High thermal shock resistant ceramic material and its preparation method

Abstract

The present invention discloses a high thermal shock resistance ceramic material and a preparation method thereof, which comprise the following raw materials in parts by weight: 100 parts of alumina powder, 3 - 18 parts of pretreated mullite fiber, 2 - 8 parts of binder, 2 - 5 parts of dispersant, and 2 - 8 parts of mineralizer, wherein the mineralizer is composed of 1 - 4 parts of aluminum fluoride and 1 - 4 parts of magnesium fluoride. By pretreating the mullite fiber, a low-expansion composite fiber component is formed at high temperature, and a mineralizer is introduced to stabilize the fiber strength and structure at high temperature. The alumina composite granulated powder is prepared by a spray granulation process. The mullite fiber forms a network structure in the ceramic material and has a smaller thermal expansion coefficient, effectively absorbing thermal stress, so that the ceramic material does not crack when cooled to room temperature after heating and can withstand a higher temperature change, effectively improving the thermal shock resistance of the ceramic material. At the same time, the alumina powder as the main component ensures high hardness and strength, and the addition of the mullite fiber improves the toughness and impact resistance of the material.

Description

Technical Field

[0001] The present invention relates to the technology of ceramic materials, and in particular to a high thermal shock resistance ceramic material and a preparation method thereof. Background Art

[0002] Aluminum oxide ceramic is a ceramic material mainly composed of aluminum oxide (Al2O3). Due to its excellent physical and chemical properties, it is widely used in many fields. It is divided into varieties such as 99 porcelain, 95 porcelain, 90 porcelain, 85 porcelain according to different Al2O3 contents. Among them, 99 aluminum oxide porcelain materials are used to make high-temperature crucibles, refractory furnace tubes and special wear-resistant materials; 95 aluminum oxide porcelain is mainly used as corrosion-resistant and wear-resistant components; in 85 porcelain, due to the addition of part of talc, the electrical properties and mechanical strength are improved, and it can be sealed with metals such as molybdenum, niobium, and tantalum, and some are used as devices for electro-vacuum devices.

[0003] Aluminum oxide ceramic can be used in the atmosphere up to 1650 degrees Celsius and in a vacuum environment up to 2000 degrees Celsius. At 1000 degrees Celsius, it can still maintain 50% of the tensile strength at room temperature. This characteristic makes its application in high-temperature environments possible, such as for manufacturing spark plugs, high-temperature crucibles, refractory furnace tubes, etc.

[0004] Aluminum oxide ceramic materials are widely used in MCH heating elements, but there is a problem that the thermal shock resistance of the ceramic materials is poor, and cracking is likely to occur during the process of cooling to room temperature after heating, which limits their performance and service life. Therefore, improving the thermal shock resistance of ceramic materials has become a key issue. Summary of the Invention

[0005] In view of this, aiming at the deficiencies existing in the prior art, the main purpose of the present invention is to provide a high thermal shock resistance ceramic material and a preparation method thereof, which can effectively solve the problem of poor thermal shock resistance of existing ceramic materials.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A high thermal shock resistance ceramic material, comprising the following raw materials in parts by weight: 100 parts of aluminum oxide powder, 3 - 18 parts of pretreated mullite fiber, 2 - 8 parts of binder, 2 - 5 parts of dispersant, and 2 - 8 parts of mineralizer, and the mineralizer is composed of 1 - 4 parts of aluminum fluoride and 1 - 4 parts of magnesium fluoride.

[0008] As a preferred scheme, the purity of the aluminum oxide powder is 99.5%, and the average particle size is 2 - 4μm.

[0009] As a preferred scheme, the pretreated mullite fiber is composed of mullite fiber and alumina fiber, wherein the mass content of mullite fiber is 30 - 50%, the purity is 98%, the diameter is 1 - 6μm, and the length is 100 - 300μm.

[0010] As a preferred solution, the binder is polyvinyl alcohol with a concentration of 5-10%.

[0011] As a preferred embodiment, the dispersant consists of 1-3 parts of polyacrylamide and 1-2 parts of polyethylene glycol.

