Raw material composition of carbon ceramic composite resistance material, composite resistance material and preparation method of composite resistance material

Abstract

The invention relates to a raw material composition of a carbon ceramic composite resistance material, the composite resistance material and a preparation method of the composite resistance material, and the raw material composition of the carbon ceramic composite resistance material comprises the following components in parts by weight: 50-65 parts of aluminum oxide, 20-25 parts of silicon dioxide, 10-20 parts of graphite and 2-7 parts of a sintering aid. Wherein the sintering aid is iron oxide or ferroferric oxide. According to the material, the high-purity oxide is used as a main raw material, the graphite is used for forming a conductive network, the functional additive is used as an auxiliary material, and the raw material is high in purity, stable in performance and controllable in source, so that the defect that a sintering process and even product performance are affected due to more impurities of natural raw materials can be effectively avoided, and the prepared material is controllable in phase composition and microstructure and adjustable in performance. Meanwhile, ferric oxide or ferroferric oxide is used as a sintering aid, so that the resistance material is endowed with proper magnetism.

Description

Technical Field

[0001] This invention belongs to the field of carbon ceramic composite resistors, specifically relating to a raw material composition for carbon ceramic composite resistor materials, composite resistor materials and their preparation methods. Background Technology

[0002] The closing resistor is a core component for suppressing overvoltage during high-voltage switch operation. Currently, the performance of domestically produced products falls short of ultra-high-voltage (UHV) requirements, necessitating the import of 100% of the closing resistors used in UHV projects in China. With the increasing demand from power grid construction projects, the need for closing resistors is particularly urgent, and current order cycles from overseas are delayed by more than a year. Therefore, closing resistor materials have become a critical factor restricting the construction of UHV projects.

[0003] Domestically produced related products are mostly based on natural minerals. Although these raw materials are relatively inexpensive, they contain high levels of impurities and are relatively unstable in quality. This results in a complex phase composition and poor stability of the phase composition, leading to poor stability of carbon ceramic composite resistor materials. Summary of the Invention

[0004] To address the problem of poor stability in carbon ceramic composite resistor materials, this invention provides a raw material composition for carbon ceramic composite resistor materials, comprising the following components by weight: 50-65 parts alumina, 20-25 parts silicon dioxide, 10-20 parts graphite, and 2-7 parts sintering aid; wherein the sintering aid is iron oxide or iron(II,III) oxide.

[0005] Preferably, the alumina has a particle size of 300nm~500nm; the silicon dioxide has a particle size of 1μm~30μm; the graphite is isostatically pressed graphite with a particle size of 4μm~80μm; the iron oxide has a particle size of 300nm~800nm; and the iron oxide has a particle size of 1μm~10μm.

[0006] The present invention also provides a method for preparing carbon ceramic composite resistive materials using the aforementioned raw material composition, comprising the following steps: Weigh out alumina, silicon dioxide, graphite, iron oxide or iron tetroxide raw materials in proportion, mix them to obtain a mixed powder; The mixed powder is loaded into a mold, pressed into shape, and demolded to obtain a green body; The green body is placed in a crucible containing graphite powder, the graphite powder is filled in, and the crucibles are nested together to obtain a nested crucible. The crucible of the kit is placed in a high-temperature furnace for sintering, and the crucible is removed to obtain the carbon ceramic composite resistor material.

[0007] Preferably, the mixing process specifically includes: loading the raw material powder and zirconia grinding balls into a ball mill jar at a mass ratio of 1.5:1 to 3:1, ball milling at 80 rpm to 120 rpm for 16 to 20 hours, and separating the raw material and grinding balls using a 60-100 mesh sieve.

[0008] Preferably, in the compression molding process, the molding pressure is 50MPa~120MPa, and the holding time is 10~30s.

[0009] Preferably, the step of placing the green body into a crucible containing graphite powder, filling the crucible with graphite powder, and then fitting the crucible together specifically includes: The green body is placed into a first crucible containing graphite powder; After covering the first crucible, it was inverted into the second crucible, and graphite powder was buried around the edge of its opening. Cover the second crucible to complete the crucible set.

[0010] Preferably, a third crucible is provided between the first crucible and the second crucible, the third crucible being inverted at the bottom of the second crucible and covering the first crucible.

