High flexural strength ceramic powder and method of making same

Abstract

The application relates to the technical field of high-performance ceramic powder, in particular to high-bending-strength ceramic powder and a preparation method thereof, which comprises the following steps: S1. ball milling of ceramic material raw materials; S2. drying of the raw materials after the ball milling in step S1, then crushing and sieving; 3. pre-sintering of the powder after the sieving in step S2; S4. secondary ball milling of the powder after the pre-sintering and doping; S5. drying of the powder after the ball milling in step S4, then crushing and sieving; S6. grinding and granulating of the powder after the sieving in step S5, then compression molding, sintering and finally obtaining microwave dielectric ceramic.The high-bending-strength ceramic powder can reach a bending strength of 885 MPa, and a fracture toughness of 8.56 MPa.m 1 / 2 .

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-performance ceramic powder, and particularly relates to a high-bending-strength ceramic powder and a preparation method thereof. BACKGROUND

[0002] With the gradual implementation of 5G communication technology, the signal transmission frequency is higher, the speed is faster, and the data density is higher, so that the current 3G / 4G base station cannot meet the requirements, and therefore a 5G base station needs to be built. Since the density of the 5G base station is larger, the number is more, and therefore the base station must be miniaturized and integrated. Correspondingly, as one of the devices used in large quantities in the base station, the use amount of the filter is sharply increased. That is, the filter must also be miniaturized. The solution is to replace the original metal cavity filter with a dielectric ceramic filter, which is referred to as a 5G ceramic filter. According to the principle of electromagnetism, the size of the resonator is inversely proportional to the square root of the dielectric constant of the dielectric material. Therefore, for a filter of a given frequency, the larger the dielectric constant of the dielectric material, the smaller the volume of the dielectric ceramic required, that is, the smaller the size of the filter. Therefore, the high dielectric constant of the microwave dielectric ceramic material enables the miniaturization and integration of the microwave dielectric filter.

[0003] At present, the 5G ceramic filter faces many problems, which seriously affects the station building speed of the 5G base station. Among the many problems, the microwave dielectric ceramic material cannot have microwave dielectric properties while having high bending strength, which affects the development of the microwave dielectric ceramic material. SUMMARY

[0004] The present application aims to provide a high-bending-strength ceramic powder and a preparation method thereof, and solve the technical problem that the microwave dielectric ceramic material in the prior art cannot have microwave dielectric properties while having high bending strength.

[0005] The present application discloses a high-bending-strength ceramic powder preparation method, which comprises the following steps:

[0006] S1. Ball milling of ceramic material raw materials;

[0007] S2. Drying the raw materials after ball milling in step S1, and then crushing and sieving;

[0008] S3. Pre-sintering of the sieved powder in step S2;

[0009] S4. Secondary ball milling of the doped pre-sintered powder;

[0010] S5. Drying the ball-milled powder in step S4, and then crushing and sieving;

[0011] S6. Grinding and granulating the sieved powder in step S5, and then pressing and forming, and sintering to obtain a microwave dielectric ceramic.

[0012] Further, the ceramic material raw material is (MgCO3)4·Mg(OH)2·5H2O, TiO2 and CaCO3.

[0013] Further, the doping is ZnO, SrO and Al2O3.

[0014] Further, the content of Al2O3 is 0.5wt% to 2.0%, preferably 1.0wt%.

[0015] Further, the ball milling medium is zirconia ball and the solvent is ionized water.

[0016] Further, the ball milling time in step S1 is 8-24h, preferably 12h.

[0017] Further, the rotation speed of the ball mill is 400r / min.

[0018] Further, the sieved powder in step S3 is MgTiO3 and CaTiO3 and is pre-fired at 1000℃ for 2h.

[0019] Further, the pre-firing heating rate in step S3 is 5℃ / min.

[0020] Further, the drying temperature is 100℃.

[0021] Further, the sieving is 100 mesh.

[0022] Further, the forming pressure in step S6 is 100MPa.

[0023] Further, in step S6, 8wt% of the powder is added with 5wt% PVA solution and then ground and granulated.

[0024] Further, the sintering temperature in step S6 is 1225℃-1275℃, preferably 1250℃.

[0025] Further, the sintering schedule in step S6 is 3℃ / min to 200℃ for 1h, 3℃ / min to 500℃ for 2h, and 2℃ / min to the target temperature for 4h.

[0026] A high flexural strength ceramic powder, the ceramic powder comprising a ceramic material raw material and necessary doping, the ceramic material raw material being Mg 0.95 Ca 0.05 TiO3, the doping being 0.5wt% ZnO, 0.5wt% SrO and 0.5wt% to 2.0% Al2O3.

[0027] As a preference, the optimal content of Al2O3 is 1.0wt%.

[0028] Compared with the prior art, the present application has the beneficial effects that:

[0029] 1. The present application introduces ZnO, SrO and Al2O3 to form a second phase in the matrix, thereby reducing residual stress and improving bending strength, which can reach 885MPa, while the fracture toughness is 8.56MPa·m 1 / 2 . DETAILED DESCRIPTION

[0030] 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.

