High-performance microwave dielectric ceramic and cold-sintering preparation method thereof

Abstract

The application relates to the field of high-performance ceramic technology, in particular to a high-performance microwave dielectric ceramic and a cold-sintering preparation method thereof, which comprises the following steps: firstly, (Ca 0.65 Bi 0.35 )(Ti 0.65 Zr 0.35 )O3-5wt.% Li2TiO3 ceramic powder is prepared through solid-phase reaction; 0.5wt.%-3wt.% PTFE is introduced into the ceramic powder; and the ceramic powder is prepared through a cold-sintering method. The cold-sintering method greatly reduces the sintering temperature of the microwave dielectric ceramic, saves energy and reduces cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high-performance ceramic technology, and in particular to a high-performance microwave dielectric ceramic and a cold sintering preparation method thereof. BACKGROUND

[0002] High integration is the development direction of 5G base stations. Ceramic dielectric filters have the advantages of high dielectric constant, low loss, miniaturization, high reliability, etc., and have become the optimal choice for 5G base station filters. The current domestic production capacity of 5G base station ceramic filters is less than 100 million / year, and the gap in the next three years is as high as 800 million. The key technical problems restricting the improvement of domestic high-quality ceramic filter production capacity are the two key technologies of mass production of high-performance filter ceramic powder and large-scale production of high-quality ceramic filters.

[0003] Currently, high-performance filter ceramic powder faces many problems, which seriously affects the stationing speed of 5G base stations. Among many problems, the high sintering temperature of filter ceramic increases the production cost of 5G ceramic filter performance. SUMMARY

[0004] The purpose of the present application is to provide a high-performance microwave dielectric ceramic and a cold sintering preparation method thereof, which solves the technical problem of high sintering temperature of filter ceramic in the prior art, which increases the production cost of 5G ceramic filter performance.

[0005] The present application discloses a cold sintering preparation method of high-performance microwave dielectric ceramic, comprising the following steps:

[0006] Comprising the following steps:

[0007] First, prepare (Ca 0.65 Bi 0.35 )(Ti 0.65 Zr 0.35 )O3-5wt.%Li2TiO3 ceramic powder by solid phase reaction, introduce 0.5wt.%-3wt.%PTFE to the ceramic powder, and prepare by cold sintering method.

[0008] Further, specifically comprising the following steps:

[0009] S1. Dry, ball mill, spray granulation and calcine the raw materials CaCO3, TiO2, Bi2O3 and ZrO2 in sequence to obtain (Ca 0.65 Bi 0.35 )(Ti 0.65 Zr 0.35 )O3;

[0010] S2. Dry, ball mill, spray granulation and calcine the raw materials TiO2 and Li2CO3 in sequence to obtain Li2TiO3;

[0011] S3. The obtained (Ca 0.65 Bi 0.35 )(Ti 0.65 Zr 0.35 )O3 and Li2TiO3 are ball-milled and spray granulated to obtain (Ca 0.65 Bi 0.35 )(Ti 0.65 Zr 0.35 )O3-5wt.% Li2TiO3;

[0012] S4. The obtained (Ca 0.65 Bi 0.35 )(Ti 0.65 Zr 0.35 )O3-5wt.% Li2TiO3 ceramic powder and PTFE powder are ball-milled and spray granulated;

[0013] S5. The powder obtained in step S4 is ground, and the ground powder is sieved and then hot-pressed to obtain the target composite material.

[0014] Further, the addition amount of the PTFE is 0.5wt.%-3wt.%.

[0015] Further, the ball-milling is carried out by a horizontal ball mill in anhydrous ethanol medium for 24-36h.

[0016] Further, the spray granulation temperature is 200℃.

[0017] Further, the calcination temperature is 650℃ and the holding time is 4h.

[0018] Further, the grinding is carried out by adding 7wt.% deionized water for 5min.

[0019] Further, the sieving is carried out by passing through an 80-mesh sieve.

