WO2013091560A1

WO2013091560A1 - Method for manufacturing microwave dielectric ceramic material

Info

Publication number: WO2013091560A1
Application number: PCT/CN2012/087041
Authority: WO
Inventors: 赵可沦; 陈明
Original assignee: 深圳市大富科技股份有限公司
Priority date: 2011-12-22
Filing date: 2012-12-20
Publication date: 2013-06-27

Abstract

A method for manufacturing a microwave dielectric ceramic material, comprising: mechanically and uniformly mixing the mixed powders of calcium carbonate, aluminum oxide, neodymium oxide, titanium dioxide and strontium carbonate or calcium oxide to form powder particles; ball-milling the powder particles under high energy for the first time to uniformly refine the powder particles to form refined powders; calcining the refined powders under high temperature in a closed container to form precursor powders; ball-milling the precursor powders under high energy for the second time to further uniformly refine the precursor powders to form the ceramic powders. The present method lowers the sintering temperature and reduces the sintering time, thus inhibiting "crystal lattice defect effect".

Description

Method for preparing microwave dielectric ceramic material

[Technical Field]

The invention relates to the technical field of ceramic materials, in particular to a method for preparing a microwave dielectric ceramic material.

【Background technique】

Microwave dielectric ceramic is a ceramic material suitable for the dielectric constant and high quality factor of the microwave frequency band. It functions as dielectric isolation, dielectric waveguide and dielectric resonance in the microwave circuit. It can be used to fabricate microwave tubes and tube lines. The microwave hybrid integrated circuit is constructed to greatly reduce the quality and volume of devices such as microwave dielectric resonators.

Among them, (lx)[Ca, Sr]Ti0 ₃ — x[NdA10 ₃ ] having a perovskite structure (the tube is called CTNA, wherein X represents a molar percentage) of the microwave dielectric ceramic material has a moderate dielectric constant (ε) r~45), the temperature coefficient of the resonant frequency close to zero (τ f~0) and the relatively high quality factor (Q 30000) have attracted wide attention and research in the industry. However, the research in the industry mainly depends on the microstructure and dielectric properties of the materials and the interrelationship between the firing process and the dielectric properties of the materials. Little research has been done on the preparation methods.

In the current prior art, most domestic and foreign manufacturers adopt a combination of traditional mechanical mixing and solid phase sintering, that is, the solid powder raw material is thoroughly mixed in a planetary or agitated ball mill, and then a solid phase reaction occurs under high temperature calcination conditions. The desired ceramic powder is prepared, and then press-formed and solid-phase sintered into a dielectric ceramic material. This conventional preparation method mainly has the following drawbacks: The powder has a poor reactivity during high-temperature sintering, requires a high sintering temperature (at least 1450 degrees Celsius or more) and a long sintering time, resulting in extremely high production energy consumption; The ceramic powder prepared by the reaction has a large particle size, a wide particle size distribution, and a large number of heterophases, which affects the purity of the main crystal phase of the CTNA and makes it difficult to achieve complete densification of the sintering, that is, it is difficult to obtain a dielectric ceramic material having stable and excellent microwave dielectric properties. The adverse effect of the "lattice defect effect" of the Ca element during the sintering process on the microwave performance of the product is neglected. Therefore, there is a need to provide a method for preparing a microwave dielectric ceramic material to solve the problems of excessive sintering temperature, long sintering time, and difficulty in achieving sintering densification in the preparation of a microwave dielectric ceramic material in the prior art.

[Summary of the Invention]

The technical problem to be solved by the present invention is to provide a method for preparing a microwave dielectric ceramic material, which can reduce the sintering temperature, shorten the sintering time and inhibit the "lattice defect effect" caused by the volatile element Ca in the process of preparing the microwave dielectric ceramic material.

In order to solve the above technical problem, a technical solution adopted by the present invention is: Providing a method for preparing a microwave dielectric ceramic material, comprising: mixing a carbonate powder, an alumina, a cerium oxide, and a mixed powder of titanium dioxide with barium carbonate or calcium oxide; The machine is uniformly mixed to form powder particles; the powder particles are subjected to the first high-energy ball milling to knead the powder particles to form a refined powder; the refined powder is subjected to high-temperature calcination in a closed container. Forming a precursor powder; the precursor powder is subjected to a second high-energy ball milling to further uniformly refine the precursor powder to form a ceramic powder.

Wherein, after the second high-energy ball milling step, the method further comprises: spray granulation, adding a polyvinyl alcohol aqueous solution having a concentration of 5% and a mass percentage of 5% to 10% to the ceramic powder, and forming the ceramic powder into a spherical flow. Sexual powder particles.

Wherein, after the spray granulation step, the method further comprises: press molding, and the spherical particles having spherical fluidity are formed into a ceramic green compact of a desired shape.

The press forming step further comprises: sintering, continuously sintering the ceramic compact to form a ceramic blank, wherein the highest sintering temperature is 1200-1500 degrees Celsius, and the holding time is 3-6 hours.

Wherein, when the mixed powder is calcium carbonate, aluminum oxide, cerium oxide, titanium dioxide and barium carbonate, the ceramic green compact is placed in a sealed crucible for continuous sintering, and the carbonic acid 4 bow and titanium oxide are preliminarily placed in the sealed crucible. Mix powder or ceramic powder as a mat powder.

The sintering step further comprises: machining and sample testing, surface treating the ceramic blank to obtain a ceramic sample, and measuring a dielectric property index of the ceramic sample. Wherein, the carbon powder 4, aluminum oxide, cerium oxide and the mixed powder of titanium dioxide and barium carbonate or calcium oxide are mechanically and uniformly mixed, and the steps of forming the powder particles include: placing the mixed powder in a spherical tank, adding the dioxide The honing ball is used as a grinding medium, and anhydrous ethanol or deionized water is added as an organic solvent for mechanically mixing, and after the powder particles are formed, the organic solvent is removed and dried, wherein the powder, the grinding medium, and the organic solvent are mixed. The weight ratio of the three is 1:3:3 and accounts for 60%~80% of the volume of the spherical tank, and the mixing time is 1~3 hours.

Among them, in the first high-energy ball milling step, the ball-to-batch ratio is 8:1~10:1, the ball milling time is 1~3 hours, and the rotation speed is 600~800 rpm.

Among them, the fine powder size distribution after the first high-energy ball milling is in the range of 1~2 μ m.

Among them, in the high-temperature calcination step, the closed container is resistant to high temperature, the calcination temperature is 900 to 1200 degrees Celsius, and the holding time is 3 to 6 hours.

Wherein, when the mixed powder is calcium carbonate, aluminum oxide, barium oxide, titanium dioxide and barium carbonate, in the second high energy ball milling step, the ball to material ratio is 10:1 to 12:1, and the ball milling time is 1 to 3 hours. The speed is 800~1000 rev / min.

Wherein, when the mixed powder is calcium carbonate, aluminum oxide, cerium oxide, titanium dioxide and calcium oxide, in the second high energy ball milling step, the ball to material ratio is 10:1 to 12:1, and the ball milling time is 1 to 3 hours. The speed is 600~1000 rev / min.

Among them, the ceramic powder after the second high-energy ball milling has a particle size of less than 1 μm.

