Method for liquid phase sintering of ceramic powder

Abstract

The application relates to the field of high-performance ceramic technology, and particularly relates to a method for liquid-phase sintering of ceramic powder, which comprises the following steps: step one: MgO, TiO2 and CaO are ball milled, dried, crushed, sieved, and then pre-sintered to obtain pre-sintered powder; step two: sintering aids are added into the pre-sintered powder, and the pre-sintered powder is ball milled again, dried, crushed and sieved; step three: the sieved powder is ground, granulated and then pressed into shape; and step four: the green body obtained by pressing into shape is sintered to obtain microwave dielectric ceramic.

Description

Technical Field

[0001] This invention relates to the field of high-performance ceramics technology, and more specifically to a method for liquid-phase sintering of ceramic powder. Background Technology

[0002] High integration is the development direction of 5G base stations. Ceramic dielectric filters have advantages such as high dielectric constant, low loss, miniaturization, and high reliability, making them the optimal choice for filters used in 5G base stations. Currently, the domestic production capacity of ceramic filters for 5G base stations is less than 100 million units per year, with a shortage of up to 800 million units in the next three years. The key technical issues restricting the improvement of domestic high-quality ceramic filter production capacity are: the large-scale preparation of high-performance filter ceramic powder and the large-scale preparation of high-quality ceramic filters, both of which need to be solved.

[0003] Currently, high-performance filter ceramic powders face numerous challenges, severely impacting the deployment speed of 5G base stations. Among these challenges, poor sintering and low density of the filter ceramics limit the improvement of 5G ceramic filter performance. Summary of the Invention

[0004] The purpose of this invention is to provide a method for liquid-phase sintering of ceramic powder, which solves the technical problems of poor sintering effect and low density of filter ceramics in the prior art.

[0005] This invention discloses a method for liquid-phase sintering of ceramic powder, comprising the following steps:

[0006] Step 1: Ball mill MgO, TiO2 and CaO, dry them, pulverize them, sieve them, and then pre-calcine them to obtain pre-calcine powder;

[0007] Step 2: After adding sintering aid to the pre-calcined powder, it is ball-milled again, then dried, pulverized, and sieved.

[0008] Step 3: Grind the sieved powder into granules and then press it into shape;

[0009] Step 4: After pressing and sintering the green body, microwave dielectric ceramic is obtained.

[0010] Furthermore, the sintering aids are B2O3 and V2O5.

[0011] Furthermore, the sintering aid is 1wt%-2wt% B2O3 and 2wt%-3wt% V2O5.

[0012] Furthermore, the mass ratio of the pre-calcined powder to the sintering aid is 50:1-3.

[0013] Furthermore, the preheating rate in step one is 5°C / min.

[0014] Furthermore, the ball mill rotation speed is 400 r / min.

[0015] Furthermore, the ball milling time is 4-8 hours.

[0016] Furthermore, the ball mill uses a planetary ball mill.

[0017] Furthermore, the pressing pressure in step three is 100 MPa.

[0018] Furthermore, the sintering process described in step four is as follows: heating to 200℃ at 3℃ / min and holding for 1 hour, then heating to 500℃ at 3℃ / min and holding for 2 hours; then heating to the target temperature at 2℃ / min and holding for 4 hours.

[0019] Furthermore, the sintering target temperature mentioned in step four is 1000℃-1150℃.

[0020] Furthermore, the microwave dielectric ceramic is Mg. 0.95 Ca 0.05 TiO3.

[0021] Furthermore, the pulverization and sieving process involves pulverizing through a 100-mesh sieve.

[0022] Furthermore, the pre-firing temperature is 1000℃, and the temperature is maintained for 2 hours.

[0023] Furthermore, before grinding and granulation, a 5wt% PVA solution (8wt% by weight of the powder) is added for grinding and granulation.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. A sintering aid is added to the slurry of the present invention. During sintering, the boron oxide powder and vanadium oxide powder in the sintering aid can form a liquid phase inside the green body, realizing liquid phase sintering, promoting the mass transfer process and particle rearrangement inside the ceramic product, improving the sintering effect, and increasing the density of the microwave dielectric ceramic product. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0027] Example 1

[0028] This embodiment discloses a method for liquid-phase sintering of ceramic powder, including the following steps:

[0029] Step 1: According to the formula ratio, weigh 40.3g MgO, 79.9g TiO2 and 50.1g CaO, 79.87g TiO2 powder and put them into polyurethane ball mill jars respectively. Add 200g deionized water and 200 zirconia balls, and ball mill on a planetary ball mill for 12 hours at a speed of 400r / min.

[0030] Step 2: The ball-milled raw material is placed in a drying oven and dried at 100℃, then pulverized and passed through a 100-mesh sieve; the sieved powder is placed in a sintering furnace, and MgTiO3 and CaTiO3 are heated to 1000℃ at a heating rate of 5℃ / min for pre-firing and held for 2 hours.

[0031] Step 3: Weigh 114.2g MgTiO3, 6.5g CaTiO3, 1.2g B2O3, and 2.4g V2O5 into a polyurethane ball mill jar, add 180g deionized water and 180g zirconia balls, and ball mill on a planetary ball mill for 6 hours at a speed of 400r / min.

