Electronic ceramic material and method of making the same

Abstract

This invention relates to an electronic ceramic material and its manufacturing method. The manufacturing method includes heat treatment, acid treatment, grinding, alkali treatment, and carbonation of a shellfish to obtain high-purity calcium carbonate powder. When this calcium carbonate powder is mixed with titanium dioxide, the resulting electronic ceramic material exhibits a high dielectric constant and a high quality factor. Therefore, the obtained electronic ceramic material can be used to manufacture electronic components.

Description

Technical Field

[0001] This invention relates to a method for manufacturing an electronic ceramic material, and more particularly to an electronic ceramic material obtained from shellfish shells and a method for manufacturing the same. Prior Technology

[0002] Ceramic materials are inorganic, non-metallic metal oxides and / or non-metallic oxides that, after calcination and sintering, can acquire unique crystal structures and physical properties. By using high-purity raw materials and / or micronization, precision ceramic materials can possess more uniform and finer microstructures, thereby improving their physical properties such as heat resistance, corrosion resistance, wear resistance, high rigidity, high strength, and / or low expansion.

[0003] Calcium titanate can be used as a ceramic material with a specific crystal structure and unique physical properties, such as dielectric, ferroelectric, piezoelectric, and / or thermoelectric characteristics. It can be widely used in electronic products, such as as medium-voltage ceramic capacitors, high-voltage ceramic capacitors, and thermistors. Calcium titanate can be prepared by calcining calcium oxide, calcium carbonate, and / or calcium hydroxide as the calcium source and titanium dioxide as the titanium source.

[0004] Of the aforementioned calcium sources, calcium carbonate is abundant on Earth, existing not only in rocks (such as chalk, limestone, and marble) and / or minerals (such as calcite and aragonite) but also in organisms such as eggshells, turtle shells, and shellfish shells. Shellfish shells, being inedible, are often disposed of as waste through landfill. If not disposed of promptly, discarded shellfish shells easily emit foul odors and attract insects, causing environmental problems. Although shellfish shells are rich in calcium carbonate, they also contain organic matter and other calcium precipitates, making them unsuitable for use in the preparation of suitable electronic ceramic materials.

[0005] Therefore, there is an urgent need for a manufacturing method for electronic ceramic materials to solve the above problems. Summary of the Invention

[0006] Therefore, one aspect of the present invention is to provide a method for manufacturing electronic ceramic materials, which involves heat treatment, acid treatment, grinding treatment, alkali treatment and carbonation treatment of shellfish shells, mixing them with titanium dioxide, and then performing calcination and sintering steps to obtain the material.

[0007] Another aspect of the present invention is to provide an electronic ceramic material, which is prepared by the above method and has good performance.

[0008] According to the above description of the present invention, a method for manufacturing an electronic ceramic material is provided. First, a shellfish shell is heat-treated at 300°C to 500°C for 2 to 6 hours to obtain a heat-treated shellfish shell. Next, the heat-treated shellfish shell is acid-treated with a carboxylic acid at a weight percentage of 1 to 5% for 1 to 4 hours to obtain an acid-treated shellfish shell, wherein the carboxylic acid comprises citric acid and / or acetic acid. Then, the acid-treated shellfish shell is subjected to a first grinding process to obtain shellfish shell powder.

[0009] Next, the shellfish shell powder is subjected to alkali treatment with a calcium hydroxide aqueous solution at a weight percentage of 5% to 15% to obtain an alkali-treated solution. Then, carbon dioxide is passed into the alkali-treated solution to perform carbonation treatment, thereby obtaining a carbonation-treated solution, wherein the carbon dioxide flow rate is 10 L / min to 50 L / min, the pH of the carbonation-treated solution is 7.0 to 7.6, and the carbonation-treated solution contains calcium carbonate powder. Subsequently, the calcium carbonate powder and titanium dioxide are mixed, and a calcination step and a sintering step are performed sequentially to obtain an electronic ceramic material, wherein the calcination step is performed at 1200°C to 1350°C, and the sintering step is performed at 1300°C to 1350°C.

[0010] In some embodiments of the present invention, the above manufacturing method may selectively include solid-liquid separation of the carbonation treatment liquid to separate calcium carbonate powder from the carbonation treatment liquid.