[0020] Further, the hot-pressing is carried out at a temperature of 150℃ and a pressure of 300MPa, and the holding time is 1h.

[0021] Further, the drying is carried out at 120℃ for 12h.

[0022] A high-performance microwave dielectric ceramic, which has a chemical formula of (Ca 0.65 Bi 0.35 )(Ti 0.65 Zr 0.35 )O3-5wt.% Li2TiO3.

[0023] Compared with the prior art, the present application has the beneficial effects that:

[0024] 1. The cold sintering method greatly reduces the sintering temperature of microwave dielectric ceramics, saving energy and reducing cost. DETAILED DESCRIPTION

[0025] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application.

[0026] Example 1

[0027] A high-performance microwave dielectric ceramic and a cold sintering preparation method thereof are disclosed in the present embodiment, including the following steps:

[0028] 1) Dry the raw materials CaCO3, TiO2, Bi2O3, and ZrO2, then weigh 65.06g of CaCO3, 51.92g of TiO2, 302.87g of Bi2O3, and 43.13g of ZrO2, ball mill for 24-36h through a horizontal ball mill with anhydrous ethanol as the medium, then granulate at 200°C using a spray granulator; calcine the granulated powder at 650°C for 4h to obtain (Ca 0.65 Bi 0.35 )(Ti 0.65 Zr 0.35 )O3;

[0029] (2) Dry the raw materials TiO2 and Li2CO3, weigh 79.87g of TiO2 and 73.89g of Li2CO3, then ball mill for 24-36h through a horizontal ball mill with anhydrous ethanol as the medium, then granulate at 200°C using a spray granulator; calcine the granulated powder at 650°C for 4h to obtain Li2TiO3;

[0030] (3) Weigh 400g of (Ca 0.65 Bi 0.35 )(Ti 0.65 Zr 0.35 )O3 and 20g of Li2TiO3, ball mill for 24-36h through a horizontal ball mill with anhydrous ethanol as the medium, then granulate at 200°C using a spray granulator to obtain (Ca 0.65 Bi 0.35 )(Ti 0.65 Zr 0.35 )O3-5wt.%Li2TiO3;

[0031] (4) Weigh 400g of (Ca 0.65 Bi 0.35 )(Ti 0.65 Zr 0.35)O3-5wt.%Li2TiO3 ceramic powder and 2g PTFE powder are weighed in stoichiometric ratio, ball milled in horizontal ball mill for 24-36h with ethanol as medium, and then granulated at 200℃ by spray granulator.

[0032] (5) A proper amount of powder is weighed and put into a maragda mortar, 7wt.% deionized water is added and grinded for 5min, the grinded powder is put into a hot-pressing mold after being sifted through an 80-mesh sieve, and shaped at a temperature of 150℃ and a pressure of 300MPa, and kept for 1h, and then dried at 120℃ for 12h to obtain the target composite material.

[0033] Example 2

[0034] In this embodiment as a preferred embodiment of the present application, a high-performance microwave dielectric ceramic and a cold-sintering preparation method thereof, the change is only that the addition amount of PTFE in step 2 is 4g based on Example 1.

[0035] Example 3

[0036] In this embodiment as a preferred embodiment of the present application, a high-performance microwave dielectric ceramic and a cold-sintering preparation method thereof, the change is only that the addition amount of PTFE in step 2 is 6g based on Example 1.

[0037] Example 4

[0038] In this embodiment as a preferred embodiment of the present application, a high-performance microwave dielectric ceramic and a cold-sintering preparation method thereof, the change is only that the addition amount of PTFE in step 2 is 8g based on Example 1.

[0039] Comparative Example 1

[0040] In this embodiment as a comparative example of the present application, a high-performance microwave dielectric ceramic and a cold-sintering preparation method thereof, the change is only that the addition amount of PTFE in step 2 is 16g based on Example 1.

