CN111545766A - Equipment and method for preparing high-purity spherical metal powder - Google Patents

Abstract

The invention discloses equipment and a method for preparing high-purity spherical metal powder, wherein the equipment comprises an automatic powder feeding device, a reaction generation chamber connected with the automatic powder feeding device, and a radio frequency plasma generator connected with the reaction generation chamber, wherein the automatic powder feeding device is used for feeding raw material powder particles with irregular shapes into the reaction generation chamber, and the radio frequency plasma generator is used for heating and melting the raw material powder particles fed into the reaction generation chamber to form the high-purity spherical metal powder. The invention adopts the radio frequency plasma generator to heat and melt the raw material powder particles, and can prepare the spherical metal powder with high spheroidization rate, high purity, large density and relatively narrow particle size distribution by utilizing the advantages of high energy density, high heating strength, large volume of plasma moment and the like of the radio frequency plasma generator; the invention does not pollute the product due to electrode evaporation, and is beneficial to ensuring the high purity of the prepared spherical metal powder.

Description

A kind of equipment and method for preparing high-purity spherical metal powder

technical field

The invention relates to the field of preparation of spherical metal powder, in particular to a device and method for preparing high-purity spherical metal powder.

Background technique

The core of metal 3D printing technology is materials and devices. With the development of metal 3D printing technology, the device has gradually matured. However, there are few types of materials that can be used for metal 3D printing, and the performance is unstable. Traditional metal powder materials for metallurgy are not fully applicable. Metal 3D printing process. In addition, metal powders for 3D printing require high sphericity, low oxygen content, and narrow particle size distribution, while domestic research on metal powder material properties and preparation technology data accumulation is relatively lacking. At present, most of the materials used in my country's 3D printing rapid prototyping technology need to be imported from abroad, or equipment manufacturers have invested a lot of energy and funds to develop them, which are expensive, resulting in increased production costs. Therefore, solving the performance and cost problems of materials will better promote the development of rapid prototyping technology in China.

In the current process of spherical metal powder processing, two heating methods of crucible heating and electrode induction heating are generally used to melt the metal, and the melted metal is blown and cooled under the action of air flow to produce the corresponding powder, which is then used in subsequent prints.

However, the existing spherical metal powder processing methods have the problems of high energy consumption, low spheroidization rate, wide particle size distribution, and low purity of spherical metal powder due to the fact that spherical metal powder is easily contaminated by electrode evaporation.

Therefore, the existing technology still needs to be improved and developed.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a device and method for preparing high-purity spherical metal powder, aiming to solve the problems of high energy consumption, low spheroidization rate, The wide particle size distribution and the susceptibility of spherical metal powder to contamination by electrode evaporation lead to the problem of low purity of spherical metal powder.

The technical scheme of the present invention is as follows:

A device for preparing high-purity spherical metal powder, which includes an automatic powder feeding device, a reaction generation chamber connected with the automatic powder feeding device, a radio frequency plasma generator connected with the reaction generation chamber, and the automatic powder feeding device. The powder feeding device is used to send the irregularly shaped raw material powder particles into the reaction generation chamber, and the radio frequency plasma generator is used to heat and melt the raw material powder particles sent into the reaction generation chamber and form high-purity powder particles. Spherical metal powder.

The equipment for preparing high-purity spherical metal powders further includes a control system electrically connected to the radio frequency plasma generator, wherein the control system is provided with a radio frequency power supply that is electrically connected to the radio frequency plasma generator .

The equipment for preparing high-purity spherical metal powder further includes a gas cabinet connected with the radio frequency plasma generator and the automatic powder feeding device respectively, and the gas cabinet is used for storing plasma reaction gas, protective gas and carrier gas.

The equipment for preparing high-purity spherical metal powder further comprises a vacuum glove box powder collecting system communicated with the reaction generating chamber.

The equipment for preparing high-purity spherical metal powder further comprises a cyclone dust removal device communicated with the powder collecting system of the vacuum glove box.

The equipment for preparing high-purity spherical metal powder further includes a dust-removing and powder-collecting tank arranged at the bottom of the cyclone dust-removing device.