[0012] A method for preparing a high thermal shock ceramic material comprises the following steps:

[0013] (1) Mullite fiber pretreatment: soak the mullite fiber in phosphoric acid + zirconium oxychloride solution for 1-2 hours, then rinse with 50-60°C saturated calcium hydroxide + barium hydroxide solution, and then dry for use;

[0014] (2) Mixing and stirring: Add alumina powder, pretreated mullite fiber, binder, dispersant and mineralizer into a stirring device according to proportions and mix them thoroughly for later use;

[0015] (3) Spray granulation: The mixed materials are subjected to spray granulation treatment for standby use;

[0016] (4) Molding: The powder obtained by the spray granulation is formed into a ceramic body of a desired shape by dry pressing or isostatic pressing;

[0017] (5) Sintering: The ceramic body is sintered at 1550-1620°C to obtain a high thermal shock resistance ceramic material.

[0018] As a preferred solution, the phosphoric acid concentration in the phosphoric acid + zirconium oxychloride solution is 0.5-3%, and the zirconium oxychloride concentration is 2-10%.

[0019] As a preferred solution, during the spray granulation, the inlet temperature is controlled at 180-220°C, and the outlet temperature is controlled at 80-120°C.

[0020] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, it can be seen from the above technical solution that:

[0021] By pre-treating mullite fibers, a low-expansion composite fiber component is formed at high temperature, and a mineralizer is introduced to stabilize the fiber strength and structure at high temperature. Alumina composite granulated powder is prepared by spray granulation process. The mullite fibers form a network structure in the ceramic material and have a smaller coefficient of thermal expansion, effectively absorbing thermal stress, enabling the ceramic material to not crack when cooled from a heated state to room temperature, and being able to withstand higher temperature changes, effectively improving the thermal shock resistance of the ceramic material. At the same time, the alumina powder as the main component ensures high hardness and high strength, and the addition of mullite fibers improves the toughness and impact resistance of the material. This product is applicable to MCH heating elements, meeting their high requirements for the thermal shock resistance of ceramic materials, and improving the performance and reliability of MCH heating elements. Detailed implementation mode

[0022] The present invention discloses a ceramic material with high thermal shock resistance, which comprises the following raw materials in parts by weight: 100 parts of alumina powder, 3 - 18 parts of pre-treated mullite fibers, 2 - 8 parts of binder, 2 - 5 parts of dispersant, and 2 - 8 parts of mineralizer, wherein the mineralizer consists of 1 - 4 parts of aluminum fluoride and 1 - 4 parts of magnesium fluoride.

[0023] The alumina powder, as the main component, provides the high hardness and high-temperature resistance of the ceramic material. The purity of the alumina powder is 99.5%, and the average particle size is 2 - 4μm. The pre-treated mullite fibers are composed of mullite fibers and alumina fibers, wherein the mass content of mullite fibers is 30 - 50%, the purity is 98%, the diameter is 1 - 6μm, and the length is 100 - 300μm. The mullite fibers are uniformly dispersed in the alumina powder, which can effectively improve the thermal shock resistance of the ceramic material. Mullite fibers have excellent properties such as high temperature resistance, oxidation resistance, and low coefficient of thermal expansion, forming a network structure in the ceramic material and enhancing the toughness and thermal shock resistance of the material. The binder is polyvinyl alcohol or carboxymethyl cellulose, etc., with a concentration of 5 - 10%. The binder is used to bond the alumina powder and mullite fibers together to form a stable composite granulated powder. The dispersant consists of 1 - 3 parts of polyacrylamide and 1 - 2 parts of polyethylene glycol. Selecting two dispersants promotes the uniform dispersion of mullite fibers in the alumina powder and improves the performance stability of the composite granulated powder.

[0024] The present invention also discloses a preparation method of the above-mentioned ceramic material with high thermal shock resistance, which comprises the following steps:

[0025] (1) Mullite fiber pretreatment: Immerse the mullite fiber in a phosphoric acid + zirconium oxychloride solution for activation for 1 - 2 h, then rinse it with a saturated calcium hydroxide + barium hydroxide solution at 50 - 60 °C, and then dry it for standby. The concentration of phosphoric acid in the phosphoric acid + zirconium oxychloride solution is 0.5 - 3%, and the concentration of zirconium oxychloride is 2 - 10%. The phosphoric acid + zirconium oxychloride solution activates and disperses the fiber, promotes the combination with alumina ceramics, and during the high-temperature sintering process of the fiber, the residual solution on the surface will form a negative-expansion Ca 1−x Ba x Zr4(PO4)6 compound, reducing the overall expansion coefficient of the material and thus improving the thermal shock resistance of the material.

