CN105017695A - Nano-modified polytetrafluoroethylene composite material, arc-quenching nozzle and preparation method thereof, and high voltage circuit breaker - Google Patents

Abstract

The invention discloses a nano-modified polytetrafluoroethylene composite material, an arc extinguishing nozzle and a preparation method thereof, and a high-voltage circuit breaker. The nano-modified polytetrafluoroethylene composite material is composed of the following components by weight percentage: 1-3% of nanometer boron nitride, 3-10% of micron boron nitride, and the balance is polytetrafluoroethylene. The arc extinguishing nozzle can adopt the above-mentioned nano-modified polytetrafluoroethylene composite material. The arc extinguishing nozzle of the present invention is filled with polytetrafluoroethylene compounded with nano-boron nitride and micro-boron nitride, and the filling ratio is reasonably adjusted to improve the mechanical properties of the nozzle material, improve the toughness and crack resistance of the material, and improve The thermal conductivity of the nozzle material is improved, and the arc ablation resistance performance of the material is improved; the high-voltage circuit breaker adopting the arc-extinguishing nozzle of the present invention can improve the breaking performance of the circuit breaker, thereby improving the operation stability of the high-voltage circuit breaker.

Description

A nano-modified polytetrafluoroethylene composite material, an arc extinguishing nozzle and its preparation method, and a high-voltage circuit breaker

technical field

The invention belongs to the technical field of high-voltage circuit breakers, and specifically relates to a nano-modified polytetrafluoroethylene composite material, an arc-extinguishing nozzle and a preparation method thereof, and a high-voltage circuit breaker using the arc-extinguishing nozzle.

Background technique

As an important power equipment in the power system, the high-voltage SF ₆ circuit breaker is currently developing towards high voltage and large capacity, and the requirements for providing power energy stability and operational reliability are getting higher and higher. The nozzle of the SF ₆ circuit breaker arc extinguishing chamber controls the flow of arc blowing gas during the breaking process, which directly affects the recovery characteristics of the SF ₆ gas medium strength and the arc extinguishing ability in the breaking process. When the circuit breaker breaks the short-circuit current, the nozzle that moves at high speed together with the moving contact is subjected to the ablation of the high-temperature arc above 4000K and the reaction force of the compressed gas in the compression cylinder, which is prone to surface ablation and internal decomposition, and even It will cause the fracture of the spout. Therefore, the mechanical properties and ablation resistance of the spout material directly affect the breaking capacity and service life of the high-voltage circuit breaker.

At present, the spout material mostly adopts polytetrafluoroethylene material. Polytetrafluoroethylene (PTFE) has excellent electrical insulation properties, high temperature resistance, arc resistance, excellent thermal stability, high light reflectivity, outstanding chemical inertness, excellent physical and mechanical properties and good Weather resistance, widely used in electrical appliances and high, medium and low voltage switches, used as insulating materials, circuit breaker nozzles (nozzles), gaskets, brake rings, bushings, etc. However, the PTFE material begins to decompose significantly above 400°C, and the arc temperature during the breaking process of the high-voltage circuit breaker can reach above 4000K. When pure PTFE material is used as the arc extinguishing nozzle, due to the irregular absorption of arc energy , pure PTFE materials will undergo significant surface decomposition and severe internal rupture. Therefore, in the process of making the spout, some inorganic powder materials are usually added to the PTFE material as a filler to make a composite material, making it an energy absorption center, thereby regulating the absorption of arc energy and reducing the random decomposition of the spout. In order to enhance the ablation resistance of the spout and prolong the service life of the spout.

In the prior art, composite materials filled with inorganic fillers mainly include alumina-filled PTFE composite materials, molybdenum disulfide-filled PTFE composite materials, and boron nitride-filled PTFE composite materials. Molybdenum and aluminum oxide filled PTFE composites have good mechanical properties, but their arc ablation resistance is slightly poor; boron nitride (usually micron boron nitride) filled mechanical properties of PTFE composites Performance, especially tensile strength, is significantly lower than that of molybdenum disulfide and aluminum oxide formulations.

Patent CN102731943B discloses a high-voltage, high-current arc ablation nozzle made of molybdenum disulfide-boron nitride-polytetrafluoroethylene composite materials, and its mass percentage composition is: (1-10 μm) boron nitride 1 ~8%, (1~10μm) molybdenum disulfide is 0.1~0.4%, and the balance is polytetrafluoroethylene. Today, when high-voltage circuit breakers are developing towards high voltage and large capacity, the composite spout still has the problems of poor toughness and crack resistance, and insufficient arc ablation resistance.

Contents of the invention

The invention provides a nano-modified polytetrafluoroethylene composite material, and at the same time provides an arc extinguishing nozzle using the nano-modified polytetrafluoroethylene composite material, which solves the problem of poor toughness and crack resistance of the existing composite material nozzle, and arc resistance The problem of insufficient ablative performance.