Wherein, when the mixed powder is calcium carbonate, aluminum oxide, cerium oxide, titanium oxide, and cerium carbonate, the mixed powder is formulated according to the chemical formula (1-χ) [ & _1-γ 8ι] Ή 0 ₃ — x [Nd _1-z Re _z A10 ₃ ] such that the molar percentages x, y and z thereof respectively satisfy 0.28 mol% < x < 0.48 mol%, 0.01 mol% < y < 0.25 mol%, and 0.1 mol% < z < 0.5 mol%, wherein, carbonic acid The purity of calcium, barium carbonate and alumina is more than 99.5%, and the purity of titanium dioxide and barium oxide is not less than 99.9%.

Wherein, when the mixed powder is calcium carbonate, aluminum oxide, cerium oxide, titanium oxide, and calcium oxide, the formula of the mixed powder is such that x and y are respectively satisfied according to the chemical formula (lx) Ca ₁₊ yTi0 ₃ — x[NdA10 ₃ ] 0.28 mol% < x < 0.48 mol% and 0.05 mol% < y < 0.5 mol% (y optional calcium carbonate or calcium oxide;), Among them, the purity of carbonic acid 4 bow, calcium oxide and aluminum oxide is more than 99.5%, and the purity of titanium dioxide and cerium oxide is not less than 99.9%.

Wherein, in the second high energy ball milling step, a modifying additive and a sintering aid are further added. Wherein, the modifying additive is one or more of CaO, SrO, Ti0 ₂ , ZnO, A1 ₂ 0 ₃ , Nb ₂ 0 ₅ and Ta ₂ 0 ₅ , and the sintering aid is Bi ₂ 0 ₃ , B ₂ 0 ₃ One or more of CuO, V ₂ 0 ₅ and BaO.

Wherein, when the mixed powder is calcium carbonate, aluminum oxide, cerium oxide, titanium dioxide and cerium carbonate, in the second high energy ball milling step, a modified dopant is further added, and the modified dopant is oxidized by the rare earth element. The rare earth element is one or more of 4, B, 铈, 铈, 镨, 钐, 铕, 4L, 镝, 铒 and 镱.

Among them, the formulation of microwave dielectric ceramic materials is in accordance with the chemical formula

The molar percentages x, y, and z satisfy 0.28 mol% < x < 0.48 mol%, 0.01 mol% < y < 0.25 mol%, and 0.1 mol% < z < 0.5 mol%, respectively, wherein the mass percentage of the modified additive is carbonic acid 1% to 4% of the total amount of calcium, barium carbonate, alumina, cerium oxide and titanium dioxide, and the mass percentage of sintering aid is 0.1% to 1% of the total amount of carbonic acid 4 bow, strontium carbonate, alumina, cerium oxide and titanium dioxide. .

Wherein, the formula of the microwave dielectric ceramic material is such that x and y satisfy 0.28 mol% < x < 0.48 mol% and 0.05 mol% < y < 0.5 mol%, respectively, according to the chemical formula (lx) Ca ₁₊ yTi0 ₃ — x [NdA10 ₃ ] ( y optional calcium carbonate or calcium oxide), wherein the mass percentage of the modified additive is 1% to 4% of the total amount of carbonic acid 4, calcium oxide, aluminum oxide, cerium oxide and titanium dioxide, and the mass percentage of the sintering aid is carbonic acid 4%, 1% to 1% of the total amount of bow, calcium oxide, aluminum oxide, cerium oxide and titanium dioxide.

In summary, the preparation method of the microwave dielectric ceramic material of the present invention can suppress the "lattice defect effect" of the volatile element Ca by adding cesium carbonate or calcium oxide to the raw material on the basis of two high-energy ball milling. The sintering temperature is greatly reduced and the sintering time is shortened, and high densification is achieved, which reduces production cost and technical difficulty.

The above description is only an overview of the technical solution of the present invention, in order to understand the technology of the present invention more clearly. The above and other objects, features, and advantages of the present invention will be apparent from the description and appended claims.

[Description of the Drawings]

1 is a schematic flow chart of a method for preparing a microwave dielectric ceramic material according to an embodiment of the present invention; FIG. 2 is a schematic view of a method for preparing a microwave dielectric ceramic material according to an embodiment of the present invention, using a conventional solid phase reaction synthesis method combined with high energy ball milling technology; The particle size distribution map of the refined powder prepared by the first high-energy ball milling (a) and the microwave dielectric ceramic sample prepared by the conventional solid phase reaction synthesis method combined with the high energy ball milling technique and increasing the percentage of Ca element Ray diffraction (XRD) pattern (b); FIG. 3 is a microwave dielectric ceramic sample prepared by a conventional solid phase reaction synthesis method combined with a high energy ball milling technique in a method for preparing a microwave dielectric ceramic material according to an embodiment of the present invention. Scanning electron microscopy (SEM) comparison images (a) and (b) of microwave dielectric ceramic samples prepared by a conventional solid-phase reaction synthesis method combined with high-energy ball milling technology and a suitable method for increasing the percentage of Ca element;

4 is a powder obtained by conventional mechanical mixing (12 hours) (a) and first high energy ball milling (2 hours) (b), respectively, in a method of preparing a microwave dielectric ceramic material according to another embodiment of the present invention. Scanning electron microscopy (SEM) image of the particles;

5 is a schematic diagram of a method for preparing a microwave dielectric ceramic material according to another embodiment of the present invention, using a conventional mechanical mixing + solid phase reaction method (a) and a solid phase reaction method + high energy ball milling combined with an A element replacement step (Sr). Scanning electron microscopy (SEM) images of microwave dielectric ceramic samples prepared by ²⁺ instead of Ca ²⁺ ) and sintering atmosphere control process (b).

【detailed description】

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, one of ordinary skill in the art does not create All other embodiments obtained under the premise of sexual labor are within the scope of protection of the present invention.

Embodiment 1

A method for preparing a microwave dielectric ceramic material, the flow diagram of which is shown in FIG. 1 , comprising: Step S 101 , mechanically uniformly mixing calcium carbonate, aluminum oxide, cerium oxide and titanium oxide with a mixed powder of barium carbonate or calcium oxide; , forming powder particles.

The mixed powder contains at least carbonic acid carbonate, aluminum oxide, cerium oxide and titanium oxide. In order to achieve the "lattice defect effect" caused by the inhibition of the volatile element Ca, the present embodiment further adds cerium carbonate or calcium oxide to the mixed powder.

If the mixed powder is carbonic acid, calcium oxide, aluminum oxide, cerium oxide and titanium dioxide, the mixed powder is placed in a spherical tank, the zirconia grinding ball is added as a grinding medium, and anhydrous ethanol or deionized water is added as an organic solvent. The machine is uniformly mixed, and after the powder particles are formed, the organic solvent is removed and dried, wherein the weight ratio of the mixed powder, the grinding medium and the organic solvent is 1:3:3 and accounts for 60% of the volume of the spherical tank. 80%, mixing time is 1~3 hours. Wherein, the formula of the mixed powder is such that JC and y satisfy 0.28 mol% ≤ ≤ 0.48 mol% and 0.05 mol% ≤ y ≤ 0.5 mol%, respectively, according to the chemical formula ( 1 - ) Ca _1+y Ti0 ₃ — [NdA10 ₃ ] (y Optional calcium carbonate or calcium oxide). Among them, the purity of calcium carbonate, calcium oxide and aluminum oxide is more than 99.5%, and the purity of titanium dioxide and cerium oxide is not less than 99.9%. Since the raw material has 4 strontium carbonate and calcium oxide, the molar percentage of the volatile element Ca in the CTNA-based dielectric material is increased, and the "lattice defect effect" caused by the volatile element Ca can be suppressed.

