A high-strength, high-thermal-shock-resistant ceramic material, its preparation method and application

Abstract

This invention relates to the technical field of ceramic materials, specifically to a high-strength, high-thermal-shock-resistant ceramic material, its preparation method, and its applications. This application discloses a high-strength, high-thermal-shock-resistant ceramic material comprising the following components by weight percentage: Al2O3: 92-96%, SiO2: 1-5%, CaO: 0.5-1.5%, MgO: 0.05-0.5%; the high-strength, high-thermal-shock-resistant ceramic material has a cross-section with micropores of 5-30 μm and a porosity of 1%-3%. The high-strength, high-thermal-shock-resistant ceramic material of this application improves the thermal shock resistance of alumina ceramics by adding appropriate amounts of sintering aids, pore-forming agents, and dopant phases; simultaneously, through a specific glass-alumina reaction, the sintering temperature is lowered to promote sintering, and the alumina particles are wetted, enhancing the grain boundary bonding strength; furthermore, the addition of cordierite, with its low coefficient of thermal expansion, adjusts the coefficient of thermal expansion of the material, further improving its thermal shock resistance.

Description

Technical Field

[0001] This invention relates to the technical field of ceramic materials, specifically to a high-strength, high-thermal-shock-resistant ceramic material, its preparation method, and its applications. Background Technology

[0002] Alumina ceramics possess many advantages, such as high strength, high hardness, good wear resistance and high-temperature resistance, good thermal conductivity, resistance to chemical corrosion, and electrical insulation. Therefore, alumina ceramics are widely used in many fields. However, existing alumina ceramics suffer from poor thermal shock resistance, which limits their application range. Therefore, improving the thermal shock resistance of alumina ceramics has become a technical challenge that urgently needs to be solved by those skilled in the art.

[0003] Thermal shock resistance refers to a material's ability to withstand rapid temperature changes without being damaged. The thermal shock resistance of precision ceramics is mainly related to various factors such as the intrinsic strength, coefficient of thermal expansion, porosity, thermal conductivity, grain size, and second phase of the ceramic material. Improving the thermal shock resistance of ceramics generally involves increasing the material's thermal conductivity, reducing the coefficient of thermal expansion, and controlling appropriate grain size and porosity. The thermal conductivity of alumina ceramics is generally between 20 and 40 W / m·K, which is relatively high among oxide ceramics. Therefore, reducing the coefficient of thermal expansion while controlling grain size and porosity, and selecting appropriate doping phases, are key to improving thermal shock resistance.

[0004] Therefore, this application provides a high-strength ceramic material with high thermal shock resistance, its preparation method, and its application. Summary of the Invention

[0005] This application describes a high-strength, high-thermal-shock-resistant ceramic material, its preparation method, and its application. The thermal shock resistance of alumina ceramic is improved by adding appropriate amounts of sintering aids, pore-forming agents, and dopant phases. The main mechanism is to release thermal stress by controlling the generation of an appropriate amount of uniform micropores in the ceramic body, thereby improving thermal shock resistance. Simultaneously, a specific glass-alumina reaction lowers the sintering temperature and promotes sintering, while also wetting the alumina particles and enhancing grain boundary bonding strength. Furthermore, the addition of cordierite, with its low coefficient of thermal expansion, adjusts the material's coefficient of thermal expansion, further improving thermal shock resistance.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] The primary objective of this application is to provide a high-strength ceramic material with high thermal shock resistance, comprising the following components by weight percentage:

[0008] Al2O3:92~96%, SiO2:1~5%, CaO:0.5~1.5%, MgO:0.05~0.5%;

[0009] The high-strength, high-thermal-shock-resistant ceramic material has micropores of 5-30 μm distributed in its cross-section, with a porosity of 1%-3%.

[0010] Furthermore, the high-strength, high-thermal-shock-resistant ceramic material has a flexural strength of 350~390MPa and its thermal shock resistance allows it to withstand water cooling at 200℃ without cracking.

[0011] Furthermore, the high-strength, high-thermal-shock-resistant ceramic material comprises, by weight, the following raw materials:

[0012] a parts Al2O3, b parts SiO2, c parts CaCO3, d parts CaSiO3, e parts cordierite, f parts pore-forming agent, g parts sintering aid;

[0013] a=92~96, b=1~4, c=0.5~1, d=0.2~1, e=0.5~2, f=0.2~1, g=0.5~1, and a + b + c + d+ e + f + g =100.

