Aluminum alloy powder and method for improving fluidity thereof and application method thereof

Abstract

The present invention discloses an aluminum alloy powder and a method for improving the fluidity thereof and an application method thereof, wherein the method for improving the fluidity of the aluminum alloy powder comprises the following steps: step 1, placing aluminum alloy powder with a particle size of 10 to 60 μm into a powder loading chamber of a plasma treatment device, and controlling the vacuum degree in the plasma treatment device to be below 0.01 Pa; step 2, introducing an inert gas into the plasma treatment device to make the pressure in the plasma treatment device reach 4 to 6 kPa; step 3, igniting a plasma gun in the plasma treatment device to obtain a target plasma; step 4, turning on a powder feeder, and feeding the aluminum alloy powder into a plasma flame flow at a preset powder feeding angle and powder feeding rate, so that the aluminum alloy powder undergoes surface modification. The present invention aims to improve the fluidity of aluminum alloy powder.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy powder, and in particular to an aluminum alloy powder, a method for improving fluidity thereof, and an application method thereof. Background Art

[0002] At present, selective laser melting (SLM) is a major technical approach in the additive manufacturing of metal materials. This technology uses laser as the energy source and scans the metal powder bed layer by layer according to the path planned in the three-dimensional CAD slice model. The scanned metal powder is melted and solidified to achieve the effect of metallurgical bonding, and finally the metal parts designed by the model are obtained. The raw materials used are metal powders, including aluminum alloys, copper alloys, nickel alloys, titanium alloys and other metal types. At the same time, the larger the particle size of the metal powder, the better the fluidity, but the larger the powder particles affect the absorption of laser energy, and it is not easy to form a good molten pool, resulting in an increase in porosity defects; while the smaller the particle size of the metal powder, the higher the surface activity, the more conducive to the absorption of the laser, and the more stable the molten pool, but the smaller the particle size, the lower the fluidity of the powder, which affects the uniformity of the powder.

[0003] At present, most of the existing aerosolized aluminum alloy powders in China are still imported from abroad due to problems such as high oxygen content, poor sphericity, and too large a particle size range. However, there are two main methods for the poor fluidity of aluminum alloy powders in the existing technology. The first is to increase the powder particle size, increase the D10 value as much as possible within the required particle size distribution range, and reduce the proportion of fine powder. The powder fluidity improved by this method varies with the particle size, but the powder particle size used for additive manufacturing generally has requirements, and the stability of powder forming quality will not be reduced in order to improve fluidity, so there are limitations. The second is to add lubricants, such as polyethylene glycol, lithium stearate, molybdenum disulfide, etc., to improve the flowability of powders by physical adsorption or self-lubrication. This method can improve the powder fluidity well, but additive manufacturing technology has high requirements for the composition of metal powder materials. By introducing lubricants, it is obvious that the impurity content of the powder will increase, thereby affecting the stability of powder forming. Furthermore, both of the above-mentioned two processing methods have certain disadvantages, so it is necessary to further research and develop process technologies for improving the fluidity of aluminum alloy powders for additive manufacturing. Summary of the invention

[0004] The main purpose of the present invention is to provide an aluminum alloy powder and a method for improving its fluidity and an application method thereof, aiming to solve the technical problem of poor fluidity of the existing aluminum alloy powder for additive manufacturing.

[0005] To achieve the above object, the present invention provides a method for improving the fluidity of aluminum alloy powder, the method comprising the following steps:

[0006] Step 1, placing aluminum alloy powder with a particle size of 10 to 60 μm into a powder loading chamber of a plasma treatment device, and controlling the vacuum degree in the plasma treatment device to below 0.01 Pa;

[0007] Step 2, introducing an inert gas into the plasma processing device so that the pressure in the plasma processing device reaches 4 to 6 kPa;

[0008] Step 3, igniting a plasma gun in a plasma treatment device to obtain a target plasma;

[0009] Step 4, start the powder feeder, and feed the aluminum alloy powder into the plasma flame flow at a preset powder feeding angle and powder feeding rate to modify the surface of the aluminum alloy powder.

[0010] Optionally, the step 3 specifically includes: starting the circulating air and water cooler in the plasma processing device, opening the gas outlet valve and adjusting the gas outlet flow rate, and performing arc striking to ignite the plasma gun.

[0011] Optionally, step 3 further includes controlling the current of the plasma gun to be 100-300A and the voltage to be 10-60V to control the power of the plasma.

[0012] Optionally, the powder feeding angle in step 4 is 10 to 80°, and the powder feeding rate is 10 to 20 g / min.