If the mixed powder is carbonic acid, cesium carbonate, aluminum oxide, cerium oxide, titanium dioxide, the mixed powder is placed in a spherical tank, the zirconia grinding ball is added as a grinding medium, and anhydrous ethanol or deionized water is added as an organic solvent. The machine is uniformly mixed, and after the powder particles are formed, the organic solvent is removed and dried, wherein the weight ratio of the mixed powder, the grinding medium and the organic solvent is 1:3:3 and accounts for 60% of the volume of the spherical tank. 80%, mixing time is 1~3 hours. Wherein, the mixed powder is formulated according to the formula (1-x) [Ca _1-y Sr _y ]Ti0 ₃ — [Nd _1-z Re _z A10 ₃ ] such that the percentages JC, y and z thereof respectively satisfy 0.28 mol% <<0.48 mol%, 0.01 mol% ≤ y ≤ 0.25 mol% and 0.1 mol% ≤ z ≤ 0.5 mol%. Among them, the purity of calcium carbonate, barium carbonate and alumina is more than 99.5%, and the purity of titanium dioxide and barium oxide is not less than 99.9%. Since the addition of strontium carbonate to the raw material instead of a part of calcium carbonate, that is, replacing Ca ²⁺ with Sr ²⁺ , the "lattice defect effect" caused by the volatile element Ca can be effectively suppressed.

Step S102, the powder particles are subjected to a first high-energy ball milling to uniformly refine the powder particles to form a refined powder.

In the present embodiment, the first high-energy ball milling is performed using the zirconia grinding ball as a grinding medium for high-energy ball milling, so that the particle size distribution of the refined powder after the first high-energy ball milling is in the range of 1~2μηι, effectively improving The reaction activity and contact area of the powder particles are achieved, thereby achieving the purpose of lowering the synthesis temperature of the calcination reaction, wherein the ball-to-batch ratio is 8:1 to 10:1, the ball milling time is 1 to 3 hours, and the rotation speed is 600 to 800 rpm. minute.

Step S103, the fine powder is subjected to high-temperature calcination in a closed container to form a precursor powder. In the present embodiment, the first high-energy ball-milled powder is placed in a sealed high-temperature resistant crucible, and a high-purity main crystalline phase precursor powder is synthesized by a high temperature reaction. The process parameters of the high-temperature calcination process are as follows: The closed vessel is resistant to high temperature, the calcination temperature is 900-1200 degrees Celsius, and the holding time is 3-6 hours.

Step S104, the precursor powder is subjected to a second high-energy ball milling to further uniformly refine the precursor powder to form a ceramic powder.

When the mixed powder is carbonic acid, aluminum oxide, cerium oxide, titanium dioxide and calcium oxide, the zirconia grinding ball is used as a grinding medium for high energy ball milling, and further adding a modifying additive and a sintering aid for the second time. High energy ball mill. The ceramic powder formed by the control has a particle size smaller than Ιμηι, and the modified additive is one or more of CaO, SrO, Ti0 ₂ , ZnO, A1 ₂ 0 ₃ , Nb ₂ 0 ₅ and Ta ₂ 0 ₅ , and the sintering aid is One or more of Bi ₂ 0 ₃ , B ₂ 0 ₃ , CuO, V ₂ 0 ₅ and BaO, the formulation of the microwave dielectric ceramic material is according to the chemical formula (l- ) Ca ₁₊ yTi0 ₃ _ [NdA10 ₃ ] JC and y respectively satisfy 0.28 mol% ≤ ≤ 0.48 mol% and 0.05 mol% ≤ y ≤ 0.5 mol% (y optional carbonic acid 4 bow or calcium oxide). Wherein, the mass percentage of the modified additive is 1% to 4% of the total amount of the carbonic acid 4 bow, calcium oxide, aluminum oxide, cerium oxide and titanium dioxide, and the mass percentage of the sintering aid is carbonic acid 4 bow, calcium oxide, aluminum oxide, oxidation 0.1% to 1% of the total amount of cerium and titanium dioxide. Among them, the ball-to-batch ratio is 10:1~12:1, the ball milling time is 1~3 hours, and the rotation speed is 600~1000 rev/min.

By adding a modification additive and a sintering aid, the ceramic powder can be further uniformly distributed, and the porosity between the ceramic powders can be reduced, and the sintering temperature and the microwave dielectric ceramic sintering can be reduced to some extent. The purpose of densification.

When the mixed powder is carbonic acid, aluminum oxide, cerium oxide, titanium dioxide and cerium carbonate, the zirconia grinding ball is used as a grinding medium for high energy ball milling, and further modified dopants, modified additives and sintering are added. The additive is subjected to a second high energy ball milling. The ceramic powder formed by the control has a particle size smaller than Ιμηι, the modified dopant is an oxide containing a rare earth element, and the rare earth element is one of lanthanum, cerium, lanthanum, cerium, lanthanum, cerium, lanthanum, cerium, lanthanum and cerium. Or several, the modifying additive is one or more of CaO, SrO, Ti0 ₂ , ZnO, A1 ₂ 0 ₃ , Nb ₂ 0 ₅ and Ta ₂ 0 ₅ , and the sintering aid is Bi ₂ 0 ₃ , B ₂ One or more of 0 ₃ , CuO, V ₂ 0 _5, and BaO. The formulation of the material is such that the molar percentages JC, y and z thereof satisfy 0.28 mol% << 0.48 mol%, 0.01 mol% ≤ y ≤ 0.25 mol% and 0.1 mol%, respectively, according to the chemical formula (lj^CauS TiOs-j^NdnRezAlC^). ≤ z ≤ 0.5 mol%, wherein the mass percentage of the modified additive is 1% to 4% of the total amount of carbonic acid 4 bow, strontium carbonate, alumina, cerium oxide and titanium dioxide, and the mass percentage of the sintering aid is carbonic acid 4 bow, The total amount of barium carbonate, aluminum oxide, barium oxide and titanium dioxide is 0.1% to 1%, wherein the ball-to-batch ratio is 10:1 to 12:1, the ball milling time is 1 to 3 hours, and the rotation speed is 800 to 1000 rpm.

By adding a modified dopant, a modification additive and a sintering aid, the firing temperature of the CTNA microwave dielectric ceramic can be effectively reduced, specifically, the high temperature calcination temperature is 900 to 1200 degrees Celsius; and the ceramic green compact sintering temperature is 1200 to 1500 In degrees Celsius, the ceramic powder can be further uniformly distributed, and the porosity between the ceramic powders can be reduced, so that the sintering temperature and the sintering densification of the microwave dielectric ceramic can be reduced to some extent.

Further, in the present embodiment, after the ceramic powder is formed, the following steps may be further included as needed:

Spray granulation, adding a polyvinyl alcohol aqueous solution having a concentration of 5% and a mass percentage of 5% to 10% to the ceramic powder, and forming the ceramic powder into powder particles having spherical fluidity so as to make the powder particles Has good fluidity.

Press molding, the spherical particles having spherical fluidity are formed into a ceramic green compact of a desired shape.

In this embodiment, the ceramic green compact is double-sided press-molded by a press in a manual or automatic filling manner, extruded by an extrusion forming process, or one injection by one injection molding technique. Type. Among them, the pressure of double-sided pressing is 80~120MPa.

