CN114669749A - Preparation system and method of high-performance superfine contact material - Google Patents
Preparation system and method of high-performance superfine contact material Download PDFInfo
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- CN114669749A CN114669749A CN202210339261.0A CN202210339261A CN114669749A CN 114669749 A CN114669749 A CN 114669749A CN 202210339261 A CN202210339261 A CN 202210339261A CN 114669749 A CN114669749 A CN 114669749A
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- contact material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/026—Spray drying of solutions or suspensions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
- B22F2009/043—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by ball milling
Abstract
The invention discloses a preparation system and a preparation method of a high-performance superfine contact material, which comprises a ball mill, a feeding pump, a stirrer, a spray dryer, a cyclone separator and a discharging device which are sequentially arranged; the feed pump communicates the inner chamber of ball mill and mixer, and the inner chamber of mixer communicates spray dryer's inner chamber, and spray dryer is used for carrying out the spray drying technology, and spray dryer communicates cyclone's inner chamber, and cyclone communicates discharging device. Firstly, preparing superfine particle powder by adopting a ball milling process, and then processing the superfine particle powder by a spray drying process to form the superfine contact material. The method of preparing the superfine particle powder by high-energy ball milling and then spray drying and granulating is adopted to obtain the high-performance superfine material, the problem that the superfine particle powder is difficult to press is solved, and various performances of the product can be greatly improved.
Description
Technical Field
The invention belongs to the technical field of switching appliances, and particularly belongs to a system and a method for preparing a high-performance superfine contact material.
Background
The copper-tungsten alloy is a typical pseudo alloy, namely the copper-tungsten alloy and the pseudo alloy are basically insoluble, so that the copper-tungsten alloy can be prepared only in a powder metallurgy mode. The copper-tungsten alloy prepared by the existing powder metallurgy process adopts conventional tungsten powder as a raw material. The conventional tungsten powder has single particle size and overlarge porosity of a framework, so that the copper-tungsten alloy with higher tungsten content cannot be obtained by a method of increasing pressure, the densification degree of the product is low, component segregation is easy to generate, and the densification is a key factor influencing the quality of the product, so that the multiple properties of the product are not high; in addition, the conventional tungsten powder has larger particles, the mutual contact area among the particles is small, the specific surface area is small, the sintering driving force is small, and higher temperature sintering is often needed.
The copper-tungsten alloy has wide application and prospect in the fields of electricians, war industry, aerospace, electronic packaging and the like by virtue of good conductivity, lower thermal expansion, good ablation resistance and the like, and in order to further obtain products with higher performance, the academic world starts research from various directions, and the emerging ultrafine crystal and nano material technology provides a new idea for the academic world.
The high-energy ball milling method is a method for preparing superfine/nano materials, and has the principle that common metal powder is ball-milled in a high-energy ball mill, so that grinding balls strongly impact and grind raw material powder, and shearing and impacting exist among powder particles, which is a repeated process, and finally, superfine metal powder can be obtained; the disadvantages are also obvious, impurities are easily introduced in the process, the powder is easy to agglomerate, the prepared powder is too fine and the shape of the particles is complex, so that the powder is difficult to press, and the spray drying granulation can bond and agglomerate the superfine powder into particles which are close to spheres and have good pressing property.
The spray drying method is a method of combining chemistry and physics, which is to atomize the solution or suspension by physical means to obtain uniform droplets, and then evaporate or decompose the solvent under high temperature environment to obtain the ultrafine particles. Its advantages are uniform and spherical powder.
In summary, in the prior art, the copper-tungsten contact prepared from the conventional tungsten powder has low compactness, low component segregation, small sintering driving force and large tungsten grains, so that various properties of the product, such as strength, hardness, conductivity, ablation resistance and the like, are not high.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a system and a method for preparing a high-performance superfine contact material.
In order to achieve the purpose, the invention provides the following technical scheme:
a preparation system of a high-performance superfine contact material comprises a ball mill, a feeding pump, a stirrer, a spray dryer, a cyclone separator and a discharging device which are arranged in sequence;
the feeding pump is communicated with inner cavities of the ball mill and the stirrer, the inner cavity of the stirrer is communicated with an inner cavity of the spray dryer, the spray dryer is used for performing a spray drying process, the spray dryer is communicated with an inner cavity of the cyclone separator, and the cyclone separator is communicated with the discharging device.
