阅读说明：本技术 碳化硅增韧微波介质陶瓷材料及其制备方法 (Silicon carbide toughened microwave dielectric ceramic material and preparation method thereof ) 是由 冒旭 黄庆焕 顾国治 王津 艾晨霞 梁小健 于 2020-12-30 设计创作，主要内容包括：本发明适用于介质陶瓷生产技术领域,公开了一种碳化硅增韧微波介质陶瓷材料,包括以下重量份的原料组分：氧化镁48-57份、氧化硅33-42份、氧化铝5-10份、氧化锆0.3-0.5份、氧化铈0.2-0.6份以及碳化硅0.02-0.1份。还提供了一种制备所述碳化硅增韧微波介质陶瓷材料的方法。能显著提高陶瓷材料的抗弯强度和热震性能,减少陶瓷材料在实际使用环境中因温度变化对材料性能所造成的影响；且制备工艺简单,陈本低廉,适用于工业化大规模生产。(The invention is suitable for the technical field of dielectric ceramic production, and discloses a silicon carbide toughened microwave dielectric ceramic material which comprises the following raw material components in parts by weight: 48-57 parts of magnesium oxide, 33-42 parts of silicon oxide, 5-10 parts of aluminum oxide, 0.3-0.5 part of zirconium oxide, 0.2-0.6 part of cerium oxide and 0.02-0.1 part of silicon carbide. Also provides a method for preparing the silicon carbide toughened microwave dielectric ceramic material. The bending strength and the thermal shock resistance of the ceramic material can be obviously improved, and the influence of the ceramic material on the material performance due to the temperature change in the actual use environment is reduced; and the preparation process is simple, the cost is low, and the method is suitable for industrial large-scale production.)

1. The silicon carbide toughened microwave dielectric ceramic material is characterized by comprising the following raw material components in parts by weight: 48-57 parts of magnesium oxide, 33-42 parts of silicon oxide, 5-10 parts of aluminum oxide, 0.3-0.5 part of zirconium oxide, 0.2-0.6 part of cerium oxide and 0.02-0.1 part of silicon carbide.

2. A method for preparing the silicon carbide toughened microwave dielectric ceramic material as claimed in claim 1, which comprises the steps of:

1) uniformly mixing magnesium oxide, silicon oxide, aluminum oxide, zirconium oxide, cerium oxide and silicon carbide according to the proportion to prepare a mixture;

2) ball-milling the mixture obtained in the step 1) for 3-5 hours to prepare ball-milled slurry;

3) drying the ball-milling slurry obtained in the step 2) to obtain dry powder;

4) pre-sintering the dry powder obtained in the step 3) to prepare pre-sintered powder;

5) performing ball milling treatment on the pre-sintered powder obtained in the step 4) to prepare powder with the particle size of 0.5-1 mu m;

6) carrying out spray granulation on the powder obtained in the step 5) to prepare granulated powder;

7) placing the granulated powder obtained in the step 6) into a prefabricated mold, and performing dry pressing molding under the pressure of 75-85Mpa to prepare a green body;

8) sintering the green blank obtained in the step 7) at the temperature of 1200-1400 ℃ for 4-6 hours, and cooling to obtain the silicon carbide toughened microwave dielectric ceramic material.

3. The method according to claim 2, wherein the mixture in the step 2) comprises deionized water and a dispersing agent during ball milling, and the weight ratio of the mixture to the deionized water to the dispersing agent is 100: (70-80): (0.6-0.9).

4. The method according to claim 2, wherein the powder in the step 6) further comprises deionized water, a dispersant, a binder and a release agent during spray granulation, and the weight ratio of the powder to the deionized water to the dispersant to the binder to the release agent is 100: (65-75): (1-4): (2-8): (1-4).