[0011] Preferably, the sintering process includes: heating the billet to 1300℃~1450℃ and holding it at that temperature for 3~6 hours, then cooling it to 300~450℃ at a rate of 5~10℃ / min and then cooling it to room temperature in the furnace.

[0012] Preferably, when ferric oxide is used as a sintering aid, the temperature needs to be maintained at 700~800℃ for 1~2 hours during the heating process.

[0013] The present invention also provides a carbon ceramic composite resistor material prepared by the aforementioned preparation method.

[0014] Preferably, the open porosity of the carbon ceramic composite resistor material is 14%-40%; and / or The bulk density of the carbon ceramic composite resistor material is 1.8 g / cm³. 3 -2.5g / cm 3 ; and / or The resistivity of the carbon ceramic composite resistor material is 0.01 Ω•m-50.00 Ω•m; and / or The saturation magnetization of the carbon ceramic composite resistive material is 0.5 emu•g. -1 -4.2 emu•g -1 .

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The carbon ceramic composite resistive material raw material composition proposed in this invention comprises the following components by weight: 50-65 parts alumina, 20-25 parts silicon dioxide, 10-20 parts graphite, and 2-7 parts sintering aid; wherein the sintering aid is iron oxide or magnetite. This material uses high-purity oxides as the main raw material, with graphite used to form a conductive network, supplemented by functional additives. The raw materials have high purity, stable performance, and controllable sources, which effectively avoids the shortcomings of high impurities in natural raw materials affecting the sintering process and even product performance. This allows for controllable phase composition and microstructure of the prepared material, and adjustable performance. Simultaneously, iron oxide or magnetite, used as a sintering aid, imparts appropriate magnetic properties to the resistive material. When the short-circuit current surges, the self-generated magnetic field of the magnetoresistive material increases, triggering a resistivity jump through the magnetoresistance effect, several times faster than traditional voltage triggering.

[0016] The method for preparing carbon ceramic composite resistive materials proposed in this invention uses a conventional high-temperature furnace and a graphite powder-embedded crucible set for sintering, which reduces the requirements for sintering equipment and corresponding factory buildings, simplifies the preparation process, and reduces sintering costs. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the preparation process of the carbon ceramic composite resistive material of the present invention. Figure 2 This is a schematic diagram of the graphite powder embedding crucible set of the present invention; Figure 3 The phase composition of the carbon ceramic composite resistive material in Example 1 of this invention is shown below, where Intensity: intensity, 2θ: diffraction angle; Corundum: corundum, Mullite: mullite, Graphite: graphite, Anorthite: anorthite; PDF XX-XXXX are the standard spectrum numbers of the corresponding minerals in the crystal diffraction standard database. Figure 4 The phase composition of the carbon ceramic composite resistor material in Embodiment 2 of the present invention is shown in the figure, wherein Cristoblite is cristobalite and Quartz is quartz. Figure 5 The phase composition of the carbon ceramic composite resistive material in Example 3 of the present invention is shown, wherein Hematite is a type of hematite. Figure 6 The hysteresis loop of the carbon ceramic composite resistive material in Embodiment 5 of the present invention is shown, where M represents magnetization and H represents magnetic field strength. Among them, 1. First crucible; 2. Second crucible; 3. Third crucible; 4. Green body; 5. Graphite powder; 6. Pad. 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] This invention provides a carbon ceramic composite resistor material, the raw materials of which include the following components by weight: 50-65 parts alumina, 20-25 parts silicon dioxide, 10-20 parts graphite, and 2-7 parts sintering aid. The sintering aid is iron oxide or magnetite.

[0020] The raw materials used are high-purity powders with suitable particle size distribution. The alumina has a particle size of 300nm~500nm; the silicon dioxide has a particle size of 1μm~30μm; the graphite is isostatically pressed graphite with a particle size of 4μm~80μm; the iron oxide has a particle size of 300nm~800nm; and the iron oxide has a particle size of 1μm~10μm. Due to the reasonable particle size distribution of the raw materials, a high-strength green body can be obtained without the addition of a binder. The addition of additives not only effectively promotes the solid-state reaction and sintering between the raw materials, but also benefits the control of the thermal properties of the resulting new material. Furthermore, by adjusting the amount and particle size of graphite, its threshold value can be effectively changed, resulting in a wide range of adjustable resistivity.

