Microwave dielectric filter based on agarose-epoxy resin composite system and preparation method thereof

Abstract

The invention discloses a microwave dielectric filter based on an agarose-epoxy resin composite system and a preparation method of the microwave dielectric filter. Deionized water, a dispersing agent, a pH regulator and a surface modifier are taken to be prepared into a premixed liquid material, the premixed liquid material is subjected to ball milling to obtain premixed liquid, and microwave dielectric ceramic powder is added into the premixed liquid in batches to obtain slurry; carrying out ball milling on the slurry to obtain microwave dielectric ceramic slurry; deionized water, agarose powder and epoxy resin are taken to be prepared into gel, and the gel is heated, dissolved and mixed to obtain agarose-epoxy resin composite gel; mixing the microwave dielectric ceramic slurry with the agarose-epoxy resin composite gel, heating and stirring to obtain microwave dielectric ceramic slurry for gel casting, performing vacuum defoaming, injecting the microwave dielectric ceramic slurry into a microwave dielectric ceramic filter mold, putting the microwave dielectric ceramic filter mold into a constant-temperature and constant-humidity box, cooling, drying and demolding to obtain a biscuit, and performing degumming and sintering in a sintering furnace to obtain the microwave dielectric ceramic filter. The microwave dielectric filter based on the agarose-epoxy resin composite system is obtained by polishing and grinding, and the whole-process green manufacturing is realized by combining the biocompatibility of the agarose and the epoxy resin.

Description

Technical Field

[0001] This invention belongs to the field of microwave dielectric ceramic filter molding and manufacturing technology, specifically relating to a microwave dielectric filter based on an agarose-epoxy resin composite system and its preparation method. Background Technology

[0002] Microwave dielectric ceramics are ceramics used in microwave frequency circuits as dielectric materials to achieve one or more functions. Their dielectric properties are mainly measured by dielectric constant (εr), quality factor (Q×f), and temperature coefficient of resonant frequency (τf). The characteristics of low εr, high Q×f, and near-zero τf make them widely used in microwave communication devices. Ceramic filters are indispensable electronic devices in 5G communication technology. At present, their forming methods mainly include dry pressing, 3D printing, and gel casting. Among them, dry pressing is highly precise, fast, and widely used in industrial production, but it is limited by high mold costs and uneven product density. 3D printing can realize rapid device design and production, but it faces problems such as limited compatible materials and difficulties in post-processing of closed structure cavities. Gel casting, on the other hand, spontaneously forms through slurry polymerization reaction, which has the advantages of easy reaction control, simple operation, and the ability to form complex structures with net dimensions.

[0003] Agarose, due to its environmental friendliness and ease of acquisition, is increasingly widely used in gel casting. Patent document CN105835209A discloses a method for gel casting ceramics based on agarose, in which an agarose solution is injected into a preheated ceramic slurry after vacuum degassing, and then injected together into a preheated mold to cool and obtain a green body. Ceramics prepared using agarose as a gelling agent have a certain strength and can be further processed. Patent document CN111592341B discloses a method for preparing porous alumina ceramics, in which alumina powder, magnesium oxide, agarose, and a ceramic pore-forming agent are uniformly mixed to prepare a slurry. The obtained slurry is heated to 80°C and then injected into a mold, and naturally cooled to room temperature to obtain a molded sample. All of the above patents use agarose as a gelling agent to prepare ceramics, but they are all single gelling agent systems (agarose gel systems). The resulting samples have a certain strength, but cannot meet the working conditions required for microwave dielectric ceramics. To address the issue of low strength in ceramics prepared using agarose alone, patent document CN119306470A discloses a method for preparing basalt fiber SiO2 aerogel composite thermal insulation material. This patent uses a composite binder system, silica sol-agarose system, to bond short basalt fibers, thereby improving the mechanical properties of the composite material.

[0004] Microwave dielectric ceramics require higher strength and better flexural strength due to the complex operating conditions and diverse environments they are used in. Experiments and patent literature reveal that microwave dielectric ceramic filters prepared using single agarose as a gelling agent often fail to meet the strength requirements of these applications. Therefore, to meet these requirements, it is necessary to address the issue of low strength in microwave dielectric ceramic filters prepared using a single agarose gel system.