Sintering, the ceramic compact is continuously sintered to form a ceramic blank, wherein the highest sintering temperature is 1200-1500 degrees Celsius, and the holding time is 3-6 hours.

In the present embodiment, the ceramic green compact is placed in a closed high-temperature resistant alumina crucible for continuous sintering, and a solid phase reaction occurs at a high temperature to form a dense ceramic blank. Further, when the mixed powder is calcium carbonate, aluminum oxide, cerium oxide, titanium oxide, and barium carbonate, a calcium carbonate and titanium oxide mixed powder or ceramic powder is previously placed in the sealed body as a mat powder to be sintered. Atmospheric control is performed, and a solid phase reaction occurs at a high temperature to form a dense ceramic blank.

Machining and sample testing, ceramic blanks are surface treated to obtain ceramic samples, and the dielectric properties of ceramic samples are measured.

In this embodiment, the ceramic blank can be surface-treated by grinding, polishing, etc. to obtain a ceramic sample of a desired size, and the dielectric properties of the ceramic sample are measured by a network analyzer: dielectric constant, temperature coefficient of resonance frequency T _f and quality factor Q.

Embodiment 2

A method for preparing a microwave dielectric ceramic material, the mixed powder being calcium carbonate, aluminum oxide, cerium oxide, titanium dioxide and calcium oxide, the method comprising:

Step 1. Pre-sinter the cerium oxide powder at 800 °C for 3 hours before batching to remove moisture for drying; according to the chemical formula 0.72Ca ₁₊ . _.lm . _1% TiO _₃ _{_0.28NdAlO} ₃ 4 ratio bow carbonate, calcium oxide, aluminum oxide, neodymium oxide and titania, zirconia balls were added as a mixed powder in the grinding media, adding ethanol as an organic or deionized water The solvent is placed in a spherical tank for mechanical mixing, and after the powder particles are formed, the organic solvent is removed for drying, and the ratio of the mixed powder, the grinding ball, and the solvent (weight) is 1:3:3 and the ball is occupied. The tank volume is 60%~80%, and the raw material mixing time is 3 hours.

In this embodiment, the stoichiometric ratio of calcium carbonate and titanium dioxide is 0.72 mol%, the stoichiometric ratio of alumina and cerium oxide is 0.28 mol%, and the stoichiometric ratio of calcium oxide is 0.1 mol% to increase Ca element. Percentage. It should be noted that the purity of the carbonate 4, calcium oxide and alumina powders is more than 99.5%, and the purity of the titanium dioxide and cerium oxide powders is not less than 99.9%. Step 2: using the zirconia grinding ball as a grinding medium, drying the powder particles formed in the first step and performing the first high-energy ball milling to uniformly refine the powder particles to form a refined powder. Among them, the high-energy ball milling time is 2 hours, the ball-to-batch ratio is 8:1, and the rotation speed is 400 rpm.

Step 3: The refined powder formed in the second step is placed in a closed high temperature resistant crucible, and a precursor powder having a high purity main crystalline phase is synthesized by a high temperature calcination reaction. Among them, the calcination temperature was 1000 ° C and the temperature retention time was 3 hours.

Step 4: using a zirconia grinding ball as a grinding medium, and subjecting the calcined precursor powder to a second high-energy ball milling to obtain a ceramic powder which is further uniformly refined. Among them, the high-energy ball milling time is 1 hour, the ball-to-batch ratio is 10:1, and the rotation speed is 1000 rpm.

Step 5: adding 10% by mass of a polyvinyl alcohol (PVA) aqueous solution (concentration: 5%) to the ceramic powder obtained in the fourth step, and using a drying tower or a granulator to form a spherical and fluid powder. Particles.

Step 6. Pressing the powder particles obtained in the fifth step into a ceramic compact of the desired shape by a press (manual or automatic filler) by double-sided pressing, the pressing pressure is 120 MPa; or obtaining the desired shape by one injection molding technique Ceramic compact.

Step 7. The ceramic green compact is placed in a sealed high temperature resistant alumina crucible for continuous sintering to form a ceramic blank. Among them, the highest sintering temperature is 1350 degrees Celsius, and the holding time is 3 hours.

Step 8. The fired ceramic blank is taken out and subjected to surface treatment such as grinding and polishing to obtain a ceramic sample of a desired size for testing. Then, the dielectric performance indicators measured by the network analyzer are: ε _Γ =43·7; τ wide 21.5ppm/°C; Qx household 41000 (test frequency is l.lGHz).

Embodiment 3

Step 1. Pre-sinter the cerium oxide powder at 800 °C for 3 hours before batching to remove moisture for drying; according to the chemical formula 0.62Ca ₁₊ . _.15m . _1% TiO ₃ — 0.38 NdAlO _{3 is} blended with carbonic acid 4 bow, calcium oxide, aluminum oxide, cerium oxide and titanium dioxide, and a zirconia grinding ball is added as a grinding medium to the mixed powder. Add anhydrous ethanol or deionized water as an organic solvent, place it in a spherical tank for mechanical mixing, and after forming the powder particles, remove the organic solvent for drying, mixing the powder, grinding balls, solvent (weight) ratio It is 1:3:3 and it accounts for 60%~80% of the volume of the spherical tank, and the mixing time of the raw materials is 2 hours.

In this embodiment, the stoichiometric ratio of calcium carbonate and titanium dioxide is 0.62 mol%, the stoichiometric ratio of alumina and cerium oxide is 0.38 mol%, and the stoichiometric ratio of calcium oxide is 0.15 mol% to increase

The percentage of Ca element. It should be noted that the purity of the carbonated carbon, calcium oxide and alumina powders is greater than 99.5%, and the purity of the titanium dioxide and cerium oxide powders is not less than 99.9%.

Step 2: using the zirconia grinding ball as a grinding medium, drying the powder particles formed in the first step and performing the first high-energy ball milling to uniformly refine the powder particles to form a refined powder. Among them, the high-energy ball milling time is 3 hours, the ball-to-batch ratio is 12:1, and the rotation speed is 800 rpm.

Step 3: The refined powder formed in the second step is placed in a closed high temperature resistant crucible, and a precursor powder having a high purity main crystalline phase is synthesized by a high temperature calcination reaction. Among them, the calcination temperature was 900 ° C and the temperature retention time was 5 hours.

Step 4: using a zirconia grinding ball as a grinding medium, and subjecting the calcined precursor powder to a second high-energy ball milling to obtain a ceramic powder which is further uniformly refined. Among them, the high-energy ball milling time is 2 hours, the ball-to-batch ratio is 10:1, and the rotation speed is 800 rpm.

Step 5: adding 10% by mass of a polyvinyl alcohol (PVA) aqueous solution (concentration: 5%) to the ceramic powder obtained in the fourth step, and using a spray drying tower or a granulator to form a spherical and fluid powder. Body particles.

Step 7. The ceramic green compact is placed in a sealed high temperature resistant alumina crucible for continuous sintering to form a ceramic blank. Among them, the highest sintering temperature is 1450 degrees Celsius, and the holding time is 4 hours.

Step 8. The fired ceramic blank is taken out and subjected to surface treatment such as grinding and polishing to obtain a ceramic sample of a desired size for testing. Then, using the network analyzer to measure its dielectric performance indicators respectively For: s _r =45.2; τ 5.6 ppm/°C; Qx 48400 (test frequency is l.lGHz).