[0021] This invention also provides a carbon-ceramic composite resistor material, prepared using the aforementioned carbon-ceramic composite resistor material raw material composition. It features controllable phase composition and microstructure, and adjustable performance, making it suitable for circuit breakers of different voltages. The open porosity of the carbon-ceramic composite resistor material is 14%~40%, and its bulk density is 1.8 g / cm³. 3 ~2.5g / cm 3 Its resistivity is 0.01 Ω•m to 50.00 Ω•m, and its saturation magnetization is 0.5 emu·g. -1 -4.2 emu·g -1 .

[0022] This invention also provides a method for preparing a carbon ceramic composite resistive material, such as... Figure 1 As shown, it includes the following steps: Step S10: Mix alumina, silicon dioxide, graphite, iron oxide or iron(II,III) oxide in a certain proportion to obtain a mixed powder; Step S20: The mixed powder is loaded into a steel mold, pressed into shape, and demolded to obtain a green blank; Step S30: Place the green body into a crucible containing graphite powder, fill with graphite powder, and then fit the crucible together. Step S40: Place the crucible of the set in a high-temperature furnace for sintering, remove the crucible, and obtain the carbon ceramic composite resistor material.

[0023] Step S10 includes: Step S11: Calculate and weigh the alumina, silicon dioxide, graphite, iron oxide or iron(II,III) oxide according to a certain ratio; Step S12: The above powder and zirconia grinding balls are loaded into a ball mill jar and ball-milled for 16-20 hours. The powder and grinding balls are then separated by sieving to obtain a mixed powder. In step S12, the mass ratio of grinding balls to powder is 1.5:1 to 3:1, the ball mill speed is 80 rpm to 120 rpm, and sieving is performed using a 60-100 mesh sieve. Further, step S20 includes: The mixed powder is loaded into a steel mold, pressed into shape under a certain pressure, and then slowly depressurized to obtain a green body. The pressing pressure is between 80MPa and 120MPa.

[0024] Step S30 includes: Step S31: Place the green blank 4 into the first crucible 1 containing graphite powder 5; Step S32: After covering the first crucible 1, invert it into the second crucible 2 and fill the edge of its opening with graphite powder 5; the bottom of the second crucible 2 is provided with a pad 6, and the first crucible 1 is inverted on the pad 6; Step S33: Cover the second crucible 2 to complete the crucible set.

[0025] To further compress the first crucible 1, a third crucible 3 is provided between the first crucible 1 and the second crucible 2. The third crucible 3 is inverted and placed over the bottom of the second crucible 2, covering the first crucible 1. Figure 2 As shown.

[0026] The embedded graphite powder used is the same as the conductive filler, and this graphite powder can be reused.

[0027] In step S40, the crucible is placed in a high-temperature furnace and heated to the calcination temperature at a rate of 2°C / min, held at the temperature for 5 hours for calcination, and then cooled to 300°C at a rate of 5°C / min before being cooled to room temperature with the furnace. Among them, materials using iron tetroxide as a sintering aid need to be held at 750℃ for 1 hour to ensure slow and complete decomposition; the calcination temperature is set between 1300℃ and 1450℃ depending on the performance requirements.

[0028] Therefore, the controllable preparation method for carbon ceramic composite resistive materials according to embodiments of the present invention employs a simple dry mixing process, simplifying the preparation process; and uses a high-temperature furnace + graphite powder-embedded crucible set for calcination, reducing the requirements for sintering equipment and corresponding plant facilities, and lowering sintering costs. Furthermore, by adjusting the proportions of various components in the raw materials and the calcination temperature, the phase composition and microstructure of the sample can be effectively controlled, thereby enabling control over the porosity, bulk density, and resistivity of the final sample.

[0029] The preparation method of the carbon ceramic composite resistive material according to the present invention is described below with reference to specific embodiments.

[0030] Example 1 This embodiment provides a carbon ceramic composite resistor material, the raw materials of which include: alumina at 50% of the total mass, silicon dioxide at 25% of the total mass, iron oxide at 5% of the total mass, and isostatic graphite at 20% of the total mass. The alumina has a particle size of 300 nm, the silicon dioxide has a particle size of 4 μm, the iron oxide has a particle size of 800 nm, and the isostatic graphite is 300 mesh.