[0005] In-depth research revealed a limited number of publications and patents on improving the strength of microwave dielectric ceramic filters prepared with agarose. Current research primarily focuses on agarose as a gelling agent and its inherent properties, lacking comprehensive formulation studies to enhance the strength of microwave dielectric ceramic filters made from agarose. This provides a new direction and entry point for future research. Summary of the Invention

[0006] Technical problem to be solved: This invention provides a microwave dielectric filter based on an agarose-epoxy resin composite system and its preparation method, which solves the core technical problems of insufficient gel strength, long gel time and low production efficiency in the prior art.

[0007] To achieve the above objectives, this application provides the following technical solution: A method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system includes the following steps: Step 1: Weigh the premixed liquid materials: Weigh 85-90 parts of deionized water, 2-5 parts of dispersant, 2-5 parts of pH adjuster, and 2-5 parts of surface modifier according to the mass ratio. Step 2: Place the premixed liquid material into a ball mill jar and ball mill at a speed of 400~600 r / min for 2~5 min until fully mixed to obtain the prepared premixed liquid for slurry preparation. Step 3: Add 9-11 parts of microwave dielectric ceramic powder to the premixed liquid in 4 batches to obtain a slurry; Step 4: Place the slurry on a ball mill and ball mill it. After passing it through a screen, prepare a microwave dielectric ceramic slurry. Step 5: Weigh the gelling agent materials: Weigh 90-95 parts of deionized water, 1-4 parts of agarose powder, and 2-5 parts of epoxy resin according to the mass ratio. Step 6: Heat and mix the gelling agent material on a magnetic stirrer until the material is fully dissolved to obtain an agarose-epoxy resin composite gelling agent; Step 7: Mix 65 parts of microwave dielectric ceramic slurry with 10.4-10.5 parts of agarose-epoxy resin composite gelling agent according to the mass ratio, place the mixture on a magnetic stirrer and heat and stir to obtain microwave dielectric ceramic slurry for gel casting. Step 8: After vacuum degassing the microwave dielectric ceramic slurry used for gel casting, inject it into the microwave dielectric ceramic filter mold; Step 9: Place the microwave dielectric ceramic filter mold containing the injected ceramic slurry in a constant temperature and humidity chamber for cooling and drying. After drying, remove the mold to obtain the green blank. Step 10: Place the demolded blank in a sintering furnace for debinding and sintering. After vacuum sintering, polish and grind to obtain a microwave dielectric filter based on an agarose-epoxy resin composite system.

[0008] Furthermore, in the first step, the dispersant is one or more of polyacrylic acid, ammonium polyacrylate, and ammonium citrate, the pH adjuster is an alkaline adjuster, the surface modifier is polyethylene glycol, and the pH adjuster adjusts the premixed liquid material to a pH of 9-11.

[0009] Furthermore, in the third step, the microwave dielectric ceramic powder is added to the premixed liquid in four batches: 3.5 to 4 parts for the first batch, 2 to 2.5 parts for the second batch, 2 to 2.5 parts for the third batch, and 1.5 to 2 parts for the fourth batch, with an interval of 1.8 to 2.3 hours.

[0010] Furthermore, in the fourth step, the ball milling speed is 300~800 r / min, the ball milling time is 8~10 h, and the screen is 50~200 mesh.

[0011] Furthermore, in the sixth step, the heating temperature is 80~90℃, the magnetic stirring speed is 100~150r / min, and the stirring time is 5~10min.

[0012] Furthermore, in the seventh step, the heating temperature is 80~90℃, the magnetic stirring speed is 300~500r / min, and the stirring time is 10~30min.

[0013] Furthermore, in the eighth step, the microwave dielectric ceramic filter mold material is one or more of silicone, resin, and soft rubber; the vacuum degree in the vacuum degassing process is -10Kpa to -20Kpa.

[0014] Furthermore, in the ninth step, the temperature of the constant temperature and humidity chamber is 20℃~40℃, the humidity is 60%~70%, and the drying time is 10~15h.