[0013] Optionally, the air outlet flow rate is 30 to 80 L / min.

[0014] Optionally, the inert gas in step 2 is at least one of argon, helium, nitrogen and hydrogen.

[0015] Optionally, the powder feeding angle in step 4 is 60°.

[0016] Optionally, the air outlet flow rate is 45 L / min.

[0017] In addition, to achieve the above-mentioned purpose, the present invention also provides an aluminum alloy powder, which is obtained according to any of the above-mentioned methods for improving the fluidity of the aluminum alloy powder.

[0018] In addition, to achieve the above-mentioned purpose, the present invention also provides an application method of aluminum alloy powder, the application method comprising: using the aluminum alloy powder material as a printing material, and using 3D printing to print the printing material into a finished product based on a three-dimensional graphic file to be printed.

[0019] The present invention proposes an aluminum alloy powder and a method for improving its fluidity and an application method thereof, wherein the aluminum alloy powder with a particle size of 10 to 60 μm is placed in a powder loading chamber of a plasma treatment device, and the vacuum degree in the plasma treatment device is controlled to be below 0.01 Pa; Step 2, an inert gas is introduced into the plasma treatment device to make the pressure in the plasma treatment device reach 4 to 6 kPa; Step 3, a plasma gun in the plasma treatment device is ignited to obtain a target plasma; Step 4, a powder feeder is turned on to feed the aluminum alloy powder into a plasma flame flow at a preset powder feeding angle and powder feeding rate, so that the aluminum alloy powder undergoes surface modification. After the above-mentioned process steps, the powder particle size distribution does not change much and no new impurity elements are introduced, and there is no agglomeration between the powder particles, and the particles are mutually incoherent and dispersed, thereby effectively improving the fluidity of the powder. The principle is that after the aluminum alloy powder particles pass through a high temperature field, their surfaces are remelted and cooled, and the roughness is reduced, which reduces the friction between the powder particles and improves the powder fluidity; and the powder particles are also remelted and micro-oxidized on their surfaces, which reduces the agglomeration of the powders and further improves the powder fluidity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic flow chart of an embodiment of a method for improving the fluidity of aluminum alloy powder according to the present invention;

[0021] Figure 2 Shown is a scanning electron microscope image of the treated aluminum alloy powder in Example 1.

[0022] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0023] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0024] Reference Figure 1 , which is a schematic flow chart of a first embodiment of a method for improving the fluidity of aluminum alloy powder according to the present invention, comprising the following steps:

[0025] Step 1, placing aluminum alloy powder with a particle size of 10 to 60 μm into the powder loading cabin of the plasma treatment device, and controlling the vacuum degree in the plasma treatment device to below 0.01 Pa. Wherein, the aluminum alloy powder is prepared by atomization, and the atomized aluminum alloy powder also contains strengthening elements such as magnesium, silicon, zirconium, rare earth, and the powder is further screened by airflow classification technology to obtain aluminum alloy powder with a target powder particle size distribution. And the vacuuming step is to place the target aluminum alloy powder into the powder loading cabin of the plasma treatment device, close the hatch, open the slide valve pump and Roots pump in the plasma treatment device in turn, and extract the air in the device until the vacuum degree in the device reaches the target required value.

[0026] Step 2: Introduce an inert gas into the plasma processing device to make the pressure in the plasma processing device reach 4-6 kPa; then open the inert gas charging valve to inject the inert gas into the device until the pressure reaches a preset value. The inert gas includes at least one of argon, helium, nitrogen and hydrogen, preferably argon.

[0027] Step 3, ignite the plasma gun in the plasma treatment device to obtain the target plasma; specifically, before igniting the plasma gun, it is necessary to pre-open the circulating air and water cooler in the plasma treatment device, open the gas outlet valve and adjust the gas outlet flow rate, and it is necessary to control the gas outlet flow rate to 30-80L / min; preferably, the gas outlet flow rate is 45L / min, and then perform arc initiation, ignite the plasma gun, adjust its current value and voltage value, and control the power of the plasma, wherein the current of the plasma gun is controlled to be 100-300A and the voltage is 10-60V to obtain a plasma of the target power.

[0028] Step 4, start the powder feeder, and feed the aluminum alloy powder into the plasma flame flow at a preset powder feeding angle and powder feeding rate to modify the surface of the aluminum alloy powder. The powder feeding angle is 10-80°, the powder feeding rate is 10-20 g / min, and preferably, the powder feeding angle is 60° as the side powder feeding angle.