[0011] In some embodiments of the present invention, the above manufacturing method may selectively include a second grinding process and a pressing step for the electronic ceramic material.

[0012] In some embodiments of the present invention, the shellfish shells include oysters, clams, mussels, peacock clams, oysters, abalone, pearl oysters, butterfly oysters, and / or scallops.

[0013] In some embodiments of the present invention, the weight ratio of shellfish shell powder to calcium carbonate powder is 500:600 to 500:700.

[0014] In some embodiments of the present invention, the particle size of the shellfish powder is 3 μm to 10 μm.

[0015] In some embodiments of the present invention, the weight ratio of calcium carbonate powder to titanium dioxide is 1:0.5 to 1:1.5.

[0016] In some embodiments of the present invention, the calcium carbonate powder contains calcium carbonate at a weight percentage greater than or equal to 99.0%.

[0017] According to another aspect of the present invention, an electronic ceramic material is provided, which is prepared by the above-described manufacturing method, and has a dielectric constant (k) of 150 to 200.

[0018] In some embodiments of the present invention, the quality factor (Q×f) is 2000 to 3000.

[0019] The electronic ceramic material and its manufacturing method of the present invention are obtained by mixing shellfish shells with titanium dioxide after heat treatment, acid treatment, grinding treatment, alkali treatment and carbonation treatment, followed by calcination steps. The material has good dielectric constant and quality factor, can be used to prepare electronic components, and can solve the problem of large quantities of discarded shellfish shells. Simple Explanation of the Diagram

[0020] To make the above and other objects, features, advantages and embodiments of the present invention more apparent and understandable, the detailed description of the accompanying drawings is as follows: Figure 1 is a flowchart illustrating a method for manufacturing an electronic ceramic material according to an embodiment of the present invention. Implementation

[0021] As previously stated, this invention provides an electronic ceramic material and its manufacturing method, which may include, but is not limited to, heat treatment, acid treatment, alkali treatment, and carbonation treatment of shellfish shells to obtain high-purity calcium carbonate powder. The electronic ceramic material made from this calcium carbonate powder can possess a high dielectric constant and a high quality factor.

[0022] The term "shellfish shell" as used herein may refer to, but is not limited to, shells of single-valved and / or bivalved mollusks. There are no particular restrictions on the species from which shellfish shells may be derived, and they may include, but are not limited to, oysters, clams, mussels, peacock clams, oysters, abalone, pearl oysters, butterfly oysters, scallops, combinations thereof, or other suitable species. Generally, the main component of shellfish shells is calcium carbonate, comprising approximately 94% by weight. In addition to calcium carbonate, shellfish shells may also contain, but are not limited to, organic matter and / or other calcium precipitates besides calcium carbonate.

[0023] The term "high purity" in this article refers to a high calcium carbonate content in the calcium carbonate powder, such as 99.0% by weight. If the calcium carbonate content in the calcium carbonate powder is too low, the dielectric constant and quality factor of the resulting electronic ceramic material will be low, failing to meet market demands for electronic components.

[0024] The term "high dielectric constant" as used herein refers to the ability of an electronic ceramic material to store electrical charge. A high dielectric constant can be evaluated, for example, by its dielectric constant (k). In some embodiments, a high dielectric constant may be, for example, greater than or equal to 150, such as 150 to 200, or 160 to 180.

[0025] The "quality factor (Q×f)" mentioned in this article is the ratio (unitless) of the energy stored in an electronic ceramic material to the energy lost per cycle. A higher quality factor indicates lower energy loss, meaning better quality. Therefore, a high quality factor in an electronic ceramic material indicates good power storage and low power loss. In some embodiments, the quality factor of the electronic ceramic material may be, for example, between 2000 and 3000, such as 2200 to 2700.