[0031] The preparation method of the carbon ceramic composite resistor material in this embodiment includes the following steps: 1) Place the weighed ceramic powder and zirconia grinding balls together in a ball mill jar and mix them on a drum ball mill for 20 hours. The mass of the zirconia grinding balls is twice the total mass of the raw material powder. 2) Pour out the mixed powder and sieve it through an 80-mesh sieve to separate the zirconia grinding balls and the uniformly mixed powder; 3) The uniformly mixed powder is loaded into a steel mold in batches, pressed and shaped under a pressure of 100 MPa for 20 seconds, and then the pressure is released and the mold is demolded to obtain a green blank. 4) Load the blank into the crucible and proceed as follows: Figure 2 The powder-embedded crucible is set up as shown. The set crucible is placed in a high-temperature furnace and heated to 750°C at a rate of 2°C / min and held for 1 hour. Then, the temperature is increased to 1450°C and held for 5 hours. The temperature is then decreased to 300°C at a rate of 5°C / min and cooled to room temperature with the furnace to obtain a carbon ceramic composite resistive material.

[0032] The obtained X-ray diffraction (XRD) pattern of the carbon ceramic composite resistor material is as follows: Figure 3 As shown. From Figure 3 It can be seen that the material is mainly composed of mullite, corundum, anorthite, and graphite. Corundum provides the material with high strength, while mullite and anorthite effectively reduce the material's thermal conductivity and coefficient of thermal expansion. Graphite forms the conductive network within the material. The resulting carbon ceramic composite resistor material has an apparent porosity of 30.9% and a bulk density of 1.95 g / cm³. 3Its resistivity is 0.12 Ω·m, and its saturation magnetization is 3.2 emu•g. -1 .

[0033] Example 2 This embodiment provides a carbon ceramic composite resistor material, the raw materials of which include: alumina at 60% of the total mass, silicon dioxide at 20% of the total mass, iron oxide at 5% of the total mass, and isostatic graphite at 15% of the total mass. The alumina particle size is 300 nm, the silicon dioxide particle size is 4 μm, the iron oxide particle size is 800 nm, and the isostatic graphite is 300 mesh.

[0034] The preparation method of the carbon ceramic composite resistor material in this embodiment includes the following steps: 1) Place the weighed ceramic powder and zirconia grinding balls together in a ball mill jar and mix them on a drum ball mill for 20 hours. The mass of the zirconia grinding balls is twice the total mass of the raw material powder.

[0035] 2) Pour out the mixed powder and sieve it with an 80-mesh sieve to separate the zirconia grinding balls and the uniformly mixed powder.

[0036] 3) The uniformly mixed powder is loaded into a steel mold in batches, pressed and shaped under a pressure of 100 MPa for 20 seconds, and then the green blank is obtained by depressurization and demolding.

[0037] 4) Load the blank into the crucible and proceed as follows: Figure 2 The powder-embedded crucible is set up as shown. The set crucible is placed in a high-temperature furnace and heated to 750°C at a rate of 2°C / min and held for 1 hour. Then, the temperature is increased to 1300°C and held for 5 hours. The temperature is then decreased to 300°C at a rate of 5°C / min and cooled to room temperature with the furnace to obtain a carbon ceramic composite resistive material.

[0038] The obtained X-ray diffraction (XRD) pattern of the carbon ceramic composite resistor material is as follows: Figure 4 As shown. From Figure 4 It can be seen that the material is mainly composed of corundum, cristobalite, anorthite, quartz, and graphite. Corundum provides the material with high strength, anorthite effectively reduces the material's thermal conductivity and coefficient of thermal expansion, cristobalite and quartz improve the material's thermal properties, and graphite forms the conductive network within the material. The resulting carbon ceramic composite resistor material has an apparent porosity of 38.1% and a bulk density of 1.82 g / cm³. 3 Its resistivity is 1.21 Ω·m, and its saturation magnetization is 2.1 emu•g. -1 Among them, the porosity and bulk density were measured by boiling method based on Archimedes' principle, the resistivity was determined and calculated by DC bridge, and the saturation magnetization of the sample was measured and obtained by vibrating sample magnetometer.