[0029] After the aluminum alloy powder in the present invention is processed through the above process steps, the powder fluidity can be improved without much change in the powder particle size distribution and without introducing new impurity elements, and the improvement effect is good. The principle is that after the aluminum alloy powder particles pass through the high temperature field, the surface is remelted and cooled, the roughness is reduced, the friction between the powder particles is reduced, and the powder fluidity is reduced; and the surface of the powder particles is also remelted and slightly oxidized, which reduces the agglomeration phenomenon between the powders, thereby further improving the powder fluidity.

[0030] Further, in order to better illustrate the effect of the treatment process of the present invention on improving the fluidity of aluminum alloy powder, the same batch of aluminum alloy powder was used to carry out the following treatment processes of Examples 1-2 and Comparative Example 1, wherein the particle size distribution of the aluminum alloy powder before treatment is shown in Table 1:

[0031] Table 1- Particle size distribution of aluminum alloy powder before treatment

[0032]

[0033] For those skilled in the art, the D10 particle size that meets the particle size requirements for metal powder used in additive manufacturing is about 15 μm, and the D90 particle size is about 53 μm.

[0034] Example 1

[0035] The aluminum alloy powder prepared by atomization and screening is placed in the powder loading cabin of the DC plasma treatment device, the hatch is closed, and the slide valve pump and the Roots pump are opened in sequence to extract the air in the device until the pre-vacuum degree in the device reaches 0.01Pa, and then the argon gas charging valve is opened to flush argon into the device until the inert gas protection charging pressure reaches 5kPa, and then the circulating air and water cooler are turned on, the outlet valve is opened, and the outlet flow rate is adjusted to 30L / min, arc treatment is performed, and the plasma gun is ignited, and its current value is adjusted to 200A and the voltage value is adjusted to 20V to obtain a plasma of the target power, and then the powder feeder is turned on to feed the aluminum alloy powder into the plasma flame flow of the device at an angle of 60° and a powder feeding rate of 10g / min, so that the conveyed powder can be quickly surface modified in the high-temperature and high-energy plasma flow. After the treatment is completed, the powder feeder is turned off, the voltage and current of the plasma gun are adjusted to the minimum, the fan is turned off, and the powder is cooled in an inert atmosphere. The air release valve is opened to allow air to be slowly introduced into the device, and the powder collecting tank is removed. The collected powder is further subjected to airflow classification treatment to obtain the treated aluminum alloy powder 1, and the powder particle size distribution is measured, as shown in Table 2:

[0036] Table 2 - Particle size distribution of the treated aluminum alloy powder in Example 1

[0037]

[0038] Compared with the particle size distribution before treatment, the particle size of the alloy powder after treatment in this embodiment is slightly smaller, and the particle size of D10 is 18.22μm, and the particle size of D90 is 58.53μm, thereby meeting the particle size requirements of metal powder for additive manufacturing. The angle of repose test was performed, and the results are shown in Table 3 below.

[0039] Table 3 Aluminum alloy powder repose angle test

[0040] Performance Indicators Before treatment After treatment Repose Angle 37° 32° <![CDATA[D 90 Value]]> 61μm 58μm

[0041] Example 2

[0042] The aluminum alloy powder before treatment in Example 1 is placed in the powder loading cabin of the DC plasma treatment device, the hatch is closed, the slide valve pump and the Roots pump are opened in sequence, the air in the device is extracted until the pre-vacuum degree in the device reaches 0.01Pa, and then the argon gas charging valve is opened to flush argon into the device until the inert gas protection charging pressure reaches 4kPa. After that, the circulating air and water cooler are turned on, the outlet valve is opened, the outlet flow rate is adjusted to 50L / min, the arc is struck, the plasma gun is ignited, the current value is adjusted to 100A and the voltage value is adjusted to 60V, and the plasma of the target power is obtained, and then the powder feeder is turned on to feed the aluminum alloy powder into the plasma flame flow of the device at an angle of 80° and a powder feeding rate of 10g / min, so that the conveyed powder is quickly surface-modified in the high-temperature and high-energy plasma flow. After the treatment is completed, the powder feeder is turned off, the voltage and current of the plasma gun are adjusted to the minimum, the fan is turned off, and the powder is cooled in an inert atmosphere. The vent valve is opened to allow air to be slowly introduced into the device, and the powder collecting tank is removed. The collected powder is further subjected to airflow classification treatment to obtain the treated aluminum alloy powder 2, and the powder particle size distribution is measured, as shown in Table 4:

[0043] Table 4 - Particle size distribution of the treated aluminum alloy powder in Example 2

[0044]

[0045] It can be seen from Table 4 and Table 1 that, compared with the particle size distribution before treatment, the particle size of the alloy powder after treatment in this embodiment is slightly smaller, and the particle size of D10 is 12.63 μm, and the particle size of D90 is 46.34 μm, which meets the particle size requirements of metal powder for additive manufacturing. The repose angle test is further performed, and the results are shown in Table 5 below.