[0015] Furthermore, in the tenth step, the heating rate during the debinding stage is 1℃ / min, the heating rate during the sintering stage is 2℃ / min, and the sintering temperature is 1300℃~1400℃.

[0016] A microwave dielectric filter based on an agarose-epoxy resin composite system prepared by any of the above preparation methods.

[0017] This application provides a microwave dielectric filter based on an agarose-epoxy resin composite system and its preparation method, which has the following advantages compared with the prior art: 1. This invention provides a method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system, and for the first time uses agarose as a gelling agent in a gel casting system to prepare a microwave dielectric ceramic filter; 2. The agarose gel system used in this invention has the characteristics of short gelation time, high-temperature melting, and low-temperature solidification, which effectively shortens the time required for cooling, drying, and demolding of the green blank; 3. The single agarose system utilizes the physical characteristics of high-temperature melting and low-temperature solidification to encapsulate the powder and achieve in-situ solidification. Compared with the traditional agarose gel system, this invention adds epoxy resin and utilizes the epoxy resin to solidify the cross-linked three-dimensional network structure and the agarose to solidify the three-dimensional network structure in-situ. The dual three-dimensional network structure efficiently and tightly encapsulates the ceramic powder during the gelation process, effectively improving the strength and molding integrity of the green body. 4. The microwave dielectric ceramic filter obtained by the agarose-epoxy resin composite gel system of this invention has improved compressive strength and flexural strength compared with the single agarose gel system, thus expanding the application range of the agarose gel system; 5. All raw materials used in this invention are environmentally friendly. Combined with the biocompatibility of agarose and epoxy resin, green manufacturing is achieved throughout the entire process from raw materials to finished products. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the agarose-epoxy resin composite system of this application; Figure 2 These are images of the high-strength microwave dielectric ceramic filter blank and sintered physical object prepared in Example 1 of this application, wherein the left image is the high-strength microwave dielectric ceramic filter blank and the right image is the sintered physical object of the high-strength microwave dielectric ceramic filter. Figure 3 This is a comparison diagram of the bending strength of the high-strength microwave dielectric ceramic filter blank and sintered sample prepared in Example 1 of this application with the blank and sintered sample prepared by a single agarose system. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention.

[0020] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0021] Example 1: This example provides a method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system, specifically including the following steps: Step 1: Weigh out 90 parts of deionized water, 3.3 parts of dispersant, 3.3 parts of alkaline pH adjuster, and 3.3 parts of surface modifier polyethylene glycol according to the mass ratio. That is, weigh out 13.69g of deionized water, 0.5g of ammonium polyacrylate, 0.5g of alkaline pH adjuster, and 0.5g of polyethylene glycol, for a total of 15.2g, and premix them to form a premixed solution with a pH of 9-11. Step 2: Place the premixed liquid material into a ball mill jar and ball mill for 3 minutes at a speed of 500 r / min until fully mixed to obtain the prepared premixed liquid for slurry preparation. Step 3: Add microwave dielectric ceramic powder to the premixed liquid in 4 batches to obtain slurry. The first batch contains 3.85 parts, the second batch contains 2.31 parts, the third batch contains 2.31 parts, and the fourth batch contains 1.54 parts. That is, after adding 25g (38.5wt.%) of microwave dielectric ceramic powder for the first time, 25g (23.1wt.%) of microwave dielectric ceramic powder is added after an interval of 2 hours, 25g (23.5wt.%) of microwave dielectric ceramic powder is added after an interval of 2 hours, and 15g (15.4wt.%) of microwave dielectric ceramic powder is added after an interval of 2 hours, for a total of 65g of microwave dielectric ceramic powder. Step 4: Place the slurry on a ball mill and ball mill at a speed of 550 r / min for 8 hours. After passing through a 100-mesh sieve, prepare the microwave dielectric ceramic slurry. Step 5: Weigh 92.4 parts of deionized water, 2.8 parts of agarose powder, and 4.8 parts of epoxy resin according to the mass ratio, that is, weigh 9.7g of deionized water, 0.3g of agarose powder, and 0.5g of epoxy resin, for a total of 10.5g, and premix them into a gelling agent material. Step 6: Heat and dissolve the gelling agent material at 85°C on a magnetic stirrer. The magnetic stirring speed is 100 r / min and the stirring time is 8 min, until the material is fully dissolved to obtain the agarose-epoxy resin composite gelling agent. Step 7: Mix 65 parts of microwave dielectric ceramic slurry with 10.5 parts of agarose-epoxy resin composite gelling agent according to the mass ratio, place the mixture on a magnetic stirrer and heat and stir it. The heating temperature is 88℃, the magnetic stirring speed is 400r / min, and the stirring time is 15min to obtain microwave dielectric ceramic slurry for gel casting. Step 8: After degassing the microwave dielectric ceramic slurry used for gel casting under vacuum at -10Kpa, inject it into the silicone mold of the microwave dielectric ceramic filter. Step 9: Place the microwave dielectric ceramic filter mold with injected ceramic slurry in a constant temperature and humidity chamber at 25°C and 60% humidity for cooling and drying for 12 hours, then demold to obtain the green blank. Step 10: Place the demolded blank in a sintering furnace for debinding and sintering. The heating rate during the debinding stage is 1℃ / min, from room temperature to 560℃, and hold for 1 hour. The heating rate during the sintering stage is 2℃ / min, the sintering temperature is 1350℃, and hold for 3.5 hours. After vacuum sintering, cool with the furnace and polish to obtain a microwave dielectric filter based on the agarose-epoxy resin composite system.

