Low-loss microwave dielectric ceramic material and preparation method thereof

Abstract

The invention relates to the technical field of electronic ceramics, in particular to a low-loss microwave dielectric ceramic material and a preparation method thereof.The preparation method comprises the steps that first powder slurry is put into a drying oven to be dried, and dried powder is obtained; sieving the dried powder, and pre-sintering in a muffle furnace; cooling the pre-sintered powder, adding absolute ethyl alcohol, and performing wet grinding for 4 hours to obtain second powder slurry; drying the second powder slurry, granulating, and pressing into a ceramic green body; and sintering the ceramic green body at 1270 DEG C for 3 hours to obtain the low-loss microwave dielectric ceramic material. The talc powder is used as the unique initial raw material, the microwave performance of the material is excellent, the dielectric constant epsilon r is 4.98-5.89, the quality factor Q * f is 32860-42633 GHz, the temperature coefficient of resonance frequency tau f is-77.73--39.99 ppm / DEG C, meanwhile, the cost of the initial raw material talc is extremely low, the preparation process is simple, and therefore the problem that an existing microwave dielectric ceramic material is high in production cost is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic ceramics, and in particular to a low-loss microwave dielectric ceramic material and a preparation method thereof. Background Art

[0002] Microwave dielectric ceramics, as a dielectric material used in microwave frequency band (300MHz~300GHz) circuits, have the advantages of low loss, good temperature stability, and small device size. They are mainly used to prepare microwave components such as resonators, filters, and oscillators.

[0003] With the development of communication technology, microwave components are constantly developing towards low cost, miniaturization and high frequency. Low dielectric constant can increase the rate of signal transmission and reduce cross coupling between conductors. In order to ensure its practical application ability, it is also necessary to have a high Q value so that it has good frequency selection characteristics and improves the signal-to-noise ratio. It is also necessary to have a temperature coefficient of nearly 0 to reduce the frequency drift of microwave devices during operation. Summary of the invention

[0004] The object of the present invention is to provide a low-loss microwave dielectric ceramic material and a preparation method thereof, aiming to solve the problem of high production cost of existing microwave dielectric ceramic materials.

[0005] To achieve the above object, in a first aspect, the present invention provides a method for preparing a low-loss microwave dielectric ceramic material, comprising the following steps:

[0006] Wet-grind talcum powder and anhydrous ethanol in a mass ratio of 1:1 for 6 hours to obtain a first powder slurry;

[0007] Putting the first powder slurry into a drying oven for drying to obtain dry powder;

[0008] The dried powder is sieved and then placed in a muffle furnace for pre-calcination;

[0009] After the pre-calcined powder is cooled, anhydrous ethanol is added and wet-grinded for 4 hours to obtain a second powder slurry;

[0010] drying the second powder slurry, granulating the slurry, and pressing the slurry into a ceramic green body;

[0011] The ceramic green body is sintered at 1250° C. to 1270° C. for 3 hours to obtain a low-loss microwave dielectric ceramic material.

[0012] Among them, in “placing the first powder slurry in a drying oven for drying to obtain dry powder”, the drying dimension of the drying oven is 85°C-100°C.

[0013] Among them, in “screening the dry powder and then placing it in a muffle furnace for pre-calcination”, the screening uses a 80-mesh screen, the pre-calcination temperature of the muffle furnace is 900° C., and the calcination time is 2 hours.

[0014] Wherein, in the step of “drying the second powder slurry, granulating it, and pressing it into a ceramic green body”, the drying temperature is 85° C.-100° C., and the granulation uses a 30% polymethyl methacrylate solution as a binder.

[0015] In a second aspect, a low-loss microwave dielectric ceramic material is prepared by the method for preparing the low-loss microwave dielectric ceramic material according to the first aspect, and includes talc powder.

[0016] A method for preparing a low-loss microwave dielectric ceramic material of the present invention comprises the following steps: wet-grinding talcum powder and anhydrous ethanol in a mass ratio of 1:1 for 6 hours to obtain a first powder slurry; placing the first powder slurry in a drying oven to dry to obtain a dry powder; sieving the dry powder and placing it in a muffle furnace for pre-calcination; cooling the pre-calcined powder and adding anhydrous ethanol for wet-grinding for 4 hours to obtain a second powder slurry; drying the second powder slurry, granulating it, and pressing it into a ceramic green body; sintering the ceramic green body at 1270°C for 3 hours to obtain a low-loss microwave dielectric ceramic material. The present invention uses talcum powder as the only initial raw material and prepares microwave dielectric materials by a solid-phase sintering method. The microwave performance of the material is relatively excellent: the dielectric constant ε r is 4.98~5.89, the quality factor Q×f is 32860~42633GHz, and the resonant frequency temperature coefficient τ f The temperature of the microwave dielectric ceramic material is -77.73 to -39.99 ppm / ℃. At the same time, due to the extremely low cost of the initial raw material talc and the simple preparation process, the present invention has great commercial potential, thereby solving the problem of high production cost of existing microwave dielectric ceramic materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The present invention provides a flow chart of a method for preparing a low-loss microwave dielectric ceramic material. DETAILED DESCRIPTION

[0019] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0020] See also Figure 1 In a first aspect, the present invention provides a method for preparing a low-loss microwave dielectric ceramic material, comprising the following steps:

[0021] S1: wet-grinding talcum powder and anhydrous ethanol in a mass ratio of 1:1 for 6 hours to obtain a first powder slurry;

[0022] The drying temperature of the drying oven is 85°C-100°C.