Preferably, a vibration table is arranged at the bottom of the discharging device.
Preferably, the device further comprises an alcohol recovery device, and the spray dryer is communicated with the alcohol recovery device.
A preparation method of a high-performance superfine contact material comprises the following steps,
firstly, preparing superfine particle powder by adopting a ball milling process, and then processing the superfine particle powder by a spray drying process to form the superfine contact material.
Preferably, the method specifically comprises the following steps,
and 3, feeding the dried spherical powder into a discharging device from a discharge hole of the spray drying tower to form the superfine contact material.
Further, in step 1, before ball milling, grinding balls are selected according to the characteristics of the material object, and the diameter of the grinding balls, the amount of forming agent solution and powder and the corresponding forming agent required by ball milling are calculated.
Further, the forming agent is SBP glue solution.
Further, the grinding balls are tungsten carbide steel balls.
Furthermore, the diameter range of the grinding ball is 0.5-1 cm.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention provides a preparation system of a high-performance superfine contact material, which combines a ball milling process and a spray drying process, ball-mills powder for a certain time, then feeds the powder into a stirrer of a spray dryer through a feeding pump, and granulates the powder through the spray dryer. The process comprises the steps of preparing metal powder into ultrafine powder by a high-energy ball milling technology, adding a surfactant or a forming agent into suspension slurry, and preparing spherical particles by spray drying. Through high-energy ball milling and spray drying granulation, the prepared powder has high sphericity, small particle size and narrow particle size distribution, so that the uniformity of copper and tungsten in a copper-tungsten alloy product is improved, the obtained product has more stable performance, the apparent density and the fluidity are improved, the subsequently sintered product has good density, higher precision and good mechanical property, and the punctiform concentrated discharge caused by potential difference between copper and tungsten is avoided, thereby reducing the loss of the copper-tungsten alloy and improving the electric arc burning loss resistance.
Furthermore, the bottom of the discharging device is provided with the vibrating table, and the vibrating table guarantees smooth output of materials through vibration and does not remain on equipment.
Further, by arranging the alcohol recovery device, waste and pollution caused by recycling alcohol are avoided.
The invention provides a preparation method of a high-performance superfine contact material, superfine particle powder obtained by high-energy ball milling is beneficial to forming a sintering neck and densification due to large surface energy and lattice distortion energy, so that a product with higher performance is obtained.
Drawings
FIG. 1 is a schematic diagram of a system for preparing a high performance ultra-fine contact material according to the present invention;
FIG. 2 is a 1500-fold SEM image of the resulting copper-tungsten alloy powder;
FIG. 3 is a 100-fold SEM image of the resulting copper-tungsten alloy powder;
fig. 4 is a 500-fold SEM image of the resulting copper-tungsten alloy powder;
FIG. 5 is a 200 SEM image of the resulting copper tungsten alloy powder;
FIG. 6 is a 50 SEM image of the resulting copper-tungsten alloy powder;
in the drawings: 1 is a ball mill; 2 is a feeding pump; 3 is a stirrer; 4 is a spray drier; 5 is a cyclone separator; 6 is a discharging device; 7 is a vibration table; and 8 is an alcohol recovery device.
Detailed Description
The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.
As shown in figure 1, the system for preparing the high-performance superfine contact material comprises a ball mill 1, a feeding pump 2, a stirrer 3, a spray dryer 4, a cyclone separator 5, a discharging device 6, a vibration table 7 and an alcohol recovery device 8.
The feed pump 2 communicates the inner chambers of the ball mill 1 and the stirrer 3, the inner chamber of the stirrer 3 communicates the inner chamber of the spray dryer 4, the spray dryer 4 is used for carrying out the spray drying process, the spray dryer 4 communicates the inner chamber of the cyclone separator 5, and the cyclone separator 5 communicates the discharging device 6. The bottom of the discharging device 6 is provided with a vibration table 7. The spray dryer 4 is communicated with an alcohol recovery device 8.