[0026] (2) Mixing and stirring: Add alumina powder, pretreated mullite fiber, binder, dispersant, and mineralizer in proportion to a stirring device for sufficient mixing and stirring for standby. The stirring time and speed are adjusted according to the actual situation to ensure uniform mixing of each component.

[0027] (3) Spray granulation: Subject the mixed material to spray granulation treatment for standby. Set appropriate spray granulation parameters, such as inlet temperature, outlet temperature, atomization pressure, etc. When spray granulating, the inlet temperature is controlled at 180 - 220 °C, and the outlet temperature is controlled at 80 - 120 °C.

[0028] (4) Forming: Use the powder obtained by the above spray granulation to form a ceramic green body of the required shape by methods such as dry pressing or isostatic pressing.

[0029] (5) Sintering: Sinter the ceramic green body at 1550 - 1620 °C to obtain a ceramic material with high thermal shock resistance.

[0030] The following further elaborates on the present invention with multiple examples and comparative examples:

[0031] Example 1:

[0032] This example discloses a ceramic material with high thermal shock resistance, including the following raw materials in parts by weight: 100 parts of alumina powder, 3 parts of pretreated mullite fiber, 4 parts of binder, 2 parts of dispersant, and 3 parts of mineralizer. The mineralizer consists of 1 part of aluminum fluoride and 2 parts of magnesium fluoride.

[0033] The purity of the alumina powder is 99.5%, and the average particle size is 3 μm. The pretreated mullite fiber consists of mullite fiber and alumina fiber, among which the mass content of mullite fiber is 35%, the purity is 98%, the diameter is 5 μm, and the length is 100 μm. The binder is polyvinyl alcohol with a concentration of 5%. The dispersant consists of 1 part of polyacrylamide and 1 part of polyethylene glycol.

[0034] This embodiment also discloses a preparation method of the aforementioned high thermal shock resistant ceramic material, which includes the following steps:

[0035] (1) Mullite fiber pretreatment: Soak the mullite fiber in a phosphoric acid + zirconium hydroxide solution for activation for 1.3 h, then rinse it with a 52°C saturated calcium hydroxide + barium hydroxide solution, and then dry it for standby. The concentration of phosphoric acid in the phosphoric acid + zirconium hydroxide solution is 0.8%, and the concentration of zirconium hydroxide is 7%.

[0036] (2) Mixing and stirring: Add alumina powder, pretreated mullite fiber, binder, dispersant, and mineralizer in proportion to a stirring device for sufficient mixing and stirring for standby. The stirring time and speed are adjusted according to the actual situation to ensure uniform mixing of each component.

[0037] (3) Spray granulation: Perform spray granulation on the mixed material for standby. Set appropriate spray granulation parameters, such as inlet temperature, outlet temperature, atomization pressure, etc. The inlet temperature during spray granulation is controlled at 190°C, and the outlet temperature is controlled at 120°C.

[0038] (4) Forming: Use the powder obtained by the above spray granulation to form a ceramic green body with the required shape by methods such as dry pressing or isostatic pressing.

[0039] (5) Sintering: Sinter the ceramic green body at 1600°C to obtain a high thermal shock resistant ceramic material.

[0040] Example 2:

[0041] This embodiment discloses a high thermal shock resistant ceramic material, which includes the following raw materials in parts by weight: 100 parts of alumina powder, 15 parts of pretreated mullite fiber, 2 parts of binder, 2.1 parts of dispersant, and 5 parts of mineralizer. The mineralizer is composed of 2 parts of aluminum fluoride and 3 parts of magnesium fluoride.

