Resistance-adjustable carbon ceramic raw material, material and preparation method thereof

Abstract

The invention relates to a resistance-adjustable carbon ceramic raw material, a material and a preparation method thereof. The resistance-adjustable carbon ceramic material is prepared from the following raw materials in parts by weight: 60-70 parts of aluminum oxide; 20-25 parts of silicon dioxide; 5 to 10 parts of graphite; 1-5 parts of carbon black; 3-6 parts of a sintering aid; wherein the sintering aid is calcium carbonate. The aluminum oxide and the silicon dioxide are used as the framework, the graphite and the carbon black are used as the conductive filler, and the calcium carbonate is used as the sintering aid, so that the accurate and linear adjustment of the resistance value of the carbon ceramic material is realized by changing the contents of the graphite and the carbon black. According to the formula, the defects of high resistance value dispersity and poor performance reproducibility caused by component fluctuation and impurity introduction of traditional natural raw materials are effectively overcome, and a foundation is laid for obtaining stable and uniform phase composition and microstructure, so that the electrical property stability, designability and long-term use reliability of the material are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of carbon ceramic linear resistor technology, specifically relating to a raw material, material and preparation method of a carbon ceramic material with adjustable resistance. Background Technology

[0002] Carbon ceramic materials, possessing the electrical conductivity and thermal shock resistance of carbon materials combined with the high strength and hardness of ceramic materials, have significant application value in power equipment fields such as high-temperature conductive components and circuit breaker closing resistors. An ideal closing resistor material needs stable resistance-temperature characteristics, good thermal shock resistance, and controllable resistivity to withstand frequent voltage surges and thermal load cycles during high-voltage switching. By adjusting the carbon content and optimizing the conductive network structure, the resistance performance of carbon ceramic materials can be effectively controlled, making it a research hotspot in this field.

[0003] However, existing carbon ceramic materials mostly use natural minerals such as clay and bauxite as ceramic matrix raw materials. Their complex composition and high impurity content lead to uneven distribution of glass and crystalline phases in the sintered material, unstable conductive pathways, and large dispersion and poor repeatability of resistivity values. In addition, impurity elements in natural raw materials are prone to triggering unexpected reactions at high temperatures, affecting the formation and growth of key crystalline phases such as mullite, further causing uncontrollable microstructure of the material, which restricts the precise design and long-term stability of the resistivity performance of carbon ceramics. Summary of the Invention

[0004] To address the problems of large resistance dispersion and poor performance reproducibility in existing carbon ceramic materials, this invention provides a raw material for a carbon ceramic material with adjustable resistance, comprising the following components by weight: 60-70 parts alumina; 20-25 parts silicon dioxide; 5-10 parts graphite; 1-5 parts carbon black; and 3-6 parts sintering aid; wherein the sintering aid is calcium carbonate.

[0005] Preferably, the raw materials satisfy one or more of the following: The alumina has a purity of not less than 99.98% and a particle size range of 250–450 μm; The purity of the silica is not less than 99.95%, and the particle size range is 1 to 30 μm; The graphite is isostatically pressed graphite with a carbon content of not less than 99.9% and a particle size range of 1–40 μm; The carbon black is conductive carbon black with an oil absorption value of 0.9–1.5 mL / g and a particle size range of 30–500 nm. The calcium carbonate has a purity of not less than 99.5% and a particle size range of 1–30 μm.

[0006] Preferably, the raw materials further comprise 1-3 parts of binder and 1-2 parts of dispersant; The adhesive is a polyvinyl alcohol aqueous solution with a concentration of 1~6wt%; The dispersant is an aqueous solution of sodium methylenebisnaphthyl sulfonate with a concentration of 0.1~2 g / L.

[0007] This invention also provides a method for preparing a carbon ceramic material with adjustable resistance, comprising the following steps: Weigh out the raw material powders of alumina, silicon dioxide, graphite, carbon black and sintering aid according to the composition of the raw materials, and ball mill them together to obtain a mixed powder. Add binder, dispersant and pure water to the mixed powder, stir and mix well, spray granulation to obtain granulated powder; The granulated powder is pressed into a ceramic blank. The ceramic blank is sintered to obtain the adjustable resistance carbon ceramic material.