5. The method according to claim 4, wherein the dispersant in the step 6) is a sodium salt of a polycarboxylic acid.

6. The method of claim 4, wherein the binder in step 6) is an aqueous solution of polyvinyl alcohol.

7. The method according to claim 4, wherein the release agent in step 6) is an aqueous dispersion of calcium stearate.

8. The method as claimed in claim 2, wherein the drying temperature in step 3) is 180-260 ℃ and the drying time is 3-5 hours.

9. The method as claimed in claim 2, wherein the pre-sintering temperature in step 4) is 1150-1250 ℃ and the pre-sintering treatment time is 4-6 hours.

Technical Field

The invention relates to the technical field of dielectric ceramic production, in particular to a silicon carbide toughened microwave dielectric ceramic material and a preparation method thereof.

Background

With the rapid development of the current communication technology, mobile communication is continuously developing towards high reliability and small size, and the requirement of the communication technology on materials is higher and higher. The microwave device prepared from the microwave dielectric ceramic is a key material in a microwave circuit and plays the roles of dielectric isolation, dielectric waveguide and dielectric resonance in the microwave circuit.

In the resonator field, compared with components and parts consisting of traditional metal resonant cavities and wave guides, the dielectric resonator can better meet the requirements of portability, miniaturization and integration of communication equipment in production and life, and has the advantages of low loss and stable performance along with temperature change. But the microwave dielectric ceramic has larger brittleness, so the thermal shock resistance is often poorer; the thermal shock resistance refers to the capability of the ceramic material to bear the sudden change of the external temperature, and great thermal stress can be generated in the process of rapidly heating or cooling the ceramic material, so that the strength of the ceramic material is greatly reduced, and the ceramic material is easy to crack or even break; poor thermal shock resistance has been an important factor limiting the use of ceramic materials in different natural environments. The thermal shock resistance of a ceramic material is influenced by some thermodynamic and mechanical parameters of the material itself, such as the coefficient of thermal expansion, thermal conductivity, elastic modulus, fracture energy, and the like.

Research suggests that the main approach to improve the thermal shock resistance of ceramic materials is to increase the fracture energy of the materials, i.e., to improve the fracture toughness of the ceramic materials, and therefore, a method for toughening microwave dielectric ceramics so as to improve the thermal shock resistance temperature and maintain good dielectric properties is urgently needed.

Disclosure of Invention

In view of the above-mentioned drawbacks, the present invention provides a silicon carbide toughened microwave dielectric ceramic material, which has a low dielectric constant, a high quality factor, an excellent bending strength and a good thermal shock resistance, and can be applied to a microwave dielectric ceramic filter.

The invention is realized by the following technical scheme:

a silicon carbide toughened microwave dielectric ceramic material comprises the following raw material components in parts by weight: 48-57 parts of magnesium oxide, 33-42 parts of silicon oxide, 5-10 parts of aluminum oxide, 0.3-0.5 part of zirconium oxide, 0.2-0.6 part of cerium oxide and 0.02-0.1 part of silicon carbide.

In one embodiment, the silicon carbide toughened microwave dielectric ceramic material comprises the following raw material components in parts by weight: 53 parts of magnesium oxide, 38 parts of silicon oxide, 9 parts of aluminum oxide, 0.4 part of zirconium oxide, 0.3 part of cerium oxide and 0.05 part of silicon carbide.

In one embodiment, the silicon carbide toughened microwave dielectric ceramic material comprises the following raw material components in parts by weight: 50 parts of magnesium oxide, 41 parts of silicon oxide, 9 parts of aluminum oxide, 0.4 part of zirconium oxide, 0.2 part of cerium oxide and 0.08 part of silicon carbide.

In one embodiment, the silicon carbide toughened microwave dielectric ceramic material comprises the following raw material components in parts by weight: 48 parts of magnesium oxide, 42 parts of silicon oxide, 10 parts of aluminum oxide, 0.3 part of zirconium oxide, 0.2 part of cerium oxide and 0.02 part of silicon carbide.

