Preparation method of starting resistor of direct-current power transmission system and starting resistor

Abstract

The invention relates to a preparation method of a starting resistor of a direct-current power transmission system and the starting resistor, and the method comprises the following steps: uniformly mixing conductive particles and a naphthalene sulfonic acid-formaldehyde condensate, and performing primary ball milling to obtain a raw material; adding ceramic aggregate into the raw materials, and carrying out secondary ball-milling treatment to obtain ball-milled slurry; carrying out drying treatment on the ball-milled slurry to obtain mixed powder; polyvinyl alcohol is added into the mixed powder for grinding and granulation, and granulated powder is obtained; the granulated powder is subjected to dry pressing forming treatment, and a dry pressing briquette is obtained; and sintering the dry-pressed briquette in a protective atmosphere to obtain the ceramic resistor substrate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of starting resistance of DC power transmission system, and particularly relates to a preparation method of starting resistance of DC power transmission system and starting resistance. BACKGROUND

[0002] Flexible DC power transmission technology has significant advantages such as long transmission distance, low loss, strong stability, high reliability, and can adapt to complex terrain and geological conditions, be suitable for power transmission systems of different voltage levels, improve the flexibility and controllability of the power transmission system, and help optimize the configuration of power resources. As the starting resistance of flexible DC power transmission, carbon ceramic linear resistance plays a crucial role in the reliable operation of the power system.

[0003] The existing carbon ceramic resistance has obvious defects in material performance, such as high room temperature resistivity, which affects the electrical conductivity; poor stability when subjected to transient high energy impact, easy to cause irreversible damage and lead to performance degradation; limited energy absorption capacity, which is difficult to meet the application requirements of high voltage circuit breakers under high energy impact.

[0004] In addition, the preparation process is also relatively complex, and the requirement for sintering equipment is extremely high, which increases the production cost and process difficulty. For example, the commonly used nitrogen atmosphere sintering is easy to cause oxidation and uneven distribution of carbon materials, which affects the performance of the final material.

[0005] The above information disclosed in the background section is only used to enhance the understanding of the background of the present application, and therefore can contain information that is not prior art known to those of ordinary skill in the art. SUMMARY

[0006] The present application provides a preparation method of starting resistance of DC power transmission system and starting resistance, which effectively reduces the room temperature resistivity of carbon ceramic resistance by adjusting the ratio of conductive particles and ceramic aggregates, and significantly improves its electrical conductivity. Secondly, the improved sintering process greatly enhances the stability and tolerance of carbon ceramic resistance under transient high energy impact, and improves its energy absorption capacity, so that it can better adapt to the working conditions of DC power transmission system. In addition, the present application simplifies the preparation process, reduces the requirement for sintering equipment, and through the use of argon atmosphere sintering and optimization of sintering temperature, not only reduces the production cost, but also improves the stability of the process and the consistency of the material.

[0007] A preparation method of starting resistance of DC power transmission system comprises:

[0008] The conductive particles and naphthalene formaldehyde condensate are uniformly mixed, and primary ball milling is performed to obtain raw materials;

[0009] The raw materials are added to the ceramic aggregates for secondary ball milling treatment to obtain a ball milling slurry;

[0010] The ball-milling slurry is dried to obtain a mixed powder;

[0011] Polyvinyl alcohol is added to the mixed powder and ground to obtain a granulated powder;

[0012] The granulated powder is dry-pressed to obtain a dry-pressed block;

[0013] The dry-pressed block is sintered in a protective atmosphere to obtain a ceramic resistance base.

[0014] In the preparation method of the direct current transmission system starting resistance, the content of each component is as follows, based on the total mass of the ceramic resistance base being 100%:

[0015] Conductive particles: 8% to 15%;

[0016] Naphthalene sulfonate formaldehyde condensate: 1%;

[0017] Ceramic aggregate: 84% to 91%.

[0018] In the preparation method of the direct current transmission system starting resistance, the ceramic aggregate comprises the following components in the following mass percentages:

[0019] Alumina: 50% to 60%;

[0020] Silicon oxide: 24% to 34%;

[0021] Kyanite: 6%;

[0022] Albite: 10%.

[0023] In the preparation method of the direct current transmission system starting resistance, the carbon black is carbon black particles with a purity of 99.9%, the particle size is , the alumina is particles with a purity of 99.9%, the particle size is , and the silicon oxide is particles with a purity of 99.9%, the particle size is .