[0008] Preferably, the ball milling and mixing specifically includes: loading the raw material powder and agate grinding balls into a ball mill jar at a mass ratio of 1:1 to 3:1, ball milling at 90 to 150 r / min for 24 to 36 hours, and separating the raw material powder and agate balls using a 60 to 120 mesh sieve.

[0009] Preferably, the step of adding a binder, dispersant, and pure water to the mixed powder and stirring to mix thoroughly specifically includes: Pure water and the mixed powder are added into the mixing chamber at a mass ratio of 1:2 to 1:3.2 to obtain a slurry; The dispersant and the slurry are added to the mixing chamber at a mass ratio of 1:100 to 2:100. The binder and the slurry are added to the mixing chamber in two batches at a mass ratio of 1:100 to 3:100, each batch being half of the total volume. The mixture is stirred at 10 to 40 r / min for 4 to 6 hours.

[0010] Preferably, the spray granulation drying temperature is 110–130°C.

[0011] Preferably, the pressing pressure is 100-150 MPa and the holding time is 60-70 s.

[0012] Preferably, the sintering treatment specifically includes: heating the ceramic blank to 1300℃~1450℃, holding it at that temperature for 2~6 hours, and then cooling it to room temperature in the furnace; the sintering process is carried out under a nitrogen atmosphere with a pressure of 0.3~1.0 kPa.

[0013] The present invention also provides a carbon ceramic material with adjustable resistance prepared by the aforementioned preparation method.

[0014] Preferably, the porosity of the adjustable-resistance carbon ceramic material is 20%–35%; and / or The bulk density of the adjustable-resistance carbon ceramic material is 1.9–2.8 g / cm³. 3 ; and / or The resistivity of the adjustable carbon ceramic material is 0.2–1000 Ω·cm; and / or The temperature coefficient of resistance of the adjustable carbon ceramic material is -0.2 to 0.1% / ℃; and / or The thermal conductivity of the adjustable-resistance carbon ceramic material is 1.5–5 W / (m·K); The flexural strength loss rate of the adjustable-resistance carbon ceramic material is 3-15% within the range of 25-250℃.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The raw materials for the adjustable-resistance carbon ceramic material proposed in this invention comprise the following components by weight: 60-70 parts alumina; 20-25 parts silicon dioxide; 5-10 parts graphite; 1-5 parts carbon black; and 3-6 parts sintering aid, wherein the sintering aid is calcium carbonate. By employing the specific components and proportions described above—using alumina and silicon dioxide as the framework, graphite and carbon black as conductive fillers, and calcium carbonate as the sintering aid—the resistivity of the carbon ceramic material can be precisely and linearly adjusted by changing the content of graphite and carbon black. This formulation effectively overcomes the drawbacks of traditional natural raw materials, such as large resistance dispersion and poor performance reproducibility caused by compositional fluctuations and impurities. It lays the foundation for obtaining a stable and uniform phase composition and microstructure, thereby significantly improving the electrical performance stability, designability, and long-term reliability of the material.

[0016] The present invention proposes a method for preparing a carbon ceramic material with adjustable resistance, comprising the following steps: weighing alumina, silicon dioxide, graphite, carbon black, and sintering aid powders according to their components, ball milling and mixing them to obtain a mixed powder; adding a binder, dispersant, and pure water to the mixed powder, stirring and mixing, and spray granulating to obtain a granulated powder; pressing the granulated powder into a ceramic green body; and sintering the ceramic green body to obtain the carbon ceramic material with adjustable resistance. By first precisely ball milling and mixing the raw materials, and then combining the synergistic addition of binder and dispersant with spray granulation, uniform dispersion and stable coating of each component, especially the nanoscale conductive filler, are achieved, effectively avoiding component segregation and uneven distribution of the conductive network; subsequently, through controllable pressure molding and nitrogen-protected sintering, the densification of the ceramic skeleton and crystal phase development are promoted while inhibiting carbon phase oxidation. This method not only ensures the uniformity and reproducibility of the material's microstructure, but also achieves linear and stable adjustable resistance over a wide range, significantly improving the batch consistency and overall performance reliability of the carbon ceramic material. Attached Figure Description

[0017] Figure 1This is a flowchart of the preparation method of the resistivity-adjustable carbon ceramic material of the present invention; Figure 2 This is a schematic diagram illustrating the heating and cooling process during the sintering of the adjustable-resistance carbon ceramic material of the present invention. Figure 3 This is a schematic diagram of nitrogen pressure control during the sintering process of the adjustable resistance carbon ceramic material of the present invention. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other instances that are improved or modified by those skilled in the art are within the scope of protection of the present invention. It should be understood that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the methods used in the embodiments are conventional methods.

