Device and method for preparing superfine low-temperature metal powder based on liquid phase crushing

Abstract

The invention relates to a device and method for preparing metal powder, in particular to a device and method for preparing superfine low-temperature metal powder based on liquid phase smashing. In order to overcome the defects of low superfine powder preparation yield and high cost in the prior art, the invention provides a device for preparing superfine low-temperature metal powder based on liquid-phase crushing, which comprises a metal smelting furnace, a medium oil tank, a liquid-phase crushing tank, a driving unit, a radiator and a solid-liquid separator, and crushing blades are arranged at the bottom of the liquid-phase crushing tank. According to the method based on the device, metal liquid is smashed into tiny metal liquid drops through the smashing blades at the bottom of the liquid phase smashing tank to be dispersed in the medium oil, the medium oil containing the tiny metal liquid drops is cooled to be below the melting point of low-temperature metal through the radiator, and the tiny metal liquid drops are solidified into metal powder particles; and then the metal powder particles and the medium oil are separated through a solid-liquid separator, and the metal powder is obtained.

Description

Technical Field

[0001] The invention relates to a device and a method for preparing metal powder, and in particular to a device and a method for preparing ultrafine low-temperature metal powder based on liquid phase pulverization. Background Art

[0002] Existing methods for preparing low-temperature metal powders include gas atomization, centrifugal atomization, ultrasonic atomization, improved centrifugal atomization, etc., and based on this, different standards and different quality subdivisions are produced.

[0003] The atomization method mainly uses a high-speed nitrogen gas flow to flow out through a nozzle, breaking up the molten liquid and atomizing it into small droplets. After sedimentation, it is solidified into powder particles by cooling. This method has high powder making efficiency and large output, but the powder particles formed are ellipsoidal in shape, with a relatively rough surface and adsorbed with micropowder, and the oxygen content of the powder particles is also high. The particle size distribution of the powder particles is wide, and the proportion of fine powder is relatively high. The subsequent processing technology is difficult. In addition, this method has high nitrogen consumption, resulting in excessively high production and processing costs. It is no longer used.

[0004] The centrifugal atomization method directs the molten metal from the melting device to the center of the rotating disk. Relying on the inertia of the rotating disk and the centrifugal effect, the molten metal is distributed radially along the rotating disk, forming a thin liquid film on the rotating disk. After the liquid film reaches the edge of the rotating disk, it disperses into droplets. The droplets cool and solidify to obtain a highly round metal powder. The centrifugal atomization method has been valued for its controllable advantages in the size and shape of the metal powder. Its low production cost has made it more widely used. It has now become one of the important methods for preparing metal powder or alloy powder. Compared with the gas atomization method, the solder powder prepared by this method using centrifugal atomization is more convenient in controlling the atmosphere, has good spherical roundness, relatively low oxidation degree, and easy to control particle size, but its yield can only reach 50% to 60%.

[0005] Ultrasonic atomization is a new technology developed in recent years. It mainly uses ultrasonic atomization. The molten metal droplets are atomized into powder under the action of ultrasonic transducers. Compared with the above two methods, this method can maximize the sphericity of the welding metal powder, the powder particle size distribution is narrow, the oxygen content is low, and the operation is simple, the energy consumption is low, and the cost investment is low; however, its output is small and the suitable particle size range is narrow.

[0006] The improved centrifugal atomization method is improved and optimized based on the traditional centrifugal atomization method. The equipment size of this method is small, the diameter of the atomization bin space is about 1.8m, the processing process is fully sealed, the nitrogen consumption is also small, the motor speed is relatively high, and the atomization disk used has also been fully upgraded. At the same time, the product center particle size can be adjusted, the yield rate is high, and this method can achieve good control regardless of product quality or oxygen content.