[0024] In the preparation method of the direct current transmission system starting resistance, the sintering temperature of the dry-pressed block in the protective atmosphere is 1350-1450℃, the heating / cooling rate is 5℃ / min, and the holding time is 4h.

[0025] The preparation method of the starting resistance of the direct current power transmission system comprises: a first ball milling, a second ball milling, a drying treatment, a dry pressing forming, and a sintering.

[0026] The preparation method of the starting resistance of the direct current power transmission system comprises: a first ball milling, a second ball milling, a drying treatment, a dry pressing forming, and a sintering.

[0027] The preparation method of the starting resistance of the direct current power transmission system comprises: a first ball milling, a second ball milling, a drying treatment, a dry pressing forming, and a sintering.

[0028] The preparation method of the starting resistance of the direct current power transmission system comprises: a first ball milling, a second ball milling, a drying treatment, a dry pressing forming, and a sintering.

[0029] The preparation method of the starting resistance of the direct current power transmission system comprises: a first ball milling, a second ball milling, a drying treatment, a dry pressing forming, and a sintering.

[0030] Compared with the prior art, the starting resistance prepared by the method has the following advantages: the conductive particles are mixed with the ceramic aggregate raw material by ball milling, the conductive particles are uniformly dispersed in the ceramic aggregate, the conductivity of the starting resistance at room temperature is improved, the dry-pressed green body is obtained through dry pressing, and the high-performance carbon ceramic starting resistance is obtained through atmosphere sintering and polishing processing, the starting resistance has excellent conductivity, mechanical strength and stability, the problems of the material prepared by the existing preparation process, such as relatively large room temperature resistivity, poor stability, high manufacturing cost and high requirement for sintering equipment, are solved, the performance of the existing material under transient large energy impact is improved, the preparation process is simplified, the requirement for sintering equipment is reduced, and the production cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0031] Various other advantages and benefits of the present application will become apparent to those of ordinary skill in the art, upon reading the following detailed description of the preferred embodiment. The accompanying drawings are included to provide a better understanding of the preferred embodiment and are not to be considered limitations of the present application. It should be readily understood that the drawings are merely illustrative of the present application and that they, therefore, do not limit the present application, as claimed. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained according to these drawings without creative labor for those skilled in the art. Moreover, the same reference numbers are used to represent the same components throughout the drawings.

[0032] In the drawings:

[0033] Fig. 1 Process flow chart of the present application;

[0034] Fig. 2 EDS chart of carbon ceramic resistor provided in the embodiment of the present application;

[0035] Fig. 3 X-ray diffraction chart of carbon ceramic resistor composition provided in the embodiment of the present application;

[0036] Fig. 4 Compression resistance performance test chart of carbon ceramic resistor provided in the embodiment of the present application.

[0037] The present application will be further explained in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0038] The specific embodiments of the present application will be described in conjunction with the accompanying drawings. Although specific embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided so that the present application can be more thoroughly understood and the scope of the present application can be accurately conveyed to those skilled in the art.

[0039] It should be noted that certain terms are used throughout the specification and claims which have particular meanings. Those skilled in the art will appreciate that the same component can be referred to by different names. The present specification and claims do not serve as a basis for distinguishing components based on terminology differences. Instead, the present specification and claims serve as a basis for distinguishing components based on functional differences. As used throughout the specification and claims, "comprise" or "include" is an open term that should be interpreted as "comprise but not limited to." The subsequent description is provided as a preferred embodiment of implementing the present application, and the description is for the purpose of illustrating the general principles of the present application, not to limit the scope of the present application. The scope of the present application is defined by the appended claims.

[0040] For the convenience of understanding the embodiments of the present application, the following will be further explained and described with specific embodiments as examples in conjunction with the accompanying drawings, and each drawing does not constitute a limitation to the embodiments of the present application.

[0041] As shown in the figure, the preparation method of the direct current transmission system starting resistor comprises the following steps: Figs. 1 to 4

[0042] The conductive particles and the naphthalene sulfonate formaldehyde condensate are uniformly mixed, and primary ball milling is performed to obtain raw materials;

[0043] The raw materials are added to the ceramic aggregate for secondary ball milling treatment to obtain a ball milling slurry;

[0044] ​The ball-milling slurry is dried to obtain a mixed powder;

[0045] Polyvinyl alcohol is added to the mixed powder and ground to obtain a granulated powder;

[0046] The granulated powder is dry-pressed to obtain a dry-pressed block;

[0047] The dry-pressed block is sintered in a protective atmosphere to obtain a ceramic resistance substrate.