[0023] Specifically, a certain amount of talc powder was weighed, and anhydrous ethanol was added in a mass ratio of 1:1 for ball milling. The ball milling time was 6 hours and the rotation speed was 350 rpm.

[0024] S2: placing the first powder slurry into a drying oven for drying to obtain dry powder;

[0025] Specifically, the powder slurry obtained in S1 is placed in a drying oven and dried at 85°C.

[0026] S3: sieving the dry powder and pre-calcining it in a muffle furnace;

[0027] The sieving uses a sieve of 80 mesh, the pre-firing temperature of the muffle furnace is 900° C., and the calcination time is 2 hours.

[0028] Specifically, the sieved powder is placed in a muffle furnace, pre-fired at 900° C., and kept warm for 2 hours.

[0029] S4: cooling the pre-calcined powder, adding anhydrous ethanol and wet grinding for 4 hours to obtain a second powder slurry;

[0030] Specifically, the calcined powder of S3 was subjected to a second ball milling by adding anhydrous ethanol in a mass ratio of 1:1. The ball milling time was 4 hours at a rotation speed of 300 rpm.

[0031] S5 drying the second powder slurry, granulating the slurry, and pressing the slurry into a ceramic green body;

[0032] The drying temperature is 85° C.-100° C., and the granulation uses 30% polymethyl methacrylate solution as a binder.

[0033] Specifically, the powder slurry obtained in S4 is placed in a drying oven, dried at 85° C., granulated using a 30% polymethyl methacrylate solution as a binder, passed through an 80-mesh sieve, and then pressed into a ceramic green body using a tablet press.

[0034] S6: sintering the ceramic green body at 1250° C. to 1270° C. for 3 hours to obtain a low-loss microwave dielectric ceramic material.

[0035] Specifically, the green body of S5 is sintered at 1270° C. for 3 hours to obtain a low-loss microwave dielectric ceramic material.

[0036] Embodiment 1:

[0037] Using talc powder as the only raw material, microwave dielectric ceramic materials are prepared by solid phase sintering. The specific implementation steps are as follows:

[0038] (1) Weigh a certain amount of talc powder, add anhydrous ethanol in a mass ratio of 1:1, and ball mill for 6 hours at a speed of 350 rpm;

[0039] (2) placing the powder slurry obtained in step (1) in a drying oven and drying at 85° C.;

[0040] (3) placing the sieved powder in step (2) into a muffle furnace, pre-calcining at 900° C., and keeping the temperature for 2 hours;

[0041] (4) adding anhydrous ethanol in a mass ratio of 1:1 to the powder calcined in step (3) and performing a second ball milling for 4 hours at a speed of 300 rpm;

[0042] (5) placing the powder slurry obtained in step (4) in a drying oven, drying at 85° C., granulating the slurry using a 30% polymethyl methacrylate solution as a binder, passing the slurry through an 80-mesh sieve, and pressing the slurry into a ceramic green body using a tablet press;

[0043] (6) sintering the green body of step (5) at 1250° C. for 3 hours;

[0044] (7) The microwave dielectric properties of the prepared samples were tested by network analyzer, ε r =4.98, Q×f=32860GHz, τ f =-77.73ppm / ℃.

[0045] Embodiment 2:

[0046] The implementation steps are as follows:

[0047] Using talc powder as the only raw material, microwave dielectric ceramic materials are prepared by solid phase sintering. The specific implementation steps are as follows:

[0048] (1) Weigh a certain amount of talc powder, add anhydrous ethanol in a mass ratio of 1:1, and ball mill for 6 hours at a speed of 350 rpm;

[0049] (2) placing the powder slurry obtained in step (1) in a drying oven and drying at 85° C.;

[0050] (3) placing the sieved powder in step (2) into a muffle furnace, pre-calcining at 900° C., and keeping the temperature for 2 hours;

[0051] (4) adding anhydrous ethanol in a mass ratio of 1:1 to the powder calcined in step (3) and performing a second ball milling for 4 hours at a speed of 300 rpm;

[0052] (5) placing the powder slurry obtained in step (4) in a drying oven, drying at 85° C., granulating the slurry using a 30% polymethyl methacrylate solution as a binder, passing the slurry through an 80-mesh sieve, and pressing the slurry into a ceramic green body using a tablet press;

[0053] (6) sintering the green body of step (5) at 1260° C. for 3 hours;

[0054] (7) The microwave dielectric properties of the prepared samples were tested by network analyzer, ε r =5.69, Q×f=33105GHz, τ f =-42.01ppm / ℃.