The equipment for preparing high-purity spherical metal powder further includes a water-ring vacuum pump group connected with the reaction generating chamber and the radio frequency plasma generator.

A method for preparing high-purity spherical metal powder based on the device, comprising the steps of:

The automatic powder feeding device sends the raw powder particles into the reaction generation chamber;

The radio frequency plasma generator is activated to heat and melt the raw material powder particles sent into the reaction generating chamber to obtain spherical metal droplets, and the spherical metal droplets solidify to form the high-purity spherical metal powder.

Beneficial effects: The present invention provides a device for preparing high-purity spherical metal powder, which includes an automatic powder feeding device, a reaction generation chamber connected with the automatic powder feeding device, and a radio frequency plasma connected with the reaction generation chamber generator, the automatic powder feeding device is used to send the raw material powder particles with irregular shapes into the reaction generation chamber, and the radio frequency plasma generator is used to carry out the raw material powder particles sent into the reaction generation chamber. Heating to melt and form high-purity spherical metal powder. The invention adopts the radio frequency plasma generator to heat and melt the raw powder particles, and the radio frequency plasma generator has the advantages of high energy density, high heating intensity, large volume of the plasma moment, simple process for processing materials and the like, and can prepare the balls. Spherical metal powder with high conversion rate, high purity, high density and relatively narrow particle size distribution; and the present invention does not use electrodes, and will not contaminate the product due to electrode evaporation, which is beneficial to ensure the high purity of the spherical metal powder obtained. .

Description of drawings

FIG. 1 is a schematic structural diagram of a preferred embodiment of an apparatus for preparing high-purity spherical metal powder according to the present invention.

FIG. 2 is a flow chart of a preferred embodiment of a method for preparing high-purity spherical metal powder according to the present invention.

Detailed ways

The present invention provides a device and method for preparing high-purity spherical metal powder. In order to make the purpose, technical solution and effect of the present invention clearer and clearer, the present invention is further described below in detail. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Please refer to FIG. 1 . FIG. 1 is a device for preparing high-purity spherical metal powder provided by the present invention. As shown in the figure, it includes an automatic powder feeding device 10 and a reaction generating chamber connected to the automatic powder feeding device 10 20. The radio frequency plasma generator 30 connected to the reaction generation chamber 20, the automatic powder feeding device 10 is used for feeding the raw powder particles with irregular shapes into the reaction generation chamber 20, the radio frequency plasma The generator 30 is used for heating and melting the raw material powder particles sent into the reaction generating chamber 20 to form high-purity spherical metal powder.

In this embodiment, the raw material powder particles are heated and melted by the radio frequency plasma generator to obtain molten particles, and the molten particles can form metal droplets with high sphericity under the action of their surface tension. And it solidifies rapidly in a very short time to form high-purity spherical metal powder.

In this embodiment, a radio frequency plasma generator is used to heat and melt the raw material powder particles, and the radio frequency plasma generator has the advantages of high energy density, high heating intensity, large volume of the plasma moment, and simple processing material process. Spherical metal powder with high spheroidization rate, high purity, high density and relatively narrow particle size distribution; and the present invention does not use electrodes, and will not contaminate the product due to electrode evaporation, which is beneficial to ensure the high quality of the spherical metal powder obtained. purity.

In some embodiments, the raw material powder particles may be copper powder particles, titanium powder particles, molybdenum powder particles or gold powder particles, but are not limited thereto. Taking molybdenum powder particles as an example, the equipment of the invention is used to prepare the molybdenum powder particles into high-purity spherical metal powders, the production capacity is ≥3kg/h, the spheroidization rate is ≥95%, and the particle size is D50=20-35μm.

In some embodiments, the automatic powder feeding device 10 has an automatic feeding function, which can feed raw powder particles with irregular shapes into the reaction generation chamber 20 under the protection of inert gas. In this embodiment, the particle size range of the raw material powder particles is 10-200 microns, the powder feeding rate of the automatic powder feeding device 10 is 1-40 kg/h, and the automatic powder feeding device can continuously Monitoring and real-time regulation. Specifically, the automatic feeding device 10 is provided with a feeding bin, a continuous feeding bin and a pneumatic feeding structure. As an example, the volume of the feeding bin is 6L, and the volume of the feeding bin is 5L.