[0019] Example 1 This embodiment provides a carbon ceramic material with adjustable resistance, the raw materials of which, by weight, include: 65 parts alumina, 22 parts silicon dioxide, 7 parts graphite, 3 parts carbon black, and 3 parts calcium carbonate. The alumina has a purity of 99.98% and a particle size of 300 μm; the silicon dioxide has a purity of 99.95% and a particle size of 10 μm; the graphite is isostatically pressed graphite with a carbon content of 99.9% and a particle size of 20 μm; the carbon black is conductive carbon black with an oil absorption value of 1.2 mL / g and a particle size of 100 nm; and the calcium carbonate has a purity of 99.5% and a particle size of 5 μm.

[0020] like Figure 1 The method for preparing the resistivity-adjustable carbon ceramic material in this embodiment includes the following steps: (1) The weighed raw material powder and agate grinding balls are loaded into the ball mill jar at a mass ratio of 1:2 and ball milled at 120 r / min for 30 h. The raw material and agate balls are separated by an 80 mesh sieve. (2) Mix the raw material powder with pure water, binder and dispersant evenly: Put pure water and raw material powder into the mixing chamber at a mass ratio of 1:2.5 to obtain slurry; add dispersant (sodium methylene bis(naphthyl)sulfonate aqueous solution, concentration 0.1 g / L) and slurry into the mixing chamber at a mass ratio of 1.5:100 at once; add binder (polyvinyl alcohol aqueous solution, concentration 3 wt%) and slurry into the mixing chamber in two batches at a mass ratio of 2:100, each batch being 1 / 2 of the total amount; stir at 20 r / min for 5 h; (3) Spray granulation is used for granulation, and the spray drying temperature is 120℃; (4) The granulated powder is loaded into a mold and pressed into shape under a pressure of 120MPa, and the pressure is held for 65s to obtain a ceramic green body; (5) The ceramic blank is placed in a graphite box and placed in an atmosphere sintering furnace. Under a nitrogen atmosphere of 0.5 kPa, the temperature is raised to 1400℃ and held for 4 hours. Then, it is cooled to room temperature with the furnace to obtain a carbon ceramic material with adjustable resistance. Figure 2 , 3 The diagram shown illustrates the temperature rise and fall process and the nitrogen pressure control during the sintering of the adjustable resistance carbon ceramic material.

[0021] The resulting resistivity-adjustable carbon ceramic material has an open porosity of 25.5% and a bulk density of 2.32 g / cm³. 3 It has a resistivity of 12 Ω•cm, a temperature coefficient of resistance of -0.09% / ℃, a thermal conductivity of 3.1 W / (m•K), and a flexural strength loss rate of 5.2% within the range of 25~250℃.

[0022] Example 2 This embodiment provides a carbon ceramic material with adjustable resistance, the raw materials of which, by weight, include: 60 parts alumina, 25 parts silicon dioxide, 8 parts graphite, 2 parts carbon black, and 5 parts calcium carbonate. The alumina has a purity of 99.98% and a particle size of 350 μm; the silicon dioxide has a purity of 99.95% and a particle size of 5 μm; the graphite is isostatically pressed graphite with a carbon content of 99.9% and a particle size of 15 μm; the carbon black is conductive carbon black with an oil absorption value of 1.0 ml / g and a particle size of 200 nm; and the calcium carbonate has a purity of 99.5% and a particle size of 10 μm.

