Preparation method of titanium alloy powder

Abstract

The invention relates to a preparation method of titanium alloy powder, in particular to the field of metal powder manufacturing, and the preparation method comprises the steps that in an inert environment, a titanium alloy bar is subjected to induction melting, meanwhile, supersonic inert gas is adopted for blowing liquid titanium alloy to enable the liquid titanium alloy to be dispersed and atomized, and titanium alloy powder is obtained; the heating power of the induction melting is 12 to 30 kW. According to the preparation method, by optimizing the preparation process of the titanium alloy powder, the index of the obtained titanium alloy powder can be remarkably improved, the titanium alloy powder has the advantages of being narrow in particle size distribution, high in sphericity degree and high in fluidity, particles with the particle size being 40-50 micrometers account for 85% or above of the mass of all the powder, the sphericity degree is larger than or equal to 0.98, and the Hall flow velocity is smaller than or equal to 20 s / 50 g.

Description

Technical Field

[0001] This invention relates to the field of metal powder manufacturing, and more specifically to a method for preparing titanium alloy powder. Background Technology

[0002] Currently, the main methods for producing titanium and titanium alloy powders are metallothermic reduction, hydrogenation dehydrogenation, centrifugal atomization, and gas atomization.

[0003] Metallothermic reduction, also known as sodium reduction, produces titanium powder that is extremely cheap. However, it has poor flowability and contains NaCl that may be mixed with or remain in the powder during production, leading to pores in the sintered body. Therefore, the production of titanium powder using sodium reduction has been discontinued in recent years.

[0004] The hydrogenation-dehydrogenation method utilizes the brittleness of titanium hydride to hydrogenate titanium, then pulverizes and dehydrogenates it under high temperature and vacuum to obtain titanium powder. This powder is usually called HDH powder. Its product has a wide particle size range and is suitable for general powder metallurgy processes such as metal molding and cold pressing. However, the mechanical properties of its alloy products are far lower than those of atomized powder titanium alloys and melt-forged materials, especially in terms of fatigue and fracture properties. In addition, the products obtained by this method have relatively high contents of impurities such as oxygen, hydrogen, iron, silicon, nitrogen, and carbon.

[0005] Centrifugal atomization, also known as plasma rotating electrode method or PREP method, is a method that uses a plasma gun to melt a high-speed rotating raw material and then splashes and solidifies the molten metal radially under centrifugal force to obtain titanium powder. The problems with this method are that the high-speed rotation and sealing issues limit the rotation speed, strict electrode specifications are required, and the continuous feeding is poor, resulting in high production costs, coarse powder, and a small market.

[0006] Gas atomization is a mechanical powder production method. It is a method of producing metal or alloy powder by directly crushing liquid metal or alloy liquid with high-pressure inert gas (Ar, N, etc.). The outstanding advantages of gas atomization powder are that the powder is spherical, has high loose density, good flowability, low oxygen content, good arching effect, and high compact strength.

[0007] For example, CN114406273A discloses a method for preparing multi-stage gas atomization spherical powder. By controlling the gas atomization pressure and the feed rate of the bar in stages, the collision probability of the molten metal droplets during the gas atomization stage is reduced, thereby achieving coordinated control of particle size and surface quality during the gas atomization preparation of the alloy 3D printing powder.

[0008] CN103846447A discloses a method for preparing fine spherical titanium or titanium alloy powder by gas atomization. The method includes the following steps: (1) selecting sponge titanium or titanium hydride or titanium with at least two alloying elements for batching; (2) pre-vacuuming the melting chamber and atomization chamber, and then filling them with argon or helium protective gas; (3) melting the titanium-containing batch using a water-cooled copper crucible to form a titanium or titanium alloy melt; (4) using a double-layer atomization nozzle to atomize and hydrogenate the titanium or titanium alloy melt to produce powder; (5) after the powder is cooled, collecting the fine spherical titanium or titanium alloy powder by cyclone separation.

[0009] However, the powder produced by current atomization powder production still suffers from defects such as poor sphericity, wide particle size distribution, and poor flowability. Summary of the Invention

[0010] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for preparing titanium alloy powder, so as to solve the defects of poor sphericity, wide particle size distribution and poor flowability of powder obtained by gas atomization powder preparation.

[0011] To achieve this objective, the present invention adopts the following technical solution:

[0012] This invention provides a method for preparing titanium alloy powder, the method comprising:

[0013] In an inert environment, titanium alloy rods are induction melted, and at the same time, supersonic inert gas is used to blow the liquid titanium alloy to disperse and atomize the liquid titanium alloy, thus obtaining titanium alloy powder.

[0014] The heating power for induction melting is 12-30kW.