Embodiment 4

Step 1. Pre-burn the cerium oxide raw powder at 800 ° C for 3 hours before batching to dry; according to the chemical formula 0.52Ca _{1+ 25m} . _1% TiO ₃ — 0.48NdAlO _{3 is} matched with carbonic acid 4 bow, calcium oxide, aluminum oxide, cerium oxide and titanium dioxide. Tirconia grinding balls are added to the mixed powder as grinding media, and anhydrous ethanol or deionized water is added as organic The solvent is placed in a spherical tank for mechanical mixing, and after the powder particles are formed, the organic solvent is removed for drying, and the ratio of the mixed powder, the grinding ball, and the solvent (weight) is 1:3:3 and the ball is occupied. The tank volume is 60%~80%, and the raw material mixing time is 3 hours.

In this embodiment, the stoichiometric ratio of calcium carbonate and titanium dioxide is 0.52 mol%, the stoichiometric ratio of alumina and cerium oxide is 0.48 mol%, and the stoichiometric ratio of calcium carbonate is 0.25 mol% to increase Ca element. Percentage. It should be noted that the purity of the carbonated carbon, calcium oxide and alumina powders is greater than 99.5%, and the purity of the titanium dioxide and cerium oxide powders is not less than 99.9%.

Step 2: using the zirconia grinding ball as a grinding medium, drying the powder particles formed in the first step and performing the first high-energy ball milling to uniformly refine the powder particles to form a refined powder. Among them, the high-energy ball milling time is 3 hours, the ball-to-batch ratio is 10:1, and the rotation speed is 600 rpm.

Step 3: The refined powder formed in the second step is placed in a closed high temperature resistant crucible, and a precursor powder having a high purity main crystalline phase is synthesized by a high temperature calcination reaction. Among them, the calcination temperature was 1150 ° C and the temperature retention time was 4 hours.

Step 4: using a zirconia grinding ball as a grinding medium, and subjecting the calcined precursor powder to a second high-energy ball milling to obtain a ceramic powder which is further uniformly refined. Among them, the high-energy ball milling time is 2 hours, the ball-to-batch ratio is 8:1, and the rotation speed is 1000 rpm.

Step 5: adding 10% by mass of a polyvinyl alcohol (PVA) aqueous solution (concentration: 5%) to the ceramic powder obtained in the fourth step, and using a spray drying tower or a granulator to form a spherical and fluid powder. Body particles. Step 6. Pressing the powder particles obtained in the fifth step into a ceramic compact of the desired shape by a press (manual or automatic filler) by double-sided pressing, the pressing pressure is 120 MPa; or obtaining the desired shape by one injection molding technique Ceramic compact.

Step 7. The ceramic green compact is placed in a sealed high temperature resistant alumina crucible for continuous sintering to form a ceramic blank. Among them, the highest sintering temperature is 1250 degrees Celsius and the holding time is 6 hours.

Step 8. The fired ceramic blank is taken out and subjected to surface treatment such as grinding and polishing to obtain a ceramic sample of a desired size for testing. Then, the dielectric performance indicators measured by network analyzer are: ε _Γ =44·7; τ wide -8.4ppm/°C; Qx household 42600 (test frequency is 1.1GHz).

Embodiment 5

Using the same process parameters as the preparation method of the microwave dielectric ceramic material of the third embodiment, a sample having an appropriate amount of Ca element percentage (y) is subjected to trial production and detection, thereby describing the above-described embodiment of the present invention in a specific environment for detailed description. The basic performance indicators of the obtained samples are shown in Table 1-2. Table 1 Dielectric properties of samples with different molar percentages of 4丐(CaC0 ₃ )

Table 2 Dielectric properties of different molar percentages of calcium oxide (CaO) corresponding samples

Embodiment 6

In the medium sample preparation process of the third embodiment, a modified additive and a sintering aid are added in an appropriate amount, and the modified additive is one of CaO, SrO, Ti0 ₂ , ZnO, A1 ₂ 0 ₃ , Nb ₂ 0 ₅ and Ta ₂ 0 ₅ One or more of the sintering aids are one or more of Bi ₂ O ₃ , B ₂ 0 ₃ , CuO, V ₂ 0 ₅ and BaO, and the wave dielectric ceramic material is formulated according to the chemical formula 0.62Ca _{G+ i5m} . _1% ) TiO ₃ -0.38NdAlO ₃ ) was blended. Wherein, the mass percentage of the modified additive is 1% to 4% of the total amount of the carbonic acid 4 bow, calcium oxide, aluminum oxide, cerium oxide and titanium dioxide, and the mass percentage of the sintering aid is carbonic acid 4 bow, calcium oxide, aluminum oxide, oxidation The total amount of bismuth and titanium dioxide is 0.1%~1%, and the same process parameters are used for sample trial production and testing, so that the above embodiments of the present invention are applied to specific environments for detailed description. The basic performance indexes are shown in Table 3-4. Table 3 Dielectric properties of samples corresponding to different proportioning modified additives

Table 4 Dielectric properties of samples corresponding to different proportions of sintering aids

The embodiment of the invention combines the high-energy ball milling technology on the basis of the traditional mechanical mixing and solid phase reaction method, and promotes the finening of the ceramic powder by the first high-energy ball milling, which not only effectively reduces the calcination temperature of the powder, but also ensures the reaction. The synthesized ceramic powder main crystalline phase has high purity. Through the second high energy ball grinding The powder particles are further densified to lay a good particle size basis for spray granulation, and the sintering temperature is lowered, and the molar percentage of the volatile element Ca is increased in the raw material, thereby suppressing the volatilization of Ca element during sintering. The "lattice defect effect" ensures a high degree of densification of the fired ceramic.

Referring to FIG. 2, FIG. 2 is a view showing a method for preparing a microwave dielectric ceramic material according to an embodiment of the present invention, using a conventional solid phase reaction synthesis method combined with high energy ball milling technology to obtain a refined powder obtained by the first high energy ball milling. The particle size distribution map (a) and the X-ray diffraction (XRD) pattern of the microwave dielectric ceramic sample prepared by the conventional solid phase reaction synthesis method combined with the high energy ball milling technique and the addition of the Ca element percentage.

The abscissa of the particle size distribution map (a) is the particle size diameter, the unit is μηι, and the ordinate is the volume of the powder, and the unit is %. From the particle size distribution diagram (a), the preparation method of the microwave dielectric ceramic material using the present invention can be seen. After the first high-energy ball milling, the fine powder particle size is highly concentrated, the particle size is narrowed, and the diameter is generally less than 1 μm. The X-ray diffraction (XRD) pattern (b) has an abscissa of 2Θ in degrees and the ordinate is the count detected by the receiver in CPS. Nothing is found from the X-ray diffraction (XRD) pattern (b). The hetero peak, and thus its crystal structure (main crystal phase) is a single-phase orthogonal type perovskite structure.

Referring to FIG. 3, FIG. 3 is a diagram showing a microwave dielectric ceramic sample prepared by a conventional solid phase reaction synthesis method combined with a high energy ball milling technique and using a conventional method for preparing a microwave dielectric ceramic material according to an embodiment of the present invention. Scanning electron microscopy (SEM) contrast images (a) and (b:) of microwave dielectric ceramic samples prepared by solid phase reaction synthesis combined with high energy ball milling techniques and prepared by a suitable amount of Ca element percentage.

