, and the heating rate and the cooling rate in the sintering process are both 3-5 ℃/min.

Technical Field

The invention relates to the field of dielectric ceramic materials, in particular to a composite ceramic material and a preparation method thereof.

Background

Compared with super capacitors and lithium ion batteries, dielectric energy storage capacitors have ultra-high power density, very fast charge and discharge rates and long cycle life. They are important novel power storage devices, and have huge potential applications in new energy automobiles, smart grids and medical devices. Currently, commercial pulsed energy storage capacitors are Predominantly Polypropylene (PP), which has a recoverable energy storage density (W)_rec) Very low (typically less than 1J/cm)³). To increase W_recIn recent years, researchers have developed a number of dielectric materials to replace PP, including PVDF polymers, glass ceramics, ferroelectric and antiferroelectric ceramics. Although W_recHave improved, but the energy storage efficiency is still low. How to design high W_recAnd high energy storage efficiency (η) are critical issues that need to be addressed.

Most of the traditional dielectric energy storage ceramics are lead-based antiferroelectric materials, but because the lead-containing materials pollute the environment and harm the health of human bodies, the lead-free materials are the development direction of the dielectric energy storage ceramics at present. The lead-free dielectric ceramic mainly comprises BaTiO₃、(Bi_0.5Na_0.5)TiO₃、(K_0.5Na_0.5)NbO₃、AgNbO₃And NaNbO₃And (4) preparing the system. Wherein, BaTiO₃Radical and NaNbO₃W of base ceramics_recLow (K)_0.5Na_0.5)NbO₃Poor temperature stability of the base ceramic, whereas AgNbO₃These problems severely limit their use due to the complex process and high raw material cost of the base ceramics required to control the oxygen partial pressure. On the contrary, based on (Bi)_0.5Na_0.5)TiO₃Has a higher W_recAnd η, better temperature stability and simple preparation process, have attracted extensive attention of researchers in the field of functional ceramics in recent years.

Recently, some researchers have increased (Bi) by binary/ternary solid solution modification, grain refinement and ceramic-glass compounding_0.5Na_0.5)TiO₃Releasable energy storage density and storage efficiency of the base ceramic. However, based on (Bi)_0.5Na_0.5)TiO₃W of ceramics_recThe value is still not high enough (less than 2.5J/cm)³) And is difficult to have a high W_recAnd a high η of greater than 85%.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a composite ceramic material with high energy storage density and high energy storage efficiency and a preparation method thereof.

The technical scheme of the invention is as follows:

a composite ceramic material is prepared from 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃The powder and boron nitride particles are according to the chemical formula 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃0.5 (Bi) of_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃The powder is made of Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂According to chemical formula 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃The components are mixed to obtain the product.

Wherein the average particle size of the boron nitride particles is 300nm, and the added mass fraction accounts for 1-7 wt% of the total mass of the material.

A preparation method of a composite ceramic material comprises the following steps:

(1) separately adding Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂According to chemical formula 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃After the materials are mixed, the materials are sequentially ball-milled, mixed and dried to form 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃Powder;

(2) 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃Putting the powder into a crucible, and pre-burning in an air atmosphere;

(3) 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃Granulating and sieving the pre-sintered powder, then putting the powder into a crucible, and carrying out high-temperature heat treatment in an air atmosphere;

(4) 0.5 (Bi) heat-treated at high temperature_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃Pouring the powder and the boron nitride particles into a ball milling tank, ball milling and drying;

(5) drying 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃And granulating and sieving the mixed powder with the boron nitride, pressing into a wafer, and sintering the wafer in a nitrogen-hydrogen mixed gas to obtain the composite ceramic material.

In the steps (1) and (4), the ball milling is carried out under anhydrous ethanol, the drying temperature is 80 ℃, and in the step (4), the ball milling time is 3 hours.

In step (2), the pre-firing requirement is 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃The powder was burned in air at 850 ℃ for 3 hours.

In step (3), for 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃The powder is heat treated at 1000 deg.c for 1 hr.

In the step (5), the pressure for pressing the wafer is 100-150 MPa.

In step (5), the wafer is a green wafer having a diameter of 10mm and a thickness of about 1 mm.

In the step (5), the volume ratio of the nitrogen to the hydrogen of the nitrogen-hydrogen mixture is 95:5, the air flow rate is 0.5L/min.

In the step (5), the sintering requirement is that the wafer is sintered for 3 hours at 1120-1180 ℃ in the nitrogen-hydrogen mixed gas, and the heating rate and the cooling rate in the sintering process are both 3-5 ℃/min.

