Disclosure of Invention
Based on the defects in the prior art, the invention provides an aluminate microwave dielectric ceramic material with low dielectric constant and a preparation method thereof.
A preparation method of low dielectric constant aluminate microwave dielectric ceramic material comprises the following steps:
(1) preparing materials: raw material CaCO3And Al2O3According to the stoichiometric ratio of 1: 2, preparing materials;
(2) mixing materials: mixing the raw materials, ball milling beads and absolute ethyl alcohol according to the proportion of 1: 1: 2, placing the mixture in a ball mill for wet ball milling for 24 hours to obtain slurry raw materials;
(3) drying: putting the slurry raw material obtained in the step (2) into an oven to be dried to constant weight;
(4) pre-burning: sieving and dispersing the powder obtained in the step (3), and then placing the powder in a high-temperature furnace for presintering for 3 hours at the presintering temperature of 1050 and 1200 ℃ to generate CaAl4O7A compound;
(5) secondary ball milling: the CaAl generated in the step (4)4O7The compound is placed in a ball mill for ball milling to form CaAl4O7Sizing agent;
(6) secondary drying: the CaAl in the step (5)4O7Placing the slurry in an oven to dry to constant weight;
(7) and (3) granulation: sieving the powder obtained in the step (6), and then mixing the powder with an adhesive according to a ratio of 94: 6, uniformly mixing the components in percentage by mass;
(8) tabletting: pressing and molding the powder uniformly mixed in the step (7) to obtain a cylindrical green body;
(9) and (3) sintering: and (4) sintering the green body obtained in the step (8), and finally cooling to room temperature along with the furnace to obtain the aluminate microwave dielectric ceramic material with the low dielectric constant.
Preferably, the preparation method further comprises the following steps:
(10) and (3) post-processing: and (4) grinding and polishing the low-dielectric-constant aluminate microwave dielectric ceramic material sintered in the step (9) to make the surface flat and smooth.
Preferably, the pressure of the press molding in the step (8) is 100-200 MPa.
Preferably, the sintering process in the step (9) includes: heating to 650 ℃ at the speed of 5 ℃/min, keeping the temperature for 2h, then continuously heating to 1500-1600 ℃ at the speed of 5 ℃/min, keeping the temperature for 3h, and finally cooling to 1100 ℃ at the speed of 1 ℃/min.
Preferably, the raw material CaCO is added before the material preparation3And Al2O3Grinding is carried out for 24 h.
Preferably, the raw material CaCO3And Al2O3The purity of (A) was 99.99%.
Preferably, the ball mill is a planetary ball mill.
Preferably, the pre-firing temperature in the step (4) is 1200 ℃.
Preferably, the diameter of the cylindrical green body is 12mm, and the height of the cylindrical green body is 5 mm.
The invention also provides the low dielectric constant aluminate microwave dielectric ceramic material prepared by the preparation method of any scheme, and the dielectric constant epsilon is within the microwave frequency ranger6.6-8.7, and the quality factor Qf value is 14097-25533GHz, thus having great application value in the fields of millimeter wave communication and the like.
Compared with the prior art, the invention has the beneficial effects that:
the low dielectric constant aluminate microwave dielectric ceramic material prepared by the invention has the raw material price (CaCO)3And Al2O3) Low cost, simple preparation process and low production cost.
By designing different sintering temperatures, the microwave dielectric ceramic material with low dielectric constant (6.6-8.7) and better quality factor (25533GHz) can be stably obtained. The ceramic can be widely applied to components of wireless communication equipment such as microwave substrates and the like, and has great application value.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the following method and technical solutions are further described with reference to the accompanying drawings and specific embodiments, but should not be construed as limiting the present invention.