[0046] Table 5 Aluminum alloy powder repose angle test

[0047] Performance Indicators Before treatment After treatment Repose Angle 37° 30° <![CDATA[D 90 Value]]> 61μm 46μm

[0048] Example 3

[0049] The aluminum alloy powder before treatment in Example 1 is placed in the powder loading cabin of the DC plasma treatment device, the hatch is closed, the slide valve pump and the Roots pump are opened in sequence, the air in the device is extracted until the pre-vacuum degree in the device reaches 0.01Pa, and then the argon gas charging valve is opened to flush argon into the device until the inert gas protection charging pressure reaches 6kPa. After that, the circulating air and water cooler are turned on, the outlet valve is opened, the outlet flow rate is adjusted to 80L / min, the arc is struck, the plasma gun is ignited, the current value is adjusted to 300A and the voltage value is adjusted to 10V, and the plasma of the target power is obtained, and then the powder feeder is turned on, and the aluminum alloy powder is fed into the plasma flame flow of the device at an angle of 10° and a powder feeding rate of 20g / min, so that the conveyed powder is quickly surface-modified in the high-temperature and high-energy plasma flow. After the treatment is completed, the powder feeder is turned off, the voltage and current of the plasma gun are adjusted to the minimum, the fan is turned off, and the powder is cooled in an inert atmosphere. The vent valve is opened to allow air to be slowly introduced into the device, and the powder collecting tank is removed. The collected powder is further subjected to airflow classification treatment to obtain the treated aluminum alloy powder 3, and the powder particle size distribution is measured, as shown in Table 6.

[0050] Table 6 - Particle size distribution of the treated aluminum alloy powder in Example 3

[0051]

[0052] Compared with the particle size distribution before treatment, the particle size of the alloy powder after treatment in this embodiment is slightly smaller, and the particle size of D10 is 13.67 μm, and the particle size of D90 is 48.78 μm, thereby meeting the particle size requirements of metal powder for additive manufacturing. Further repose angle tests are performed, and the results are shown in Table 7 below.

[0053] Table 7 Aluminum alloy powder repose angle test

[0054] Performance Indicators Before treatment After treatment Repose Angle 37° 31° <![CDATA[D 90 Value]]> 61μm 48μm

[0055] Comparative Example 1

[0056] The aluminum alloy powder before the same treatment as in Example 1 is placed in the powder loading cabin of the DC plasma treatment device, the hatch is closed, the slide valve pump and the Roots pump are opened in sequence, the air in the device is extracted until the pre-vacuum degree in the device reaches 0.01Pa, and then the argon gas inflation valve is opened to flush argon into the device until the inert gas protection inflation pressure reaches 5KPa. After that, the circulating air and water cooler are turned on, the outlet valve is opened, the outlet flow rate is adjusted to 10L / min, the arc treatment is carried out, the plasma gun is ignited, and its current value is adjusted to 30A and the voltage value is adjusted to 5V to control the power of the plasma. The powder feeder is turned on, and the aluminum alloy powder is fed into the DC arc plasma flame flow of the device at an angle of 80° and a powder feeding rate of 30g / min, and the conveyed powder is rapidly surface modified in the high-temperature and high-energy plasma flow. After the treatment is completed, the powder feeder is turned off, the voltage and current of the plasma gun are adjusted to the minimum, the fan is turned off, and the powder is cooled in an inert atmosphere. The air release valve is opened to allow air to be slowly introduced into the device, and the powder collecting tank is removed. The collected powder is further subjected to airflow classification treatment to obtain the treated aluminum alloy powder 3, and the powder particle size distribution is measured, as shown in Table 8:

[0057] Table 8 - Particle size distribution of the treated aluminum alloy powder in Comparative Example 1

[0058]

[0059] Compared with the particle size distribution before treatment, the particle size of the alloy powder after treatment in this embodiment is slightly smaller, and the particle size of D10 is 19.78 μm, and the particle size of D90 is 60.54 μm, which basically meets the particle size requirements of metal powder for additive manufacturing. The repose angle test is further performed, and the results are shown in Table 9 below.