[0026] Please refer to Figure 1 for a method of manufacturing electronic ceramic materials using shellfish shells. Figure 1 is a flowchart illustrating a method 100 for manufacturing electronic ceramic materials according to some embodiments of the present invention. First, step 110 is performed, which involves heat-treating the shellfish shell to cause the organic matter in the shellfish shell to form carbon dioxide and water vapor, thereby obtaining a heat-treated shellfish shell. The heat treatment temperature can be, for example, 300°C to 500°C, such as 350°C, 400°C, or 450°C, which is the temperature at which the high molecular weight organic matter can be completely converted into carbon dioxide and water vapor. If the temperature is too low, the organic matter cannot be completely converted into carbon dioxide and water. If the temperature is too high, it will increase costs and prevent further improvement in the purity of the obtained calcium carbonate powder. The heat treatment time can be, for example, 2 hours to 6 hours, such as 3 hours, 4 hours, or 5 hours, to ensure that the organic matter can be completely converted into carbon dioxide and water vapor. In some embodiments, the heat treatment is carried out using a high-temperature oven, and this process is waterless.

[0027] In some embodiments, prior to step 110, the shellfish shell may be selectively cleaned by mechanical force to remove sand, algae, and / or biofilms formed by microorganisms adhering to the shellfish shell surface. In some specific examples, the method of cleaning the shellfish shell may include, but is not limited to, cleaning with a powerful water jet and / or scrubbing with a brush.

[0028] Next, the heat-treated shellfish shells are acid-treated to obtain acid-treated shellfish shells, as shown in step 120. Acid treatment can be performed using carboxylic acids, such as aliphatic mono-, di-, or polycarboxylic acids. In some embodiments, the carboxylic acid may include, but is not limited to, acetic acid and / or citric acid. Since shellfish shells contain calcium precipitates other than calcium carbonate, acid treatment with carboxylic acids results in salts that are soluble or slightly soluble in water, facilitating the removal of other calcium precipitates from the surface of the heat-treated shellfish shells, thereby improving the purity of the resulting calcium carbonate powder. In some embodiments, the acid treatment may be performed for, for example, 1 to 4 hours, to effectively remove other calcium precipitates from the shellfish shell surface while retaining a significant amount of calcium carbonate. The concentration of the carboxylic acid may be, for example, 1 to 5 weight percent, such as 4 to 5 weight percent. If the carboxylic acid is too acidic, excessive calcium carbonate may be lost; if the carboxylic acid is not acidic enough, other calcium precipitates may remain in the obtained calcium carbonate powder, resulting in insufficient purity of the calcium carbonate powder. There are no particular restrictions on the temperature of acid treatment; it can be carried out at room temperature. In some specific cases, room temperature may be, for example, 20°C to 40°C.

[0029] Following step 120, step 130 is performed, which involves a first grinding process on the acid-treated shellfish. The first grinding process is not particularly limited and may include, but is not limited to, roller milling, planetary milling, stirring milling, vibratory milling, air jet milling, and / or sand milling. The particle size of the shellfish powder is not particularly limited and may be, for example, from 3 μm to 10 μm.

[0030] Next, the shellfish shell powder is immersed in an aqueous solution of calcium hydroxide for alkali treatment, thereby obtaining an alkali-treated solution, as shown in step 140. It is worth noting that alkali treatment cannot be performed using an aqueous solution of sodium hydroxide, as there is a possibility of sodium residue, which could affect the electrical properties of the resulting electronic ceramic material. Conversely, using calcium hydroxide allows it to further react to form calcium carbonate in subsequent steps, helping to improve the purity of the obtained calcium carbonate powder, thus enabling the production of electronic ceramic materials with high dielectric constant and quality factor. It should be further noted that because the calcium carbonate content varies among different shellfish, some shellfish may have lower calcium carbonate content. If a batch of shellfish shells has a low calcium carbonate content, using a low-concentration aqueous solution of calcium hydroxide may result in poor purity of the calcium carbonate powder, leading to unstable quality. Using an aqueous solution of calcium hydroxide with a concentration of 5% to 15% by weight ensures that each batch of calcium carbonate powder has the required purity.

[0031] In some embodiments, the alkali treatment time may be, for example, 60 to 100 minutes, to obtain calcium carbonate powder with better purity. In some embodiments, the weight of the shellfish shell powder and the weight of the calcium hydroxide aqueous solution are not particularly limited, and may be, for example, 1:1 to 1:3, to obtain calcium carbonate powder with better purity.