Example 1:
the preparation method of the low dielectric constant aluminate microwave dielectric ceramic material comprises the following steps:
(1) preparing materials: raw material CaCO3And Al2O3Proportioning according to the stoichiometric ratio in the chemical expression; specifically, 15.3995g of CaCO was weighed in order3And 31.3758gAl2O3The raw materials of (1); raw material CaCO3And Al2O3The purity of (A) is 99.99%;
(2) mixing materials: pouring the raw materials into a ball mill, wherein the raw materials, ball milling beads and absolute ethyl alcohol are mixed according to the proportion of 1: 1: 2, placing the mixture in a ball mill for wet ball milling for 24 hours to obtain slurry raw materials;
(3) drying: drying the slurry in a 70 ℃ oven to obtain a dry mixture;
(4) pre-burning: passing the dried powder through a 100-target standardDispersing by a sieve, then presintering for 3 hours in a high temperature furnace at the presintering temperature of 1200 ℃ to enable the powder to react primarily to generate CaAl4O7A compound;
(5) secondary ball milling: the CaAl synthesized by the preliminary reaction4O7Ball milling the compound in a ball mill for 24h to form finely dispersed CaAl4O7Sizing agent;
(6) secondary drying: drying the slurry in a 70 ℃ oven to obtain dry CaAl4O7A compound powder;
(7) and (3) granulation: taking CaAl4O7The powder was sieved through a 100 mesh sieve, after which the powder was mixed with a binder (polyvinyl alcohol PVA) according to a 94: 6, uniformly mixing the components in percentage by mass;
(8) tabletting: putting the powder obtained by granulation into a die, and pressing the powder into a cylindrical green body under the pressure of 200 MPa; the diameter of the cylindrical green body is 12mm, and the height of the cylindrical green body is 5 mm;
(9) and (3) sintering: heating the green body obtained in the step (8) to 650 ℃ at the speed of 5 ℃/min, preserving heat for 2h, then continuously heating to 1500 ℃ at the speed of 5 ℃/min, preserving heat for 3h, then cooling to 1100 ℃ at the speed of 1 ℃/min, and finally cooling to room temperature along with the furnace;
(10) and (3) post-processing: and (4) grinding and polishing the ceramic sintered in the step (9) to obtain a ceramic sample with a smooth surface.
FIG. 1 is an XRD diffraction pattern of the ceramic sample of this example, illustrating that the ceramic sample obtained is CaAl4O7. The XRD diffraction pattern of the low dielectric constant aluminate microwave dielectric ceramic material of the following example is the same as that of the present example.
Example 2:
the preparation method of the low dielectric constant aluminate microwave dielectric ceramic material comprises the following steps:
(1) preparing materials: raw material CaCO3And Al2O3Proportioning according to the stoichiometric ratio in the chemical expression; specifically, 15.3995g of CaCO was weighed in order3And 31.3758gAl2O3The raw materials of (1); raw material CaCO3And Al2O3The purity of (A) is 99.99%;
(2) mixing materials: pouring the raw materials into a ball mill, wherein the raw materials, ball milling beads and absolute ethyl alcohol are mixed according to the proportion of 1: 1: 2, placing the mixture in a ball mill for wet ball milling for 24 hours to obtain slurry raw materials;
(3) drying: drying the slurry in a 70 ℃ oven to obtain a dry mixture;
(4) pre-burning: dispersing the dried powder through a standard sieve of 100 meshes, then presintering the powder in a high-temperature furnace for 3 hours at the presintering temperature of 1200 ℃ to enable the powder to react initially to generate CaAl4O7A compound;
(5) secondary ball milling: the CaAl synthesized by the preliminary reaction4O7Ball milling the compound in a ball mill for 24h to form finely dispersed CaAl4O7Sizing agent;
(6) secondary drying: drying the slurry in a 70 ℃ oven to obtain dry CaAl4O7A compound powder;
(7) and (3) granulation: taking CaAl4O7The powder was sieved through a 100 mesh sieve, after which the powder was mixed with a binder (polyvinyl alcohol PVA) according to a 94: 6, uniformly mixing the components in percentage by mass;
(8) tabletting: putting the powder obtained by granulation into a die, and pressing the powder into a cylindrical green body under the pressure of 200 MPa; the diameter of the cylindrical green body is 12mm, and the height of the cylindrical green body is 5 mm;
(9) and (3) sintering: heating the green body obtained in the step (8) to 650 ℃ at the speed of 5 ℃/min, preserving heat for 2h, then continuously heating to 1525 ℃ at the speed of 5 ℃/min, preserving heat for 3h, then cooling to 1100 ℃ at the speed of 1 ℃/min, and finally cooling to room temperature along with the furnace;
(10) and (3) post-processing: and (4) grinding and polishing the ceramic sintered in the step (9) to obtain a ceramic sample with a smooth surface.