[0031] Example 1

[0032] A high-bending-strength ceramic powder and a preparation method thereof are disclosed in the present embodiment, which comprises the following steps:

[0033] Step 1: 165.92g (MgCO3)4·Mg(OH)2·5H2O, 79.87g TiO2 and 100.09g CaCO3, 79.87g TiO2 mixed powder were weighed and put into polyurethane ball milling tanks respectively, 200g deionized water and 200 zirconia balls were added, and ball milling was carried out on a planetary ball mill for 12h at a speed of 400r / min.

[0034] Step 2: The ball-milled raw materials were dried in a drying box at 100℃, and then crushed through a 100-mesh sieve; the sieved powder was put into a sintering furnace, and MgTiO3 and CaTiO3 were pre-sintered at a temperature increasing rate of 5℃ / min to 1000℃, and then kept for 2h.

[0035] Step 3: 114.12g MgTiO3, 6.78g CaTiO3, 0.6g ZnO, 0.6g SrO and 1.2g Al2O3 were weighed and put into polyurethane ball milling tanks, 180g deionized water and 180g zirconia balls were added, and ball milling was carried out on a planetary ball mill for 6h at a speed of 400r / min.

[0036] Step 4: The ball-milled powder was dried in a drying box at 100℃, and then crushed through a 100-mesh sieve; the sieved powder was put into a mortar, 8wt% of PVA solution with a concentration of 5wt% was added, and grinding and granulation were carried out, and then a tablet press was used to press the green body into 45mm*5mm*4mm at a pressure of 100MPa.

[0037] Step 5: the press-formed green body is put into a sintering furnace, heated to 200℃ at a heating rate of 3℃ / min for 1h, heated to 500℃ at a heating rate of 3℃ / min for 2h, and heated to 1250℃ at a heating rate of 2℃ / min for 4h, to obtain the microwave dielectric ceramic.

[0038] Example 2

[0039] In the present embodiment as a preferred embodiment of the present application, a high-performance ceramic powder and a preparation method thereof are disclosed, and the only change on the basis of Example 1 is that the addition amount of Al2O3 in step 3 is changed to 0.6g.

[0040] Example 3

[0041] In the present embodiment as a preferred embodiment of the present application, a high-performance ceramic powder and a preparation method thereof are disclosed, and the only change on the basis of Example 1 is that the addition amount of Al2O3 in step 3 is changed to 1.8g.

[0042] Example 4

[0043] In the present embodiment as a preferred embodiment of the present application, a high-performance ceramic powder and a preparation method thereof are disclosed, and the only change on the basis of Example 1 is that the addition amount of Al2O3 in step 3 is changed to 2.4g.

[0044] Comparative Example 1

[0045] In the present embodiment as a comparative example of the present application, a high-performance ceramic powder and a preparation method thereof are disclosed, and the only change on the basis of Example 1 is that the addition amount of Al2O3 in step 3 is changed to 0.24g.

[0046] Comparative Example 2

[0047] In the present embodiment as a comparative example of the present application, a high-performance ceramic powder and a preparation method thereof are disclosed, and the only change on the basis of Example 1 is that the addition amount of Al2O3 in step 3 is changed to 3.0g.

[0048] The microwave dielectric ceramics in Examples 1-4 and Comparative Examples 1-2 are subjected to mechanical property testing according to GB / T23806-2009, and dielectric property testing according to GB / T29306.1-2012 and GB / T 29306.2-2012, and the results are shown in Table 1.

[0049] Table 1: Key parameters and mechanical property testing results of the present application

[0050]

[0051] As can be seen from Table 1, the high-bending-strength ceramic powder of the present application can have a bending strength of 885 MPa, and a fracture toughness of 8.56 MPa·m 1 / 2 However, when the content of Al2O3 is too high or too low, the bending strength cannot reach a high level.

[0052] 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 a high flexural strength ceramic powder, characterized by: The method comprises the following steps: S1. Ball milling ceramic material raw materials, which are (MgCO3)4·Mg(OH)2·5H2O, TiO2 and CaCO3; S2. Drying and crushing the raw materials after ball milling in step S1; S3. Pre-sinter the sieved powder of step S2 to obtain powder Mg 0.95 Ca 0.05 TiO3; S4. The pre-fired powder Mg 0.95 Ca 0.05 TiO3, doped with 0.5 wt% ZnO, 0.5 wt% SrO and 0.5 wt% to 2.0% Al2O3, followed by secondary ball milling. S5. Drying and crushing the powder after ball milling in step S4; S6. Grinding and granulating the powder after screening in step S5, then pressing and sintering to obtain microwave dielectric ceramic, wherein the sintering temperature is 1225-1275℃.

2. The method of claim 1, wherein the ceramic powder has a high bending strength. The content of Al2O3 is 1.0wt%.

3. The method of claim 1, wherein the ceramic powder has a high bending strength. The ball milling medium is zirconia ball, and the solvent is deionized water.

4. The method of claim 1, wherein the ceramic powder has a high bending strength. The powder after screening in step S3 is pre-sintered at 1000℃ and kept for 2h.

5. The method of claim 4, wherein the ceramic powder has a high bending strength. The pre-sintering heating rate in step S3 is 5℃ / min.

6. The method of claim 1, wherein the ceramic powder has a high bending strength. In step S6, 8wt% of PVA solution with a concentration of 5wt% is added to the powder, and then the powder is ground and granulated.

7. A high flexural strength ceramic powder, characterized by: The method is used to prepare a high-bending-strength ceramic powder.

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