[0039] Example 3 This embodiment provides a carbon ceramic composite resistor material, the raw materials of which include: alumina at 60% of the total mass, silicon dioxide at 20% of the total mass, iron oxide at 5% of the total mass, and isostatic graphite at 15% of the total mass. The alumina particle size is 300 nm, the silicon dioxide particle size is 4 μm, the iron oxide particle size is 4 μm, and the isostatic graphite is 300 mesh.

[0040] The preparation method of the carbon ceramic composite resistor material in this embodiment includes the following steps: 1) Place the weighed ceramic powder and zirconia grinding balls together in a ball mill jar and mix them on a drum ball mill for 20 hours. The mass of the zirconia grinding balls is twice the total mass of the raw material powder. 2) Pour out the mixed powder and sieve it with an 80-mesh sieve to separate the zirconia grinding balls and the uniformly mixed powder.

[0041] 3) The uniformly mixed powder is loaded into a steel mold in batches, pressed and shaped under a pressure of 100 MPa for 20 seconds, and then the pressure is released and the mold is demolded to obtain a green blank. 4) Load the blank into the crucible and proceed as follows: Figure 2 The powder-embedded crucible is set up as shown. The set crucible is placed in a high-temperature furnace and heated to 1350℃ at a rate of 2℃ / min and held for 5 hours. Then, it is cooled to 300℃ at a rate of 5℃ / min and cooled to room temperature with the furnace to obtain a carbon ceramic composite resistive material.

[0042] The obtained X-ray diffraction (XRD) pattern of the carbon ceramic composite resistor material is as follows: Figure 5 As shown. From Figure 5 It can be seen that the material is mainly composed of corundum, quartz, cristobalite, iron oxide, and graphite. Corundum provides the material with high strength, while cristobalite, quartz, and iron oxide improve the material's thermal properties, and graphite forms the conductive network within the material. The resulting carbon ceramic composite resistor material has an apparent porosity of 35.2% and a bulk density of 2.25 g / cm³. 3 Its resistivity is 1.31 Ω·m, and its saturation magnetization is 1.5 emu•g. -1 .

[0043] Example 4 This embodiment provides a carbon ceramic composite resistor material, the raw materials of which include: alumina at 63% of the total mass, silicon dioxide at 21% of the total mass, iron oxide at 3% of the total mass, and isostatic graphite at 13% of the total mass. The alumina particle size is 300 nm, the silicon dioxide particle size is 4 μm, the iron oxide particle size is 800 nm, and the isostatic graphite is 300 mesh.

[0044] The preparation method of the carbon ceramic composite resistor material in this embodiment includes the following steps: 1) Place the weighed ceramic powder and zirconia grinding balls together in a ball mill jar and mix them on a drum ball mill for 20 hours. The mass of the zirconia grinding balls is twice the total mass of the raw material powder. 2) Pour out the mixed powder and sieve it through a 100-mesh sieve to separate the zirconia grinding balls and the uniformly mixed powder; 3) The uniformly mixed powder is loaded into a steel mold in batches, pressed and shaped under a pressure of 100 MPa for 20 seconds, and then the pressure is released and the mold is demolded to obtain a green blank. 4) Load the blank into the crucible and proceed as follows: Figure 2 The powder-embedded crucible is set up as shown. The set crucible is placed in a high-temperature furnace and heated to 750°C at a rate of 2°C / min and held for 1 hour. Then, the temperature is increased to 1350°C and held for 5 hours. The temperature is then decreased to 300°C at a rate of 5°C / min and cooled to room temperature with the furnace to obtain a carbon ceramic composite resistive material.

[0045] The obtained carbon-ceramic composite resistive material is mainly composed of corundum, mullite, graphite, anorthite, and quartz, with an apparent porosity of 26.9%, a bulk density of 2.24 g / cm³, a resistivity of 9.05 Ω·m, and a saturation magnetization of 1.1 emu•g. -1 .

[0046] Example 5 This embodiment provides a carbon ceramic composite resistor material, the raw materials of which include: alumina at 64% of the total mass, silicon dioxide at 22% of the total mass, iron oxide at 3% of the total mass, and isostatic graphite at 11% of the total mass. The alumina particle size is 300 nm, the silicon dioxide particle size is 4 μm, the iron oxide particle size is 800 nm, and the isostatic graphite is 800 mesh.