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

(1) replacing part 0.5 (Bi) by Boron Nitride (BN) second phase with high chemical stability, high thermal conductivity, low dielectric constant and high breakdown field strength_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃The relaxor ferroelectric ceramic improves the breakdown electric field, thereby greatly increasing the energy storage density and maintaining high energy storage efficiency. Has 2.52-4.36J/cm at room temperature³High energy storage density and high energy storage efficiency of more than 90 percent. The composite ceramic material makes the application of the lead-free ceramic with high energy storage density possible, and can be used for manufacturing high-power dielectric energy storage devices;

(2) the composite ceramic material is simple to prepare, easy to control process conditions, convenient to implement and strong in practicability;

(3) the green and nontoxic lead-free ceramic material is adopted to replace the traditional lead-containing material for the existing capacitor, so that the environment pollution can not be caused during production and after abandonment, and the method is environment-friendly and environment-friendly.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed for the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic view of boron nitride in the form of particles embedded in a relaxor ferroelectric ceramic matrix according to the present invention;

FIG. 2 is a surface topography map of a first and a fourth embodiment of the present invention;

FIG. 3 is a graph comparing the breakdown field strength and the room temperature P-E curve of the first and fourth embodiments of the present invention;

fig. 4 is a schematic diagram of a model of a dielectric capacitor with an uneven structure according to a second embodiment to a fifth embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In order to explain the technical means of the present invention, the following description will be given by way of specific examples.

The invention discloses a composite ceramic material, which is prepared from 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃The powder and boron nitride are represented by the chemical formula 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃In which boron nitride is embedded in the form of particles at 0.5 (Bi) as shown in FIG. 1_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃Medium and 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃The powder is made of Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂According to chemical formula 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃The components are mixed to obtain the product.

Wherein the average particle size of the boron nitride particles is 300nm, and the added mass fraction accounts for 1-7 wt% of the total mass of the material. The grain diameter and the addition amount are not more than 0.5 (Bi) in the sintering process_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃The mass transfer and grain growth among the powder particles ensure that the composite ceramic has high density and high performance.

The composite ceramic material has the voltage of 2.52-4.36J/cm under an electric field of 220-350 kV/cm³High energy storage density and high energy storage efficiency of more than 90 percent.

Boron nitride can also be replaced by other ceramic materials with high thermal conductivity, low dielectric constant and high breakdown field strength, for example: si₃N₄(100～300W m^-1K^-1)、AlN(150～300W m^-1K^-1)、SiC(220～300W m^-1K^-1)、BAs(800～1000W m^-1K^-1) And diamond (1300-2400W m)^-1K^-1)。

The preparation method of the composite ceramic material comprises the following preparation steps:

step one, respectively adding Bi₂O₃、Na₂CO₃、SrCO₃、TiO₂According to chemical formula 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃Mixing, ball-milling the mixture under anhydrous alcohol medium to obtain slurry, oven-drying the slurry at 80 deg.C to obtain 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃Powder;

step two, the 0.5 (Bi) obtained in the previous step_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃Placing the powder in a crucible, pre-sintering in air atmosphere, and mixing with 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃Burning the powder in air at 850 deg.C for 3 hr;

step three, mixing 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃Granulating and sieving the pre-sintered powder, placing into a crucible, and performing high temperature heat treatment in air atmosphere at 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃Adding 8 wt% of polyvinyl alcohol solution (with the concentration of 5%) into the pre-sintered powder, granulating, sieving with a 60-mesh sieve, and keeping the temperature of the granulated powder at 1000 ℃ for 1 hour;

step four, heat-treating 0.5 (Bi) by high temperature_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃The powder and the boron nitride particles are mixed in different mass ratios, such as: 1/99, 3/97, 5/95 and 7/93, pouring the mixture into a ball milling tank filled with absolute ethyl alcohol, ball milling the mixture for 3 hours, and then putting the mixture into an oven to dry the mixture at 80 ℃;

step five, drying the dried 0.5 (Bi)_0.5Na_0.5)TiO₃-0.5(Sr_0.7Bi_0.2)TiO₃The powder mixture with boron nitride was granulated and sintered, and specifically, PVA was added as a binder for granulation and passed through a 60-mesh sieve. And then pressing the blank into a wafer green body with the diameter of 10mm and the thickness of about 1mm under the pressure of 100-150 MPa. Sintering the pressed wafer in a nitrogen-hydrogen mixed gas at 1120-1180 ℃ for 3 hours, wherein the volume ratio of nitrogen to hydrogen of the nitrogen-hydrogen mixed gas is 95:5, the air flow rate is 0.5L/min. And (3) the heating rate and the cooling rate in the sintering process are both 3-5 ℃/min, and then the silver electrode is brushed after grinding and surface polishing, so that the composite ceramic material is finally obtained.