阅读说明：本技术 一种碳陶瓷线性电阻多孔高阻涂层及其制备方法 (Carbon ceramic linear resistance porous high-resistance coating and preparation method thereof ) 是由 陈炜岳 陈维 姚旭瑞 马红梅 赵栓翠 于 2020-06-05 设计创作，主要内容包括：本发明公开一种碳陶瓷线性电阻多孔高阻涂层及其制备方法,多孔高阻涂层采用包括本膨润土0～30份,左云土0～30份,莫来石粉或煅烧矾土40～80份和氧化铬3～6份原料制备而成,制备时首先将膨润土、左云土、莫来石粉或煅烧矾土和氧化铬经球磨均匀混合成高阻层浆料,将高阻层浆料涂覆在未烧结的碳陶瓷电阻坯体侧面然后与电阻一同烧结,在电阻侧面得到一层结合稳定的高阻层；本发明制备的多孔高阻涂层具备良好的散热、抗腐蚀以及耐污能力,并能显著地提高线性电阻的耐压能力。(The invention discloses a carbon ceramic linear resistance porous high-resistance coating and a preparation method thereof, wherein the porous high-resistance coating is prepared by adopting raw materials comprising 0-30 parts of bentonite, 0-30 parts of levo-cloud soil, 40-80 parts of mullite powder or calcined alumina and 3-6 parts of chromium oxide, the preparation method comprises the steps of firstly ball-milling the bentonite, the levo-cloud soil, the mullite powder or calcined alumina and the chromium oxide to uniformly mix into high-resistance layer slurry, coating the high-resistance layer slurry on the side surface of an unsintered carbon ceramic resistance blank body, and then sintering the carbon ceramic resistance blank body and a resistance together to obtain a stably combined high-resistance layer on the side surface of the resistance; the porous high-resistance coating prepared by the invention has good heat dissipation, corrosion resistance and stain resistance, and can remarkably improve the pressure resistance of the linear resistor.)

1. The porous high-resistance coating of the carbon ceramic linear resistor is characterized by being prepared from the following raw materials in parts by mass:

the contents of bentonite and levo-bentonite are not zero at the same time, and the contents of the bentonite and the levo-bentonite are not less than 20 parts.

2. The carbon ceramic linear resistance porous high-resistance coating according to claim 1, characterized in that: the particle size of the mullite powder or the calcined alumina is 325 meshes.

3. A method for preparing the carbon ceramic linear resistance porous high-resistance coating according to claim 1 or 2, which is characterized by comprising the following steps:

a. mixing the raw materials according to a ratio to obtain mixed powder, mixing the mixed powder with zirconia balls and deionized water according to a mass ratio of 1:2:0.7, and performing ball milling for half an hour to obtain coating slurry;

b. uniformly coating the coating slurry obtained in the step a on the side of a linear resistor, controlling the thickness to be 0.2-0.6 mm, and drying the linear resistor coated with the coating slurry in an oven;

c. and c, sintering the linear resistor dried in the step b in a high-temperature furnace, heating the linear resistor to 400 ℃ from room temperature at a speed of 150 ℃/h, then heating the linear resistor to 1350-1550 ℃ from 400 ℃ at a speed of 250 ℃/h, preserving heat for 120 minutes, cooling the linear resistor along with the furnace after the heat preservation is finished, and forming a porous high-resistance coating on the side edge of the linear resistor.

4. The preparation method of the carbon ceramic linear resistance porous high-resistance coating according to claim 3, characterized in that: in the step b, the drying temperature is 100-120 ℃, and the drying time is more than 4 h.

5. The preparation method of the carbon ceramic linear resistance porous high-resistance coating according to claim 3, characterized in that: and in the step c, hydrogen or nitrogen is used as protective gas in the sintering process.

6. A carbon ceramic linear resistor comprising a porous high resistance coating prepared according to the method of claims 3-5.

Technical Field

The invention belongs to the field of electronic and electrical elements, relates to a carbon ceramic linear resistor for high-voltage switch protection, and particularly relates to a porous high-resistance coating of the carbon ceramic linear resistor and a preparation method thereof.

Background

The carbon ceramic linear resistor is a parallel resistor applied to two sides of a main gate of a high-voltage circuit breaker with over 330kV, and in the switching-on process of the circuit breaker, the parallel resistor is used for absorbing electric energy and converting part of electric energy in a power grid into heat energy so as to weaken electromagnetic oscillation generated in a circuit and limit overvoltage on two sides of the main gate. The parallel resistor may facilitate the extinguishing of the arc during the opening of the circuit breaker. The carbon ceramic resistance card of the common high-voltage circuit breaker is usually 2-40 omega, the carbon resistance resistivity is low, and the surface of the side surface of the resistor is in a non-insulated semiconductor state. Under the action of high voltage, the carbon ceramic linear resistor is easy to generate side surface flashover and even breakdown. Therefore, in order to prevent the resistance side from flashover and improve the flashover voltage and impulse current resistance of the sample, a high-resistance layer insulating layer needs to be prepared on the resistance side to prevent the flashover from occurring on the resistance side.