[0007] However, due to the limitation of motor speed, the gas atomization method, centrifugal atomization method and improved centrifugal atomization method have low yield, poor sphericity and wide particle size distribution when preparing ultrafine powder with finer particle size, and cannot achieve accurate sorting of powder particles with a particle size of less than 15 μm. There are defects such as small content of particles with a particle size of less than 10 μm and high oxygen content, which seriously affect the preparation and use performance of ultrafine welding powder. In order to solve the above problems, the prior art adopts liquid phase forming method to prepare powder particles. Liquid phase forming method uses ultrasound to disperse molten metal droplets in liquid phase to prepare ultrafine powder. However, high-power ultrasonic devices will generate a lot of heat during operation and cannot be loaded in high temperature environment for a long time. Therefore, it is difficult to achieve high-efficiency continuous production and cannot meet market demand. In addition, the liquid phase medium used in the production process cannot be recycled, which increases material waste and loss.

[0008] A Chinese patent with publication number CN116408208A discloses a centrifugal liquid phase forming method, which combines centrifugal atomization technology with liquid phase forming technology to achieve a high concentration of particle size distribution. However, the centrifugal equipment is limited by its principle, has a small volume, low output, poor system stability, and complex maintenance, resulting in high powder particle processing costs. Summary of the invention

[0009] The purpose of the present invention is to solve the shortcomings of low output and high cost of ultrafine powder preparation in the prior art, and to provide a device and method for preparing ultrafine low-temperature metal powder based on liquid phase pulverization.

[0010] To achieve the above objectives, the technical solutions provided by the present invention are as follows:

[0011] A device for preparing ultrafine low-temperature metal powder based on liquid phase pulverization, which is special in that it includes a metal melting furnace, a medium oil tank, a liquid phase pulverizing tank, a driving unit, a radiator and a solid-liquid separator; the metal melting furnace is used to melt low-temperature metal, the medium oil tank is used to store medium oil, the outlet of the metal melting furnace and the outlet of the medium oil tank are respectively connected to the inlet of the liquid phase pulverizing tank; a pulverizing blade is arranged at the bottom of the liquid phase pulverizing tank, the output end of the driving unit is connected to the pulverizing blade, which is used to drive the pulverizing blade to rotate and pulverize the metal liquid into tiny metal droplets dispersed in the medium oil; the inlet of the radiator is connected to the outlet of the liquid phase pulverizing tank, and the outlet is connected to the inlet of the solid-liquid separator, the radiator is used to cool the medium oil containing tiny metal droplets to below the melting point of the low-temperature metal, so that the tiny metal droplets are solidified into metal powder particles, and the solid-liquid separator is used to separate the metal powder particles and the medium oil.

[0012] Furthermore, it also includes a delivery pump and a heating thermostat;

[0013] The input end of the delivery pump is connected to the liquid outlet of the solid-liquid separator, and the output end is connected to the medium oil tank, so as to return the medium oil separated from the solid and liquid to the medium oil tank;

[0014] The heating constant temperature device is set corresponding to the medium oil tank and the metal melting furnace, and is used to heat the medium oil tank and the metal melting furnace so that their temperature is 10°C-50°C higher than the melting point of the metal.

[0015] Furthermore, it also includes a heat preservation device arranged on the liquid phase crushing tank, and the heat preservation device is used to keep the liquid phase crushing tank warm so that its temperature is higher than the melting point of the metal.

[0016] Furthermore, the driving unit is a grinding motor.

[0017] At the same time, a method for preparing ultrafine low-temperature metal powder based on liquid phase pulverization is also provided. The device for preparing ultrafine low-temperature metal powder based on liquid phase pulverization is special in that it includes the following steps:

[0018] S1. Control the metal melting furnace to melt the low-temperature metal to obtain liquid metal, and add the medium oil and the liquid metal to the liquid phase crushing tank; the volume ratio of the medium oil to the liquid metal is (5-80):1; the low-temperature metal is a metal having a melting point temperature below 340°C;

[0019] S2. Control the drive unit to drive the crushing blade to rotate, crushing the liquid metal into tiny metal droplets; the operating speed of the crushing blade is 1000-10000 revolutions per minute;

[0020] S3. The medium oil containing tiny metal droplets is discharged into the radiator, and the temperature is lowered to below the melting point of the metal, wherein the tiny metal droplets solidify to form metal powder particles, and the medium oil containing metal powder particles is obtained;

[0021] S4. Performing solid-liquid separation on the medium oil containing the metal powder particles through a solid-liquid separator to obtain metal powder.