[0032] Next, according to step 150, carbon dioxide is introduced into the alkaline treatment solution to perform carbonation treatment, thereby carbonating the treatment solution. During the carbonation treatment process, calcium hydroxide in the calcium hydroxide aqueous solution can form calcium carbonate, which is then deposited on the surface of the shell powder, thus forming calcium carbonate powder in the carbonation treatment solution. The pH of the carbonation treatment solution can be, for example, between pH 7.0 and pH 7.6, to ensure that most of the calcium hydroxide in the carbonation treatment solution forms calcium carbonate.

[0033] There are no particular restrictions on the flow rate of carbon dioxide. The flow rate can be, for example, from 10 L / min to 50 L / min, or from 10 L / min to 30 L / min. If the flow rate is too slow, the time cost is too high; if the flow rate is too high, the particle size of the obtained calcium carbonate powder will be too large, thus increasing the cost of subsequent processing (such as a second grinding process). Experiments have shown that the weight ratio of shellfish shell powder to calcium carbonate powder can be, for example, 500:600 to 500:700, indicating that alkaline treatment and carbonation under the above conditions can indeed further increase the calcium carbonate content.

[0034] Then, calcium carbonate powder and titanium dioxide are mixed and subjected to a calcination step, followed by a sintering step to obtain an electronic ceramic material, as shown in step 160. There is no particular weight ratio of calcium carbonate powder and titanium dioxide; in some embodiments, the weight ratio of calcium carbonate powder to titanium dioxide may be, for example, 1:0.5 to 1:1.5 to achieve a higher yield.

[0035] The calcination step can be performed at temperatures, for example, 1200°C to 1350°C, to form the crystal structure of calcium titanate (CaTiO3). If the calcination temperature is too low, the resulting electronic ceramic material will have insufficient calcium titanate crystal content. If the calcination temperature is too high, it will not further increase the calcium titanate crystal content and will instead consume excessive energy. The sintering step can be performed at temperatures, for example, 1300°C to 1350°C, to increase the strength and density of the electronic ceramic material.

[0036] In some embodiments, prior to step 160, the carbonation treatment solution may be selectively subjected to solid-liquid separation to separate calcium carbonate powder from the carbonation treatment solution. The method of solid-liquid separation is not particularly limited and may include, for example, drying, centrifugation, and / or vacuum filtration.

[0037] In some embodiments, after step 160, the electronic ceramic material may be selectively subjected to a second grinding process and a pressing and forming step to shape the electronic ceramic material into the desired form. The method of the second grinding process is not particularly limited and may be the same as the first grinding process. In other embodiments, the method of the second grinding process may differ from the first grinding process; for example, the first grinding process may be an air jet milling method, and the second grinding process may be a drum ball milling method or a planetary ball milling method.

[0038] Experiments have confirmed that the calcium carbonate content of the calcium carbonate powder obtained by heat treatment, acid treatment, grinding treatment, alkali treatment and carbonation treatment of shellfish shells can be greater than or equal to 99% by weight, indicating that the calcium carbonate powder obtained by the manufacturing method shown in this invention does have high purity.

[0039] Secondly, experiments have confirmed that the dielectric constant of the electronic ceramic material made from this calcium carbonate powder can be, for example, 150 to 200, and the quality factor can be, for example, 2000 to 3000. This indicates that the calcium carbonate powder produced by the manufacturing method of the present invention can be used to produce electronic ceramic materials, and can be further applied to the manufacture of electronic components.

[0040] The following examples illustrate the application of the present invention, but they are not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Preparation Example 1

[0041] Rinse the oyster shells with clean water to initially remove any adhering substances such as algae, biofilm, and / or sand. After sun-drying the cleaned oyster shells for 30 days, subject them to heat treatment at 400℃ to remove organic matter.

[0042] Next, the oyster shells were soaked in acetic acid at 5% by weight for 4 hours at room temperature to remove calcium precipitates other than calcium carbonate from the surface of the oyster shells. Then, the oyster shells were ground into oyster shell powder with a particle size of 3 to 10 μm, and the oyster shell powder was soaked in an aqueous solution of calcium hydroxide for 1 hour, wherein the weight ratio of oyster shell powder to calcium hydroxide aqueous solution was 1:2, and the concentration of calcium hydroxide aqueous solution was 10% by weight, thereby obtaining an alkaline treatment solution.