[0022] Example 2: A method for fabricating a microwave dielectric filter based on an agarose-epoxy resin composite system, specifically including the following steps: Step 1: Weigh out 85 parts deionized water, 5 parts dispersant, 5 parts alkaline pH adjuster, and 3.35 parts surface modifier polyethylene glycol according to the mass ratio. That is, weigh out 12.92g of deionized water, 0.76g of ammonium polyacrylate, 0.76g of alkaline pH adjuster, and 0.76g of polyethylene glycol, for a total of 15.2g, and premix them to form a premixed solution with a pH of 9-11. Step 2: Place the premixed liquid material into a ball mill jar and ball mill for 2 minutes at a speed of 500 r / min until fully mixed to obtain the prepared premixed liquid for slurry preparation. Step 3: Add microwave dielectric ceramic powder to the premixed liquid in 4 batches to obtain slurry. The first batch contains 4 parts, the second batch contains 2 parts, the third batch contains 2 parts, and the fourth batch contains 2 parts. That is, after adding 26g (40wt.%) microwave dielectric ceramic powder for the first time, 13g (20wt.%) microwave dielectric ceramic powder is added after an interval of 1.8h, 13g (20wt.%) microwave dielectric ceramic powder is added after an interval of 1.8h, and 13g (20wt.%) microwave dielectric ceramic powder is added after an interval of 1.8h, for a total of 65g microwave dielectric ceramic powder is added. Step 4: Place the slurry on a ball mill and ball mill at a speed of 400 r / min for 9 hours. After passing through a 200-mesh sieve, prepare the microwave dielectric ceramic slurry. Step 5: Weigh 91.4 parts of deionized water, 3.8 parts of agarose powder, and 4.8 parts of epoxy resin according to the mass ratio, that is, weigh 9.6g of deionized water, 0.4g of agarose powder, and 0.4g of epoxy resin, for a total of 10.4g, and premix them into a gelling agent. Step 6: Heat the gelling agent at 90°C on a magnetic stirrer at a speed of 150 r / min for 5 min until the material is fully dissolved to obtain the agarose-epoxy resin composite gelling agent. Step 7: Mix 65 parts of microwave dielectric ceramic slurry with 10.4 parts of agarose-epoxy resin composite gelling agent according to the mass ratio, place the mixture on a magnetic stirrer and heat and stir it. The heating temperature is 90℃, the magnetic stirring speed is 300r / min, and the stirring time is 10min to obtain microwave dielectric ceramic slurry for gel casting. Step 8: After degassing the microwave dielectric ceramic slurry used for gel casting under vacuum at -15Kpa, inject it into the silicone mold of the microwave dielectric ceramic filter. Step 9: Place the microwave dielectric ceramic filter mold with injected ceramic slurry in a constant temperature and humidity chamber at 30°C and 65% humidity for cooling and drying for 10 hours, then demold to obtain the green blank. Step 10: Place the demolded blank in a sintering furnace for debinding and sintering. The heating rate during the debinding stage is 1℃ / min, from room temperature to 560℃, and hold for 1.5h. The heating rate during the sintering stage is 2℃ / min, the sintering temperature is 1300℃, and hold for 3h. After vacuum sintering, cool with the furnace and polish to obtain a microwave dielectric filter based on the agarose-epoxy resin composite system.