[0015] The preparation method provided by this invention can significantly improve the properties of the obtained titanium alloy powder by optimizing the preparation process of titanium alloy powder. It has the advantages of narrow particle size distribution, high sphericity and high flowability. Among them, the particles of 40-50μm account for more than 85% of the total powder mass, the sphericity is ≥0.98 and the Hall flow rate is ≤20s / 50g.

[0016] As a preferred embodiment of the present invention, the absolute pressure of the inert gas in the inert environment is 0.9-1.3 bar.

[0017] As a preferred embodiment of the present invention, the absolute value of the difference between the ambient air pressure of induction melting and the ambient air pressure of atomization is ≤300mbar.

[0018] As a preferred embodiment of the present invention, the diameter of the titanium alloy rod is 40-60 mm.

[0019] As a preferred embodiment of the present invention, the frequency of the induction melting is 60-80kHz.

[0020] As a preferred embodiment of the present invention, the pressure of the supersonic inert gas is 3-5 MPa.

[0021] As a preferred embodiment of the present invention, the flow rate of the supersonic inert gas is 1000-1300 m / s.

[0022] As a preferred embodiment of the present invention, the angle between the flow direction of the supersonic inert gas and the axial direction of the titanium alloy rod is 45-90°.

[0023] As a preferred technical solution of the present invention, the titanium alloy is subjected to ultrasonic cleaning and drying sequentially before induction melting.

[0024] As a preferred embodiment of the present invention, the ultrasonic cleaning time is 10-20 minutes.

[0025] Preferably, the drying temperature is 100-120°C.

[0026] Preferably, the drying time is 2-3 hours.

[0027] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0028] (1) The preparation method provided by the present invention optimizes the powder preparation process parameters, such as induction heating power, frequency, gas pressure and airflow angle, to achieve the preparation of high-performance titanium alloy powder, so that the particles of 40-50μm account for more than 85% of the total powder mass, the sphericity is ≥0.98, and the Hall flow rate is ≤20s / 50g.

[0029] (2) The preparation method provided by the present invention avoids the problems of continuous production and product quality control in crucible melting, and significantly improves the quality of titanium alloy powder.

[0030] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0031] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0032] Currently, titanium alloy powder is typically prepared using gas atomization. However, current gas atomization equipment uses crucibles to hold the molten material, which presents two problems: 1) Crucible material issues, including limited operating temperatures, inability to handle high-melting-point metals, high chemical stability requirements for the molten material, especially difficulty in controlling contamination and inclusions during the melting of active metals, leading to material contamination from impurities such as tungsten and copper in contact with the molten titanium metal, and a short equipment lifespan; 2) Difficulty in controlling continuous production and product quality during crucible melting. Induction melting is currently used to address these shortcomings. However, even with induction melting, the powder produced by gas atomization still suffers from poor sphericity, wide particle size distribution, and poor flowability. Therefore, this invention optimizes the powder preparation process parameters to significantly improve the properties of the obtained titanium alloy powder, resulting in a narrow particle size distribution, high sphericity, and high flowability, as detailed below:

[0033] I. This embodiment provides a method for preparing titanium alloy powder, the method comprising:

[0034] In an inert environment, titanium alloy rods are induction melted, and simultaneously, supersonic inert gas is used to blow the liquid titanium alloy to disperse and atomize it, thus obtaining titanium alloy powder.

[0035] In this invention, an inert environment refers to an inert gas environment.

[0036] In this invention, inert gas refers to a gas that does not affect the material properties during the preparation process, i.e., it does not react with titanium alloys, such as helium, neon, argon, nitrogen, etc.

[0037] The titanium alloy undergoes ultrasonic cleaning and drying sequentially before induction melting.

[0038] In this invention, between ultrasonic cleaning and drying, water washing, alcohol washing, or other processes can be optionally added to remove residual cleaning agents and other substances from the surface, thereby further ensuring the final powder production effect.

[0039] In this invention, the cleaning agent used in ultrasonic cleaning can be a commercially available cleaning agent commonly used in the field, such as a neutral water-based environmentally friendly cleaning agent, such as HFE-347 cleaning solution or ZESTRON VIGON N600 cleaning solution, to remove stains, oil stains, rust stains, dust and other impurities from the surface of titanium alloy materials, so as to avoid affecting the purity and other properties of the product. The relevant operating parameters of ultrasonic cleaning can be designed according to conventional requirements to ensure that the conventional surface requirements in the field are met.