[0043] Carbon dioxide was passed into the alkaline treatment solution at a flow rate of 10 L / min for 5 minutes until the pH of the alkaline treatment solution reached 7.0 to 7.6, to obtain calcium carbonate powder with a weight of 630 g. This calcium carbonate powder was mixed with titanium dioxide and then calcined at 1200°C to 1350°C. After grinding and pressing the calcium titanate into ingots, it was sintered at 1300°C to 1350°C to obtain the electronic ceramic material of Preparation Example 1. Preparation Example 2

[0044] The manufacturing method of the electronic ceramic material in Preparation Example 2 is the same as that in Preparation Example 1, except that clam shells are used instead of oyster shells in Preparation Example 2. Preparation of Comparative Example 1 and Preparation of Comparative Example 2

[0045] The manufacturing methods for the electronic ceramic materials of Comparative Example 1 and Comparative Example 2 were the same as those for the electronic ceramic material of Comparative Example 1. The difference was that the oyster shells of Comparative Example 1 were only subjected to heat treatment and grinding, without acid treatment, alkali treatment, or carbonation treatment, while the oyster shells of Comparative Example 2 were subjected to heat treatment, acid treatment, and grinding, without alkali treatment or carbonation treatment. The manufacturing methods of the calcium carbonate powders of Comparative Example 1, Comparative Example 2, and Comparative Example 1 were recorded in Table 1, where "V" indicates the treatment performed on the oyster shells or clam shells, and "X" indicates the treatment not performed on the oyster shells or clam shells. Evaluation methods and results Calcium carbonate powder calcium carbonate content

[0046] First, the calcium carbonate powder of Preparation Example 1 was neutralized with excess hydrochloric acid. After carbon dioxide was no longer produced, potassium hydrogen phthalate indicator was added, and a sample was taken and titrated with sodium hydroxide until the sample solution changed from colorless to red. The calcium carbonate content of the calcium carbonate powder could be calculated by the amount of hydrochloric acid and sodium hydroxide used. The calcium carbonate content of the calcium carbonate powders of Preparation Example 2, Comparative Example 1, and Comparative Example 2 was obtained using the same method, and the results are recorded in Table 1. Dielectric constant of ceramic materials

[0047] After coating both sides of the ceramic material of Preparation Example 1 with a certain thickness of silver paste, the capacitance and dielectric loss of the ceramic material of Preparation Example 1 at a fixed frequency of 1 MHz were measured using an inductance-capacitance-resistance (LCR) meter to calculate the dielectric constant of the ceramic material. The dielectric constants of the ceramic materials of Preparation Example 2, Comparative Example 1, and Comparative Example 2 were obtained using the same method, and the results are recorded in Table 1. Quality factor (Q×f) of ceramic materials

[0048] The ratio of stored power to lost power in the ceramic material of Preparation Example 1 was measured using the Hakki-Coleman method under AC at a certain frequency (e.g., 20 GHz). The quality factors of the ceramic materials of Preparation Example 2, Comparative Example 1, and Comparative Example 2 were obtained using the same method, and the results are recorded in Table 1. Table 1

[0049] As shown in Preparation Examples 1 and 2 of Table 1, the calcium carbonate powder prepared using the manufacturing method of this invention has a calcium carbonate content greater than or equal to 99% by weight. The ceramic material prepared from this calcium carbonate powder has a dielectric constant of 150 to 200 and a quality factor of 2000 to 3000.

[0050] The shell of Comparative Example 1 was subjected to only heat treatment and grinding. The calcium carbonate powder obtained had a calcium carbonate content of 94% by weight, and the ceramic material made from this calcium carbonate powder had a dielectric constant of 73 and a quality factor of 319. The shell of Comparative Example 2 was subjected to only heat treatment, acid treatment, and grinding. Although the calcium carbonate powder obtained had a higher calcium carbonate content than that of Comparative Example 1, at 97.5% by weight, the dielectric constant and quality factor of the ceramic material made from it did not meet the requirements.