In one embodiment, the silicon carbide toughened microwave dielectric ceramic material comprises the following raw material components in parts by weight: 55 parts of magnesium oxide, 36 parts of silicon oxide, 9 parts of aluminum oxide, 0.4 part of zirconium oxide, 0.3 part of cerium oxide and 0.05 part of silicon carbide.

The invention also provides a method for preparing the silicon carbide toughened microwave dielectric ceramic material, which comprises the following steps:

1) uniformly mixing magnesium oxide, silicon oxide, aluminum oxide, zirconium oxide, cerium oxide and silicon carbide according to the proportion to prepare a mixture;

2) ball-milling the mixture for 3-5 hours to prepare ball-milled slurry;

3) drying the ball-milling slurry to obtain dry powder;

4) pre-sintering the dry powder to prepare pre-sintered powder;

5) performing ball milling treatment on the pre-sintered powder to prepare powder with the particle size of 0.5-1 mu m;

6) performing spray granulation on the powder to prepare granulated powder;

7) placing the granulated powder in a prefabricated mould, and performing dry pressing forming under the pressure of 75-85Mpa to prepare a green body;

8) sintering the green body at the temperature of 1200-1400 ℃ for 4-6 hours, and cooling to obtain the silicon carbide toughened microwave dielectric ceramic material.

The mixture in the step 2) comprises deionized water and a dispersing agent during ball milling, and the weight ratio of the mixture to the deionized water to the dispersing agent is 100: (70-80): (0.6-0.9).

The powder material in the step 6) further comprises deionized water, a dispersing agent, a binder and a release agent during spray granulation, and the weight parts of the powder material, the deionized water, the dispersing agent, the binder and the release agent are 100: (65-75): (1-4): (2-8): (1-4).

Optionally, the dispersant in step 6) is a sodium polycarboxylate salt.

Optionally, the binder in step 6) is an aqueous solution of polyvinyl alcohol.

Optionally, the release agent in the step 6) is an aqueous dispersion of calcium stearate.

Wherein the drying temperature in the step 3) is 180-260 ℃, and the drying treatment time is 3-5 hours.

Wherein the pre-sintering temperature in the step 4) is 1150-1250 ℃, and the pre-sintering treatment time is 4-6 hours.

The silicon carbide toughened microwave dielectric ceramic material prepared by the invention has the advantages of low dielectric constant of 6.5-8.0 and high quality factor of 180000GHz, is a thermal shock resistant microwave dielectric material, can obviously improve the thermal shock resistance of a microwave component, has no cracking phenomenon in a 120 ℃ thermal shock test, and has a thermal shock temperature difference of 95 ℃. The method has the advantages of simple process and low cost, and is suitable for large-scale industrial production.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clear and complete, some embodiments of the present invention will be described below. The examples are for illustrative purposes only and do not limit the scope of the present invention in any way. Unless otherwise indicated, the materials used in the examples are conventional or commercially available materials, and the materials and reagents are used in addition in a manner conventional in the art. The meanings stated are all customary in the art, for example 10% NaOH solution means mass fraction and 55% ethanol solution means volume fraction.

Example 1 silicon carbide toughened microwave dielectric ceramic material

The components are as follows: 53 parts of magnesium oxide, 38 parts of silicon oxide, 9 parts of aluminum oxide, 0.4 part of zirconium oxide, 0.3 part of cerium oxide and 0.05 part of silicon carbide.