It can be clearly seen from the figure that the microwave dielectric ceramic material prepared by the preparation method of the microwave dielectric ceramic material of the invention not only has no obvious local pores (pores), but also has a more uniform and dense distribution of the ceramic particles, effectively suppressing the "crystal". Grid defect effect".

Example 7

A method for preparing a microwave dielectric ceramic material, the mixed powder is calcium carbonate, aluminum oxide, cerium oxide, titanium dioxide and cerium carbonate, the method comprising:

Step 1. Pre-burn the yttrium oxide powder at 800 °C for 3 hours before batching to remove moisture. Drying, and calcining the original titanium dioxide powder at 1280 ° C for 3 hours; according to the chemical formula 0.72 (Ca.. ₉ Sr _ai ) TiO ₃ _0.28 NdAlO ₃ ratio of carbonic acid 4 bow, strontium carbonate, alumina, cerium oxide and titanium dioxide Adding zirconia grinding balls as a grinding medium to the mixed powder, adding anhydrous ethanol or deionized water as an organic solvent, placing them in a spherical tank for mechanically mixing, and removing the organic solvent after forming the powder particles. The drying treatment is carried out, and the ratio of the mixed powder, the grinding ball, and the solvent (weight) is 1:3:3 and it accounts for 60% to 80% of the volume of the spherical tank, and the mixing time of the raw materials is 3 hours.

In the present embodiment, the stoichiometric ratio of calcium carbonate and titanium oxide was 0.72 mol%, the stoichiometric ratio of alumina and cerium oxide was 0.28 mol%, and the stoichiometric ratio of cerium carbonate was 0.1 mol%. It should be noted that the purity of the carbonic acid carbonate, strontium carbonate and alumina powders is more than 99.5%, and the purity of the titanium dioxide and cerium oxide powders is not less than 99.9%.

Step 2: using the zirconia grinding ball as a grinding medium, drying the powder particles formed in the first step and performing the first high-energy ball milling to uniformly refine the powder particles to form a refined powder. Among them, the high-energy ball milling time is 1 hour, the ball-to-batch ratio is 8:1, and the rotation speed is 800 rpm.

Step 3: The refined powder formed in the second step is placed in a closed high temperature resistant crucible, and a precursor powder having a high purity main crystalline phase is synthesized by a high temperature calcination reaction. Among them, the calcination temperature was 1200 ° C and the temperature retention time was 3 hours.

Step 6. Using a press (manual or automatic packing) to press the powder particles obtained in the fifth step into a ceramic compact of the desired shape by a double-sided pressing, the pressing pressure is 120 MPa, and the extrusion molding process is used for extrusion or adopting A single injection molding technique produces a ceramic compact of the desired shape.

Step 7. Place the ceramic compact into a sealed high temperature resistant alumina crucible for continuous sintering. Into a ceramic blank. Among them, the highest sintering temperature is 1450 degrees Celsius, and the holding time is 4 hours. In the present embodiment, a mixed powder of titanium carbonate and titanium oxide or a ceramic powder is placed in the sealed high-temperature resistant alumina crucible as a mat powder in advance to control the atmosphere during sintering, and a solid phase reaction occurs at a high temperature. A dense ceramic blank is produced.

Step 8. The fired ceramic blank is taken out and subjected to surface treatment such as grinding and polishing to obtain a ceramic sample of a desired size for testing. Then, the dielectric performance indicators measured by the network analyzer are: ε _Γ =45·1; τ wide 1.3ppm/°C; Qx household 48400 (test frequency is l. lGHz).

Example eight

Step 1. Pre-sinter the cerium oxide powder at 800 °C for 3 hours before batching, remove the water for drying, and pre-burn the titanium dioxide raw powder at 1280 °C for 3 hours; according to the chemical formula 0.62 (Ca ₀ . ₈ Sr _a2 ) TiO _₃ _0.38NdAlO ₃ 4 Hack ratio carbonate, strontium carbonate, aluminum oxide, neodymium oxide and titania, zirconia balls were added as a mixed powder in the milling media was added deionized water or ethanol as the organic solvent , placed in a spherical tank for mechanical mixing, and after the formation of powder particles, the organic solvent is removed for drying, the ratio of mixed powder, grinding ball, solvent (weight) is 1:3:3 and it accounts for the spherical tank The volume is 60%~80%, and the raw material mixing time is 2 hours.

In the present embodiment, the stoichiometric ratio of calcium carbonate and titanium oxide was 0.62 mol%, the stoichiometric ratio of alumina and cerium oxide was 0.38 mol%, and the stoichiometric ratio of cerium carbonate was 0.2 mol%. It should be noted that the purity of the carbonic acid carbonate, strontium carbonate and alumina powders is more than 99.5%, and the purity of the titanium dioxide and cerium oxide powders is not less than 99.9%.

Step 2: using the zirconia grinding ball as a grinding medium, drying the powder particles formed in the first step and performing the first high-energy ball milling to uniformly refine the powder particles to form a refined powder. Among them, the high-energy ball milling time is 2 hours, the ball-to-batch ratio is 12:1, and the rotation speed is 800 rpm.

Step 3: The refined powder formed in the second step is placed in a closed high temperature resistant crucible, and a precursor powder having a high purity main crystalline phase is synthesized by a high temperature calcination reaction. Among them, the calcination temperature is 900 degrees Celsius, The temperature is 10 hours.

Step 4: using a zirconia grinding ball as a grinding medium, and subjecting the calcined precursor powder to a second high-energy ball milling to obtain a ceramic powder which is further uniformly refined. Among them, the high-energy ball milling time is 1 hour, the ball-to-batch ratio is 10:1, and the rotation speed is 800 rpm.

Step 7. The ceramic green compact is placed in a sealed high temperature resistant alumina crucible for continuous sintering to form a ceramic blank. Among them, the highest sintering temperature is 1350 ° C and the holding time is 4 hours.

In the present embodiment, a mixed powder of titanium carbonate and titanium oxide or a ceramic powder is placed in the sealed high-temperature resistant alumina crucible as a mat powder in advance to control the atmosphere during sintering, and a solid phase reaction occurs at a high temperature. A dense ceramic blank is produced.

Step 8. The fired ceramic blank is taken out and subjected to surface treatment such as grinding and polishing to obtain a ceramic sample of a desired size for testing. Then, the dielectric performance indicators measured by the network analyzer are: ε _Γ =42·6; τ wide 7.3ppm/°C; Qx household 46200 (test frequency is l.lGHz).

Example nine

Step 1. Pre-sinter the yttrium oxide powder at 800 °C for 3 hours before batching, remove the moisture for drying, and pre-burn the original titanium dioxide powder at 1280 °C for 3 hours; according to the chemical formula 0.52 (Ca ₀ . ₇₅ Sr ₀ . ₂₅₎ TiO _₃ _0.48NdAlO ₃ 4 hack ratio carbonate, strontium carbonate, aluminum oxide, neodymium oxide and titania, zirconia balls were added as a mixed powder in the grinding media, adding ethanol or deionized water as Organic solvent, placed in a spherical tank for mechanical mixing, and after forming powder particles, The organic solvent is dried, and the ratio of the mixed powder, the grinding ball, and the solvent (weight) is 1:3:3 and it accounts for 60% to 80% of the volume of the spherical tank, and the mixing time of the raw material is 3 hours.