[0022] Further, in step S1, the metal is tin or a tin alloy;

[0023] In step S2, the crushing blade starts at a low speed, gradually increases to a working speed within 2-25 minutes, and then maintains the working speed for 5-30 minutes;

[0024] In step S3, the cooling rate of the heat sink is ≥5°C / min.

[0025] Further, in step S1, the volume ratio of the medium oil to the metal liquid is 10:1;

[0026] In step S2, the speed of the crushing blade is gradually increased from 1500 rpm to 6600 rpm within 10 minutes, and then maintained at 6600 rpm for 5 minutes;

[0027] In step S3, the cooling rate of the heat sink is 15°C / min.

[0028] Beneficial effects of the present invention:

[0029] 1. The device for preparing ultrafine low-temperature metal powder based on liquid phase crushing of the present invention has a relatively simple structure and is easy to operate and control. The crushing blade crushes the metal liquid and forms a centrifugal force, so that the tiny metal droplets can always be in a rotating state in the medium oil to avoid their fusion. The powder particle size can be controlled by controlling the working speed and rotation time of the crushing blade.

[0030] 2. The method for preparing ultrafine low-temperature metal powder based on liquid phase crushing of the present invention comprises the following steps: melting low-temperature metal and adding it into medium oil; a high-speed rotating crushing blade is arranged at the bottom of the liquid phase crushing tank to crush the metal liquid into tiny metal droplets; and then the medium oil containing the tiny metal droplets is quickly cooled down to obtain metal powder by solid-liquid separation. The production process is simple, the operation is convenient, and the control is easy. The processing cost is low and the production capacity is large, which is suitable for large-scale production.

[0031] 3. In the method for preparing ultrafine low-temperature metal powder based on liquid phase crushing of the present invention, the crushing process is carried out in medium oil to prevent the metal droplets from being oxidized by air, and the shape of the metal droplets in the medium oil is closer to a spherical shape, and the metal powder particles finally cooled and formed are also closer to a spherical shape. The entire production process has low noise, small vibration, and little damage to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of a device for preparing ultrafine low-temperature metal powder based on liquid phase pulverization according to the present invention.

[0033] Description of reference numerals:

[0034] 1-metal melting furnace, 2-liquid phase crushing tank, 3-crushing blade, 4-crushing motor, 5-radiator, 6-filter, 7-solid-liquid separator, 8-transfer pump, 9-medium oil tank. DETAILED DESCRIPTION

[0035] The present invention provides a device for preparing ultrafine low-temperature metal powder based on liquid phase pulverization. Figure 1 As shown, it includes a metal melting furnace 1, a medium oil tank 9, a liquid phase crushing tank 2, a crushing motor 4, a radiator 5, a solid-liquid separator 7 and a heating constant temperature device; the metal melting furnace 1 is used to melt low-temperature metal to obtain metal liquid, the medium oil tank 9 is used to store high-temperature medium oil, and the outlet of the metal melting furnace 1 and the outlet of the medium oil tank 9 are respectively connected to the inlet of the liquid phase crushing tank 2; a crushing blade 3 is arranged at the bottom of the liquid phase crushing tank 2, and the output end of the crushing motor 4 is connected to the crushing blade 3, which is used to drive the crushing blade 3 to rotate and crush the metal liquid into tiny metal droplets dispersed in the medium oil; the inlet of the radiator 5 is connected to the outlet of the liquid phase crushing tank 2, and the outlet is connected to the inlet of the solid-liquid separator 7. The radiator 5 is used to cool the medium oil containing tiny metal droplets to below the melting point of the metal, so that the tiny metal droplets are solidified into metal powder particles. In this embodiment, the radiator 5 is an oil cooler in the form of air cooling, and a filter screen 6 is arranged in the solid-liquid separator 7 to separate the metal powder particles and the medium oil by filtering. In other embodiments of the present invention, the radiator 5 can also use a liquid spray device or a gas spray device. The heating thermostat is provided corresponding to the medium oil tank 9 and the metal melting furnace 1, and is used to heat them so that their temperature is 10°C-50°C higher than the melting point of the low-temperature metal.