[0023] The method for preparing the resistivity-adjustable carbon ceramic material in this embodiment includes the following steps: (1) The weighed raw material powder and agate grinding balls were loaded into the ball mill jar at a mass ratio of 1:1.5 and ball milled at 100 r / min for 36 h. The raw material and agate balls were separated by a 100 mesh sieve. (2) Mix the raw material powder with pure water, binder and dispersant evenly: Put pure water and raw material powder into the mixing chamber at a mass ratio of 1:3 to obtain slurry; add dispersant (sodium methylene bis(naphthyl)sulfonate aqueous solution, concentration 0.5 g / L) and slurry into the mixing chamber at a mass ratio of 1:100 at once; add binder (polyvinyl alcohol aqueous solution, concentration 1 wt%) and slurry into the mixing chamber in two batches at a mass ratio of 1:100, each batch being 1 / 2 of the total amount; stir at 30 r / min for 4 h; (3) Spray granulation is used for granulation, and the spray drying temperature is 110℃; (4) The granulated powder is loaded into a mold and pressed into shape under a pressure of 150 MPa, and the pressure is held for 60 s to obtain a ceramic green body; (5) The ceramic blank is placed in a graphite box and placed in an atmosphere sintering furnace. Under a nitrogen atmosphere of 0.3 kPa, the temperature is raised to 1350°C and held for 6 hours. Then, it is cooled to room temperature with the furnace to obtain a carbon ceramic material with adjustable resistance.

[0024] The obtained tunable carbon ceramic material has an open porosity of 32.1% and a bulk density of 1.96 g / cm³. 3 It has a resistivity of 150 Ω•cm, a temperature coefficient of resistance of -0.07% / ℃, a thermal conductivity of 1.8W / (m•K), and a flexural strength loss rate of 11.5% within the range of 25~250℃.

[0025] Example 3 This embodiment provides a carbon ceramic material with adjustable resistance, the raw materials of which, by weight, include: 70 parts alumina, 20 parts silicon dioxide, 5 parts graphite, 1 part carbon black, and 4 parts calcium carbonate. The alumina has a purity of 99.98% and a particle size of 250 μm; the silicon dioxide has a purity of 99.95% and a particle size of 1 μm; the graphite is isostatically pressed graphite with a carbon content of 99.9% and a particle size of 10 μm; the carbon black is conductive carbon black with an oil absorption value of 0.9 mL / g and a particle size of 30 nm; and the calcium carbonate has a purity of 99.5% and a particle size of 1 μm.

[0026] The method for preparing the resistivity-adjustable carbon ceramic material in this embodiment includes the following steps: (1) The weighed raw material powder and agate grinding balls were loaded into the ball mill jar at a mass ratio of 1:3 and ball milled at 150 r / min for 24 h. The raw material and agate balls were separated by a 60 mesh sieve. (2) Mix the raw material powder with pure water, binder and dispersant evenly: Put pure water and raw material powder into the mixing chamber at a mass ratio of 1:2 to obtain slurry; add dispersant (sodium methylene bis(naphthyl)sulfonate aqueous solution, concentration 2 g / L) and slurry into the mixing chamber at a mass ratio of 2:100 at once; add binder (polyvinyl alcohol aqueous solution, concentration 6 wt%) and slurry into the mixing chamber in two batches at a mass ratio of 3:100, each batch being 1 / 2 of the total amount; stir at 10 r / min for 6 h; (3) Spray granulation is used for granulation, and the spray drying temperature is 130℃; (4) The granulated powder is loaded into a mold and pressed into shape under a pressure of 100MPa, and the pressure is held for 70s to obtain a ceramic green body; (5) The ceramic blank is placed in a graphite box and placed in an atmosphere sintering furnace. Under a nitrogen atmosphere of 1.0 kPa, the temperature is raised to 1450°C and held for 2 hours. Then, it is cooled to room temperature with the furnace to obtain a carbon ceramic material with adjustable resistance.

[0027] The resulting tunable carbon ceramic material has an open porosity of 20.3% and a bulk density of 2.79 g / cm³. 3 It has a resistivity of 800 Ω•cm, a temperature coefficient of resistance of -0.02% / ℃, a thermal conductivity of 1.5 W / (m•K), and a flexural strength loss rate of 3.3% within the range of 25~250℃.