[0047] The preparation method of the carbon ceramic composite resistor material in this embodiment includes the following steps: 1) Place the weighed ceramic powder and zirconia grinding balls together in a ball mill jar and mix them on a drum ball mill for 20 hours. The mass of the zirconia grinding balls is twice the total mass of the raw material powder.

[0048] 2) Pour out the mixed powder and sieve it through a 100-mesh sieve to separate the zirconia grinding balls and the uniformly mixed powder.

[0049] 3) The uniformly mixed powder is loaded into a steel mold in batches, pressed and shaped under a pressure of 120 MPa for 20 seconds, and then the green blank is obtained by depressurization and demolding.

[0050] 4) Load the blank into the crucible and proceed as follows: Figure 2 The powder-embedded crucible is set up as shown. The set crucible is placed in a high-temperature furnace and heated to 750°C at a rate of 2°C / min and held for 1 hour. Then, the temperature is increased to 1350°C and held for 5 hours. The temperature is then decreased to 300°C at a rate of 5°C / min and cooled to room temperature with the furnace to obtain a carbon ceramic composite resistive material.

[0051] XRD analysis revealed that the material is mainly composed of corundum, mullite, anorthite, and graphite. Corundum provides high strength, while mullite and anorthite effectively reduce thermal conductivity and coefficient of thermal expansion. Graphite forms the conductive network within the material. The resulting carbon-ceramic composite resistive material exhibits an apparent porosity of 28.2%, a bulk density of 2.22 g / cm³, a resistivity of 0.02 Ω·m, and a saturation magnetization of 1.2 emu•g. -1 The hysteresis loop of the sample is as follows Figure 6 As shown.

[0052] Comparative Example 1 This comparative example provides a carbon ceramic composite resistor material, the raw materials of which include: alumina with an addition amount of 60% of the total mass, silicon dioxide with an addition amount of 25% of the total mass, and isostatic graphite with an addition amount of 15% of the total mass. The alumina particle size is 300 nm, the silicon dioxide particle size is 4 μm, and the isostatic graphite is 300 mesh.

[0053] The preparation method of the carbon ceramic composite resistor material in this embodiment includes the following steps: 1) Place the weighed ceramic powder and zirconia grinding balls together in a ball mill jar and mix them on a drum ball mill for 20 hours. The mass of the zirconia grinding balls is twice the total mass of the raw material powder.

[0054] 2) Pour out the mixed powder and sieve it through a 100-mesh sieve to separate the zirconia grinding balls and the uniformly mixed powder.

[0055] 3) The uniformly mixed powder is loaded into a steel mold in batches, pressed and shaped under a pressure of 800 MPa for 20 seconds, and then the green blank is obtained by depressurization and demolding.

[0056] 4) Load the blank into the crucible and proceed as follows: Figure 2 The powder-embedded crucible is set up as shown. The set crucible is placed in a high-temperature furnace and heated to 1350℃ at a rate of 2℃ / min and held for 5 hours. Then, it is cooled to 300℃ at a rate of 5℃ / min and cooled to room temperature with the furnace to obtain a carbon ceramic composite resistive material.

[0057] The obtained carbon-ceramic composite resistor material is mainly composed of quartz, graphite, corundum, and cristobalite, with an apparent porosity of 35.9% and a bulk density of 2.01 g / cm³. 3Its resistivity is 2.14 Ω·m.

[0058] Results Analysis Table 1 shows the performance comparison of Examples 1-5 and Comparative Example 1.

[0059] Table 1 Performance Comparison

[0060] The results show that as the calcination temperature increases, the material phase changes from being mainly composed of corundum, quartz, and graphite to being mainly composed of mullite, corundum, and graphite, and the porosity also changes accordingly. With increasing graphite content, the resistivity of the material decreases at the same calcination temperature. With increasing alumina / silicon oxide ratio, the resistivity of the material increases at the same graphite content and calcination temperature. At the same graphite content, alumina / silicon oxide ratio, and calcination temperature, the material using iron(III) oxide as an additive has lower porosity and resistivity compared to the material using iron oxide as an additive. Therefore, by rationally designing the raw material ratio, graphite content, and calcination temperature, carbon ceramic composite resistive materials with controllable phase composition and microstructure and tunable performance can be obtained, showing broad application prospects.