[0036] In order to realize the recycling of medium oil, a delivery pump 8 is also provided. The input end of the delivery pump 8 is connected to the liquid outlet of the solid-liquid separator 7, and the output end is connected to the medium oil tank 9, which is used to return the medium oil separated by solid and liquid to the medium oil tank 9.

[0037] In order to ensure the crushing effect, the present invention also provides a heat preservation device on the liquid phase crushing tank 2, through which the liquid phase crushing tank 2 is insulated to maintain the temperature in the liquid phase crushing tank 2 always higher than the melting point of the low-temperature metal during the crushing process.

[0038] In the present invention, because the specific gravity of low-temperature metal is greater than that of dielectric oil, it is easy to sink to the bottom. Therefore, the metal liquid is crushed by the crushing blade 3 arranged at the bottom. At the same time, the crushing blade 3 rotates at a high speed to keep the dielectric oil rotating and flowing, driving the tiny metal droplets therein to concentrate at a position close to the side wall of the liquid phase crushing tank 2 under the action of centrifugal force. Once tiny metal droplets gather into large liquid beads, they will fall to the bottom of the tank and be crushed again by the crushing blade 3 after falling. In addition, the dielectric oil containing tiny metal droplets quickly passes through the radiator, and cold water and cold wind are used to reduce the boiling point of the oil and quickly evaporate to take away a large amount of heat, so that the tiny metal droplets are quickly cooled and quickly formed. At the same time, the prior art is powdered in the air, and most of the tiny metal droplets will form the shape of water droplets under the action of air resistance. When in the dielectric oil, because the resistance of the dielectric oil is significantly greater than the air resistance, the shape of the obtained tiny metal droplets is closer to spherical.

[0039] The above-mentioned device for preparing ultrafine low-temperature metal powder based on liquid phase pulverization is used to prepare ultrafine low-temperature metal powder. In the present invention, low-temperature metal refers to a metal with a melting point temperature lower than 340° C. In this embodiment, tin or a tin alloy is preferred, and specifically comprises the following steps:

[0040] S1. Control the metal melting furnace 1 to melt the low-temperature metal to obtain liquid metal, and add the medium oil and liquid metal to the liquid phase crushing tank 2;

[0041] The volume ratio of medium oil to metal liquid is (5-80):1. When the proportion of medium oil is too low, the tiny metal droplets will quickly combine together to form large liquid droplets after crushing, which is not conducive to the preparation of small-particle metal powder; when the proportion of medium oil is too high, it will affect the powder making efficiency and the energy consumption will be too high. At the same time, since the medium oil itself contains tiny oxygen bubbles, it is easy to mix with more oxygen from the air during the heating process. Therefore, the more medium oil is used or the higher the proportion, the more difficult it is to control the oxygen content, which is not conducive to the control of the oxygen content of the metal powder.

[0042] In this embodiment, the volume ratio of the dielectric oil to the metal liquid is 10:1.

[0043] S2 controls the crushing motor 4 to drive the crushing blade 3 to rotate and crush the liquid metal into tiny metal droplets;

[0044] The working speed of the crushing blade 3 is 1000-10000 revolutions per minute and is continuously adjustable; the powder particle size is controlled by controlling the working speed and rotation time of the crushing blade 3. The higher the working speed and the longer the rotation time, the smaller the powder particle size, and vice versa. In the actual working process, the crushing blade 3 starts at a lower speed and then gradually increases to the working speed, thereby gradually breaking up the metal liquid to form a more uniform suspension.