The high resistance layer meeting the requirements should have the characteristics of moisture resistance, stain resistance and improvement of electric field distribution, thereby improving the surface flashover voltage, and also have better heat dissipation performance and appropriate bonding strength with a resistance substrate. Because the resistor can generate short-time high temperature during working, the technical condition requires that the high-resistance layer can resist 1000 ℃, and the use of organic materials is limited.

The insulating property of the side surface of the resistor can be improved by adopting an inorganic substance as the high-resistance layer, and the following problems still exist at present: 1. the carbon ceramic linear resistor needs to bear the action of impact current with large energy, a large amount of heat generated inside the resistor needs to be discharged through air holes, and the heat dissipation performance of the linear resistor is affected by the fact that the high-resistance layer coated is a compact layer. 2. The resistor coated with the insulating coating needs to be placed into a sintering furnace for high-temperature sintering, the sintering process is a process of firstly heating and then cooling, in the process of heating and cooling, the expansion and shrinkage phenomena are generated between the carbon ceramic linear resistor and the insulating coating due to the change of temperature, and the unmatched expansion coefficient can cause the insulating coating to crack, peel and the like, so that the electrical property of the resistor is influenced.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a carbon ceramic linear resistor porous high-resistance coating and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical application:

the porous high-resistance coating of the carbon ceramic linear resistor is prepared from the following raw materials in parts by mass:

the contents of bentonite and levo-bentonite are not zero at the same time, and the contents of the bentonite and the levo-bentonite are not less than 20 parts.

Further, the particle size of the mullite powder or the calcined alumina is 325 meshes.

A preparation method of a carbon ceramic linear resistance porous high-resistance coating comprises the following steps:

a. mixing the raw materials according to a ratio to obtain mixed powder, mixing the mixed powder with zirconia balls and deionized water according to a mass ratio of 1:2:0.7, and performing ball milling for half an hour to obtain coating slurry;

b. uniformly coating the coating slurry obtained in the step a on the side of a linear resistor, controlling the thickness to be 0.2-0.6 mm, and drying the linear resistor coated with the coating slurry in an oven;

c. and c, sintering the linear resistor dried in the step b in a high-temperature furnace, heating the linear resistor to 400 ℃ from room temperature at a speed of 150 ℃/h, then heating the linear resistor to 1350-1550 ℃ from 400 ℃ at a speed of 250 ℃/h, preserving heat for 120 minutes, cooling the linear resistor along with the furnace after the heat preservation is finished, and forming a porous high-resistance coating on the side edge of the linear resistor.

Further, in the step b, the drying temperature is 100-120 ℃, and the drying time is more than 4 h.

Further, hydrogen or nitrogen is used as a protective gas in the sintering process in the step c.

A carbon ceramic linear resistor comprising a porous high resistance coating.

Compared with the prior art, the invention has the following advantages:

1. the porous high-resistance coating has wide sintering temperature range, can be sintered with the carbon ceramic linear resistor at one time, and saves the time and the material cost in the resistor sintering process.

2. The high-resistance layer adopts the aggregate consistent with the carbon ceramic linear resistor body, so that the expansion rate of the high-resistance layer can be matched with the linear resistor body, and the phenomena of cracking, peeling and the like of the high-resistance layer in the sintering process are improved. Meanwhile, the linear resistor can also play a role in making up for the defects of side air holes and insulation structures of the linear resistor.

3. The high-resistance layer is made of plastic clay to form slurry, and has the characteristics of easy coating and uniform coating.

4. The preparation process of the linear resistance coating is simple and easy to operate, the preparation time is short, the cost is low, the performance is reliable, the production is easy, and the used materials are nontoxic and pollution-free.

5. The high-resistance layer prepared by the invention has high strength, firm adhesion and difficult shedding, does not change the resistivity of the linear resistor, has good improvement effect on the side flashover of the high-resistance layer, improves the capability of the resistance card for enduring high voltage and large current, and can fully meet the protection requirement of a switch circuit breaker.

6. The high-resistance layer prepared by the method has the porosity of 18-26%, and the porous structure ensures that heat generated when the resistance is subjected to through-flow resistance is discharged in time, so that the thermal damage generated when a resistance sample is subjected to high-current high-power injection is reduced.

Detailed Description

The present invention will be described in further detail with reference to the following examples, which are not intended to limit the invention thereto.