In some embodiments, according to the degree of ionization, plasma is divided into fully ionized plasma with ultra-high temperature and ultra-high energy density (such as nucleation degree) and weakly ionized plasma with ionization degree less than 1% (such as arc discharge, etc. ) two categories, this weakly ionized plasma is divided into equilibrium plasma, namely high temperature plasma and non-equilibrium plasma (ie low temperature plasma) according to whether the neutral particles, ions and electrons are in thermal equilibrium. two categories. The temperature of high temperature plasma is very high, about 4500℃ to tens of thousands of degrees Celsius, and the heat capacity is also very large, which can be used for heating and melting materials; The gas is ionized, the temperature is low, generally not more than 1000 ℃, and the heat capacity is also very small, mainly used for material surface treatment.

In some embodiments, the RF plasma generator may be a plasma heat gun. The plasma heating gun includes an arc plasma gun and a high-frequency plasma gun. The principle of the plasma heating gun is: a working gas arc is generated between the cathode (usually thorium tungsten or cerium tungsten electrodes) and the copper nozzle as the anode. The arc formed by the discharge, the arc plasma forms a small-diameter beam due to the pressure of the working gas and the compression of the nozzle orifice. Because the arc is not transferred to the heated material, it is called a non-transferred arc type; if the arc generated between the electrode and the nozzle is transferred to the material connected to the power supply anode after generation, it is called a transferred arc type. The arc between the cathode and the material is due to the mechanical compression effect (caused by the nozzle opening), the thermal shrinkage effect (due to the higher temperature, higher ionization degree, and high conductivity of the arc column center than its periphery, the current naturally tends to the center of the arc column) and magnetic The compression effect (caused by the magnetic field of the arc column itself) is the combined action of the three, and under strong compression, the arc column becomes slender (as thin as a needle, and can also grow to more than 1m). Under the condition of maintaining balance with the expansion pressure inside the arc column, the gas in the center of the arc column is highly ionized, its temperature can reach 10,000-52,000°C, and the gas flow velocity can be as high as 10,000m/s. Transfer arc plasma guns are the most widely used in plasma heating. In practical applications, sometimes in addition to the arc between the cathode and the material - the main arc, the arc between the cathode and the copper nozzle - the maintenance arc is still retained.

The working gas is excited and ionized by the high-frequency induction coil and the capacitive electrode respectively, and the generated plasma can be sprayed through the nozzle to form a plasma flame, and can also be left in the working area for heating materials. The advantage of high-frequency plasma is that it is not polluted by electrode materials, but the production cost is high, the generator power is small, and it is used less. The power supply of the arc plasma gun is generally a DC power supply with a steep drop characteristic, positive connection, and a three-phase AC power supply is also used. Above 3000V, the power supply of the high-frequency plasma gun usually uses a high-frequency tube oscillator, and the frequency is in the range of 0.4 to 75MHz. Heating devices vary according to equipment use, such as plasma melting furnaces with refractory linings or furnace bodies for water-cooled crystallizers; workbenches or work trolleys for plasma cutting and spraying devices.

In some embodiments, the maximum temperature generated by the RF plasma generator in this embodiment can reach 10,000 degrees Celsius, and a ceramic plasma confinement tube is provided to provide high-purity processing capability; the ceramic plasma confinement tube For the water-cooled structure, on the other side of the cooling channel is an induction coil embedded in the torch body and connected to the RF power supply; the gas distribution head upstream of the discharge chamber allows the entry of different gas flows.

In some embodiments, as shown in FIG. 1 , the reaction generation chamber 20 adopts a water-cooled double-wall stainless steel (ss304) structure, and the bottom of the reaction generation chamber is provided with a vacuum glove box powder collecting system 40 in communication therewith. The vacuum glove box powder collecting system 40 includes a vacuum glove box and several powder collecting tanks arranged in the vacuum glove box. Protected by an inert atmosphere to ensure that the heated and melted metal powder is not in contact with air throughout the process to ensure its purity.