[0045] In this embodiment, the speed of the crushing blade 3 is gradually increased from 1500 rpm to 6600 rpm within 10 minutes, and then maintained at the working speed of 6600 rpm for 5 minutes.

[0046] S3. Control the crushing blade 3 to stop, and discharge the medium oil containing tiny metal droplets to the radiator 5, so that the temperature is reduced to below the melting point of the low-temperature metal, and the tiny metal droplets therein solidify to form metal powder particles.

[0047] Before the tiny metal droplets solidify, the cooling rate of the heat sink 5 is ≥5°C / min. After solidification, there is no special requirement for the cooling rate. In this embodiment, the melting point of the tin-lead alloy T6 used is 183°C, so the cooling rate is maintained at 15°C / min until the temperature drops to 180°C, and then the cooling rate is reduced to less than 10°C / min.

[0048] S4. The solid-liquid separator 7 performs solid-liquid separation on the medium oil containing the metal powder particles to obtain metal powder.

[0049] Table 1 shows the particle size distribution of T6 tin powder prepared by using tin-lead alloy in the present invention. It can be seen that 95.80% of the powder particle size is within the range of 5 μm to 15 μm, the distribution range is narrow, and the yield is high.

[0050]

[0051] Embodiment 2

[0052] The difference between the method for preparing tin powder using tin in this embodiment and preparing ultrafine low-temperature metal powder based on liquid phase pulverization and the method in the first embodiment lies in the parameters of steps S1 to S3, which are specifically:

[0053] In step S1, the volume ratio of the medium oil to the metal liquid is 15:1.

[0054] In step S2, the speed of the crushing blade 3 is gradually increased from 1000 rpm to 10000 rpm within 10 minutes, and the working speed of 10000 rpm is maintained for 14 minutes.

[0055] In step S3, the cooling rate is 15°C / min.

[0056] In this embodiment, T8 tin powder was prepared, and the particle size distribution is shown in Table 2. It can be seen that 86.5% of the powder particle size meets the requirement of 2 μm to 8 μm, and the yield is relatively high.

[0057]

[0058] Embodiment 3

[0059] The method for preparing tin powder using tin in this embodiment and preparing ultrafine low-temperature metal powder based on liquid phase pulverization is different from that in the first embodiment only in the parameters of steps S1 to S3, which are specifically:

[0060] In step S1, the volume ratio of the medium oil to the metal liquid is 8:1.

[0061] In step S2, the speed of the crushing blade 3 is gradually increased from 500 rpm to 2800 rpm in 5 minutes, and the working speed of 2800 rpm is maintained for 5 minutes.

[0062] In step S3, the cooling rate is 10°C / min.

[0063] In this embodiment, T4 tin powder was prepared, and the particle size distribution is shown in Table 3. It can be seen that 92.5% of the powder particle size meets the range of 25 μm to 45 μm, and the yield is relatively high.

[0064]

[0065] Embodiment 4

[0066] The method for preparing tin powder using tin in this embodiment and preparing ultrafine low-temperature metal powder based on liquid phase pulverization is different from that in the first embodiment only in the parameters of steps S1 to S3, which are specifically:

[0067] In step S1, the volume ratio of the medium oil to the metal liquid is 80:1.

[0068] In step S2, the speed of the crushing blade 3 is gradually increased from 1000 rpm to 10000 rpm in 25 minutes, and the working speed of 10000 rpm is maintained for 30 minutes.

[0069] In step S3, the cooling rate is 5°C / min.

[0070] In this embodiment, T9 tin powder was prepared, and the particle size distribution is shown in Table 4. It can be seen that 82.1% of the powder particle size meets the requirement of 1 μm to 5 μm, and the yield is relatively high.

[0071]

[0072] In the present invention, the higher the proportion of the medium oil is and the higher the rotation speed of the crushing blade 3 is, the smaller the particle size of the tin powder that can be prepared is.