The preparation method of the silicon carbide toughened microwave dielectric ceramic material comprises the following steps:

1) weighing the following components in percentage by mass: 53 parts of magnesium oxide, 38 parts of silicon oxide, 9 parts of aluminum oxide, 0.4 part of zirconium oxide, 0.3 part of cerium oxide and 0.05 part of silicon carbide to prepare a mixture;

2) mixing the mixture with deionized water and a dispersing agent according to the proportion of 100: 75: 0.8, mixing and ball-milling for 4.5 hours to obtain uniform ball-milling slurry;

3) drying the ball-milled slurry at 230 ℃ for 4 hours to obtain dry powder;

4) pre-sintering the dried powder in the step 3) at 1200 ℃ for 5 hours to obtain pre-sintered powder;

5) ball-milling the pre-sintered powder, wherein the particle size of the powder after ball-milling and drying is 0.8 mu m, so as to prepare powder;

6) powder, deionized water, a dispersing agent, a binder and a release agent are mixed according to the weight ratio of 100: 70: 1.5: 5: 1.5, carrying out spray granulation to prepare granulated powder;

7) placing the granulated powder in a prefabricated mould, and performing dry pressing forming under the pressure of 80MPa to prepare a green body;

8) and (3) placing the green body in a furnace at 1320 ℃ for high-temperature sintering for 5 hours, and cooling along with the furnace to obtain the silicon carbide toughened microwave dielectric ceramic material.

Wherein, the mould is made according to actual production demand.

Wherein the dispersing agent in the step 6) is a sodium polycarboxylate, the binder is a polyvinyl alcohol aqueous solution, and the release agent is a calcium stearate aqueous dispersion.

For the cylindrical sample obtained in example 1, a vector network analyzer was used for microwave performance testing; for the strip sample of size 30mm 4mm 3mm obtained in example 1, the breaking strength test was carried out using a universal tester, and the thermal shock test was carried out by a quenching method, according to the following procedure:

1) setting the temperature of a constant temperature box, placing the sample in a burning net after the temperature in the furnace rises to the set temperature, and placing the sample in the furnace for heat preservation for 15 minutes;

2) taking out the sample, immediately putting the sample into room-temperature water, soaking the sample in the room-temperature water for 5 minutes, and taking out the sample;

3) putting the soaked sample into red ink to be soaked for 30 minutes and then taking out;

4) and observing whether cracks appear on the surface of the ceramic under strong light, counting the number of the cracks and recording data.

5) If no crack exists, the temperature is raised by 5 ℃, the steps 1 to 4 are repeated until cracks appear, and the test is finished.

The test results are shown in table 1.

Table 1 example 1 test results

Example 2 silicon carbide toughened microwave dielectric ceramic material

The components are as follows: 50 parts of magnesium oxide, 41 parts of silicon oxide, 9 parts of aluminum oxide, 0.4 part of zirconium oxide, 0.2 part of cerium oxide and 0.08 part of silicon carbide.

The preparation method of the silicon carbide toughened microwave dielectric ceramic material comprises the following steps:

1) weighing the following components in percentage by mass: 50 parts of magnesium oxide, 41 parts of silicon oxide, 9 parts of aluminum oxide, 0.4 part of zirconium oxide, 0.2 part of cerium oxide and 0.08 part of silicon carbide to prepare a mixture;

2) mixing the mixture with deionized water and a dispersing agent according to the proportion of 100: 75: 0.8, mixing and ball-milling for 4.5 hours to obtain uniform ball-milling slurry;

3) drying the ball-milled slurry at 230 ℃ for 4 hours to obtain dry powder;

4) pre-sintering the dry powder in the step 3) for 4.5 hours at 1150 ℃ to obtain pre-sintered powder;

5) ball-milling the pre-sintered powder, wherein the particle size of the ball-milled and dried powder is 0.8 mu m, so as to prepare powder;

6) powder, deionized water, a dispersing agent, a binder and a release agent are mixed according to the weight ratio of 100: 75: 3: 2: 3, carrying out spray granulation to prepare the granulated powder.

7) And placing the granulated powder into a prefabricated mold, and performing dry pressing molding under the pressure of 80 MPa.

8) And (4) placing the ceramic blank obtained in the step (7) into a furnace at the temperature of 1320 ℃ for high-temperature sintering for 5 hours, and cooling along with the furnace to obtain the silicon carbide toughened microwave dielectric ceramic material.