[0014] The second objective of this application is to provide a method for preparing the high-strength, high-thermal-shock-resistant ceramic material described above, comprising the following steps:

[0015] S1. Prepare the ingredients by weighing a parts Al2O3, b parts SiO2, c parts CaCO3, d parts CaSiO3, e parts cordierite, f parts pore-forming agent, and g parts sintering aid.

[0016] a=92~96, b=1~4, c=0.5~1, d=0.2~1, e=0.5~2, f=0.2~1, g=0.5~1, and a + b + c + d+ e + f + g =100;

[0017] S2. Ball mill and mix the ingredients from step S1 until homogeneous, then dry them;

[0018] S3. The powder dried in step S2 is mixed with binder and water to form a slurry, and then spray granulation is performed to produce spray granulated powder.

[0019] S4. Press the powder after spray granulation in step S3 into a mold, and then sinter it in an air atmosphere to obtain a high-strength ceramic material with high thermal shock resistance.

[0020] Furthermore, in step S1, the pore-forming agent is one or more of carbon powder, graphite powder, PMMA, PVB, and starch, and the particle size of the pore-forming agent is 1~10μm.

[0021] Furthermore, in step S1, the sintering aid is a CaO-MgO-SiO2 glass with a particle size of 2~3μm.

[0022] Furthermore, in step S2, the ingredients are subjected to planetary ball milling for 3 to 12 hours, and the particle size D50 of the slurry is controlled to be 1 to 5 μm.

[0023] Furthermore, in step S3, the adhesive is a polyvinyl alcohol (PVA) adhesive.

[0024] Furthermore, in step S3, the sintering temperature in the air atmosphere is 1600℃~1700℃.

[0025] Furthermore, the softening temperature of the CaO-MgO-SiO2 glass is 650~750℃.

[0026] The third objective of this application is to provide the application of the aforementioned high-strength, high-thermal-shock-resistant ceramic material, namely, to apply the high-strength, high-thermal-shock-resistant ceramic material to the production of high-strength, heat-resistant sealing components and / or structural components.

[0027] The beneficial effects of this application are:

[0028] 1. The ceramic material described in this application improves the thermal shock resistance of alumina ceramics by adding appropriate amounts of sintering aids, pore-forming agents, and dopant phases. The main mechanism is to release thermal stress by controlling the generation of an appropriate amount of uniform micropores in the ceramic body, thereby improving the thermal shock resistance. At the same time, through the specific reaction between glass and alumina, the sintering temperature is reduced to promote sintering, and the alumina particles are wetted to enhance the grain boundary bonding strength. In addition, the addition of cordierite with a low coefficient of thermal expansion can adjust the coefficient of thermal expansion of the material, further improving the thermal shock resistance.

[0029] 2. The preparation method described in this application adopts in-situ sintering, which is simple, easy to operate, and easy to control. The resulting high-strength, high-thermal-shock-resistant ceramic material has a strength of over 350 MPa and thermal shock resistance that can withstand 200℃ water cooling for ten cycles without cracking. This provides the possibility for expanding the application of alumina ceramics as heat-resistant seals and structural components under high-temperature conditions. Attached Figure Description

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] Figure 1 This is a process flow diagram of the preparation method of a high-strength, high-thermal-shock-resistant ceramic material as described in this application;

[0032] Figure 2 This is a SEM image of the ceramic material prepared in Example 1 of this application;

[0033] Figure 3 This is a SEM image of the ceramic material prepared in Comparative Example 1 of this application. Detailed Implementation

[0034] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention.

[0035] As used herein, “and / or” includes all combinations of any and one or more of the associated listed items. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a,” “an,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. Further understanding is needed; when used in this specification, “comprising” designates the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0036] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Further understanding is that terms, such as those defined in common dictionaries, are interpreted in accordance with their meaning in the context of the relevant field and are not idealized or overly formal, unless expressly defined herein.

[0037] The exemplary invention described herein may suitably omit any one or more limiting elements, which are not specifically disclosed herein. Therefore, terms such as “comprising,” “including,” “containing,” etc., should be interpreted broadly and non-limitingly. Furthermore, the terminology used herein is for descriptive purposes without limitation, and it is unintentional to use terms that do not include any equivalent characteristics, but only to describe a portion of their characteristics; however, various modifications are possible within the scope of the invention according to the claims. Therefore, while the invention has been specifically disclosed through preferred embodiments and optional features, variations of the invention embodied by the modifications disclosed herein may be noted by those skilled in the art, and such modifications and variations are considered to be within the scope of the invention.