[0028] Example 4 This embodiment provides a carbon ceramic material with adjustable resistance, the raw materials of which, by weight, include: 62 parts alumina, 23 parts silicon dioxide, 6 parts graphite, 4 parts carbon black, and 5 parts calcium carbonate. The alumina has a purity of 99.98% and a particle size of 400 μm; the silicon dioxide has a purity of 99.95% and a particle size of 20 μm; the graphite is isostatically pressed graphite with a carbon content of 99.9% and a particle size of 40 μm; the carbon black is conductive carbon black with an oil absorption value of 1.5 mL / g and a particle size of 500 nm; and the calcium carbonate has a purity of 99.5% and a particle size of 20 μm.

[0029] The method for preparing the resistivity-adjustable carbon ceramic material in this embodiment includes the following steps: (1) The weighed raw material powder and agate grinding balls were loaded into the ball mill jar at a mass ratio of 1:1 and ball milled at 90 r / min for 28 h. The raw material and agate balls were separated by a 120 mesh sieve. (2) Mix the raw material powder with pure water, binder and dispersant evenly: Put pure water and raw material powder into the mixing chamber at a mass ratio of 1:3.2 to obtain slurry; add dispersant (sodium methylene bis(naphthyl)sulfonate aqueous solution, concentration 1 g / L) and slurry into the mixing chamber at a mass ratio of 1:100 at once; add binder (polyvinyl alcohol aqueous solution, concentration 4 wt%) and slurry into the mixing chamber in two batches at a mass ratio of 2.5:100, each batch being 1 / 2 of the total amount; stir at 40 r / min for 4.5 h; (3) Spray granulation is used for granulation, and the spray drying temperature is 115℃; (4) The granulated powder is loaded into a mold and pressed into shape under a pressure of 130 MPa, and the pressure is held for 65 s to obtain a ceramic green body; (5) The ceramic blank is placed in a graphite box and placed in an atmosphere sintering furnace. Under a nitrogen atmosphere of 0.7 kPa, the temperature is raised to 1300℃ and held for 5 hours. Then, it is cooled to room temperature with the furnace to obtain a carbon ceramic material with adjustable resistance.

[0030] The obtained tunable carbon ceramic material has an open porosity of 34.2% and a bulk density of 1.84 g / cm³. 3 It has a resistivity of 2.5 Ω•cm, a temperature coefficient of resistance of 0.05% / ℃, a thermal conductivity of 4.9 W / (m•K), and a flexural strength loss rate of 13.4% within the range of 25~250℃.

[0031] Example 5 This embodiment provides a carbon ceramic material with adjustable resistance, the raw materials of which, by weight, include: 68 parts alumina, 21 parts silicon dioxide, 4 parts graphite, 3 parts carbon black, and 4 parts calcium carbonate. The alumina has a purity of 99.98% and a particle size of 450 μm; the silicon dioxide has a purity of 99.95% and a particle size of 30 μm; the graphite is isostatically pressed graphite with a carbon content of 99.9% and a particle size of 1 μm; the carbon black is conductive carbon black with an oil absorption value of 1.3 mL / g and a particle size of 300 nm; and the calcium carbonate has a purity of 99.5% and a particle size of 30 μm.

[0032] The method for preparing the resistivity-adjustable carbon ceramic material in this embodiment includes the following steps: (1) The weighed raw material powder and agate grinding balls were loaded into the ball mill jar at a mass ratio of 1:2.5 and ball milled at 140 r / min for 32 h. The raw material and agate balls were separated by a 90 mesh sieve. (2) Mix the raw material powder with pure water, binder and dispersant evenly: Put pure water and raw material powder into the mixing chamber at a mass ratio of 1:2.8 to obtain slurry; add dispersant (sodium methylene bis(naphthyl)sulfonate aqueous solution, concentration 1.5 g / L) and slurry into the mixing chamber at a mass ratio of 1.8:100 at once; add binder (polyvinyl alcohol aqueous solution, concentration 2 wt%) and slurry into the mixing chamber in two batches at a mass ratio of 1.5:100, each batch being 1 / 2 of the total amount; stir at 25 r / min for 5.5 h; (3) Spray granulation is used for granulation, and the spray drying temperature is 125℃; (4) The granulated powder is loaded into a mold and pressed into shape under a pressure of 140 MPa, and the pressure is held for 62 s to obtain a ceramic green body; (5) The ceramic blank is placed in a graphite box and placed in an atmosphere sintering furnace. Under a nitrogen atmosphere of 0.4 kPa, the temperature is raised to 1420°C and held for 3 hours. Then, it is cooled to room temperature with the furnace to obtain a carbon ceramic material with adjustable resistance.