[0048] In the preferred embodiment of the preparation method of the direct-current power transmission system starting resistance, the content of each component is as follows, based on the total mass of the ceramic resistance substrate being 100%:

[0049] Conductive particles: 8% to 15%;

[0050] Naphthalene sulfonate formaldehyde condensate: 1%;

[0051] Ceramic aggregate: 84% to 91%.

[0052] In the preferred embodiment of the preparation method of the direct-current power transmission system starting resistance, the ceramic aggregate comprises the following components in the following mass percentages:

[0053] Alumina: 50% to 60%;

[0054] Silicon oxide: 24% to 34%;

[0055] Cyprine: 6%;

[0056] Albite: 10%.

[0057] In the preferred embodiment of the preparation method of the direct-current power transmission system starting resistance, the carbon black is carbon black particles with a purity of 99.9%, the particle size is , the alumina is particles with a purity of 99.9%, the particle size is , and the silicon oxide is particles with a purity of 99.9%, the particle size is .

[0058] In the preferred embodiment of the preparation method of the direct-current power transmission system starting resistance, the sintering temperature of the dry-pressed block in the protective atmosphere is 1350-1450℃, the heating / cooling rate is 5℃ / min, and the holding time is 4h.

[0059] In the preferred embodiment of the preparation method of the starting resistance of the direct current transmission system, zirconium oxide balls are used in the first ball milling, and the wet ball milling is added with deionized water accounting for 5% of the total mass of the ball milling material, the rotation speed of the first ball milling is 400 r / min, and the time is 1 h, zirconium oxide balls are used in the second ball milling, and the wet ball milling is added with deionized water accounting for 10% of the total mass of the ball milling material, the rotation speed of the second ball milling is 500 r / min, and the time is 2 h.

[0060] In the preferred embodiment of the preparation method of the starting resistance of the direct current transmission system, the drying treatment is constant-temperature air drying, the drying temperature is 110°C, and the drying treatment time is 8 h.

[0061] In the preferred embodiment of the preparation method of the starting resistance of the direct current transmission system, polyvinyl alcohol is added for grinding and granulation, and the amount of the added polyvinyl alcohol is 10% based on 100% of the mass of the ceramic resistance matrix, and the polyvinyl alcohol concentration is 10% wt.

[0062] In the preferred embodiment of the preparation method of the starting resistance of the direct current transmission system, the pressure of the dry pressing forming is 70-120 MPa, and the pressure holding time is 30 s.

[0063] A starting resistance prepared by the method.

[0064] The formula amount is 10% of conductive particles and 1% of naphthalene sulfonate formaldehyde condensate by weight, and the conductive particles are carbon black or graphite. Naphthalene sulfonate formaldehyde condensate is an anionic surfactant containing a large number of sulfonic acid groups in its molecular structure. When it ionizes into negatively charged sulfonate ions in water, it can be adsorbed on the surface of carbon black particles, further increasing the negative charge density on the surface of carbon black particles. These negatively charged carbon black particles will produce electrostatic repulsion between them, preventing the mutual approach and agglomeration of particles, thereby maintaining good dispersibility of carbon black in deionized water.

[0065] In the preferred embodiment of the preparation method of the starting resistance of the direct current transmission system, the carbon black is carbon black particles with a purity of 99.9%, and the particle size is .

[0066] In the preferred embodiment of the preparation method of the starting resistance of the direct current transmission system, the conductive particles account for , the naphthalene sulfonate formaldehyde condensate accounts for , and the ceramic aggregate accounts for .

[0067] In the preferred embodiment of the preparation method of the starting resistance of the direct current transmission system, the ceramic aggregate raw material includes alumina, silicon oxide, kyanite, albite.

[0068] In the preparation method of the starting resistance of the direct current transmission system, the alumina is a particle with a purity of 99.9%, and a particle size of The silicon oxide is a particle with a purity of 99.9%, and a particle size of .

[0069] In the preferred embodiment of the preparation method of the starting resistance of the direct current transmission system, the primary ball milling is wet ball milling with zirconium oxide balls and 5% deionized water compared to the total mass of the ball milling material, the rotation speed of the primary ball milling is 400 r / min, and the time is 1 h, the secondary ball milling is wet ball milling with zirconium oxide balls and 10% deionized water compared to the total mass of the ball milling material, and the rotation speed of the secondary ball milling is 500 r / min, and the time is 2 h.

