Carbon nanotube-doped graphite ceramic resistor and preparation method thereof

Abstract

The invention discloses a graphite ceramic resistor doped with carbon nanotubes, which comprises a graphite ceramic matrix, and the graphite ceramic matrix is internally provided with uniformly dispersed carbon nanotubes. The preparation method of the carbon nanotube-doped graphite ceramic resistor comprises the following steps: S1, preparing raw materials; s2, dispersing the carbon nano tube; s3, mixing and forming; s4, sintering; and S5, post-processing. The carbon nanotubes are doped in the graphite ceramic matrix, so that the electrical conductivity, thermal stability and mechanical strength of the resistor are remarkably improved, the problem that an existing graphite ceramic resistor is unstable in performance in high-temperature, high-pressure and corrosive environments is solved, and the preparation method is simple, low in production cost, suitable for industrial large-scale production and suitable for industrial large-scale production. The cable is suitable for high-temperature, high-pressure and corrosive environments, such as the fields of high-speed rails, subways, rail transit equipment, high-voltage power transmission and transformation and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of power electronic components, and in particular relates to a carbon nanotube-doped graphite ceramic resistor and a preparation method thereof. Background Art

[0002] Graphite ceramic resistor is a resistor material composed of 6 raw materials: Al2O3, kaolin, talc, graphite, sodium silicate, binder and dispersant. This resistor material is made through processes such as crushing, pulping, granulation and sintering. It has high reliability and does not have the failure phenomenon of film and wire-wound resistors.

[0003] However, traditional graphite ceramic resistor materials are easily damaged under high temperature, high pressure and corrosive environments, and their conductivity is unstable. In order to overcome these defects, researchers are constantly exploring new resistor materials. Carbon nanotubes have become an ideal choice for improving the performance of resistor materials due to their excellent conductivity, thermal stability and mechanical properties. However, how to effectively and evenly disperse carbon nanotubes and dope them into a graphite ceramic matrix is ​​still a technical problem. Therefore, a graphite ceramic resistor doped with carbon nanotubes and a preparation method thereof are urgently needed to solve the above problems. Summary of the invention

[0004] In view of the problems raised by the above background technology, the purpose of the present invention is to provide a carbon nanotube-doped graphite ceramic resistor and a preparation method thereof.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A carbon nanotube-doped graphite ceramic resistor comprises a graphite ceramic matrix in which uniformly dispersed carbon nanotubes are arranged.

[0007] It is further defined that the carbon nanotubes have a length of 10 to 100 μm and a diameter of 1 to 10 nm.

[0008] It is further defined that the carbon nanotubes account for 1-10% of the total mass of the graphite ceramic matrix.

[0009] A method for preparing a carbon nanotube-doped graphite ceramic resistor comprises the following steps:

[0010] S1: Raw material preparation:

[0011] Graphite ceramic powder: As the main matrix material, it is composed of graphite, alumina (Al 2 O 3 )、ZrO 2 ), aluminosilicate material and quartz;

[0012] Carbon nanotubes: as doping materials, purity ≥ 95%, length 10-100 μm, diameter 1-10 nm;

[0013] Dispersants: polyvinyl pyrrolidone (PVP) and sodium dodecyl sulfate (SDS), used to improve the dispersibility of carbon nanotubes in solvents;

[0014] Solvents: ethanol and water, used to prepare carbon nanotube dispersions;

[0015] S2: Carbon nanotube dispersion:

[0016] Adding carbon nanotubes and dispersants into a solvent in a certain ratio, and performing ultrasonic dispersion to obtain a uniform carbon nanotube dispersion;

[0017] S3: Mixing and forming:

[0018] Graphite, ceramic powder and carbon nanotube dispersion are mixed in a certain proportion, stirred evenly to obtain a mixed slurry, and then the mixed slurry is pressed or isostatically pressed to obtain a green body;

[0019] S4: Sintering:

[0020] The green body is placed in a high-temperature furnace protected by inert gas, and the temperature is raised to 1200-1400°C at a heating rate of 5-10°C / min, and the temperature is kept, so that the green body is sintered into a dense graphite ceramic resistor body;

[0021] S5: Post-processing:

[0022] The sintered resistor body is surface-grinded to remove surface impurities and burrs, and a conductive metal electrode, such as silver or aluminum, is sprayed on the surface of the resistor body to enhance conductivity and stability.