[0051] In summary, the specific shellfish shells, specific carboxylic acids, specific processes, or specific evaluation methods described above are merely illustrative of the electronic ceramic materials and manufacturing methods of the present invention. However, those skilled in the art will understand that other shellfish shells, other carboxylic acids, other processes, or other evaluation methods can also be used for the electronic ceramic materials and manufacturing methods without departing from the spirit and scope of the present invention, and are not limited to the above. For example, other shellfish shells or other carboxylic acids can be used without affecting the purity of the obtained calcium carbonate powder and the dielectric constant and quality factor of the electronic ceramic material. For example, acid treatment with carboxylic acids such as acetic acid or citric acid can also produce high-purity calcium carbonate powder.

[0052] As can be seen from the above embodiments, the advantages of the electronic ceramic material and its manufacturing method of the present invention are that the calcium carbonate powder obtained by heat treatment, acid treatment, grinding treatment, alkali treatment and carbonation treatment of shellfish shells not only has high purity, but also the electronic ceramic material obtained has high dielectric constant and quality factor, which can be used to manufacture electronic components and can solve the problem of shellfish shell waste.

[0053] While the present invention has been disclosed above with reference to several specific embodiments, various modifications, alterations, and substitutions can be made to the foregoing disclosure. It should be understood that, without departing from the spirit and scope of the invention, certain features of the embodiments of the invention may be used in some cases, but other features may not be used accordingly. Therefore, the spirit and scope of the invention should not be limited to the embodiments described above.

[0054] 100: Manufacturing Method 110, 120, 130, 140, 150, 160: Steps

Claims

1. A method for manufacturing an electronic ceramic material, comprising: heat-treating a shellfish shell at 300°C to 450°C for 2 to 6 hours to obtain a heat-treated shellfish shell, wherein the heat treatment process is anhydrous; acid-treating the heat-treated shellfish shell with a carboxylic acid at a weight percentage of 1 to 5% for 1 to 4 hours to obtain an acid-treated shellfish shell, wherein the carboxylic acid comprises citric acid and / or acetic acid; performing a first grinding process on the acid-treated shellfish shell to obtain a shellfish shell powder, wherein the particle size of the shellfish shell powder is 3 μm to 10 μm; alkali-treating the shellfish shell powder with an aqueous solution of calcium hydroxide at a weight percentage of 5 to 15% to obtain an alkali-treated solution; and passing carbon dioxide into the alkali-treated solution to perform carbonation treatment, thereby obtaining a carbonation-treated solution, wherein the flow rate of the carbon dioxide is 10 L / min to 50 L / min, and the pH of the carbonation-treated solution is pH 7.0 to pH 10.

0. 7.6, and the carbonation treatment liquid contains calcium carbonate powder, wherein the calcium carbonate powder contains calcium carbonate at a weight percentage greater than or equal to 99.0%; after mixing the calcium carbonate powder and titanium dioxide, a calcination step and a sintering step are performed sequentially to obtain the electronic ceramic material, wherein the calcination step is performed at 1200°C to 1350°C, and the sintering step is performed at 1300°C to 1350°C.

2. The method for manufacturing electronic ceramic materials as described in claim 1 further includes performing a solid-liquid separation process on the carbonation treatment liquid to separate the calcium carbonate powder from the carbonation treatment liquid.

3. The method for manufacturing electronic ceramic material as described in claim 1 further includes a second grinding process and a pressing step for the electronic ceramic material.

4. A method for manufacturing electronic ceramic materials as described in claim 1, wherein the shellfish includes oysters, clams, mussels, peacock clams, oysters, abalone, pearl oysters, butterfly oysters, and / or scallops.

5. The method for manufacturing electronic ceramic material as described in claim 1, wherein the weight ratio of the shellfish shell powder to the calcium carbonate powder is 500:600 to 500:

700.

6. The method for manufacturing the electronic ceramic material as described in claim 1, wherein the weight ratio of the calcium carbonate powder and the titanium dioxide is from 1:0.5 to 1:1.

5.

7. An electronic ceramic material, which is prepared by the manufacturing method described in any one of claims 1 to 6, wherein the dielectric constant (k) of the electronic ceramic material is 150 to 200.

8. The electronic ceramic material as described in claim 7, wherein the quality factor (Q×f) of the electronic ceramic material is 2000 to 3000.

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