[0042] The purity of the alumina powder is 99.5%, and the average particle size is 2 μm. The pretreated mullite fiber is composed of mullite fiber and alumina fiber, among which the mass content of mullite fiber is 35%, the purity is 98%, the diameter is 2 μm, and the length is 150 μm. The binder is polyvinyl alcohol with a concentration of 9%. The dispersant is composed of 1 part of polyacrylamide and 1.1 parts of polyethylene glycol.

[0043] This embodiment also discloses a preparation method of the aforementioned high thermal shock resistant ceramic material, which includes the following steps:

[0044] (1) Pretreatment of mullite fiber: The mullite fiber was activated by soaking in phosphoric acid + zirconium oxychloride solution for 1.3 hours, then rinsed with 52°C saturated calcium hydroxide + barium hydroxide solution, and then dried for use. The phosphoric acid concentration in the phosphoric acid + zirconium oxychloride solution was 1%, and the zirconium oxychloride concentration was 2%.

[0045] (2) Mixing and stirring: Add alumina powder, pretreated mullite fiber, binder, dispersant and mineralizer into a mixing device in proportion and mix them thoroughly for later use. The stirring time and speed are adjusted according to the actual situation to ensure that all components are evenly mixed.

[0046] (3) Spray granulation: The mixed materials are subjected to spray granulation for standby use. Appropriate spray granulation parameters are set, such as inlet temperature, outlet temperature, atomization pressure, etc. During the spray granulation, the inlet temperature is controlled at 190°C and the outlet temperature is controlled at 120°C.

[0047] (4) Molding: The powder obtained by the spray granulation is formed into a ceramic body of a desired shape by dry pressing or isostatic pressing.

[0048] (5) Sintering: The ceramic body is sintered at 1550°C to obtain a high thermal shock resistance ceramic material.

[0049] Embodiment 3:

[0050] This embodiment discloses a high thermal shock ceramic material, comprising the following raw materials in parts by weight: 100 parts of alumina powder, 5 parts of pretreated mullite fibers, 7 parts of a binder, 3.6 parts of a dispersant, and 4 parts of a mineralizer, wherein the mineralizer is composed of 3 parts of aluminum fluoride and 1 part of magnesium fluoride.

[0051] The purity of the alumina powder is 99.5%, and the average particle size is 2.5 μm. The pretreated mullite fiber is composed of mullite fiber and alumina fiber, wherein the mass content of the mullite fiber is 35%, the purity is 98%, the diameter is 3 μm, and the length is 250 μm. The binder is polyvinyl alcohol with a concentration of 7%. The dispersant is composed of 2 parts of polyacrylamide and 1.6 parts of polyethylene glycol.

[0052] This embodiment also discloses a method for preparing the aforementioned high thermal shock ceramic material, comprising the following steps:

[0053] (1) Pretreatment of mullite fiber: The mullite fiber was activated by soaking in phosphoric acid + zirconium oxychloride solution for 1.3 hours, then rinsed with 52°C saturated calcium hydroxide + barium hydroxide solution, and then dried for use. The phosphoric acid concentration in the phosphoric acid + zirconium oxychloride solution was 3%, and the zirconium oxychloride concentration was 5%.

[0054] (2) Mixing and stirring: Add alumina powder, pretreated mullite fiber, binder, dispersant, and mineralizer into a stirring device according to the proportion for sufficient mixing and stirring for standby. The stirring time and speed are adjusted according to the actual situation to ensure uniform mixing of each component.

[0055] (3) Spray granulation: Perform spray granulation on the mixed material for standby. Set appropriate spray granulation parameters, such as inlet temperature, outlet temperature, atomization pressure, etc. The inlet temperature during spray granulation is controlled at 190 °C, and the outlet temperature is controlled at 120 °C.

[0056] (4) Forming: Use the powder obtained by the above spray granulation to form a ceramic green body with the required shape by methods such as dry pressing or isostatic pressing.

[0057] (5) Sintering: Sinter the ceramic green body at 1610 °C to obtain a high thermal shock resistance ceramic material.

[0058] Example 4:

[0059] This example discloses a high thermal shock resistance ceramic material, including the following raw materials in parts by weight: 100 parts of alumina powder, 10 parts of pretreated mullite fiber, 8 parts of binder, 5 parts of dispersant, and 2 parts of mineralizer. The mineralizer is composed of 1 part of aluminum fluoride and 1 part of magnesium fluoride.