[0055] Embodiment 3:

[0056] The implementation steps are as follows:

[0057] Using talc powder as the only raw material, microwave dielectric ceramic materials are prepared by solid phase sintering. The specific implementation steps are as follows:

[0058] (1) Weigh a certain amount of talc powder, add anhydrous ethanol in a mass ratio of 1:1, and ball mill for 6 hours at a speed of 350 rpm;

[0059] (2) placing the powder slurry obtained in step (1) in a drying oven and drying at 85° C.;

[0060] (3) placing the sieved powder in step (2) into a muffle furnace, pre-calcining at 900° C., and keeping the temperature for 2 hours;

[0061] (4) adding anhydrous ethanol in a mass ratio of 1:1 to the powder calcined in step (3) and performing a second ball milling for 4 hours at a speed of 300 rpm;

[0062] (5) placing the powder slurry obtained in step (4) in a drying oven, drying at 85° C., granulating the slurry using a 30% polymethyl methacrylate solution as a binder, passing the slurry through an 80-mesh sieve, and pressing the slurry into a ceramic green body using a tablet press;

[0063] (6) sintering the green body of step (5) at 1270° C. for 3 hours;

[0064] (7) The microwave dielectric properties of the prepared samples were tested by network analyzer, ε r =5.85,Q×f=

[0065] 42633GHz, τ f =-43.39ppm / ℃.

[0066] Embodiment 4:

[0067] The implementation steps are as follows:

[0068] Using talc powder as the only raw material, microwave dielectric ceramic materials are prepared by solid phase sintering. The specific implementation steps are as follows:

[0069] (1) Weigh a certain amount of talc powder, add anhydrous ethanol in a mass ratio of 1:1, and ball mill for 6 hours at a speed of 350 rpm;

[0070] (2) placing the powder slurry obtained in step (1) in a drying oven and drying at 85° C.;

[0071] (3) placing the sieved powder in step (2) into a muffle furnace, pre-calcining at 900° C., and keeping the temperature for 2 hours;

[0072] (4) adding anhydrous ethanol in a mass ratio of 1:1 to the powder calcined in step (3) and performing a second ball milling for 4 hours at a speed of 300 rpm;

[0073] (5) placing the powder slurry obtained in step (4) in a drying oven, drying at 85° C., granulating the slurry using a 30% polymethyl methacrylate solution as a binder, passing the slurry through an 80-mesh sieve, and pressing the slurry into a ceramic green body using a tablet press;

[0074] (6) sintering the green body of step (5) at 1280° C. for 3 hours;

[0075] (7) The microwave dielectric properties of the prepared samples were tested by network analyzer, ε r =5.89, Q×f=33507GHz, τ f =-39.99ppm / ℃.

[0076] Table 1

[0077] Examples composition Sintering temperature <![CDATA[ε r ]]> Q×f(GHz) <![CDATA[τ f (ppm / ℃)]]> 1 talc 1250℃ 4.98 32860 -77.73 2 talc 1260℃ 5.69 33105 -42.01 3 talc 1270℃ 5.84 42633 -43.39 4 talc 1280℃ 5.89 33507 -39.99

[0078] In a second aspect, a low-loss microwave dielectric ceramic material is prepared by the method for preparing the low-loss microwave dielectric ceramic material according to the first aspect, and includes talc powder.

[0079] The above disclosure is only a preferred embodiment of a low-loss microwave dielectric ceramic material and a preparation method thereof of the present invention. Of course, this cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for preparing a low-loss microwave dielectric ceramic material, characterized in that: The following steps are involved: Wet-grind talcum powder and anhydrous ethanol in a mass ratio of 1:1 for 6 hours to obtain a first powder slurry; Putting the first powder slurry into a drying oven for drying to obtain dry powder; The dried powder is sieved and then placed in a muffle furnace for pre-calcination; After the pre-calcined powder is cooled, anhydrous ethanol is added and wet-grinded for 4 hours to obtain a second powder slurry; drying the second powder slurry, granulating the slurry, and pressing the slurry into a ceramic green body; The ceramic green body is sintered at 1250° C. to 1280° C. for 3 hours to obtain a low-loss microwave dielectric ceramic material.

2. The method for preparing a low-loss microwave dielectric ceramic material according to claim 1, characterized in that: In "placing the first powder slurry in a drying oven for drying to obtain dry powder", the drying dimension of the drying oven is 85°C-100°C.

3. The method for preparing a low-loss microwave dielectric ceramic material according to claim 1, characterized in that: In "screening the dry powder and then placing it in a muffle furnace for pre-calcination", a 80-mesh screen is used for screening, the pre-calcination temperature of the muffle furnace is 900° C., and the calcination time is 2 hours.

4. The method for preparing a low-loss microwave dielectric ceramic material according to claim 1, characterized in that: In the step of "drying the second powder slurry, granulating it, and pressing it into a ceramic green body", the drying temperature is 85° C.-100° C., and the granulation uses a 30% polymethyl methacrylate solution as a binder.

5. A low-loss microwave dielectric ceramic material, prepared by the method for preparing a low-loss microwave dielectric ceramic material according to any one of claims 1 to 4, characterized in that: Contains talc.

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