[0070] In the preferred embodiment of the preparation method of the starting resistance of the direct current transmission system, the drying treatment is constant temperature air drying, the temperature of the drying is 110°C, and the drying treatment time is 8 h.

[0071] In the preferred embodiment of the preparation method of the starting resistance of the direct current transmission system, polyvinyl alcohol is added for grinding and granulation, and the amount of the polyvinyl alcohol added is 10% based on the mass of the ceramic resistance base body, and the concentration of the polyvinyl alcohol is 10% wt.

[0072] In the preferred embodiment of the preparation method of the starting resistance of the direct current transmission system, the protective atmosphere is argon, the sintering temperature is 1350-1450°C, the heating and cooling rates of the sintering are both 5°C / min, the holding time of the sintering is 4 h, and polishing processing is performed after the sintering. Sintering in an argon atmosphere isolates air, ensuring that the conductive particles are not lost due to reaction with air during high-temperature sintering, so that the conductive chain formed by the conductive particles in the ceramic aggregate is complete. At the same time, controlling the heating rate ensures the growth of the crystal cells of the ceramic aggregate during the sintering process, which can form a relatively uniform void structure. A large number of uniform voids help the ceramic resistance to dissipate heat and expand under a transient large energy impact, maintaining the stability of the ceramic resistance base body.

[0073] A starting resistance comprising a ceramic resistance base body prepared via the method.

[0074] In one embodiment, polyvinyl alcohol is added to the mixed powder for grinding and granulation and is passed through 40 mesh and 100 mesh screens to obtain the granulated powder.

[0075] In one embodiment, the drying temperature is above 100℃.

[0076] In one embodiment, the dry-pressing pressure is 70-120Mpa, and the dry-pressing dwell time is 30s.

[0077] Preferably, the dry-pressing pressure is 90-110Mpa.

[0078] In one embodiment, the ceramic resistor comprises conductive particles, dispersant naphthalene formaldehyde condensate and ceramic aggregate. The conductive particles and naphthalene formaldehyde condensate are ball-mixed according to a certain ratio, and then the raw materials of the ceramic aggregate are added, dried and granulated, and then dry-pressed. Finally, the formed compact is sintered in an atmosphere. By optimizing the ratio of the conductive particles and the ceramic aggregate, the room temperature resistivity of the carbon ceramic resistor is significantly reduced, and the electrical conductivity is improved. At the same time, the improved sintering process greatly enhances the stability and resistance of the carbon ceramic resistor under transient high energy impact.

[0079] Preferably, the ceramic resistor substrate is a carbon ceramic resistor. The conductive particles account for , for example, 8.5%, 9%, 10%, 12%, etc. The ceramic aggregate of the carbon ceramic resistor accounts for , for example: 50%, 52%, 54%, 56%, 60%, etc. The silicon oxide accounts for , for example: 24%, 26%, 28%, 30%, 22%, 34%, etc.

[0080] Preferably, the sintering temperature is 1350-1450℃, for example, 1350℃, 1370℃, 1400℃, 1420℃, 1450℃, etc.

[0081] Embodiment 1

[0082] The embodiment provides a preparation method of a direct current transmission system starting resistor based on a carbon ceramic material, and the preparation method comprises the following steps:

[0083] Step (1) : taking the mass of the carbon ceramic resistor as 100%, 8% conductive particle carbon black and 1% naphthalene formaldehyde condensate are ball-mixed at a speed of 400r / min for 1h to obtain a first ball-mixed material.

[0084] The purity of the carbon black particles is 99.9%, and the particle size is 4 ;

[0085] The first ball-milling method is wet ball-milling, and zirconia balls and 5% deionized water compared to the total mass of the ball-mixed material are used for the first ball-milling.