Wherein, the mould is made according to actual production demand.

Wherein the dispersing agent in the step 6) is a sodium polycarboxylate, the binder is a polyvinyl alcohol aqueous solution, and the release agent is a calcium stearate aqueous dispersion.

For the cylindrical sample obtained in example 2, a vector network analyzer was used for microwave performance testing; for the strip sample of size 30mm 4mm 3mm obtained in example 2, the breaking strength test was carried out using a universal tester, and the thermal shock test was carried out by a quenching method, according to the following procedure:

1) setting the temperature of a constant temperature box, placing the sample in a burning net after the temperature in the furnace rises to the set temperature, and placing the sample in the furnace for heat preservation for 15 minutes;

2) taking out the sample, immediately putting the sample into room-temperature water, soaking the sample in the room-temperature water for 5 minutes, and taking out the sample;

3) putting the soaked sample into red ink to be soaked for 30 minutes and then taking out;

4) and observing whether cracks appear on the surface of the ceramic under strong light, counting the number of the cracks and recording data.

5) If no crack exists, the temperature is raised by 5 ℃, the steps 1 to 4 are repeated until cracks appear, and the test is finished.

The test results are shown in table 2.

Table 2 example 2 test results

Example 3 silicon carbide toughened microwave dielectric ceramic material

The components are as follows: 48 parts of magnesium oxide, 42 parts of silicon oxide, 10 parts of aluminum oxide, 0.3 part of zirconium oxide, 0.2 part of cerium oxide and 0.02 part of silicon carbide.

The preparation method of the silicon carbide toughened microwave dielectric ceramic material comprises the following steps:

1) weighing the following components in percentage by mass: 48 parts of magnesium oxide, 42 parts of silicon oxide, 10 parts of aluminum oxide, 0.3 part of zirconium oxide, 0.2 part of cerium oxide and 0.02 part of silicon carbide to prepare a mixture;

2) mixing the mixture with deionized water and a dispersing agent according to the proportion of 100: 75: 0.8, mixing and ball-milling for 4.5 hours to obtain uniform ball-milling slurry;

3) drying the ball-milled slurry at 230 ℃ for 4 hours to obtain dry powder;

4) pre-sintering the dry powder in the step 3) for 4.5 hours at 1150 ℃ to obtain pre-sintered powder;

5) ball-milling the pre-sintered powder, wherein the particle size of the ball-milled and dried powder is 0.8 mu m, so as to prepare powder;

6) powder, deionized water, a dispersing agent, a binder and a release agent are mixed according to the weight ratio of 100: 75: 3: 2: 3, carrying out spray granulation to prepare granulated powder;

7) placing the granulated powder into a prefabricated mould, and performing dry pressing forming under the pressure of 80 MPa;

8) and (4) placing the ceramic blank obtained in the step (7) into a furnace at the temperature of 1320 ℃ for high-temperature sintering for 5 hours, and cooling along with the furnace to obtain the silicon carbide toughened microwave dielectric ceramic.

Wherein, the mould is made according to actual production demand.

Wherein the dispersing agent in the step 6) is a sodium polycarboxylate, the binder is a polyvinyl alcohol aqueous solution, and the release agent is a calcium stearate aqueous dispersion.

For the cylindrical sample obtained in example 3, a vector network analyzer was used for microwave performance testing; for the strip sample of size 30mm 4mm 3mm obtained in example 3, the breaking strength test was carried out using a universal tester, and the thermal shock test was carried out by a quenching method, according to the following procedure:

1) setting the temperature of a constant temperature box, placing the sample in a burning net after the temperature in the furnace rises to the set temperature, and placing the sample in the furnace for heat preservation for 15 minutes;

2) taking out the sample, immediately putting the sample into room-temperature water, soaking the sample in the room-temperature water for 5 minutes, and taking out the sample;

3) putting the soaked sample into red ink to be soaked for 30 minutes and then taking out;

4) and observing whether cracks appear on the surface of the ceramic under strong light, counting the number of the cracks and recording data.