[0038] All raw materials or reagents used in the embodiments and comparative examples of this invention were purchased from mainstream manufacturers on the market. Those without specified manufacturers or concentrations are all analytical grade raw materials or reagents that are routinely available. There are no particular restrictions as long as they achieve the expected effect. The instruments and equipment used in this embodiment were all purchased from major manufacturers on the market. There are no particular limitations as long as they achieve the expected effect. Where specific techniques or conditions are not specified in this embodiment, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions.

[0039] In order to reduce the coefficient of thermal expansion while controlling grain size and porosity, the inventors selected appropriate doping phases to improve thermal shock resistance, and provided a high-strength ceramic material with high thermal shock resistance, comprising the following components by weight percentage: Al2O3: 92~96%, SiO2: 1~5%, CaO: 0.5~1.5%, MgO: 0.05~0.5%;

[0040] The high-strength, high-thermal-shock-resistant ceramic material has 5-30 μm micropores distributed in its cross-section and a porosity of 1%-3%. The flexural strength of the high-strength, high-thermal-shock-resistant ceramic material is 350-390 MPa, and its thermal shock resistance allows it to withstand water cooling at 200℃ without cracking.

[0041] In one or more embodiments, the chemical composition of the above-mentioned ceramic material, by weight percentage, is required to be (controlled within): Al2O3: 92~96%, SiO2: 1~5%, CaO: 0.5~1.5%, MgO: 0.05~0.5%, and contains unavoidable impurities.

[0042] For example, the chemical composition of ceramic materials, by weight percentage, includes the following specific components: Al2O3: 93%, SiO2: 5%, CaO: 1.5%, MgO: 0.5%, and contains unavoidable impurities; or Al2O3: 94.45%, SiO2: 5%, CaO: 0.5%, MgO: 0.05%, and contains unavoidable impurities; Al2O3: 96%, SiO2: 1%, CaO: 1.5%, MgO: 0.5%, and contains unavoidable impurities; Al2O3: 95%, SiO2: 3.5%, CaO: 1%, MgO: 0.5%, and contains unavoidable impurities.

[0043] Specifically, the above-mentioned chemical composition requirements can be achieved by combining the following raw materials in parts by weight, followed by batching, ball milling, spray granulation, pressing, and sintering; the high-strength, high-thermal-shock-resistant ceramic material, measured in parts by weight, includes the following raw materials:

[0044] a parts Al2O3, b parts SiO2, c parts CaCO3, d parts CaSiO3, e parts cordierite, f parts pore-forming agent, g parts sintering aid;

[0045] a=92~96, b=1~4, c=0.5~1, d=0.2~1, e=0.5~2, f=0.2~1, g=0.5~1, and a + b + c + d+ e + f + g =100.

[0046] Specifically, the raw material combination can be 92 parts Al2O3, 2 parts SiO2, 1 part CaCO3, 1 part CaSiO3, 2 parts cordierite, 1 part pore-forming agent, and 1 part sintering aid;

[0047] Alternatively, it could be 96 parts Al2O3, 2.1 parts SiO2, 0.5 parts CaCO3, 0.2 parts CaSiO3, 0.5 parts cordierite, 0.2 parts pore-forming agent, and 0.5 parts sintering aid;

[0048] Alternatively, it could be 94 parts Al2O3, 1 part SiO2, 1 part CaCO3, 1 part CaSiO3, 2 parts cordierite, 0.5 parts pore-forming agent, and 0.5 parts sintering aid;

[0049] Alternatively, it could be 93 parts Al2O3, 4 parts SiO2, 1 part CaCO3, 0.5 parts CaSiO3, 0.5 parts cordierite, 0.5 parts pore-forming agent, and 0.5 parts sintering aid.

[0050] Alternatively, it could be 93 parts Al2O3, 1 part SiO2, 1 part CaCO3, 2 parts CaSiO3, 0.5 parts cordierite, 1 part pore-forming agent, and 1 part sintering aid.

[0051] The specific raw materials include: Al2O3, purity ≥99.7%, crystalline form α-alumina, primary crystal particle size 1~5μm; SiO2, purity ≥99.5%, particle size 1~3μm; CaCO3, purity ≥99.5%, particle size 1~3μm; CaSiO3, purity ≥99.5%, particle size 1~3μm. The pore-forming agent is one or more of carbon powder, graphite powder, PMMA, PVB, and starch, with a particle size 1~10μm. The sintering aid is a CaO-MgO-SiO2 based glass, with a particle size 2~3μm.