[0086] Step (2), the primary ball milling slurry obtained in step (1) is added with ceramic aggregate at a mass of 91% based on 100% of the mass of the carbon ceramic resistor. 50% of alumina, 34% of silica, 8% of sodium feldspar, and 8% of kyanite are added based on 100% of the ceramic aggregate of the carbon ceramic resistor, and secondary ball milling is performed at a rotation speed of 500 r / min for 2 h;

[0087] The secondary ball milling is performed by wet ball milling, and zirconium oxide balls and deionized water at 10% of the total mass of the ball milling material are used for the primary ball milling;

[0088] The purity of the alumina and the silica is 99.9%, and the particle size is 2 ;

[0089] Step (3), the secondary ball milling slurry obtained in step (2) is dried at 110°C for 8 h;

[0090] Step (4), the dried powder in step (3) is added with polyvinyl alcohol at a concentration of 10% wt, and the amount of polyvinyl alcohol added is 10% based on 100% of the mass of the carbon ceramic resistor, and the powder is ground and granulated;

[0091] Step (5), the powder after granulation in step (4) is dry-pressed to obtain a formed block;

[0092] The pressure of the dry pressing is 100 MPa, and the pressure holding time is 30 s;

[0093] Step (6), the formed block in step (5) is sintered at 1350°C for 4 h in an argon atmosphere, and then surface polishing is performed. The carbon ceramic starting resistor is obtained;

[0094] Example 2

[0095] The present embodiment provides a DC power transmission system starting resistor based on a carbon ceramic material. In step (6) of the preparation method of the carbon ceramic resistor, the sintering temperature is adjusted from 1350°C to 1375°C, and other conditions are the same as those in Example 1.

[0096] Example 3

[0097] The present embodiment provides a DC power transmission system starting resistor based on a carbon ceramic material. In step (6) of the preparation method of the carbon ceramic resistor, the sintering temperature is adjusted from 1350°C to 1400°C, and other conditions are the same as those in Example 1.

[0098] Example 4

[0099] The embodiment provides a DC power transmission system starting resistor based on a carbon ceramic material, and the sintering temperature is adjusted from 1350 DEG C to 1450 DEG C in step (6) of the carbon ceramic resistor preparation method, and other conditions are completely same with those in embodiment 1.

[0100] Embodiment 5

[0101] The embodiment provides a DC power transmission system starting resistor based on a carbon ceramic material, and in step (1) of the carbon ceramic resistor preparation method, the adding amount of conductive particle carbon black is adjusted from 8% to 10% and the amount of ceramic aggregate is adjusted to 89% based on 100% of the mass of the carbon ceramic resistor, the sintering temperature is adjusted from 1350 DEG C to 1400 DEG C in step (6) of the carbon ceramic resistor preparation method, and other conditions are completely same with those in embodiment 1.

[0102] Embodiment 6

[0103] The embodiment provides a DC power transmission system starting resistor based on a carbon ceramic material, and in step (1) of the carbon ceramic resistor preparation method, the adding amount of conductive particle carbon black is adjusted from 8% to 12% and the amount of ceramic aggregate is adjusted to 87% based on 100% of the mass of the carbon ceramic resistor, and other conditions are completely same with those in embodiment 1.

[0104] Embodiment 7

[0105] The embodiment provides a DC power transmission system starting resistor based on a carbon ceramic material, and in step (1) of the carbon ceramic resistor preparation method, the adding amount of conductive particle carbon black is adjusted from 8% to 15% and the amount of ceramic aggregate is adjusted to 84% based on 100% of the mass of the carbon ceramic resistor, and other conditions are completely same with those in embodiment 1.

[0106] Embodiment 8

[0107] The embodiment provides a DC power transmission system starting resistor based on a carbon ceramic material, and in step (5) of the carbon ceramic resistor preparation method, the pressure of dry pressing forming is adjusted from 100 MPa to 90 MPa, and other conditions are completely same with those in embodiment 1.

[0108] Embodiment 9

[0109] The embodiment provides a DC power transmission system starting resistor based on a carbon ceramic material, and in step (5) of the carbon ceramic resistor preparation method, the pressure of dry pressing forming is adjusted from 100 MPa to 110 MPa, and other conditions are completely same with those in embodiment 1.

[0110] Embodiment 10

[0111] The embodiment provides a carbon ceramic material-based starting resistance of a direct current transmission system, and the carbon ceramic resistance is prepared by the following method: in step (2), the amount of added alumina is adjusted from 50% to 55% and the amount of added silicon oxide is adjusted from 34% to 29% based on 100% of ceramic aggregates of the carbon ceramic resistance, and other conditions are completely same as those in the embodiment 1.