[0023] It is further defined that in S2, an ultrasonic dispersion method is used and the dispersion time is 1 to 3 hours.

[0024] It is further defined that in said S4, the inert gas may be nitrogen.

[0025] It is further defined that in said S4, the heat preservation time is 2 to 4 hours.

[0026] It is further defined that in said S5, the sprayed conductive metal electrode is silver or aluminum.

[0027] The beneficial effects of the present invention are as follows: the present invention significantly improves the conductivity, thermal stability and mechanical strength of the resistor by doping carbon nanotubes into the graphite ceramic matrix, and solves the problem of unstable performance of existing graphite ceramic resistors under high temperature, high pressure and corrosive environments. The preparation method of the present invention is simple, the production cost is low, and it is suitable for industrial large-scale production, and is suitable for high temperature, high pressure and corrosive environments, such as high-speed railways, subways, rail transit equipment and high-voltage power transmission and transformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention can be further illustrated by the non-limiting examples given in the accompanying drawings;

[0029] Figure 1 This is a schematic structural diagram of a carbon nanotube-doped graphite ceramic resistor according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the steps and flow of a method for preparing a carbon nanotube-doped graphite ceramic resistor according to an embodiment of the present invention;

[0031] The main component symbols are described as follows:

[0032] Graphite ceramic matrix 1, carbon nanotube 2. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0034] like Figure 1 As shown, a carbon nanotube-doped graphite ceramic resistor of the present invention comprises a graphite ceramic matrix 1 in which carbon nanotubes 2 are uniformly dispersed.

[0035] Preferably, the carbon nanotubes 2 have a length of 10 to 100 μm and a diameter of 1 to 10 nm.

[0036] Preferably, the carbon nanotubes 2 account for 1-10% of the total mass of the graphite ceramic substrate 1 .

[0037] like Figure 2 As shown, a method for preparing a carbon nanotube-doped graphite ceramic resistor of the present invention comprises the following steps:

[0038] S1: Raw material preparation:

[0039] Graphite ceramic powder: As the main matrix material, it is composed of graphite, alumina (Al 2 O 3 )、ZrO 2 ), aluminosilicate material and quartz;

[0040] Carbon nanotubes: as doping materials, purity ≥ 95%, length 10-100 μm, diameter 1-10 nm;

[0041] Dispersants: polyvinyl pyrrolidone (PVP) and sodium dodecyl sulfate (SDS), used to improve the dispersibility of carbon nanotubes in solvents;

[0042] Solvents: ethanol and water, used to prepare carbon nanotube dispersions;

[0043] S2: Carbon nanotube dispersion:

[0044] Adding carbon nanotubes and dispersants into a solvent in a certain ratio, and performing ultrasonic dispersion to obtain a uniform carbon nanotube dispersion;

[0045] S3: Mixing and forming:

[0046] Graphite, ceramic powder and carbon nanotube dispersion are mixed in a certain proportion, stirred evenly to obtain a mixed slurry, and then the mixed slurry is pressed or isostatically pressed to obtain a green body;

[0047] S4: Sintering:

[0048] The green body is placed in a high-temperature furnace protected by inert gas, and the temperature is raised to 1200-1400°C at a heating rate of 5-10°C / min, and the temperature is kept, so that the green body is sintered into a dense graphite ceramic resistor body;

[0049] S5: Post-processing:

[0050] The sintered resistor body is surface-grinded to remove surface impurities and burrs, and a conductive metal electrode, such as silver or aluminum, is sprayed on the surface of the resistor body to enhance conductivity and stability.

[0051] Preferably, in S2, ultrasonic dispersion is used and the dispersion time is 1 to 3 hours.