[0023] Example 3: A method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system, specifically including the following steps: Step 1: Weigh out 88 parts of deionized water, 4 parts of dispersant, 4 parts of alkaline pH adjuster, and 4 parts of surface modifier polyethylene glycol according to the mass ratio. That is, weigh out 13.4g of deionized water, 0.6g of ammonium polyacrylate, 0.6g of alkaline pH adjuster, and 0.6g of polyethylene glycol, for a total of 15.2g, and premix them to form a premixed solution with a pH of 9-11. Step 2: Place the premixed liquid material into a ball mill jar and ball mill for 5 minutes at a speed of 500 r / min until fully mixed to obtain the prepared premixed liquid for slurry preparation. Step 3: Add microwave dielectric ceramic powder to the premixed liquid in 4 batches to obtain a slurry. The first batch is 3.5 parts, the second batch is 2.5 parts, the third batch is 2.5 parts, and the fourth batch is 1.5 parts. That is, after adding 22.75g (35wt.%) of microwave dielectric ceramic powder for the first time, 16.25g (25wt.%) of microwave dielectric ceramic powder is added after an interval of 2.2 hours, 16.25g (25wt.%) of microwave dielectric ceramic powder is added after an interval of 2.2 hours, and 9.75g (15wt.%) of microwave dielectric ceramic powder is added after an interval of 2.2 hours, for a total of 65g of microwave dielectric ceramic powder. Step 4: Place the slurry on a ball mill and ball mill at a speed of 600 r / min for 10 h. After passing through a 50 mesh screen, prepare the microwave dielectric ceramic slurry. Step 5: Weigh 93.4 parts of deionized water, 1.8 parts of agarose powder, and 4.8 parts of epoxy resin according to the mass ratio, that is, weigh 9.8g of deionized water, 0.2g of agarose powder, and 0.5g of epoxy resin, for a total of 10.5g, and premix them into a gelling agent material. Step 6: Heat and mix the gelling agent material at 80°C on a magnetic stirrer. The magnetic stirring speed is 125 r / min and the stirring time is 10 min, until the material is fully dissolved to obtain the agarose-epoxy resin composite gelling agent. Step 7: Mix 65 parts of microwave dielectric ceramic slurry with 10.5 parts of agarose-epoxy resin composite gelling agent according to the mass ratio, place the mixture on a magnetic stirrer and heat and stir it. The heating temperature is 80℃, the magnetic stirring speed is 500r / min, and the stirring time is 30min to obtain microwave dielectric ceramic slurry for gel casting. Step 8: After degassing the microwave dielectric ceramic slurry used for gel casting under -20Kpa vacuum, inject it into the silicone mold of the microwave dielectric ceramic filter; Step 9: Place the microwave dielectric ceramic filter mold with injected ceramic slurry in a constant temperature and humidity chamber at 40°C and 70% humidity for cooling and drying for 15 hours, then demold to obtain the green blank. Step 10: Place the demolded blank in a sintering furnace for debinding and sintering. The heating rate during the debinding stage is 1℃ / min, from room temperature to 560℃, and hold for 1 hour. The heating rate during the sintering stage is 2℃ / min, the sintering temperature is 1400℃, and hold for 4 hours. After vacuum sintering, cool with the furnace and polish to obtain a microwave dielectric filter based on the agarose-epoxy resin composite system.

[0024] The embodiments selected in the above materials are for ease of understanding and not for limiting the process method. Those skilled in the art can easily modify the process flow or transfer it to other cases without inventive change. If these modifications also fall under the category of similar claims or similar technology of this invention, then the intent of this invention also includes these modifications.