In the present embodiment, the stoichiometric ratio of calcium carbonate and titanium oxide was 0.52 mol%, the stoichiometric ratio of alumina and cerium oxide was 0.48 mol%, and the stoichiometric ratio of cerium carbonate was 0.25 mol%. It should be noted that the purity of the carbonic acid carbonate, strontium carbonate and alumina powders is more than 99.5%, and the purity of the titanium dioxide and cerium oxide powders is not less than 99.9%.

Step 3: The refined powder formed in the second step is placed in a closed high temperature resistant crucible, and a precursor powder having a high purity main crystalline phase is synthesized by a high temperature calcination reaction. Among them, the calcination temperature was 1050 degrees Celsius and the temperature retention time was 6 hours.

Step 4: using a zirconia grinding ball as a grinding medium, and subjecting the calcined precursor powder to a second high-energy ball milling to obtain a ceramic powder which is further uniformly refined. Among them, the high-energy ball milling time is 1 hour, the ball-to-batch ratio is 8:1, and the rotation speed is 1000 rpm.

Step 6. Using a press (manual or automatic filler) to press the powder particles obtained in the fifth step into a ceramic compact of the desired shape by a double press, the pressing pressure is 100 MPa, and the extrusion molding process is used for extrusion or adopting A single injection molding technique produces a ceramic compact of the desired shape.

Step 7. The ceramic green compact is placed in a sealed high temperature resistant alumina crucible for continuous sintering to form a ceramic blank. Among them, the maximum sintering temperature is 1200 ° C and the holding time is 6 hours.

In the present embodiment, a mixed powder of titanium carbonate and titanium oxide or a ceramic powder is placed in the sealed high-temperature resistant alumina crucible as a mat powder in advance to control the atmosphere during sintering, and a solid phase reaction occurs at a high temperature. A dense ceramic blank is produced. Step 8. The fired ceramic blank is taken out and subjected to surface treatment such as grinding and polishing to obtain a ceramic sample of a desired size for testing. Then, the dielectric performance indicators measured by the network analyzer are: ε

Qx household 42300 (test frequency is 1.1GHz).

Example ten

The trial production and detection of different group distribution ratio (y) samples are carried out by using the same process parameters as the preparation method of the microwave dielectric ceramic material of the seventh embodiment, so that the above embodiments of the present invention are applied to specific environments for detailed description, and the basic samples are obtained. Performance indicators are shown in Table 5. Table 5 Dielectric properties of different components (y) ratio 0.72Ca ₍₁ _ _y )Sr _y TiO ₃ -0.28NdAlO ₃

Embodiment 11

In the medium sample preparation process of the seventh embodiment, a modified dopant, a modification additive and a sintering aid are added in an appropriate amount, and the modified dopant is an oxide containing a rare earth element, and the rare earth elements are lanthanum, cerium, lanthanum, cerium, One or more of cerium, lanthanum, 4L, lanthanum, cerium, and lanthanum, and the modifying additive is one of CaO, SrO, Ti0 ₂ , ZnO, A1 ₂ 0 ₃ , Nb ₂ 0 _{5 ,} and Ta ₂ 0 ₅ or more, the sintering aid is a _{_{_{Bi 2 0 3, B 2 0}}} 3, CuO, V 2 0 5 and one or more of BaO, the material formulation of microwave dielectric ceramics according to the chemical formula 0.72Ca _0. ₉ Sro. iTi0 ₃ -0.28NdA10 _{3 is} used for the ratio. Wherein, the mass percentage of the modified additive is 1% to 4% of the total amount of calcium carbonate, barium carbonate, aluminum oxide, barium oxide and titanium dioxide, and the mass percentage of the sintering aid is calcium carbonate, barium carbonate, aluminum oxide, barium oxide and The total amount of titanium dioxide is 0.1%~1%, and the same process parameters are used for sample trial production and testing, so that the above embodiments of the present invention are applied to specific environments for detailed description. The basic performance indexes are shown in Table 6-8. Table 6 Dielectric properties of doped samples modified with different ratios of rare earth elements

Table 7 Dielectric properties of samples corresponding to different proportions of sintering aids

Table 8 Dielectric properties of samples corresponding to different proportions of sintering aids

The embodiment of the invention combines high energy ball milling technology on the basis of traditional mechanical mixing and solid phase reaction methods Through the first high-energy ball milling, the ceramic powder is densified, which not only effectively reduces the calcination temperature of the powder, but also ensures the high purity of the main crystal phase of the ceramic powder synthesized by the reaction. Through the second high-energy ball milling, the powder particles are further densified, which lays a good grain foundation for spray granulation, and reduces the sintering temperature. By using Sr ²⁺ instead of Ca ²⁺ element in the raw material and sintering atmosphere control process The "lattice defect effect" caused by the volatilization of Ca in the sintering process is suppressed, and the high density of the fired ceramic is ensured.

Referring to FIG. 4, FIG. 4 illustrates a method for preparing a microwave dielectric ceramic material according to another embodiment of the present invention, which is subjected to conventional mechanical mixing (12 hours) (a) and first high energy ball milling (2 hours) ( b) Scanning electron microscopy (SEM) image of the prepared powder particles.

As is apparent from the figure, Fig. (b) shows no significant block (sheet) as compared with the powder particles after high energy ball milling of Fig. (a), and the particle size is more uniform.

Referring to FIG. 5, FIG. 5 illustrates a method for preparing a microwave dielectric ceramic material according to another embodiment of the present invention, which is respectively combined with a conventional mechanical mixing + solid phase reaction method (a) and a solid phase reaction method + high energy ball milling. Scanning electron microscopy (SEM) images of microwave dielectric ceramic samples prepared by the A-site element replacement step (Sr ²⁺ instead of Ca ²⁺ ) and the sintering atmosphere control process (b).

It is apparent from the figure that the microwave dielectric ceramic material prepared by the preparation method of the microwave dielectric ceramic material of the present invention has not only obvious cracks and local pores (pores), but also the ceramic particles are more uniform and dense, and effectively inhibited. The "lattice defect effect" caused by the volatile element Ca.

In the above manner, the microwave dielectric ceramic material preparation method of the present invention adds cesium carbonate to the raw material on the basis of two high-energy ball milling, replaces part of the Ca element with the Sr element, and controls the atmosphere during sintering, or increases the volatile element Ca. The molar percentage in the raw material suppresses the "lattice defect effect" of the volatile element Ca, greatly reduces the sintering temperature and shortens the sintering time, and achieves high densification, thereby reducing production cost and technical difficulty.

The above is only the embodiment of the present invention, and is not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the specification and the drawings of the present invention may be directly or indirectly applied to other related technologies. The scope of the invention is included in the scope of patent protection of the present invention.

Claims

Rights request

A method for preparing a microwave dielectric ceramic material, comprising:

Mixing powder of carbonic acid carbonate, aluminum oxide, cerium oxide and titanium dioxide with cerium carbonate or calcium oxide to form a powder particle;

Performing the first high-energy ball milling on the powder particles to knead the powder particles to form a refined powder;

The fine powder is subjected to high temperature calcination in a closed vessel to form a precursor powder;

The precursor powder is subjected to a second high-energy ball milling to further uniformly refine the precursor powder to form a ceramic powder.