The ball mill 1 determines the particle diameter of the powder; the feed pump 2 conveys the slurry into the stirrer; the stirrer 3 stirs constantly to ensure that the slurry is not solidified or precipitated; granulating by a spray dryer 4, and preparing the superfine powder prepared by ball milling into an agglomerated ball shape; the cyclone separator 5 separates and outputs particles with different particle sizes; the discharging device 6 ensures smooth output of the powder particles; the vibration table 7 ensures that the material is smoothly output and does not remain on the equipment; the alcohol recovery device 8 recycles alcohol to avoid waste and pollution.
According to the invention, a ball milling process and a spray drying process are combined, powder is subjected to ball milling for a certain time, then is fed into a stirrer of a spray dryer through a feeding pump, and is granulated through a spray dryer 4. The process comprises the steps of preparing metal powder into ultrafine powder by a high-energy ball milling technology, adding a surfactant or a forming agent into suspension slurry, and preparing spherical particles by spray drying.
The invention relates to a preparation method of a high-performance superfine contact material, which is realized by the following steps;
1. preparing materials: calculating the amount of grinding balls, forming agent solution and powder required by ball milling, preparing corresponding forming agents for the powder of different materials, and selecting the grinding balls according to the characteristics of material objects. The forming agent is SBP glue solution, the grinding ball is tungsten carbide steel ball, and the diameter is 0.5-1 cm.
2. Feeding: firstly, adding grinding balls, then adding a forming agent solution, and setting the rotating speed and the ball milling time of the ball mill 1 according to ball milling materials. Such as the ball milling rotation speed: ball milling is carried out for 70r/min for half an hour and 120r/min for one and a half hours, and the diameter of the finally prepared powder particle pellets is 1-2 microns.
The size of the powder particle pellets can be controlled by parameters such as ball milling time, can be adjusted from nanometer to micron, and can be adjusted according to requirements, the size range is determined according to the size of raw materials, such as tungsten powder, the raw materials are 8-16 microns, powder particles of 1-2 microns can be obtained, and powder particles of 100-1000 nanometers can also be obtained.
3. Feeding and granulating; the slurry in the ball mill 1 is sent into a stirrer 3 (charging bucket) of a spray dryer 4 through a feeding pump 2, the slurry enters the spray dryer 4 from the charging bucket through a high-pressure pump, the pumped slurry is rapidly dispersed in the spray dryer 4 through a pressure type nozzle, liquid is rapidly evaporated, particles are rapidly dried (fog drops are fine, the surface area to volume ratio is large, the liquid is rapidly evaporated, the drying of the material is instantly completed), and powder particles are in a shape close to a sphere due to the bonding effect of a forming agent solution and the granulation effect of a spraying device.
4. The product is as follows: and the dried finished product enters a screw conveyor from a conical discharge hole at the lower part of the tower body and is further processed by the working procedure.
Most of the dried materials enter the cyclone separator 5 and the dust remover through a tail gas port of the drying tower, alcohol is recovered through the induced draft fan, and particles collected from the cyclone separator 5 and the dust remover enter the drying tower through the chute and enter the conveyor through the discharging device 6.
5: collecting; and (5) starting the vibration table 7, outputting the product from the conveyor, placing a vessel in advance at a discharge port, collecting the material and inspecting. The high-performance raw material powder is finally obtained in the step, and the subsequent step is to process the raw material prepared by the method and prepare a corresponding product through powder metallurgy or other methods.
As shown in figures 2 to 6, the ultrafine particle powder obtained by high-energy ball milling is beneficial to forming sintering necks and densification due to large surface energy and lattice distortion energy, so that a product with higher performance is obtained, the ultrafine powder is prepared into spherical particles with more uniform particle size distribution through spray drying granulation, the pressing problem is effectively solved, closed pores are not easy to form in the sintering stage, so that the product components are segregated, and in a word, compared with other methods, the process is the simplest and most suitable for practical production.
Through high-energy ball milling and spray drying granulation, the prepared powder has high sphericity, small particle size and narrow particle size distribution, so that the uniformity of copper and tungsten in a copper-tungsten alloy product is improved, the obtained product has more stable performance, the apparent density and the fluidity are improved, the subsequently sintered product has good density, higher precision and good mechanical property, and the punctiform concentrated discharge caused by potential difference between copper and tungsten is avoided, thereby reducing the loss of the copper-tungsten alloy and improving the electric arc burning loss resistance.