[0033] The obtained resistivity-tunable carbon ceramic material has an open porosity of 27.3% and a bulk density of 2.49 g / cm³. 3 It has a resistivity of 250 Ω•cm, a temperature coefficient of resistance of -0.08% / ℃, a thermal conductivity of 4.0 W / (m•K), and a flexural strength loss rate of 7.8% within the range of 25~250℃.

[0034] Comparative Example 1 This comparative example provides a carbon ceramic material, the raw materials of which include, by weight: 42 parts clay, 50 parts high-alumina bauxite, and 8 parts carbon black. The carbon black is conductive carbon black with an oil absorption value of 0.9 mL / g and a particle size of 30 nm.

[0035] The preparation method of the carbon ceramic material in this embodiment includes the following steps: (1) The weighed raw material powder and agate grinding balls were loaded into the ball mill jar at a mass ratio of 1:2.5 and ball milled at 140 r / min for 32 h. The raw material and agate balls were separated by an 80 mesh sieve. (2) Mix the raw material powder with pure water, binder and dispersant evenly: Put pure water and raw material powder into the mixing chamber at a mass ratio of 1:2.8 to obtain slurry; add dispersant (sodium methylene bis(naphthyl)sulfonate aqueous solution, concentration 1.5 g / L) and slurry into the mixing chamber at a mass ratio of 1.8:100 at once; add binder (polyvinyl alcohol aqueous solution, concentration 2 wt%) and slurry into the mixing chamber in two batches at a mass ratio of 1.5:100, each batch being 1 / 2 of the total amount; stir at 25 r / min for 5 h; (3) Spray granulation is used for granulation, and the spray drying temperature is 125℃; (4) The granulated powder is loaded into a mold and pressed into shape under a pressure of 140 MPa, and the pressure is held for 65 s to obtain a ceramic green body; (5) The ceramic blank is placed in a graphite box and placed in an atmosphere sintering furnace. Under a nitrogen atmosphere of 0.4 kPa, the temperature is raised to 1350℃ and held for 3 hours. Then the blank is cooled to room temperature with the furnace to obtain carbon ceramic linear resistor.

[0036] The obtained carbon ceramic material has an open porosity of 41.5%, a bulk density of 1.75 g / cm3, a resistivity of 120 Ω•cm, a temperature coefficient of resistance of -0.45% / ℃, a thermal conductivity of 0.8 W / (m•K), and a flexural strength loss rate of 28.5% within the range of 25~250℃.

[0037] Results Analysis Table 1 shows the performance comparison of Examples 1-5 and Comparative Example 1.

[0038] Table 1 Performance Comparison

[0039] The results above show that the resistivity of the material decreases with increasing total amounts of graphite and carbon black. When the total conductive phase content is similar, carbon black, due to its nanoscale characteristics, is significantly more efficient than graphite in reducing resistivity, as it more easily forms a conductive network and reaches the percolation threshold. With increasing alumina content and correspondingly decreasing silica content, the material's bulk density increases and its open porosity decreases, leading to improved thermal shock resistance. Comparative Example 1 shows that even with the same process, using traditional raw materials containing impurities (clay, high-alumina bauxite) during sintering results in uncontrollable microstructures (high porosity, poor uniformity), leading to drastic fluctuations in resistivity and poor stability. This demonstrates the necessity of using high-purity raw materials in this invention. Therefore, by rationally designing the proportion of high-purity raw materials and the type and ratio of conductive fillers, the microstructure, resistivity, and other key properties of carbon ceramic materials can be effectively controlled.

[0040] The controllable preparation method for resistive carbon ceramic materials according to embodiments of the present invention is based on mechanical ball milling, combined with a graded additive process and spray granulation, which allows the conductive filler to be fully mixed with other raw material powders, improving the resistance stability. The nitrogen atmosphere-protected sintering method improves the repeatability of various properties of the carbon ceramic material. The electrical and mechanical properties of the sample can be adjusted by changing the proportions of different components in the raw materials and the calcination temperature.