The method for preparing a microwave dielectric ceramic material according to claim 1, wherein the second high energy ball milling step further comprises:

Spray granulation, a polyvinyl alcohol aqueous solution having a concentration of 5% and a mass percentage of 5% to 10% is added to the ceramic powder, and the ceramic powder is made into powder particles having spherical fluidity.

The method of preparing a microwave dielectric ceramic material according to claim 2, wherein the step of the spray granulation further comprises:

Press molding, the spherical fluid powder particles are formed into a ceramic green compact of a desired shape.

The method for preparing a microwave dielectric ceramic material according to claim 3, wherein the press molding step further comprises:

The method for preparing a microwave dielectric ceramic material according to claim 4, wherein when the mixed powder is carbonic acid, aluminum oxide, cerium oxide, titanium oxide, and cerium carbonate, the ceramic green compact is placed The sealed crucible is continuously sintered, and a carbonated carbon dioxide mixed powder or a ceramic powder is previously placed in the sealed crucible as a mat powder.

The method for preparing a microwave dielectric ceramic material according to claim 4, wherein the sintering step further comprises: machining and sample testing, and surface treating the ceramic blank to obtain a ceramic Porcelain samples, and the dielectric properties of the ceramic samples were measured.

The method for preparing a microwave dielectric ceramic material according to claim 1, wherein the calcium carbonate, aluminum oxide, cerium oxide, and a mixed powder of titanium dioxide and barium carbonate or calcium oxide are mechanically uniformly mixed to form a powder. The steps of the particles include:

The mixed powder is placed in a spherical tank, a zirconia grinding ball is added as a grinding medium, anhydrous ethanol or deionized water is added as an organic solvent for mechanical uniform mixing, and after the powder particles are formed, organic is removed. The solvent is dried, wherein the mixed powder, the grinding medium and the organic solvent have a weight ratio of 1:3:3 and 60% to 80% of the volume of the spherical tank, and the mixing time is 1 to 3 hours.

The method for preparing a microwave dielectric ceramic material according to claim 1, wherein in the first high energy ball milling step, the ball to material ratio is 8:1 to 10:1, and the ball milling time is 1 to 3 hours. The speed is 600~800 rpm.

The method for preparing a microwave dielectric ceramic material according to claim 8, wherein the fine particle size distribution after the first high energy ball milling is in the range of 1~2 μ ηι.

The method for preparing a microwave dielectric ceramic material according to claim 1, wherein in the high-temperature calcination step, the sealed container is resistant to high temperature, the calcination temperature is 900 to 1200 degrees Celsius, and the holding time is 3 to 6 hours.

11. The method of preparing a microwave dielectric ceramic material according to claim 1, wherein, when the mixed powder is carbonic acid, aluminum oxide, barium oxide, titanium oxide, and barium carbonate, in the second high energy ball mill. In the step, the ball-to-batch ratio is 10: 1~12: 1 , the ball milling time is 1~3 hours, and the rotation speed is 800~1000 rev/min.

12. The method of preparing a microwave dielectric ceramic material according to claim 1, wherein, when the mixed powder is carbonic acid, aluminum oxide, cerium oxide, titanium oxide, and calcium oxide, in the second high energy ball milling. In the step, the ball-to-batch ratio is 10: 1~12: 1 , the ball milling time is 1~3 hours, and the rotation speed is 600~1000 rev / min.

The method for preparing a microwave dielectric ceramic material according to claim 12, wherein the ceramic powder after the second high energy ball milling has a particle size of less than 1 μm.

14. The method of preparing a microwave dielectric ceramic material according to claim 1, wherein when the mixed powder is carbonic acid, aluminum oxide, cerium oxide, titanium oxide, and cerium carbonate, the mixed powder is formulated according to The chemical formula (l-xMCai-yS TiOs-x[Nd _1-z Re _z A10 ₃ ] makes the molar percentages x, y and z therein satisfy 0.28 mol% < x < 0.48 mol%, 0.01 mol% < y < 0.25 mol, respectively. % and 0.1 mol% < z < 0.5 mol%, wherein the calcium carbonate, the strontium carbonate and the alumina have a purity of more than 99.5%, and the titanium dioxide and the cerium oxide have a purity of not less than 99.9%.

The method for preparing a microwave dielectric ceramic material according to claim 1, wherein when the mixed powder is carbonic acid carbonate, aluminum oxide, cerium oxide, titanium oxide, and calcium oxide, the mixed powder is formulated according to The chemical formula (lx) Ca ₁₊ yTi0 ₃ — x[NdA10 ₃ ] is such that x and y respectively satisfy 0.28 mol% < X < 0.48 mol% and 0.05 mol% < y < 0.5 mol% (y optional calcium carbonate or calcium oxide Wherein, the purity of the carbonic acid carbonate, calcium oxide and aluminum oxide are both greater than 99.5%, and the purity of the titanium dioxide and cerium oxide is not less than 99.9%.

The method of preparing a microwave dielectric ceramic material according to claim 1, wherein in the second high energy ball milling step, a modifying additive and a sintering aid are further added.

The method for preparing a microwave dielectric ceramic material according to claim 16, wherein the modifying additive is CaO, SrO, Ti0 ₂ , ZnO, A1 ₂ 0 ₃ , Nb ₂ 0 ₅ and Ta ₂ 0 ₅ one or more, the sintering aid is a _{_{_{Bi 2 0 3, B 2 0}}} 3, CuO, V 2 0 5 and BaO of one or more.

18. The method of preparing a microwave dielectric ceramic material according to claim 17, wherein, when the mixed powder is carbonic acid, aluminum oxide, barium oxide, titanium oxide, and barium carbonate, in the second high energy ball mill. In the step, a modified dopant is further added, the modified dopant is an oxide containing a rare earth element, and the rare earth elements are lanthanum, cerium, lanthanum, cerium, lanthanum, cerium, 4L, lanthanum, cerium, and lanthanum. One or several of them.

The method for preparing a microwave dielectric ceramic material according to claim 18, wherein the microwave dielectric ceramic material is formulated according to the chemical formula (lx) [Ca^Sr _y ]Ti0 ₃ — x[Nd^Re _z A10 ₃ ] The molar percentages x, y, and z therein are respectively satisfied to 0.28 mol% < x < 0.48 mol%, 0.01 mol% < y < 0.25 mol%, and 0.1 mol% z 0.5 mol%, wherein the mass percentage of the modified additive Carbon 1% to 4% of the total amount of calcium acid, barium carbonate, aluminum oxide, barium oxide and titanium dioxide, and the mass percentage of the sintering aid is 0.1% of the total amount of carbonic acid carbonate, barium carbonate, aluminum oxide, barium oxide and titanium dioxide. ~1%.

The method for preparing a microwave dielectric ceramic material according to claim 17, wherein the formulation of the microwave dielectric ceramic material satisfies x8 and y respectively according to a chemical formula (lx) Ca ₁₊ yTi0 ₃ — x[NdA10 ₃ ]. Mol% < x < 0.48 mol% and 0.05 mol% < y < 0.5 mol% (y optional calcium carbonate or calcium oxide;), wherein the mass percentage of the modifying additive is carbonic acid 4 bow, calcium oxide, aluminum oxide 1% to 4% of the total amount of cerium oxide and titanium dioxide, and the mass percentage of the sintering aid is 0.1% to 1% of the total amount of carbonic acid 4, calcium oxide, aluminum oxide, cerium oxide and titanium dioxide.