[0032] Step 4: The ball-milled powder is placed in a drying oven and dried at 100°C, then pulverized and passed through a 100-mesh sieve; the sieved powder is placed in a mortar, and 8 wt% of the powder mass of a 5 wt% PVA solution is added for grinding and granulation, and then pressed into a green compact using a tablet press at a pressure of 100 MPa.

[0033] Step 5: The pressed green body is placed in a sintering furnace and heated to 200℃ at a heating rate of 3℃ / min and held for 1 hour, then heated to 500℃ at a heating rate of 3℃ / min and held for 2 hours; then heated to 1100℃ at a heating rate of 2℃ / min and held for 4 hours to obtain microwave dielectric ceramic.

[0034] Example 2

[0035] In this embodiment, which is a preferred embodiment of the present invention, a method for liquid-phase sintering of microwave dielectric ceramics is modified from Embodiment 1 by changing the amount of B2O3 added in step 3 to 1.8g.

[0036] Example 3

[0037] In this embodiment, which is a preferred embodiment of the present invention, a method for liquid-phase sintering of microwave dielectric ceramics is modified from Embodiment 1 by changing the amount of B2O3 added in step 3 to 2.4g.

[0038] Example 4

[0039] In this embodiment, which is a preferred embodiment of the present invention, a method for liquid phase sintering of microwave dielectric ceramics is modified from Embodiment 1 by changing the amount of V2O5 added in step 3 to 3.0g.

[0040] Comparative Example 1

[0041] In this embodiment, as a comparative example of the present invention, a method for liquid-phase sintering of microwave dielectric ceramics is modified from Example 1 by changing the amount of B2O3 added in step 3 to 3.0g and the amount of V2O5 added to 4.8g.

[0042] Comparative Example 2

[0043] In this embodiment, as a comparative example of the present invention, a method for liquid-phase sintering of microwave dielectric ceramics is modified from Example 1 by changing the amount of B2O3 added in step 3 to 0.6g and the amount of V2O5 added to 0.6g.

[0044] The ceramic powders from Examples 1-4 and Comparative Examples 1-2 were subjected to dielectric property tests according to GB / T29306.1-2012 and GB / T 29306.2-2012, and the results are shown in Table 1. Where Q·f is the product of the resonant quality factor and the frequency, and τ... f The temperature coefficient of the resonant frequency.

[0045] Table 1. Test results of dielectric properties of ceramic samples in the embodiments of the present invention.

[0046]

[0047] As can be seen from Table 1, the quality factor Q·f ≥ 24700 GHz in Examples 1-4 of the present invention, while the quality factor in Comparative Examples 1 and 2 decreased significantly, indicating that too much or too little sintering aid will cause a decrease in density, thereby reducing the quality factor.

[0048] The above are the embodiments listed in this example. However, this example is not limited to the optional embodiments described above. Those skilled in the art can arbitrarily combine the above methods to obtain other various embodiments. Anyone can derive other various forms of embodiments based on the inspiration of this example. The above specific embodiments should not be construed as limiting the scope of protection of this example. The scope of protection of this example should be determined by the claims, and the specification can be used to interpret the claims.

Claims

1. A method for liquid-phase sintering of ceramic powder, characterized in that: Includes the following steps: Step 1: MgO, TiO2 and CaO are ball-milled, dried, pulverized and sieved, and then pre-calcined to obtain pre-calcined powder, wherein the pre-calcined powder is MgTiO3 and CaTiO3; Step 2: After adding sintering aid to the pre-calcined powder, it is ball-milled again, then dried, pulverized, and sieved. Step 3: Grind the sieved powder into granules and then press it into shape; Step 4: After sintering the pressed green body, microwave dielectric ceramic is obtained; The microwave dielectric ceramic is Mg. 0.95 Ca 0.05 TiO3; The sintering aid is 1 wt% - 2 wt% B2O3 and 2 wt% ~ 3 wt% V2O5.

2. The method for liquid-phase sintering of ceramic powder according to claim 1, characterized in that: The mass ratio of the pre-calcined powder to the sintering aid is 50:1-3.

3. The method for liquid-phase sintering of ceramic powder according to claim 1, characterized in that: The preheating rate in step one is 5°C / min.

4. The method for liquid-phase sintering of ceramic powder according to claim 1, characterized in that: The ball milling time is 4-8 hours.

5. The method for liquid-phase sintering of ceramic powder according to claim 1, characterized in that: The pressing pressure in step three is 100 MPa.

6. The method for liquid-phase sintering of ceramic powder according to claim 1, characterized in that: The sintering target temperature mentioned in step four is 1000℃-1150℃.

7. The method for liquid-phase sintering of ceramic powder according to claim 6, characterized in that: The sintering process described in step four is as follows: heat to 200℃ at 3℃ / min and hold for 1 hour, then heat to 500℃ at 3℃ / min and hold for 2 hours; then heat to the target temperature at 2℃ / min and hold for 4 hours.

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