Since the powder has fine crystal grains and a large specific surface area, the contact interface between particles is large. The powder particles store extremely high specific surface energy and lattice distortion energy, and the surface activity is large, so the driving force of sintering is much larger than that of conventional powder pressing. During sintering, the energy is fully released, so that obvious sintering necks are formed among particles, powder particles are bonded more tightly, the densification process of the product is accelerated, and the performance of the product is improved.
The contact material prepared by the invention has the advantages that the crystal grains are fine, the arc dispersing capacity is realized, compared with the traditional contact, the novel contact prepared by the material prepared by the invention has the advantages that the first breakdown ablation area is large, the breakdown pits are more and shallow, after multiple breakdowns, the heat dissipation of the fine-grain contact is fast, the ablation is mild, and the ablation of the traditional contact is serious because the ablation is carried out in a copper phase. The copper phase of the fine-grain contact is fine, electric arcs are uniformly dispersed on the surface, copper in the fine-grain alloy can be embedded into a compact tungsten framework, and the surface is still flat after multiple breakdowns; the power number of the fine crystal boundary is low, so that the surface temperature of the cathode and the evaporation of materials are reduced; the fine and uniform tungsten can effectively inhibit the sputtering of copper, and the surface oxide film can inhibit the transfer of contact materials.
The refined crystal grains are microscopic, and the crystal boundary phase is obviously increased, so that dislocation slippage and crack propagation are hindered, and the macroscopic mechanical property and the electric and heat conducting properties of the copper-tungsten alloy contact are improved.
Claims (9)
1. A preparation system of a high-performance superfine contact material is characterized by comprising a ball mill (1), a feeding pump (2), a stirrer (3), a spray dryer (4), a cyclone separator (5) and a discharging device (6) which are arranged in sequence;
the feeding pump (2) is communicated with inner cavities of the ball mill (1) and the stirring machine (3), the inner cavity of the stirring machine (3) is communicated with an inner cavity of the spray dryer (4), the spray dryer (4) is used for performing a spray drying process, the spray dryer (4) is communicated with an inner cavity of the cyclone separator (5), and the cyclone separator (5) is communicated with the discharging device (6).
2. The system for preparing the high-performance ultrafine contact material according to claim 1, wherein a vibrating table (7) is arranged at the bottom of the discharging device (6).
3. The system for preparing the high-performance superfine contact material according to claim 1, further comprising an alcohol recovery device (8), wherein the spray dryer (4) is communicated with the alcohol recovery device (8).
4. A preparation method of a high-performance superfine contact material is characterized by comprising the following steps,
firstly, preparing superfine particle powder by adopting a ball milling process, and then processing the superfine particle powder by a spray drying process to form the superfine contact material.
5. The method for preparing the high-performance ultrafine contact material according to claim 4, comprising the following steps,
step 1, carrying out ball milling on raw material powder in a ball mill (1) to form ultrafine particle powder slurry;
step 2, slurry in the ball mill (1) is sent into a stirrer (3) through a feeding pump (2), the stirrer (3) is used for stirring and then sending the stirred slurry into a spray drying tower (4) through a high-pressure pump, and spherical powder is formed after slurry powder particles are processed;
and 3, feeding the dried spherical powder into a discharging device (6) from a discharge hole of the spray drying tower (4) to form the superfine contact material.
6. The method for preparing a high performance ultrafine contact material according to claim 5, wherein in step 1, before ball milling, grinding balls are selected according to the characteristics of the material object, and the diameter of the grinding balls, the amount of the forming agent solution and powder and the corresponding forming agent required for ball milling are calculated.
7. The method for preparing the high-performance ultrafine contact material according to claim 6, wherein the forming agent is SBP glue solution.
8. The method for preparing the high-performance ultrafine contact material according to claim 6, wherein the grinding balls are tungsten carbide steel balls.
9. The method for preparing a high-performance ultrafine contact material according to claim 6, wherein the diameter of the grinding ball is in a range of 0.5-1 cm.
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| CN1624175A (en) * | 2003-12-02 | 2005-06-08 | 上海电器科学研究所（集团）有限公司 | Electric contact material of carbon nano pipe silver graphite and its preparation process |
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