The present invention further provides a preparation method of the above-mentioned arc extinguishing nozzle.

The present invention also provides a high-voltage circuit breaker using the arc extinguishing nozzle.

In order to achieve the above purpose, the technical solution adopted in the present invention is: a nano-modified polytetrafluoroethylene composite material, which is composed of the following components in weight percentage: 1-3% of nano-boron nitride, 3-3% of micro-boron nitride 10%, the balance is polytetrafluoroethylene.

As a preferred solution, the above-mentioned nano-modified polytetrafluoroethylene composite material is composed of the following components in weight percentage: 1-3% of nano-boron nitride, 5-10% of micro-boron nitride, and the balance is polytetrafluoroethylene. The weight percent composition of the nano-modified polytetrafluoroethylene composite material is further preferably: 2-3% of nano-boron nitride, 8-10% of micro-boron nitride, and the balance is polytetrafluoroethylene.

The arc extinguishing nozzle provided by the present invention uses the above-mentioned nano-modified polytetrafluoroethylene composite material.

Nano-boron nitride is a commercially available conventional raw material with a hexagonal crystal structure and a crystal structure similar to graphite layered structure. It has excellent dry lubrication ability, good thermal and chemical stability, low thermal expansion coefficient, and excellent thermal conductivity at high temperatures.

Using the arc extinguishing nozzle of the nano-modified polytetrafluoroethylene composite material of the present invention, on the one hand, nano-boron nitride and micro-boron nitride are easily mixed and dispersed in the composite material, so that the composite material has good uniformity; on the other hand, both By rationally adjusting the filling ratio, the nano-boron nitride component can reinforce the mechanical properties of the PTFE material, which can improve the tensile strength and elongation at break of the composite material; nano-boron nitride and micro-boron nitride A synergistic effect can occur in the composite material to further improve the thermal conductivity of the spout material, thereby rapidly transferring the energy of the arc during the breaking process of the circuit breaker, and reducing the ablation effect of the arc on the spout.

The preparation method of the above-mentioned arc extinguishing nozzle provided by the present invention comprises mixing polytetrafluoroethylene resin powder, nanometer boron nitride powder and micrometer boron nitride powder in the formula, and then molding and sintering to obtain the finished product.

The particle size of the nano boron nitride powder is 200-300nm.

The particle diameter of the polytetrafluoroethylene resin powder is 45-80 μm. The particle size of the micron boron nitride powder is 5-10 μm.

The mixing refers to stirring in a high-speed mixer at a speed of 400-600 r/min for 10-30 min.

The molding pressure is 20-30 MPa, and the holding time is 20-35 minutes.

The sintering temperature is 330-370° C., and the sintering time is 48-60 hours.

The present invention provides a high-voltage circuit breaker using the arc extinguishing nozzle. For high-voltage circuit breakers, such as open circuit breakers, tank circuit breakers, circuit breakers of all-metal-enclosed combined electrical appliances, etc., the nozzle of the arc extinguishing chamber adopts the nano-modified polytetrafluoroethylene composite material provided by the present invention, and other components of the high-voltage circuit breaker Can adopt known technology as operating mechanism, transmission mechanism, contact etc. Due to the high thermal conductivity of the arc extinguishing nozzle provided by the invention, the arc ablation resistance performance is greatly improved, the breaking performance of the circuit breaker is improved, and thus the operation stability of the high voltage circuit breaker is improved.

Description of drawings

Fig. 1 is the structural representation of embodiment 1 arc extinguishing spout;

Fig. 2 is a schematic structural view of the high voltage circuit breaker using the arc extinguishing nozzle of Embodiment 1.

Detailed ways

The present invention will be further described below in combination with specific embodiments.

Example 1

The nano-modified polytetrafluoroethylene composite material in this embodiment is composed of the following components in weight percentage: 1% of nano boron nitride, 10% of micro boron nitride, and the balance is polytetrafluoroethylene.

The arc extinguishing nozzle of this embodiment adopts the above-mentioned nano-modified polytetrafluoroethylene composite material, and its structure is shown in Figure 1, 1 is the throat of the nozzle, and the breaking process of the high-voltage circuit breaker is completed inside the nozzle. The part forms ablation.

The preparation method of the arc extinguishing nozzle of the present embodiment comprises the following steps:

1) Take the polytetrafluoroethylene resin powder, disperse it, and grind it finely. According to the formula, polytetrafluoroethylene resin powder with a particle size of 45 μm, nano-boron nitride powder with a particle size of 200 nm, and micron boron nitride powder with a particle size of 10 μm After the boron nitride powder is initially mixed, it is placed in a high-speed mixer for final mixing (the rotating speed is 500r/min, and the time is 20min) to obtain a mixture;

2) adding the mixture obtained in step 1) into a mold for compression molding, the molding pressure is 20MPa, and the mold is demoulded after holding the pressure for 20 minutes to obtain a semi-finished product;

3) The semi-finished product obtained in step 2) is sintered at 330° C. for 60 hours to obtain.