Example 3:
the preparation method of the low dielectric constant aluminate microwave dielectric ceramic material comprises the following steps:
(1) preparing materials: raw material CaCO3And Al2O3Proportioning according to the stoichiometric ratio in the chemical expression; specifically, 15.3995g of CaCO was weighed in order3And 31.3758gAl2O3The raw materials of (1); raw material CaCO3And Al2O3The purity of (A) is 99.99%;
(2) mixing materials: pouring the raw materials into a ball mill, wherein the raw materials, ball milling beads and absolute ethyl alcohol are mixed according to the proportion of 1: 1: 2, placing the mixture in a ball mill for wet ball milling for 24 hours to obtain slurry raw materials;
(3) drying: drying the slurry in a 70 ℃ oven to obtain a dry mixture;
(4) pre-burning: dispersing the dried powder through a standard sieve of 100 meshes, then presintering the powder in a high-temperature furnace for 3 hours at the presintering temperature of 1200 ℃ to enable the powder to react initially to generate CaAl4O7A compound;
(5) secondary ball milling: the CaAl synthesized by the preliminary reaction4O7Ball milling the compound in a ball mill for 24h to form finely dispersed CaAl4O7Sizing agent;
(6) secondary drying: drying the slurry in a 70 ℃ oven to obtain dry CaAl4O7A compound powder;
(7) and (3) granulation: taking CaAl4O7The powder was sieved through a 100 mesh sieve, after which the powder was mixed with a binder (polyvinyl alcohol PVA) according to a 94: 6, uniformly mixing the components in percentage by mass;
(8) tabletting: putting the powder obtained by granulation into a die, and pressing the powder into a cylindrical green body under the pressure of 200 MPa; the diameter of the cylindrical green body is 12mm, and the height of the cylindrical green body is 5 mm;
(9) and (3) sintering: heating the green body obtained in the step (8) to 650 ℃ at the speed of 5 ℃/min, preserving heat for 2h, then continuously heating to 1550 ℃ at the speed of 5 ℃/min, preserving heat for 3h, then cooling to 1100 ℃ at the speed of 1 ℃/min, and finally cooling to room temperature along with the furnace;
(10) and (3) post-processing: and (4) grinding and polishing the ceramic sintered in the step (9) to obtain a ceramic sample with a smooth surface.
Example 4:
the preparation method of the low dielectric constant aluminate microwave dielectric ceramic material comprises the following steps:
(1) ingredients: raw material CaCO3And Al2O3Proportioning according to the stoichiometric ratio in the chemical expression; specifically, 15.3995g of CaCO was weighed in order3And 31.3758gAl2O3The raw materials of (1); raw material CaCO3And Al2O3The purity of (A) is 99.99%;
(2) mixing materials: pouring the raw materials into a ball mill, wherein the raw materials, ball milling beads and absolute ethyl alcohol are mixed according to the proportion of 1: 1: 2, placing the mixture in a ball mill for wet ball milling for 24 hours to obtain slurry raw materials;
(3) drying: drying the slurry in a 70 ℃ oven to obtain a dry mixture;
(4) pre-burning: dispersing the dried powder through a standard sieve of 100 meshes, then presintering the powder in a high-temperature furnace for 3 hours at the presintering temperature of 1200 ℃ to enable the powder to react initially to generate CaAl4O7A compound;
(5) secondary ball milling: the CaAl synthesized by the preliminary reaction4O7Ball milling the compound in a ball mill for 24h to form finely dispersed CaAl4O7Sizing agent;
(6) secondary drying: drying the slurry in a 70 ℃ oven to obtain dry CaAl4O7A compound powder;
(7) and (3) granulation: taking CaAl4O7The powder was sieved through a 100 mesh sieve, after which the powder was mixed with a binder (polyvinyl alcohol PVA) according to a 94: 6, uniformly mixing the components in percentage by mass;
(8) tabletting: putting the powder obtained by granulation into a die, and pressing the powder into a cylindrical green body under the pressure of 200 MPa; the diameter of the cylindrical green body is 12mm, and the height of the cylindrical green body is 5 mm;
(9) and (3) sintering: heating the green body obtained in the step (8) to 650 ℃ at the speed of 5 ℃/min, preserving heat for 2h, then continuously heating to 1575 ℃ at the speed of 5 ℃/min, preserving heat for 3h, then cooling to 1100 ℃ at the speed of 1 ℃/min, and finally cooling to room temperature along with the furnace;
(10) and (3) post-processing: and (4) grinding and polishing the ceramic sintered in the step (9) to obtain a ceramic sample with a smooth surface.