[0052] The preparation method of the above-mentioned high-strength and high thermal shock resistant ceramic material includes the following steps:

[0053] S1. Ingredients: Weigh out a parts Al2O3, b parts SiO2, c parts CaCO3, d parts CaSiO3, e parts cordierite, f parts pore-forming agent, and g parts sintering aid;

[0054] a=92~96, b=1~4, c=0.5~1, d=0.2~1, e=0.5~2, f=0.2~1, g=0.5~1, and a + b + c + d+ e + f + g =100;

[0055] S2. Ball mill and mix the ingredients from step S1 until homogeneous, then dry them;

[0056] S3. The powder dried in step S2 is mixed with binder (polyvinyl alcohol PVA binder) and water to form a slurry. Using water as a solvent, the mixture is ball-milled for 3-12 hours, and the particle size D50 of the slurry is controlled to be 1-5 μm. Then, it is produced into spray-granulated powder by spray granulation process.

[0057] S4. Press the powder after spray granulation in step S3 into a mold, and then sinter it in an air atmosphere at 1600℃~1700℃ to obtain a high-strength ceramic material with high thermal shock resistance.

[0058] Specifically, the drying in step S2, the spray granulation process in step S3, and the spray pressing process in step S4 can be carried out using common drying, spray granulation, and pressing processes, as long as the requirements are met.

[0059] The following specific embodiments further illustrate a high-strength, high-thermal-shock-resistant ceramic material of the present invention:

[0060] Example 1

[0061] like Figure 1 The above describes a high-strength ceramic material with high thermal shock resistance, the raw material composition of which is shown in Table 1.

[0062] The preparation method includes the following steps:

[0063] S1. Weigh the appropriate ingredients;

[0064] S2. Ball mill and mix the ingredients from step S1 until homogeneous, then dry them;

[0065] S3. Add polyvinyl alcohol (PVA) binder and water to the powder dried in step S2, mix and slurry, and control the mixture by planetary ball milling for 3~12h, and control the particle size D50 of the slurry to be 1~5μm; then use spray granulation process to make spray granulated powder.

[0066] S4. Press the powder after spray granulation in step S3 into a mold, and then sinter it in an air atmosphere at 1600℃ to obtain a high-strength ceramic material with high thermal shock resistance.

[0067] Example 2

[0068] A high-strength ceramic material with high thermal shock resistance, the raw material composition of which is shown in Table 1;

[0069] The preparation method includes the following steps:

[0070] S1. Weigh the appropriate ingredients;

[0071] S2. Ball mill and mix the ingredients from step S1 until homogeneous, then dry them;

[0072] S3. Add polyvinyl alcohol (PVA) binder and water to the powder dried in step S2, mix and slurry, and control the mixture by planetary ball milling for 3~12h, and control the particle size D50 of the slurry to be 1~5μm; then use spray granulation process to make spray granulated powder.

[0073] S4. Press the powder after spray granulation in step S3 into a mold, and then sinter it in an air atmosphere at 1700℃ to obtain a high-strength ceramic material with high thermal shock resistance.

[0074] Example 3

[0075] A high-strength ceramic material with high thermal shock resistance, the raw material composition of which is shown in Table 1;

[0076] The preparation method includes the following steps:

[0077] S1. Weigh the appropriate ingredients;

[0078] S2. Ball mill and mix the ingredients from step S1 until homogeneous, then dry them;

[0079] S3. Add polyvinyl alcohol (PVA) binder and water to the powder dried in step S2, mix and slurry, and control the mixture by planetary ball milling for 3~12h, and control the particle size D50 of the slurry to be 1~5μm; then use spray granulation process to make spray granulated powder.

[0080] S4. Press the powder after spray granulation in step S3 into a mold, and then sinter it in an air atmosphere at 1650℃ to obtain a high-strength ceramic material with high thermal shock resistance.

[0081] Example 4

[0082] A high-strength ceramic material with high thermal shock resistance is prepared using the raw material composition shown in Table 1, and the preparation method is the same as in Example 1.

[0083] Comparative Example 1

[0084] A ceramic material, the raw material composition of which is shown in Table 1; the preparation method is the same as that in Example 1.

[0085] Comparative Example 2

[0086] A ceramic material, the raw material composition of which is shown in Table 1; the preparation method is the same as that in Example 1.

[0087] The ceramic materials prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to performance testing, and the relevant test results are summarized in Table 1.

[0088] Among them: bending strength, the test method is as follows: the ceramic materials obtained from the above experimental examples 1-4, and comparative examples 1 and 2 are tested for three-point bending strength using a universal testing machine in accordance with GBT_6569-2006.