[0041] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A raw material for a carbon ceramic material with adjustable resistance, characterized in that, The raw materials include the following components by weight: 60-70 parts of alumina; 20-25 parts of silicon dioxide; 5-10 parts of graphite; 1-5 parts of carbon black; 3-6 parts of sintering aid; wherein the sintering aid is calcium carbonate.

2. The raw material according to claim 1, characterized in that, The raw materials satisfy one or more of the following conditions: The purity of the alumina is not less than 99.98%, and the particle size range is 250-450 μm; The purity of the silicon dioxide is not less than 99.95%, and the particle size range is 1-30 μm; The graphite is isostatic pressing graphite, the carbon content is not less than 99.9%, and the particle size range is 1-40 μm; The carbon black is conductive carbon black, the oil absorption value is 0.9-1.5 mL / g, and the particle size range is 30-500 nm; The purity of the calcium carbonate is not less than 99.5%, and the particle size range is 1-30 μm.

3. The raw material according to claim 1, characterized in that, The raw materials further include 1-3 parts of binder and 1-2 parts of dispersant; The binder is polyvinyl alcohol aqueous solution with a concentration of 1-6 wt%; The dispersant is sodium methylene bis-naphthalene sulfonate aqueous solution with a concentration of 0.1-2 g / L.

4. A method of producing a carbon ceramic material with adjustable resistance, characterized by The method comprises the following steps: The alumina, silicon dioxide, graphite, carbon black and sintering aid raw material powders are weighed according to any one of claims 1-3, ball-mixed and uniformly mixed to obtain mixed powders; The binder, dispersant and pure water are added to the mixed powders, stirred and uniformly mixed, and then spray granulated to obtain granulated powders; The granulated powders are pressed and formed to obtain ceramic blanks; The ceramic blanks are subjected to sintering treatment to obtain the resistance-adjustable carbon ceramic material.

5. The preparation method according to claim 4, characterized in that, The ball-mixing and uniform-mixing specifically comprises: the raw material powders and agate balls are loaded into a ball mill tank at a mass ratio of 1:1-3:1, ball-milled at 90-150 r / min for 24-36 h, and the raw material powders and agate balls are separated by a 60-120 mesh screen.

6. The preparation method according to claim 4, characterized in that, The adding of the binder, dispersant and pure water to the mixed powders, stirring and uniform mixing specifically comprises: The pure water and the mixed powders are loaded into a stirring bin at a mass ratio of 1:2-1:3.2 to obtain a slurry; The dispersant and the slurry are added into the stirring bin at a mass ratio of 1:100-2:100 at one time, and the binder and the slurry are added into the stirring bin at a mass ratio of 1:100-3:100 in two times, each time being 1 / 2 of the total amount, and stirred at 10-40 r / min for 4-6 h.

7. The preparation method according to claim 4, characterized in that, The drying temperature of the spray granulation is 110-130 °C.

8. The preparation method according to claim 4, characterized in that, The pressure of the pressing and forming is 100-150 MPa, and the pressure maintaining time is 60-70 s.

9. The preparation method according to claim 4, characterized in that, The sintering treatment specifically comprises: the ceramic blanks are heated to 1300 °C-1450 °C, kept for 2-6 h, and cooled to room temperature in the furnace; the sintering process is carried out in a nitrogen atmosphere, and the gas pressure is 0.3-1.0 kPa.

10. A resistance-adjustable carbon ceramic material prepared by the preparation method of any one of claims 4-9.

11. The carbon ceramic material of claim 10, wherein, The open porosity of the resistance-adjustable carbon ceramic material is 20%-35%; and / or The volume density of the resistance-adjustable carbon ceramic material is 1.9-2.8 g / cm 3 ; and / or The resistivity of the resistance-adjustable carbon ceramic material is 0.2-1000 Ω·cm; and / or The resistance temperature coefficient of the resistance-adjustable carbon ceramic material is -0.2-0.1 % / °C; and / or The thermal conductivity of the resistance-adjustable carbon ceramic material is 1.5-5 W / (m·K). The bending strength loss rate of the resistance-adjustable carbon ceramic material is 3-15% within 25-250 DEG C.

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