[0060] The purity of the alumina powder is 99.5%, and the average particle size is 3.5 μm. The pretreated mullite fiber is composed of mullite fiber and alumina fiber, among which the mass content of mullite fiber is 35%, the purity is 98%, the diameter is 6 μm, and the length is 200 μm. The binder is polyvinyl alcohol with a concentration of 6%. The dispersant is composed of 3 parts of polyacrylamide and 2 parts of polyethylene glycol.

[0061] This example also discloses a preparation method of the above high thermal shock resistance ceramic material, including the following steps:

[0062] (1) Pretreatment of mullite fiber: Soak the mullite fiber in a phosphoric acid + zirconium oxychloride solution for activation for 1.3 h, then rinse with a 52 °C saturated calcium hydroxide + barium hydroxide solution, and then dry for standby. The concentration of phosphoric acid in the phosphoric acid + zirconium oxychloride solution is 2%, and the concentration of zirconium oxychloride is 9%.

[0063] (2) Mixing and stirring: Add alumina powder, pretreated mullite fiber, binder, dispersant, and mineralizer into a stirring device according to the proportion for sufficient mixing and stirring for standby. The stirring time and speed are adjusted according to the actual situation to ensure uniform mixing of each component.

[0064] (3) Spray granulation: The mixed materials are subjected to spray granulation for standby use. Appropriate spray granulation parameters are set, such as inlet temperature, outlet temperature, atomization pressure, etc. During the spray granulation, the inlet temperature is controlled at 190°C and the outlet temperature is controlled at 120°C.

[0065] (4) Molding: The powder obtained by the spray granulation is formed into a ceramic body of a desired shape by dry pressing or isostatic pressing.

[0066] (5) Sintering: The ceramic body is sintered at 1620°C to obtain a high thermal shock resistance ceramic material.

[0067] Embodiment 5:

[0068] This embodiment discloses a high thermal shock ceramic material, comprising the following raw materials in parts by weight: 100 parts of alumina powder, 18 parts of pretreated mullite fibers, 5 parts of a binder, 3 parts of a dispersant, and 7 parts of a mineralizer, wherein the mineralizer is composed of 3 parts of aluminum fluoride and 4 parts of magnesium fluoride.

[0069] The purity of the alumina powder is 99.5%, and the average particle size is 4 μm. The pretreated mullite fiber is composed of mullite fiber and alumina fiber, wherein the mass content of the mullite fiber is 35%, the purity is 98%, the diameter is 4 μm, and the length is 300 μm. The binder is polyvinyl alcohol with a concentration of 8%. The dispersant is composed of 1.5 parts of polyacrylamide and 1.5 parts of polyethylene glycol.

[0070] This embodiment also discloses a method for preparing the aforementioned high thermal shock ceramic material, comprising the following steps:

[0071] (1) Pretreatment of mullite fiber: The mullite fiber was activated by soaking in phosphoric acid + zirconium oxychloride solution for 1.3 hours, then rinsed with 52°C saturated calcium hydroxide + barium hydroxide solution, and then dried for use. The phosphoric acid concentration in the phosphoric acid + zirconium oxychloride solution was 0.5%, and the zirconium oxychloride concentration was 10%.

[0072] (2) Mixing and stirring: Add alumina powder, pretreated mullite fiber, binder, dispersant and mineralizer into a mixing device in proportion and mix them thoroughly for later use. The stirring time and speed are adjusted according to the actual situation to ensure that all components are evenly mixed.

[0073] (3) Spray granulation: The mixed materials are subjected to spray granulation for standby use. Appropriate spray granulation parameters are set, such as inlet temperature, outlet temperature, atomization pressure, etc. During the spray granulation, the inlet temperature is controlled at 190°C and the outlet temperature is controlled at 120°C.

[0074] (4) Shaping: The powder obtained by the above spray granulation is made into a ceramic green body of the required shape by methods such as dry pressing or isostatic pressing.

[0075] (5) Sintering: The ceramic green body is sintered at 1580 °C to obtain a ceramic material with high thermal shock resistance.