[0041] Comparative Example 2

[0042] In this embodiment as a comparative example of the present application, a high-performance microwave dielectric ceramic and a cold-sintering preparation method thereof, the change is only that the addition amount of PTFE in step 2 is 20g based on Example 1.

[0043] The ceramic powders in Examples 1-4 and Comparative Examples 1-2 are subjected to mechanical property tests, and the results are shown in Table 1. Wherein Q?f is the product of resonance quality factor and frequency, τ f is the resonance frequency temperature coefficient.

[0044] Table 1 Test results of dielectric properties of ceramic samples of the present application

[0045]

[0046]

[0047] As can be seen from Table 1, the quality factor Qf of Examples 1-4 of the present application is greater than 23000 GHz, indicating that high quality factor of microwave dielectric ceramic can be achieved under low-temperature sintering. In Comparative Examples 1 and 2, the dielectric constant and quality factor are both decreased due to too much PTFE added.

[0048] The above are the embodiments listed in the present embodiment, but the present embodiment is not limited to the above optional embodiments, and those skilled in the art can obtain other various embodiments by arbitrarily combining the above modes with each other. The above specific embodiments should not be understood as limiting the protection scope of the present embodiment, and the protection scope of the present embodiment should be defined by the claims, and the specification can be used to explain the claims.

Claims

1. A method for preparing high-performance microwave dielectric ceramics by cold sintering, characterized in that: Includes the following steps: First, ceramic powder is prepared via solid-state reaction. Then, 0.5 wt.%–3 wt.% PTFE is introduced into the ceramic powder, followed by cold sintering. The process specifically includes the following steps: S1. The raw materials CaCO3, TiO2, Bi2O3, and ZrO2 are sequentially dried, ball-milled, spray-granulated, and calcined to obtain (CaCO3, TiO2, Bi2O3, and ZrO2). 0.65 Bi 0.35 (Ti) 0.65 Zr 0.35 O3; S2. Li2TiO3 is obtained by sequentially drying, ball milling, spray granulation and calcining the raw materials TiO2 and Li2CO3. S3. Obtain (Ca) 0.65 Bi 0.35 (Ti) 0.65 Zr 0.35 (Ca)O3 and Li2TiO3 were ball-milled and spray-granulated to obtain (Ca)O3. 0.65 Bi 0.35 (Ti) 0.65 Zr 0.35 )O3-5wt.%Li2TiO3; S4. The obtained (Ca) 0.65 Bi 0.35 (Ti) 0.65 Zr 0.35 )5wt.% Li2TiO3 ceramic powder and PTFE powder were ball-milled and then spray-granulated; S5. Grind the powder obtained in step S4, sieve the ground powder, hot press it into shape, and dry it to obtain the target composite material. The grinding process involved adding 7 wt.% deionized water and grinding for 5 minutes. The hot pressing is performed at a temperature of 150°C and a pressure of 300 MPa, and then held at that temperature for 1 hour.

2. The method for preparing high-performance microwave dielectric ceramics by cold sintering according to claim 1, characterized in that: The amount of PTFE added is 0.5 wt.% to 3 wt.%.

3. The method for preparing high-performance microwave dielectric ceramics by cold sintering according to claim 1, characterized in that: The ball milling time is 24-36 hours.

4. The method for preparing high-performance microwave dielectric ceramics by cold sintering according to claim 1, characterized in that: The spray granulation temperature is 200℃.

5. The method for preparing high-performance microwave dielectric ceramics by cold sintering according to claim 1, characterized in that: The sieving process is an 80-mesh sieve.

6. The method for preparing high-performance microwave dielectric ceramics by cold sintering according to claim 1, characterized in that: The drying process involves drying at 120°C for 12 hours.

7. The high-performance microwave dielectric ceramic according to claim 1, characterized in that: The ceramic powder has the chemical formula (Ca). 0.65 Bi 0.35 (Ti) 0.65 Zr 0.35 )O3-5wt.%Li2TiO3.

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