[0089] Thermal shock resistance test method: Test the same specifications of the samples of Examples 1-4 and Comparative Examples 1-2. Place the sample in a 200°C oven and keep it at that temperature for 10 minutes. Then immediately (within 3 seconds) put it into running water at 25±1°C. Then absorb the sample with a bluing agent and observe whether cracks are generated. 100 pieces are tested in each batch. Finally, the percentage of cracked pieces in the total number of tests is counted.

[0090] Table 1

[0091]

[0092] As can be seen, the ceramic materials prepared in Examples 1-4 have a flexural strength of 358-391 MPa and 100% crack resistance under water cooling at 200℃. In contrast, the ceramic material in Comparative Example 1, containing only alumina, has a flexural strength of 410 MPa, but all of it cracks under water cooling at 200℃. In Comparative Example 2, without cordierite, sintering aid, or pore-forming agent, the ceramic material has a flexural strength of 353 MPa and 80% crack resistance under water cooling at 200℃.

[0093] from Figure 2 As can be seen, the ceramic body of Example 1 has a uniform and appropriate amount of microporous structure inside, which can improve the resistance of the ceramic body to thermal shock.

[0094] from Figure 3 As can be seen, the ceramic body structure of Comparative Example 1 is too dense, which is not conducive to thermal shock.

[0095] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A high-strength ceramic material with high thermal shock resistance, characterized in that, Includes the following components by weight percentage: Al2O3: 92~96%, SiO2: 1~5%, CaO: 0.5~1.5%, MgO: 0.05~0.5%; The high-strength, high-thermal-shock-resistant ceramic material has micropores of 5–30 μm distributed in its cross-section, with a porosity of 1%–3%. The high-strength, high-thermal-shock-resistant ceramic material comprises, by weight, the following raw materials: a parts Al2O3, b parts SiO2, c parts CaCO3, d parts CaSiO3, e parts cordierite, f parts pore-forming agent, g parts sintering aid; a=92~96, b=1~4, c=0.5~1, d=0.2~1, e=0.5~2, f=0.2~1, g=0.5~1, and a+b+c+d+e+f+g=100; The sintering aid is a CaO-MgO-SiO2 glass.

2. The high-strength, high-thermal-shock-resistant ceramic material according to claim 1, characterized in that, The high-strength, high-thermal-shock-resistant ceramic material has a flexural strength of 350–390 MPa and its thermal shock resistance allows it to withstand water cooling at 200°C without cracking.

3. The method for preparing high-strength, high-thermal-shock-resistant ceramic materials according to any one of claims 1-2, characterized in that, Includes the following steps: S1. Prepare the ingredients by weighing a parts Al2O3, b parts SiO2, c parts CaCO3, d parts CaSiO3, e parts cordierite, f parts pore-forming agent, and g parts sintering aid. Wherein: a = 92~96, b = 1~4, c = 0.5~1, d = 0.2~1, e = 0.5~2, f = 0.2~1, g = 0.5~1, and a+b+c+d+e+f+g = 100; the sintering aid is a CaO-MgO-SiO2 glass system; S2. Ball mill and mix the ingredients from step S1 until homogeneous, then dry them; S3. The powder dried in step S2 is mixed with binder and water to form a slurry, and then spray granulation is performed to produce spray granulated powder. S4. Press the powder after spray granulation in step S3 into a mold, and then sinter it in an air atmosphere to obtain a high-strength ceramic material with high thermal shock resistance.

4. The preparation method according to claim 3, characterized in that, In step S1, the pore-forming agent is one or more of carbon powder, graphite powder, PMMA, PVB, and starch, and the particle size of the pore-forming agent is 1-10 μm.

5. The preparation method according to claim 3, characterized in that, In step S1, the particle size of the CaO-MgO-SiO2 glass is 2-3 μm.

6. The preparation method according to claim 3, characterized in that, In step S2, the ingredients are subjected to planetary ball milling for 3 to 12 hours, and the particle size D50 of the slurry is controlled to be 1 to 5 μm.

7. The preparation method according to claim 3, characterized in that, In step S3, the adhesive is a polyvinyl alcohol (PVA) adhesive.

8. The preparation method according to claim 4, characterized in that, In step S3, the sintering temperature in the air atmosphere is 1600℃~1700℃.

9. The preparation method according to claim 3, characterized in that, The softening temperature of the CaO-MgO-SiO2 glass is 650–750℃.

10. The application of a high-strength, high-thermal-shock-resistant ceramic material as described in any one of claims 1-2 or a high-strength, high-thermal-shock-resistant ceramic material prepared by the preparation method described in any one of claims 3-9, characterized in that, High-strength, high-thermal-shock-resistant ceramic materials are used in the production of high-strength, heat-resistant seals and / or structural components.

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