[0076] Example 6:

[0077] This example discloses a ceramic material with high thermal shock resistance, including the following raw materials in parts by weight: 100 parts of alumina powder, 8 parts of pretreated mullite fiber, 6 parts of binder, 3.8 parts of dispersant, and 8 parts of mineralizer. The mineralizer consists of 4 parts of aluminum fluoride and 4 parts of magnesium fluoride.

[0078] The purity of the alumina powder is 99.5%, and the average particle size is 3 μm. The pretreated mullite fiber consists of mullite fiber and alumina fiber, among which the mass content of mullite fiber is 35%, the purity is 98%, the diameter is 1 μm, and the length is 180 μm. The binder is polyvinyl alcohol with a concentration of 10%. The dispersant consists of 2.5 parts of polyacrylamide and 1.3 parts of polyethylene glycol.

[0079] This example also discloses a preparation method of the above-mentioned ceramic material with high thermal shock resistance, including the following steps:

[0080] (1) Pretreatment of mullite fiber: The mullite fiber is soaked and activated in a phosphoric acid + zirconium oxychloride solution for 1.3 h, then rinsed with a 52 °C saturated calcium hydroxide + barium hydroxide solution, and then dried for standby. The concentration of phosphoric acid in the phosphoric acid + zirconium oxychloride solution is 2.5%, and the concentration of zirconium oxychloride is 8%.

[0081] (2) Mixing and stirring: The alumina powder, pretreated mullite fiber, binder, dispersant, and mineralizer are added to the stirring equipment according to the ratio for sufficient mixing and stirring for standby. The stirring time and speed are adjusted according to the actual situation to ensure uniform mixing of each component.

[0082] (3) Spray granulation: The mixed material is subjected to spray granulation for standby. Appropriate spray granulation parameters are set, such as inlet temperature, outlet temperature, atomization pressure, etc. The inlet temperature during spray granulation is controlled at 190 °C, and the outlet temperature is controlled at 120 °C.

[0083] (4) Shaping: The powder obtained by the above spray granulation is made into a ceramic green body of the required shape by methods such as dry pressing or isostatic pressing.

[0084] (5) Sintering: The ceramic green body is sintered at 1590 °C to obtain a ceramic material with high thermal shock resistance.

[0085] Comparative Example 1:

[0086] The difference between the comparative example and the above-mentioned Example 4 is as follows: In this comparative example, traditional 95 alumina ceramics are used. The rest of the content of this comparative example is the same as that of Example 4 and will not be elaborated here.

[0087] Comparative Example 2:

[0088] The difference between the comparative example and the above-mentioned Example 4 is as follows: In this comparative example, the above-mentioned mullite fiber pretreatment method is not used. The rest of the content of this comparative example is the same as that of Example 4 and will not be elaborated here.

[0089] Comparative Example 3:

[0090] The difference between the comparative example and the above-mentioned Example 4 is as follows: In this comparative example, no mineralizer is added. The rest of the content of this comparative example is the same as that of Example 4 and will not be elaborated here.

[0091] Next, the strength tests are carried out on the ceramic materials obtained in the above-mentioned various examples and comparative examples. The strength test method is a commonly used conventional strength test method. The strength test results are shown in the following table:

[0092]

[0093] As can be seen from the above table, from Examples 1, 2, 3, 4 and Comparative Example 1, it can be known that the traditional 95 alumina ceramics have low strength, serious strength loss under air cooling, and will crack after being rapidly water-cooled when heated to 210 - 220 °C, which affects the service temperature range and safety of the MCH heating element. From Examples 1, 2, 3, 4 and Comparative Example 2, it can be known that by means of the special treatment method of mullite fibers, the maximum thermal shock temperature of the final ceramic heating element can be increased. The fiber rinsing process increases the dispersibility of the fibers, and the residual substances form low-expansion components again at high temperatures. From Examples 1, 2, 4, 5 and Comparative Example 3, it can be known that by adding a mineralizer in proportion, the maximum thermal shock temperature of the final ceramic heating element can be increased. During the high-temperature sintering process, the mineralizer promotes the further formation of mullite fibers and stabilizes the mullite fiber structure.