[0060] Table 9 Aluminum alloy powder repose angle test

[0061] Performance Indicators Before treatment After treatment Repose Angle 37° 36° <![CDATA[D 90 Value]]> 61μm 60μm

[0062] As shown in Table 3 above, the angle of repose of the treated aluminum alloy powder 1 is significantly reduced, and the angle of repose directly reflects the fluidity of the powder. The smaller the angle of repose, the better the fluidity of the powder. It can be seen that the treated aluminum alloy powder 1 obtained in Example 1 has significantly improved fluidity under the premise of slightly reducing the particle size. And as shown in Tables 5 and 7 above, the angle of repose of the treated aluminum alloy powder 2-3 is significantly reduced, and the treated aluminum alloy powder 2-3 obtained in Example 2-3 has significantly improved fluidity under the premise of reducing the particle size. And according to Figure 2The electron microscope image of the aluminum alloy powder after treatment in Example 1 shows that the powder particles are less agglomerated, and most particles are independent of each other and dispersed. As shown in Table 8 above, the repose angle of the aluminum alloy powder after treatment in Comparative Example 1 does not change much, which shows that the fluidity of the aluminum alloy powder after treatment obtained in Comparative Example 1 is not improved much.

[0063] From the above, it can be seen that in the present embodiments 1 to 3, the powder particle size distribution does not change much and no new impurity elements are introduced, and there is less agglomeration between the powder particles, most of the particles are independent of each other and dispersed, and the repose angle of the treated aluminum alloy powder shown in Example 1 does not change much, and thus the fluidity of the treated aluminum alloy powder obtained in Example 1 is not improved much. It can be seen that the method for improving the fluidity of aluminum alloy powder for additive manufacturing of the present invention can effectively improve the fluidity of the powder.

[0064] In addition, to achieve the above-mentioned purpose, the present invention also provides an application method of the aluminum alloy powder for additive manufacturing prepared by the above-mentioned method, the application method comprising: using the aluminum alloy powder material as a printing material, and using 3D printing to print the printing material into a finished product based on a three-dimensional graphic file to be printed, thereby effectively improving the texture and effect of the 3D printed finished product. The principle is that when the fluidity of the aluminum alloy powder is poor, the molten aluminum is easily uneven in composition when 3D printing a part, thereby enhancing the fluidity of the aluminum alloy powder, which can effectively improve the uniformity of the composition of the molten aluminum when printing the part.

[0065] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0066] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0067] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for improving the fluidity of aluminum alloy powder, characterized in that: The method comprises the following steps: Step 1, placing aluminum alloy powder with a particle size of 10 to 60 μm into a powder loading chamber of a plasma treatment device, and controlling the vacuum degree in the plasma treatment device to below 0.01 Pa; Step 2, introducing an inert gas into the plasma processing device so that the pressure in the plasma processing device reaches 4 to 6 kPa; Step 3, igniting a plasma gun in a plasma treatment device to obtain a target plasma; Step 4, starting the powder feeder, feeding the aluminum alloy powder into the plasma flame flow at a preset powder feeding angle and powder feeding rate, so as to modify the surface of the aluminum alloy powder, wherein the powder feeding angle is 10 to 80 degrees, and the powder feeding rate is 10 to 20 g / min; Among them, the step 3 specifically includes: turning on the circulating air and water cooler in the plasma treatment device, opening the gas outlet valve and adjusting the gas outlet flow rate, performing arc initiation treatment to ignite the plasma gun, and controlling the current of the plasma gun to 100-300A and the voltage to 10-60V to control the power of the plasma, and the gas outlet flow rate is 30-80L / min.

2. The method for improving the fluidity of aluminum alloy powder according to claim 1, characterized in that: The inert gas in step 2 is at least one of argon, helium, nitrogen and hydrogen.

3. The method for improving the fluidity of aluminum alloy powder according to claim 1, characterized in that: The powder feeding angle in step 4 is 60°.

4. The method for improving the fluidity of aluminum alloy powder according to claim 1, characterized in that: The gas outlet flow rate is 45 L / min.

5. An aluminum alloy powder, characterized in that: The aluminum alloy powder is obtained according to the method for improving the fluidity of an aluminum alloy powder according to any one of claims 1 to 4.

6. A method for applying aluminum alloy powder, characterized in that: The application method comprises: using the aluminum alloy powder material according to claim 5 as a printing material, and using 3D printing to print a finished product of the printing material based on a three-dimensional graphic file to be printed.

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