[0052] Preferably, in S4, the inert gas may be nitrogen.

[0053] Preferably, in S4, the insulation time is 2 to 4 hours.

[0054] Preferably, in S5, the sprayed conductive metal electrode is silver or aluminum.

[0055] In this embodiment, raw materials such as graphite ceramic powder, carbon nanotubes, dispersant and solvent are prepared, and then the carbon nanotubes and dispersant are added to the solvent in a certain proportion, ultrasonically dispersed for 1-3 hours to obtain a uniform carbon nanotube dispersion, and then the graphite and ceramic powders are mixed with the carbon nanotube dispersion in a certain proportion, stirred evenly to obtain a mixed slurry, and the mixed slurry is pressed or isostatically pressed to obtain a green body, which is placed in a high-temperature furnace protected by an inert gas (such as nitrogen), heated to 1200-1400°C at a heating rate of 5-10°C / min, and kept warm for 2-4 hours to sinter the green body into a dense graphite ceramic resistor, and the sintered resistor is surface polished to remove surface impurities and burrs, and a conductive metal electrode, such as silver or aluminum, is sprayed on the surface of the resistor to enhance conductivity and stability.

[0056] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A graphite ceramic resistor doped with carbon nanotubes, characterized in that: It comprises a graphite ceramic matrix (1), wherein uniformly dispersed carbon nanotubes (2) are arranged in the graphite ceramic matrix (1).

2. The carbon nanotube-doped graphite ceramic resistor according to claim 1, characterized in that: The carbon nanotube (2) has a length of 10 to 100 μm and a diameter of 1 to 10 nm.

3. The carbon nanotube-doped graphite ceramic resistor according to claim 2, characterized in that: The carbon nanotubes (2) account for 1 to 10% of the total mass of the graphite ceramic matrix (1).

4. A method for preparing a carbon nanotube-doped graphite ceramic resistor according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: Raw material preparation: Graphite ceramic powder: as the main matrix material, it is composed of graphite, alumina (Al2O3), zirconium oxide (ZrO2), aluminosilicate and quartz; Carbon nanotubes: as doping materials, purity ≥ 95%, length 10-100 μm, diameter 1-10 nm; Dispersants: polyvinyl pyrrolidone (PVP) and sodium dodecyl sulfate (SDS), used to improve the dispersibility of carbon nanotubes in solvents; Solvents: ethanol and water, used to prepare carbon nanotube dispersions; S2: Carbon nanotube dispersion: Adding carbon nanotubes and dispersants into a solvent in a certain ratio, and performing ultrasonic dispersion to obtain a uniform carbon nanotube dispersion; S3: Mixing and forming: Graphite, ceramic powder and carbon nanotube dispersion are mixed in a certain proportion, stirred evenly to obtain a mixed slurry, and then the mixed slurry is pressed or isostatically pressed to obtain a green body; S4: Sintering: The green body is placed in a high-temperature furnace protected by inert gas, and the temperature is raised to 1200-1400°C at a heating rate of 5-10°C / min, and the temperature is kept, so that the green body is sintered into a dense graphite ceramic resistor body; S5: Post-processing: The sintered resistor body is surface-grinded to remove surface impurities and burrs, and a conductive metal electrode, such as silver or aluminum, is sprayed on the surface of the resistor body to enhance conductivity and stability.

5. The method for preparing a carbon nanotube-doped graphite ceramic resistor according to claim 4, characterized in that: In S2, ultrasonic dispersion is used, and the dispersion time is 1 to 3 hours.

6. The method for preparing a carbon nanotube-doped graphite ceramic resistor according to claim 5, characterized in that: In S4, the inert gas may be nitrogen.

7. The method for preparing a carbon nanotube-doped graphite ceramic resistor according to claim 6, characterized in that: In the S4, the heat preservation time is 2 to 4 hours.

8. The method for preparing a carbon nanotube-doped graphite ceramic resistor according to claim 7, characterized in that: In S5, the sprayed conductive metal electrode is silver or aluminum.

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