[0094] Compared with the traditional 95 alumina ceramics, the present invention has significant advantages: The traditional 95 alumina ceramics will crack after being rapidly water-cooled when heated to 210 - 220 °C, which affects the service temperature range and safety of the MCH heating element. After adding mullite fibers to the ceramic material of the present invention, it can be rapidly water-cooled at 260 - 250 °C without cracking, and the thermal shock performance is greatly improved.

[0095] The design focus of the present invention lies in: through the pretreatment of mullite fibers, a low-expansion composite fiber component is formed at high temperature, and a mineralizer is introduced to stabilize the fiber strength and structure at high temperature. Alumina composite granulated powder is prepared by spray granulation process. The mullite fibers form a network structure in the ceramic material and have a smaller coefficient of thermal expansion, effectively absorbing thermal stress, enabling the ceramic material not to crack when cooled from the heated state to room temperature, and being able to withstand higher temperature changes, effectively improving the thermal shock resistance of the ceramic material. At the same time, the alumina powder as the main component ensures high hardness and strength, and the addition of mullite fibers improves the toughness and impact resistance of the material. This product is applicable to MCH heating elements, meeting their high requirements for the thermal shock resistance of ceramic materials, and improving the performance and reliability of MCH heating elements.

[0096] The above is only a preferred embodiment of the present invention, and does not impose any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A high thermal shock resistance ceramic material, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of alumina powder, 3-18 parts of pretreated mullite fibers, 2-8 parts of a binder, 2-5 parts of a dispersant and 2-8 parts of a mineralizer, wherein the mineralizer is composed of 1-4 parts of aluminum fluoride and 1-4 parts of magnesium fluoride; pretreatment of the mullite fibers: soaking the mullite fibers in a phosphoric acid + zirconium oxychloride solution for activation for 1-2 hours, then rinsing with a 50-60° C. saturated calcium hydroxide + barium hydroxide solution, and then drying for standby use; the phosphoric acid concentration in the phosphoric acid + zirconium oxychloride solution is 0.5-3%, and the zirconium oxychloride concentration is 2-10%.

2. The high thermal shock resistance ceramic material according to claim 1, characterized in that: The aluminum oxide powder has a purity of 99.5% and an average particle size of 2-4 μm.

3. The high thermal shock resistance ceramic material according to claim 1, characterized in that: The pretreated mullite fiber consists of mullite fiber and alumina fiber, wherein the mass content of the mullite fiber is 30-50%, the purity is 98%, the diameter is 1-6 μm, and the length is 100-300 μm.

4. The high thermal shock resistance ceramic material according to claim 1, characterized in that: The binder is polyvinyl alcohol with a concentration of 5-10%.

5. The high thermal shock resistance ceramic material according to claim 1, characterized in that: The dispersant consists of 1-3 parts of polyacrylamide and 1-2 parts of polyethylene glycol.

6. A method for preparing a high thermal shock ceramic material according to any one of claims 1 to 5, characterized in that: The following steps are included: (1) Mullite fiber pretreatment: soak the mullite fiber in phosphoric acid + zirconium oxychloride solution for 1-2 hours, then rinse with 50-60°C saturated calcium hydroxide + barium hydroxide solution, and then dry for use; (2) Mixing and stirring: Add alumina powder, pretreated mullite fiber, binder, dispersant and mineralizer into a stirring device according to proportions and mix them thoroughly for later use; (3) Spray granulation: The mixed materials are subjected to spray granulation treatment for standby use; (4) Molding: The powder obtained by the spray granulation is formed into a ceramic body of a desired shape by dry pressing or isostatic pressing; (5) Sintering: The ceramic body is sintered at 1550-1620°C to obtain a high thermal shock resistance ceramic material.

7. The method for preparing a high thermal shock ceramic material according to claim 6, characterized in that: The phosphoric acid concentration in the phosphoric acid + zirconium oxychloride solution is 0.5-3%, and the zirconium oxychloride concentration is 2-10%.

8. The method for preparing a high thermal shock ceramic material according to claim 6, characterized in that: During the spray granulation, the inlet temperature is controlled at 180-220°C, and the outlet temperature is controlled at 80-120°C.

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