[0061] Therefore, the controllable preparation method for carbon ceramic composite resistive materials according to embodiments of the present invention employs a simple dry mixing process, simplifying the preparation process; the calcination method using a high-temperature furnace and a graphite powder-embedded crucible reduces the requirements for sintering equipment and corresponding plant facilities, and lowers sintering costs compared to conventional sintering methods. Furthermore, by adjusting the proportions of various components in the raw materials and the calcination temperature, the phase composition and microstructure of the sample can be effectively controlled, thereby enabling control over the porosity, bulk density, and resistivity of the final sample.

[0062] The above are merely 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 are included within the scope of the claims of the present invention pending approval.

Claims

1. A raw material composition for a carbon ceramic composite resistor material, characterized in that, The product comprises the following components by weight: 50-65 parts alumina, 20-25 parts silicon dioxide, 10-20 parts graphite, and 2-7 parts sintering aid; wherein the sintering aid is iron oxide or iron(II,III) oxide.

2. The raw material composition according to claim 1, characterized in that, The alumina has a particle size of 300nm~500nm; the silicon dioxide has a particle size of 1μm~30μm; the graphite is isostatically pressed graphite with a particle size of 4μm~80μm; the iron oxide has a particle size of 300nm~800nm; and the iron oxide has a particle size of 1μm~10μm.

3. A method for preparing carbon ceramic composite resistive materials using the raw material composition according to claim 1 or 2, characterized in that, Includes the following steps: Weigh out alumina, silicon dioxide, graphite, iron oxide or iron tetroxide raw materials in proportion, mix them to obtain a mixed powder; The mixed powder is loaded into a mold, pressed into shape, and demolded to obtain a green body; The green body is placed in a crucible containing graphite powder, the graphite powder is filled in, and the crucibles are nested together to obtain a nested crucible. The crucible of the kit is placed in a high-temperature furnace for sintering, and the crucible is removed to obtain the carbon ceramic composite resistor material.

4. The preparation method according to claim 3, characterized in that, The mixing process specifically includes: loading the raw material powder and zirconia grinding balls into a ball mill jar at a mass ratio of 1.5:1 to 3:1, ball milling at 80 rpm to 120 rpm for 16 to 20 hours, and separating the raw material and grinding balls using a 60-100 mesh sieve.

5. The preparation method according to claim 3, characterized in that, In the compression molding process, the molding pressure is 50MPa~120MPa, and the holding time is 10~30s.

6. The preparation method according to claim 3, characterized in that, The step of placing the green body into a crucible containing graphite powder, filling it with graphite powder, and then fitting the crucible together specifically includes: The green body is placed into a first crucible containing graphite powder; After covering the first crucible, it was inverted into the second crucible, and graphite powder was buried around the edge of its opening. Cover the second crucible to complete the crucible set.

7. The preparation method according to claim 6, characterized in that, A third crucible is provided between the first crucible and the second crucible. The third crucible is inverted over the bottom of the second crucible and covers the first crucible.

8. The preparation method according to claim 3, characterized in that, The sintering process includes: heating the billet to 1300℃~1450℃ and holding it at that temperature for 3~6 hours, then cooling it down to 300~450℃ at a rate of 5~10℃ / min and then cooling it to room temperature in the furnace.

9. The preparation method according to claim 8, characterized in that, When using ferric oxide as a sintering aid, it is necessary to hold at 700~800℃ for 1~2 hours during the heating process.

10. A carbon ceramic composite resistive material prepared by the preparation method according to any one of claims 3 to 9.

11. The carbon ceramic composite resistor material according to claim 10, characterized in that, The open porosity of the carbon ceramic composite resistor material is 14%-40%; and / or The bulk density of the carbon ceramic composite resistor material is 1.8 g / cm³. 3 -2.5g / cm 3 ; and / or The resistivity of the carbon ceramic composite resistor material is 0.01 Ω•m-50.00 Ω•m; and / or The saturation magnetization of the carbon ceramic composite resistive material is 0.5 emu•g. -1 -4.2 emu•g -1 .

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