Claims

1. A device for preparing ultrafine low-temperature metal powder based on liquid phase pulverization, characterized in that: It comprises a metal melting furnace (1), a medium oil tank (9), a liquid phase crushing tank (2), a driving unit, a radiator (5) and a solid-liquid separator (7); The metal melting furnace (1) is used to melt low-temperature metal, the medium oil tank (9) is used to store medium oil, and the outlet of the metal melting furnace (1) and the outlet of the medium oil tank (9) are respectively connected to the inlet of the liquid phase crushing tank (2); A crushing blade (3) is arranged at the bottom of the liquid phase crushing tank (2), and the output end of the driving unit is connected to the crushing blade (3) for driving the crushing blade (3) to rotate, thereby crushing the metal liquid into tiny metal droplets dispersed in the medium oil; The inlet of the radiator (5) is connected to the outlet of the liquid phase crushing tank (2), and the outlet is connected to the inlet of the solid-liquid separator (7). The radiator (5) is used to cool the medium oil containing tiny metal droplets to below the melting point of the low-temperature metal, so that the tiny metal droplets solidify into metal powder particles. The solid-liquid separator (7) is used to separate the metal powder particles and the medium oil.

2. The device for preparing ultrafine low-temperature metal powder based on liquid phase pulverization according to claim 1, characterized in that: It also includes a delivery pump (8) and a heating thermostat; The input end of the delivery pump (8) is connected to the liquid outlet of the solid-liquid separator (7), and the output end is connected to the medium oil tank (9), so as to return the medium oil after solid-liquid separation to the medium oil tank (9); The heating constant temperature device is arranged corresponding to the medium oil tank (9) and the metal melting furnace (1), and is used to heat the medium oil tank (9) and the metal melting furnace (1) so that their temperature is 10° C.-50° C. higher than the melting point of the metal.

3. The device for preparing ultrafine low-temperature metal powder based on liquid phase pulverization according to claim 1 or 2, characterized in that: It also comprises a heat preservation device arranged on the liquid phase pulverizing tank (2), the heat preservation device being used to keep the liquid phase pulverizing tank (2) warm so that its temperature is higher than the melting point of the metal.

4. The device for preparing ultrafine low-temperature metal powder based on liquid phase pulverization according to claim 3 is characterized in that: The driving unit is a pulverizing motor (4).

5. A method for preparing ultrafine low-temperature metal powder based on liquid phase pulverization, based on the device for preparing ultrafine low-temperature metal powder based on liquid phase pulverization according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Control the metal melting furnace (1) to melt the low-temperature metal to obtain liquid metal, and add the medium oil and the liquid metal to the liquid phase crushing tank (2); the volume ratio of the medium oil to the liquid metal is (5-80):1; the low-temperature metal is a metal having a melting point temperature lower than 340°C; S2. Control the drive unit to drive the crushing blade (3) to rotate, crushing the metal liquid into tiny metal droplets; the operating speed of the crushing blade (3) is 1000-10000 revolutions per minute; S3. The medium oil containing tiny metal droplets is discharged into the radiator (5), and the temperature is lowered to below the melting point of the metal, wherein the tiny metal droplets solidify to form metal powder particles, thereby obtaining a medium oil containing metal powder particles; S4. The medium oil containing the metal powder particles is subjected to solid-liquid separation by a solid-liquid separator (7) to obtain metal powder.

6. The method for preparing ultrafine low-temperature metal powder based on liquid phase pulverization according to claim 5, characterized in that: In step S1, the metal is tin or a tin alloy; In step S2, the crushing blade (3) starts at a low speed, gradually increases to a working speed within 2-25 minutes, and then maintains the working speed for 5-30 minutes; In step S3, the cooling rate of the heat sink (5) is ≥5°C / min.

7. The method for preparing ultrafine low-temperature metal powder based on liquid phase pulverization according to claim 6, characterized in that: In step S1, the volume ratio of the medium oil to the metal liquid is 10:1; In step S2, the speed of the crushing blade (3) is gradually increased from 1500 rpm to 6600 rpm within 10 minutes, and then maintained at 6600 rpm for 5 minutes; In step S3, the cooling rate of the heat sink (5) is 15°C / min.

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