In some embodiments, as shown in FIG. 1 , the equipment for preparing high-purity spherical metal powder further includes a cyclone dust removal device 50 communicated with the vacuum glove box powder collection system 40 , and the cyclone dust removal device 50 adopts multiple A flexible composite filter element to collect powder with gas purge. The bottom of the cyclone dust-removing device 50 is provided with a dust-removing and powder-collecting tank 60. The dust-removing and powder-collecting tank 60 is provided with an airtight valve and a water-cooled structure, which can be protected by an inert atmosphere to ensure that the metal powder is not in contact with the air throughout the process.

In some embodiments, as shown in FIG. 1 , the apparatus for preparing high-purity spherical metal powder further includes a control system 70 electrically connected to the radio frequency plasma generator 30 , and the control system 70 is provided with a The RF plasma generator 30 is electrically connected to the RF power supply. The control system 70 can control the output power of the radio frequency power supply, the output power of the radio frequency power supply is 15-80kw, input 380V three-phase alternating current, 50Hz, the power can be continuously and stably output; the frequency of the radio frequency plasma generator is 2 -3MHz.

In some specific implementations, as shown in meat 1, the control system 70 is further provided with a touch display screen 71 electrically connected to it, the control system 70 includes an industrial computer and a PLC, through which the industrial computer and the PLC can Realize the control of the equipment for preparing high-purity spherical metal powder, the control system 70 has two functions of automatic and manual control, the operation process is all realized on the touch display screen 71, and the formula setting, vacuum system and process system are provided. , air charging system, cooling system and other man-machine operation interface; on the industrial computer, the setting of the program process and equipment parameters can be realized through the configuration parameter setting method. The industrial computer is equipped with a multi-serial port card, which is connected to various controllers through RS232 or RS485; the control cabinet adopts international standards, the industrial computer and most of the controllers are installed on the rack, and the control cable is connected between the control cabinet and the host. High reliability and easy maintenance; high-voltage parts in the control cabinet and the main unit are equipped with protective covers to improve equipment safety; the main electrical outsourcing parts in the control cabinet are required to use products from manufacturers that have passed CE certification or ISO9001 certification to ensure Safe and reliable.

In some embodiments, as shown in FIG. 1 , the apparatus for preparing high-purity spherical metal powder further includes a gas cabinet 80 which is communicated with the radio frequency plasma generator 30 and the automatic powder feeding device 10 respectively. The cabinet 80 is used for storing plasma reaction gas, shielding gas and carrier gas. The gas tank 80 is provided with a gas circuit system inside, and the top of the gas tank 80 is provided with an air outlet and a hydrogen detector. The hydrogen detector can warn the operator when the hydrogen concentration is high. The gas circuit system is provided with mass flow meters, pressure gauges, pressure sensors, pressure regulating valves, stop valves, pipelines and joints and other components. The plasma reaction gas can be argon, hydrogen, helium, nitrogen, oxygen or air, but is not limited thereto; both the protective gas and the carrier gas can be argon, nitrogen or helium.

In some embodiments, as shown in FIG. 1 , the apparatus for preparing high-purity spherical metal powder further includes a water ring vacuum pump set 90 in communication with the reaction generating chamber 20 and the radio frequency plasma generator 30 . The working water temperature of the water ring vacuum pump group is 15°C, it is equipped with a gas-liquid separator, a plate heat exchanger, a pressure control valve, and the pre-evacuation is less than or equal to 20kPa.

In some embodiments, the device for preparing high-purity spherical metal powder further includes a pressure control system, and the pressure control system forms a closed-loop control through a vacuum pump + a controllable butterfly valve + a thin film gauge + a gas mass flow controller; the pressure The control system is interlocked with the radio frequency plasma generator system. The operating atmosphere and pressure can be freely selected from inert, reducing or oxidizing operating atmosphere. The pressure is controllable within the range of 150-760 Torr (20-101kPa), and the reactor pressure is displayed in real time.