Claims

1. A method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system, characterized in that, Specifically, the following steps are included: Step 1: Weigh the premixed liquid materials: Weigh 85-90 parts of deionized water, 2-5 parts of dispersant, 2-5 parts of pH adjuster, and 2-5 parts of surface modifier according to the mass ratio. Step 2: Place the premixed liquid material into a ball mill jar and ball mill at a speed of 400~600 r / min for 2~5 min until fully mixed to obtain the prepared premixed liquid for slurry preparation. Step 3: Add 9-11 parts of microwave dielectric ceramic powder to the premixed liquid in 4 batches to obtain a slurry; Step 4: Place the slurry on a ball mill and ball mill it. After passing it through a screen, prepare a microwave dielectric ceramic slurry. Step 5: Weigh the gelling agent materials: Weigh 90-95 parts of deionized water, 1-4 parts of agarose powder, and 2-5 parts of epoxy resin according to the mass ratio. Step 6: Heat and mix the gelling agent material on a magnetic stirrer until the material is fully dissolved to obtain an agarose-epoxy resin composite gelling agent; Step 7: Mix 65 parts of microwave dielectric ceramic slurry with 10.4-10.5 parts of agarose-epoxy resin composite gelling agent according to the mass ratio, place the mixture on a magnetic stirrer and heat and stir to obtain microwave dielectric ceramic slurry for gel casting. Step 8: After vacuum degassing the microwave dielectric ceramic slurry used for gel casting, inject it into the microwave dielectric ceramic filter mold; Step 9: Place the microwave dielectric ceramic filter mold containing the injected ceramic slurry in a constant temperature and humidity chamber for cooling and drying. After drying, remove the mold to obtain the green blank. Step 10: Place the demolded blank in a sintering furnace for debinding and sintering. After vacuum sintering, polish and grind to obtain a microwave dielectric filter based on an agarose-epoxy resin composite system.

2. The method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system according to claim 1, characterized in that, In the first step, the dispersant is one or more of polyacrylic acid, ammonium polyacrylate, and ammonium citrate; the pH adjuster is an alkaline adjuster; the surface modifier is polyethylene glycol; and the pH adjuster adjusts the premixed liquid material to a pH of 9-11.

3. The method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system according to claim 1, characterized in that, In the third step, the microwave dielectric ceramic powder is added to the premixed liquid in four batches: 3.5 to 4 parts for the first batch, 2 to 2.5 parts for the second batch, 2 to 2.5 parts for the third batch, and 1.5 to 2 parts for the fourth batch, with an interval of 1.8 to 2.3 hours.

4. The method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system according to claim 1, characterized in that, In the fourth step, the ball milling speed is 300~800 r / min, the ball milling time is 8~10 h, and the screen is 50~200 mesh.

5. The method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system according to claim 1, characterized in that, In the sixth step, the heating temperature is 80~90℃, the magnetic stirring speed is 100~150r / min, and the stirring time is 5~10min.

6. The method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system according to claim 1, characterized in that, In the seventh step, the heating temperature is 80~90℃, the magnetic stirring speed is 300~500r / min, and the stirring time is 10~30min.

7. The method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system according to claim 1, characterized in that, In the eighth step, the microwave dielectric ceramic filter mold material is one or more of silicone, resin, and soft rubber; the vacuum degree in the vacuum degassing process is -10Kpa to -20Kpa.

8. The method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system according to claim 1, characterized in that, In the ninth step, the temperature of the constant temperature and humidity chamber is 20℃~40℃, the humidity is 60%~70%, and the drying time is 10~15h.

9. The method for preparing a microwave dielectric filter based on an agarose-epoxy resin composite system according to claim 1, characterized in that, In the tenth step, the heating rate during the glue removal stage is 1℃ / min, the heating rate during the sintering stage is 2℃ / min, and the sintering temperature is 1300℃~1400℃.

10. A microwave dielectric filter based on an agarose-epoxy resin composite system prepared by the preparation method according to any one of claims 1-9.

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