The high-voltage circuit breaker of this embodiment adopts the arc extinguishing nozzle of this embodiment, and its structure is shown in Figure 2, including a static main contact 1, a static arc contact 2, a nozzle 4, a moving main contact 5, and a moving arc contact 6. The air cylinder 7 and the air piston 9, the nozzle 4, the moving main contact 5, the moving arc contact 6 and the air cylinder 7 are fixed together; when the gate is opened, the air cylinder 7 moves along the movement direction 10, and the static arc contact 2 is separated from the moving arc contact 6, an arc 3 is generated between the contacts, and the SF ₆ gas 8 in the cylinder 7 is compressed and sprayed into the nozzle 4 at a high speed, thereby extinguishing the arc 3.

Example 2-7

The weight percent of each component of the nano-modified polytetrafluoroethylene composite material in Examples 2-7 is shown in Table 1.

Table 1 embodiment 2-7 the weight percent of each component of nano-modified polytetrafluoroethylene composite material

The structure of the arc extinguishing nozzle using the nano-modified polytetrafluoroethylene composite material of Examples 2-7 is the same as that of Example 1.

The arc extinguishing nozzles of Examples 2-7 were prepared by mixing, molding and sintering using the distribution ratios of the components shown in Table 1. See Table 2 for the particle size of raw materials and the test conditions for mixing, molding and sintering.

Table 2 The preparation process conditions of the arc extinguishing spout of embodiment 2～7

The structure of the high-voltage circuit breaker using the arc extinguishing nozzles described in Embodiments 2 to 7 is the same as that of Embodiment 1.

Experimental example

In this experimental example, the performance of the arc extinguishing nozzles obtained in Examples 1 to 7 was tested, and the results are shown in Table 2. The test conditions of the ablation resistance are: a direct current voltage of 600 volts and a direct current of 5 amperes. Wherein, the base material of the arc extinguishing nozzle in Comparative Example 1 is polytetrafluoroethylene resin, the filler is alumina, and the filling mass percentage is 10%. The base material of the arc extinguishing nozzle in Comparative Example 2 is polytetrafluoroethylene resin, the filler is molybdenum disulfide, and the filling mass percentage is 2%. The base material of the arc extinguishing nozzle in Comparative Example 3 is polytetrafluoroethylene resin, the filler is boron nitride with a thickness of 1-10 μm, and the filling mass percentage is 7%. The specifications of the arc extinguishing nozzles of Comparative Examples 1-3 are the same as those of Examples 1-7, and the process conditions in the preparation method are the same as those of Example 6.

Table 3 Embodiment 1～7 and the performance detection result of comparative example arc extinguishing spout

As can be seen from the test results in Table 3, the arc extinguishing nozzle provided by the present invention has improved the mechanical properties of the nozzle material, improved the toughness and crack resistance of the material, improved the thermal conductivity of the nozzle material, and improved the thermal conductivity of the material. Arc ablation resistance performance; the high-voltage circuit breaker adopting the arc extinguishing nozzle of the present invention can improve the breaking performance of the circuit breaker, thereby improving the operation stability of the high-voltage circuit breaker.

Claims (10)

1. a nano modification ptfe composite, is characterized in that: be made up of the component of following weight percent: nm-class boron nitride 1 ~ 3%, micron boron nitride 3 ~ 10%, and surplus is tetrafluoroethylene.

2. nano modification ptfe composite according to claim 1, it is characterized in that: be made up of the component of following weight percent: nm-class boron nitride 1 ~ 3%, micron boron nitride is 5 ~ 10%, surplus is tetrafluoroethylene.

3. nano modification ptfe composite according to claim 2, is characterized in that: be made up of the component of following weight percent: nm-class boron nitride is 2 ~ 3%, and micron boron nitride is 8 ~ 10%, and surplus is tetrafluoroethylene.

4. one kind uses the quenching nozzle of nano modification ptfe composite described in claim 1.

5. a preparation method for quenching nozzle as claimed in claim 4, is characterized in that: after getting the teflon resin powder of formula ratio, nm-class boron nitride powder, the mixing of micron boron nitride powder, carry out mold pressing, sintering, to obtain final product.

6. the preparation method of quenching nozzle according to claim 5, is characterized in that: the particle diameter of nm-class boron nitride powder is 200 ~ 300nm.

7. the preparation method of quenching nozzle according to claim 5, is characterized in that: the particle diameter of micron boron nitride powder is 5 ~ 10 μm.

8. the preparation method of quenching nozzle according to claim 5, is characterized in that: the pressure of described mold pressing is 20 ~ 30MPa, and the dwell time is 20 ~ 35min.

9. the preparation method of quenching nozzle according to claim 5, is characterized in that: the temperature of described sintering is 330 ~ 370 DEG C, and sintering time is 48 ~ 60h.

10. one kind uses the primary cut-out of quenching nozzle described in claim 4.