5) If no crack exists, the temperature is raised by 5 ℃, the steps 1 to 4 are repeated until cracks appear, and the test is finished.

The test results are shown in table 3.

Table 3 example 3 test results

Example 4 silicon carbide toughened microwave dielectric ceramic materials

The components are as follows: 55 parts of magnesium oxide, 36 parts of silicon oxide, 9 parts of aluminum oxide, 0.4 part of zirconium oxide, 0.3 part of cerium oxide and 0.05 part of silicon carbide.

The preparation method of the silicon carbide toughened microwave dielectric ceramic material comprises the following steps:

1) weighing the following components in percentage by mass: 55 parts of magnesium oxide, 36 parts of silicon oxide, 9 parts of aluminum oxide, 0.4 part of zirconium oxide, 0.3 part of cerium oxide and 0.05 part of silicon carbide to prepare a mixture;

2) mixing the mixture with deionized water and a dispersing agent according to the proportion of 100: 75: 0.8, mixing and ball-milling for 4.5 hours to obtain uniform ball-milling slurry;

3) drying the ball-milled slurry at 230 ℃ for 4 hours to obtain dry powder;

4) pre-sintering the dry powder in the step 3) for 4.5 hours at 1200 ℃ to obtain pre-sintered powder;

5) ball-milling the pre-sintered powder, wherein the particle size of the ball-milled and dried powder is 0.8 mu m, so as to prepare the powder;

6) powder, deionized water, a dispersing agent, a binder and a release agent are mixed according to the weight ratio of 85: 75: 3: 2: 3, carrying out spray granulation to prepare granulated powder;

7) placing the granulated powder into a prefabricated mould, and performing dry pressing forming under the pressure of 80 MPa;

8) and (4) placing the ceramic blank obtained in the step (7) into a furnace at the temperature of 1320 ℃ for high-temperature sintering for 5 hours, and cooling along with the furnace to obtain the silicon carbide toughened microwave dielectric ceramic.

Wherein, the mould is made according to actual production demand.

Wherein the dispersing agent in the step 6) is a sodium polycarboxylate, the binder is a polyvinyl alcohol aqueous solution, and the release agent is a calcium stearate aqueous dispersion.

For the cylindrical sample obtained in example 4, a vector network analyzer was used for microwave performance testing; for the strip sample of size 30mm 4mm 3mm obtained in example 4, the breaking strength test was carried out using a universal tester, and the thermal shock test was carried out by a quenching method, according to the following procedure:

1) setting the temperature of a constant temperature box, placing the sample in a burning net after the temperature in the furnace rises to the set temperature, and placing the sample in the furnace for heat preservation for 15 minutes;

2) taking out the sample, immediately putting the sample into room-temperature water, soaking the sample in the room-temperature water for 5 minutes, and taking out the sample;

3) putting the soaked sample into red ink to be soaked for 30 minutes and then taking out;

4) and observing whether cracks appear on the surface of the ceramic under strong light, counting the number of the cracks and recording data.

5) If no crack exists, the temperature is raised by 5 ℃, the steps 1 to 4 are repeated until cracks appear, and the test is finished.

The test results are shown in table 4.

Table 4 example 4 test results

Therefore, the silicon carbide toughened microwave dielectric ceramic material prepared by the invention is a high-quality factor (150000 plus 180000GHz) microwave dielectric material with the dielectric constant of 6.5-8.0, the temperature coefficient of the dielectric constant is less than or equal to +/-10 ppm/DEG C, the bending strength (320 plus 380MPa) and the thermal shock performance (the thermal shock temperature difference is 90-95 ℃) of the ceramic material can be obviously improved, and the influence of the temperature change on the material performance of the ceramic material in the actual use environment is reduced.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it should be understood that various changes and modifications can be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.