Example 5:
the preparation method of the low dielectric constant aluminate microwave dielectric ceramic material comprises the following steps:
(1) preparing materials: raw material CaCO3And Al2O3Proportioning according to the stoichiometric ratio in the chemical expression; specifically, 15.3995g of CaCO was weighed in order3And 31.3758gAl2O3The raw materials of (1); raw material CaCO3And Al2O3The purity of (A) is 99.99%;
(2) mixing materials: pouring the raw materials into a ball mill, wherein the raw materials, ball milling beads and absolute ethyl alcohol are mixed according to the proportion of 1: 1: 2, placing the mixture in a ball mill for wet ball milling for 24 hours to obtain slurry raw materials;
(3) drying: drying the slurry in a 70 ℃ oven to obtain a dry mixture;
(4) pre-burning: dispersing the dried powder through a standard sieve of 100 meshes, then presintering the powder in a high-temperature furnace for 3 hours at the presintering temperature of 1200 ℃ to enable the powder to react initially to generate CaAl4O7A compound;
(5) secondary ball milling: the CaAl synthesized by the preliminary reaction4O7Ball milling the compound in a ball mill for 24h to form finely dispersed CaAl4O7Sizing agent;
(6) secondary drying: drying the slurry in a 70 ℃ oven to obtain dry CaAl4O7A compound powder;
(7) and (3) granulation: taking CaAl4O7The powder was sieved through a 100 mesh sieve, after which the powder was mixed with a binder (polyvinyl alcohol PVA) according to a 94: 6, uniformly mixing the components in percentage by mass;
(8) tabletting: putting the powder obtained by granulation into a die, and pressing the powder into a cylindrical green body under the pressure of 200 MPa; the diameter of the cylindrical green body is 12mm, and the height of the cylindrical green body is 5 mm;
(9) and (3) sintering: heating the green body obtained in the step (8) to 650 ℃ at the speed of 5 ℃/min, preserving heat for 2h, then continuously heating to 1600 ℃ at the speed of 5 ℃/min, preserving heat for 3h, then cooling to 1100 ℃ at the speed of 1 ℃/min, and finally cooling to room temperature along with the furnace;
(10) and (3) post-processing: and (4) grinding and polishing the ceramic sintered in the step (9) to obtain a ceramic sample with a smooth surface.
And (3) grinding and polishing the surface of the sample by using the cylindrical dielectric prepared in the embodiment 1-5 by using metallographic abrasive paper until no obvious scratch can be observed by naked eyes. Respectively testing the dielectric constant epsilon of the sample by adopting a network analyzer after the sample is ultrasonically vibrated and cleanedrAnd the quality factor Qf value, the resulting performance as a function of sintering temperature is shown in FIGS. 2 and 3.
TABLE 1 CaAl of examples 1-54O7Epsilon of ceramics at different sintering temperaturesrAnd Qf value
Sintering temperature (. degree. C.)
|
εr |
Qf(GHz)
|
1500 (example 1)
|
6.6
|
14097
|
1525 (example 2)
|
7.83
|
17250
|
1550 (example 3)
|
8.25
|
21854
|
1575 (example 4)
|
8.45
|
25533
|
1600 (example 5)
|
8.7
|
24503 |
Table 1 shows CaAl produced by the production method of the present invention4O7Epsilon of ceramics at different sintering temperaturesrAnd Qf values. As is clear from Table 1, the lowest dielectric constant was obtained in example 1 and the value thereof was 6.6, and the best quality factor was obtained in example 4 and the value thereof was 25533 GHz.
The ball mill of the above embodiment is preferably a planetary ball mill.
In the above embodiments and alternatives, the pre-firing temperature may also be 1050 ℃, 1100 ℃, 1150 ℃, 1180 ℃, etc.
In the above-described examples and alternatives thereof, the pressure of the press molding in the step (8) is 100MPa, 120MPa, 150MPa, 180MPa, or the like.
In the above examples and their alternatives, the raw CaCO is added before the batching3And Al2O3Grinding is carried out for 24 hours, and the uniformity of raw material particles is ensured.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core ideas. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.