[0112] Embodiment 11

[0113] The embodiment provides a carbon ceramic material-based starting resistance of a direct current transmission system, and the carbon ceramic resistance is prepared by the following method: in step (2), the amount of added alumina is adjusted from 50% to 60% and the amount of added silicon oxide is adjusted from 34% to 24% based on 100% of ceramic aggregates of the carbon ceramic resistance, and other conditions are completely same as those in the embodiment 1.

[0114] The carbon ceramic resistance obtained in the embodiment is tested as follows: the resistivity is tested by using a high-precision ohmmeter to measure the resistance value in a room temperature and electromagnetic interference-free environment, and is converted according to the actual size of the carbon ceramic resistance; the compressive strength is tested by a pressure test according to the standard GB / T 8489-2006, and is converted according to the actual size of the carbon ceramic resistance.

[0115] The results are shown in Table 1.

[0116] Table 1

[0117]

[0118] According to the performance requirements of the carbon ceramic resistance in the industry standard, the compressive strength , and the resistivity .

[0119] As shown in Table 1, through comparison between different embodiments, the embodiment 2 has the best performance. The resistivity of the embodiment 2 is , and the resistivity values of the other embodiments fluctuate around the value. This may be because the content of the conductive particle carbon black is less, which is not enough to form a complete conductive chain, and thus the resistivity rises; in addition, when the content of the conductive particle carbon black is more, more conductive paths are formed, so that the resistivity decreases. The compressive strength of the embodiment 2 is 109.836 MPa, and the compressive strengths of the other embodiments fluctuate around the value. This is because when the sintering temperature is too low, the crystal grains of the ceramic aggregate have not grown, which is not enough to maintain the stability of the ceramic aggregate under a large pressure, and meanwhile, when the temperature is too high, the crystal produces too much liquid phase in the sintering process, which affects the support structure of the ceramic aggregate skeleton.

[0120] The mixing and ball milling of conductive particles and dispersant uniformly mixes and ball mills the conductive particles (such as carbon black or graphite) and dispersant naphthalene sulfonate formaldehyde condensate, which helps form a uniformly distributed conductive network in the subsequent process, improving the electrical conductivity of the final product.

[0121] Secondary ball milling, after adding the ceramic aggregate raw materials, ensures that all ingredients are thoroughly mixed, resulting in a uniform slurry. This step is crucial for ensuring the consistency and stability of the internal structure of the final product.

[0122] Drying, by constant temperature blast drying, removes water from the ball mill slurry to obtain a mixed powder suitable for shaping. The appropriate drying temperature and time ensure the quality of the powder, avoiding product defects caused by residual moisture.

[0123] Addition and grinding of polyvinyl alcohol: Polyvinyl alcohol is added as a binder to the mixed powder, and the grinding process improves the flowability of the powder, making it easier to dry-press form. This step directly affects the density and strength of the finished product.

[0124] Dry pressing, dry pressing under specific pressure forms a green body with certain shape and strength. Appropriate molding pressure and holding time are very important to ensure the mechanical strength of the green body and the subsequent sintering effect.

[0125] Sintering in a protective atmosphere, high-temperature sintering in an argon or other protective atmosphere prevents the loss of conductive particles due to reaction with air, while controlling the heating rate and holding time to optimize cell growth and promote the formation of a uniform void structure, which is critical for improving the electrical conductivity of the material and its stability and resistance to high-energy impact.

[0126] Precise control of the ratio of the formula, by adjusting the ratio of conductive particles, dispersants, ceramic aggregates and other ingredients, the resistivity and compressive strength of the final product can be effectively adjusted to meet different application requirements.

[0127] Experimental design and performance testing, through the design and comparison of multiple examples, the influence of different process parameters on the performance of the final product is evaluated, providing a scientific basis for optimizing the production process.

[0128] In one embodiment, the ceramic resistance matrix is used in a direct current transmission system, with a performance retention rate ≥95% after withstanding transient high-energy impact.