In some embodiments, the equipment for preparing high-purity spherical metal powder further includes a cooling system, the cooling system has a complete water cooling system pipeline, is equipped with a flow safety locking device; has water temperature, flow monitoring and alarm systems ; Equipped with a circulating water safety treatment system in the event of water outage and power outage to ensure the safety of the equipment. The cooling system can provide the necessary cooling for the plasma power supply, the plasma torch and the powder feeding tube to ensure the continuous use of the powder feeding tube under high temperature, and provide the necessary cooling for the reaction chamber and the cyclone dust collector. Necessary cooling; it can also be used as emergency water to supplement circulating cooling water and deionized water by softening to ensure equipment safety in the event of water failure and power failure.

In some embodiments, as shown in FIG. 2, a method for preparing high-purity spherical metal powder based on the device is also provided, which comprises the steps of:

S10, the automatic powder feeding device sends the raw material powder particles into the reaction generating chamber;

S20. Start the radio frequency plasma generator to heat and melt the raw material powder particles sent into the reaction generation chamber to obtain spherical metal droplets, and the spherical metal droplets solidify to form the high-purity spherical metal powder.

In this embodiment, the raw material powder particles are heated and melted by the radio frequency plasma generator to obtain molten particles, and the molten particles can form metal droplets with high sphericity under the action of their surface tension. And it solidifies rapidly in a very short time to form high-purity spherical metal powder. In this embodiment, a radio frequency plasma generator is used to heat and melt the raw material powder particles, and the radio frequency plasma generator has the advantages of high energy density, high heating intensity, large volume of the plasma moment, and simple processing material process. Spherical metal powder with high spheroidization rate, high purity, high density and relatively narrow particle size distribution; and the present invention does not use electrodes, and will not contaminate the product due to electrode evaporation, which is beneficial to ensure the high quality of the spherical metal powder obtained. purity.

It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above descriptions, and all these improvements and transformations should belong to the protection scope of the appended claims of the present invention.

Claims (8)

1. a device for preparing high-purity spherical metal powder, is characterized in that, comprises automatic powder feeding device, the reaction generation chamber connected with described automatic powder feeding device, the radio frequency plasma generator connected with described reaction generation chamber , the automatic powder feeding device is used to send the irregularly shaped raw material powder particles into the reaction generation chamber, and the radio frequency plasma generator is used to heat and melt the raw material powder particles sent into the reaction generation chamber And form high-purity spherical metal powder. 2 . The device for preparing high-purity spherical metal powder according to claim 1 , further comprising a control system electrically connected to the radio frequency plasma generator, wherein the control system is provided with a control system connected to the radio frequency plasma generator. 3 . The radio frequency power source to which the body generator is electrically connected. 3. The equipment for preparing high-purity spherical metal powder according to claim 1, characterized in that, further comprising a gas cabinet connected with the radio frequency plasma generator and the automatic powder feeding device respectively, and the gas cabinet is used for storage Plasma reactive gas, protective gas and carrier gas. 4 . The device for preparing high-purity spherical metal powder according to claim 1 , further comprising a vacuum glove box powder collecting system communicated with the reaction generating chamber. 5 . 5 . The device for preparing high-purity spherical metal powder according to claim 4 , further comprising a cyclone dust removal device communicated with the powder collecting system of the vacuum glove box. 6 . 6 . The device for preparing high-purity spherical metal powder according to claim 5 , further comprising a dust-removing and powder-collecting tank arranged at the bottom of the cyclone dust-removing device. 7 . 7 . The device for preparing high-purity spherical metal powder according to claim 1 , further comprising a water-ring vacuum pump set communicating with the reaction generating chamber and the radio frequency plasma generator. 8 . 8. A method for preparing high-purity spherical metal powder based on any one of the equipment of claims 1-7, characterized in that, comprising the steps of: The automatic powder feeding device sends the raw powder particles into the reaction generation chamber; The radio frequency plasma generator is activated to heat and melt the raw material powder particles sent into the reaction generating chamber to obtain spherical metal droplets, and the spherical metal droplets solidify to form the high-purity spherical metal powder.

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