[0129] The synergistic dispersion of the conductive particles and the dispersant solves the problems of high resistivity and poor uniformity. The carbon black / graphite (8-15%) is wet ball milled with naphthalene sulfonate formaldehyde condensate (1%) by 400 r / min x 1 h (deionized water 5%). The sulfonic acid groups of the dispersant molecules are ionized and adsorbed on the surface of the carbon black, enhancing the electrostatic repulsion and breaking the particle agglomeration, overcoming the uneven distribution caused by nitrogen sintering. The small particle size carbon black (4-10 μm) provides a high specific surface area to form a continuous conductive network, and the resistivity of the undispersed system is reduced by more than 40%. The optimization of the proportion of ceramic aggregate improves the mechanical strength and impact resistance. The high proportion of alumina (≥50%) generates mullite and A rigid skeleton can be provided as a support structure. Kyanite / sodium feldspar promotes the conversion of mullite at high temperatures to generate a ceramic resistance support structure. The particle size gradient control of alumina (4-10 μm) and silicon oxide (10-50 μm) is matched to reduce sintering stress cracks. The compressive strength is >100 MPa (all examples meet the standard), the performance retention rate after transient impact is >95%, argon atmosphere sintering (solves oxidation loss and structural defects) argon protection, 1350-1450°C for 4 h, heating / cooling rate 5°C / min, oxygen isolation: avoid carbon black oxidation, overcome the oxidation problem of nitrogen sintering; low speed temperature change: control the grain growth rate, form uniform pores: conducive to heat expansion buffer and heat dissipation when energy impact, improve the integrity of the conductive chain, dry pressing pressure 90-110 MPa (example 1: 100 MPa→ compressive strength 112.3 MPa), polyvinyl alcohol binder (10% concentration, addition amount 10%) in the middle of the molding: avoid insufficient density caused by low pressure (<90 MPa) or microcracks caused by high pressure (>110 MPa); PVA granulation: improve the flowability of the powder, replace the complex isostatic pressing process, simplify the process, and reduce the production cost by 30%.

[0130] Although the embodiments of the present application are described above with reference to the drawings, the present application is not limited to the above-described specific embodiments and application fields, and the above-described specific embodiments are only illustrative and guiding, but not limiting. Those skilled in the art can make many forms under the guidance of this specification and without departing from the scope protected by the claims of the present application, which are all included in the protection of the present application.

Claims

1. A method of making a start-up resistor for a direct current power transmission system, characterized in that The method comprises the following steps: The conductive particles and naphthalene sulfonate formaldehyde condensate are uniformly mixed to obtain a raw material by primary ball milling; The raw material is added to ceramic aggregates to obtain a ball milling slurry by secondary ball milling; The ball milling slurry is dried to obtain a mixed powder; Polyvinyl alcohol is added to the mixed powder to obtain a granulated powder by grinding and granulation; The granulated powder is dry-pressed to obtain a dry-pressed compact; The dry-pressed compact is sintered in a protective atmosphere to obtain a ceramic resistance matrix.

2. The method of claim 1, wherein the DC power transmission system starting resistor is prepared by the steps of: Preferably, The carbon black particles have a purity of 99.9% during preparation.

3. The method of claim 2, wherein the DC power transmission system starting resistor is prepared by the steps of: The particle size of the carbon black particles is . ​ 4. The method of claim 2, wherein the DC power transmission system starting resistor is prepared by the steps of: Aluminum oxide particles with a purity of 99.9% are also used during preparation.

5. The method of claim 1, wherein the DC power transmission system starting resistor is prepared by the steps of: The sintering of the dry-pressed compact in a protective atmosphere is performed for 4 hours. ​ 6. The method of claim 1, wherein the DC power transmission system starting resistor is prepared by the steps of: Zirconium oxide balls and 5% deionized water relative to the total mass of the ball milling material are used in the wet ball milling of the primary ball milling, which is performed at a speed of 400 r / min for 1 hour. Zirconium oxide balls and 10% deionized water relative to the total mass of the ball milling material are used in the wet ball milling of the secondary ball milling, which is performed at a speed of 500 r / min for 2 hours.

7. The method for preparing a starting resistor for a DC transmission system according to claim 1, characterized in that, The drying process is constant temperature air drying, which is performed at a temperature of 110°C for 8 hours.

8. The method of claim 1, wherein the DC power transmission system starting resistor is prepared by the steps of: The polyvinyl alcohol is added to the ceramic resistance matrix by grinding and granulation, and the amount of polyvinyl alcohol added is 10% based on the mass of the ceramic resistance matrix, and the concentration of polyvinyl alcohol is 10% wt. ​ 9. The method of claim 1, wherein the DC power transmission system starting resistor is prepared by the steps of: The pressure of the dry-pressing is 70-120 MPa, and the pressure holding time is 30 seconds. ​ 10. A start-up resistor characterized by, The ceramic resistance matrix is prepared by the method of any one of claims 1-9.

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