[0040] The ultrasonic cleaning time is 10-20 minutes, for example, it can be 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes or 20 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0041] The drying temperature is 100-120℃, for example, it can be 100℃, 102℃, 104℃, 106℃, 108℃, 110℃, 112℃, 114℃, 116℃, 118℃ or 120℃, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0042] The drying time is 2-3 hours, for example, it can be 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0043] The absolute pressure of the inert gas in the inert environment is 0.9-1.3 bar, for example, it can be 0.9 bar, 0.94 bar, 0.98 bar, 1.02 bar, 1.06 bar, 1.1 bar, 1.14 bar, 1.18 bar, 1.22 bar, 1.26 bar or 1.3 bar, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0044] Wherein, the absolute value of the difference between the ambient air pressure of induction melting and the ambient air pressure of atomization is ≤300mbar, for example, it can be 300mbar, 280mbar, 260mbar, 240mbar, 220mbar, 200mbar, 180mbar, 160mbar, 140mbar, 120mbar or 100mbar, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0045] The diameter of the titanium alloy rod is 40-60mm, for example, it can be 40mm, 42mm, 44mm, 46mm, 48mm, 50mm, 52mm, 54mm, 56mm, 58mm or 60mm, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0046] In this invention, the length of the titanium alloy rod can be reasonably selected according to the amount of powder required for a single powder production, such as a length of 500-600mm.

[0047] The frequency of the induction melting is 60-80kHz, for example, it can be 60kHz, 62kHz, 64kHz, 66kHz, 68kHz, 70kHz, 72kHz, 74kHz, 76kHz, 78kHz or 80kHz, but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0048] The heating power for induction melting is 12-30 kW, for example, it can be 12 kW, 13.8 kW, 15.6 kW, 17.4 kW, 19.2 kW, 21 kW, 22.8 kW, 24.6 kW, 26.4 kW, 28.2 kW, or 30 kW, but is not limited to the listed values; other unlisted values ​​within this range are also acceptable. As a preferred embodiment of the invention, the pressure of the supersonic inert gas is 3-5 MPa, for example, it can be 3 MPa, 3.2 MPa, 3.4 MPa, 3.6 MPa, 3.8 MPa, 4 MPa, 4.2 MPa, 4.4 MPa, 4.6 MPa, 4.8 MPa, or 5 MPa, but is not limited to the listed values; other unlisted values ​​within this range are also acceptable.

[0049] The flow velocity of the supersonic inert gas is 1000-1300 m / s, for example, it can be 1000 m / s, 1030 m / s, 1060 m / s, 1090 m / s, 1120 m / s, 1150 m / s, 1180 m / s, 1210 m / s, 1240 m / s, 1270 m / s or 1300 m / s, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also acceptable.

[0050] The angle between the flow direction of the supersonic inert gas and the axis of the titanium alloy rod is 45-90°, for example, it can be 45°, 49.5°, 54°, 58.5°, 63°, 67.5°, 72°, 76.5°, 81°, 85.5° or 90°, but is not limited to the listed values. Other unlisted values ​​within this range also meet the requirements.

[0051] In this invention, the angle between the flow direction of the supersonic inert gas and the axial direction of the titanium alloy bar refers to the angle between the gas flow direction and the axial melting starting direction of the bar (i.e., the direction from the melting end of the bar to the melting beginning).

[0052] II. To illustrate the excellent properties of the titanium alloy obtained by the preparation method provided by this invention, the following examples are used for explanation:

[0053] Example 1

[0054] This embodiment provides a method for preparing titanium alloy powder, the method comprising:

[0055] In an inert environment (argon), titanium alloy rods are induction melted, and at the same time, supersonic inert gas is used to blow the liquid titanium alloy to disperse and atomize the liquid titanium alloy, thus obtaining titanium alloy powder.

[0056] The absolute pressure of the inert gas in the inert environment is 1 bar;

[0057] The titanium alloy rod has a diameter of 50 mm; before induction melting, the titanium alloy is subjected to ultrasonic cleaning (HFE-347 cleaning solution) and drying; the ultrasonic cleaning time is 15 min; the drying temperature is 110℃; and the drying time is 2.5 h.

[0058] The absolute value of the difference between the ambient air pressure for induction melting and the ambient air pressure for atomization is 0 mbar;

[0059] The heating power of the induction melting is 20kW; the frequency of the induction melting is 70kHz;

[0060] The pressure of the supersonic inert gas is 4 MPa; the flow velocity of the supersonic inert gas is 1100 m / s; and the angle between the flow direction of the supersonic inert gas and the axis of the titanium alloy rod is 60°.

[0061] Example 2

[0062] This embodiment provides a method for preparing titanium alloy powder, the method comprising:

[0063] In an inert environment (argon), titanium alloy rods are induction melted, and at the same time, supersonic inert gas is used to blow the liquid titanium alloy to disperse and atomize the liquid titanium alloy, thus obtaining titanium alloy powder.

[0064] The absolute pressure of the inert gas in the inert environment is 1.1 bar;

[0065] The titanium alloy rod has a diameter of 55 mm; before induction melting, the titanium alloy is subjected to ultrasonic cleaning (HFE-347 cleaning fluid) and drying; the ultrasonic cleaning time is 18 min; the drying temperature is 115℃; and the drying time is 2.2 h.

[0066] The absolute value of the difference between the ambient air pressure for induction melting and the ambient air pressure for atomization is 10 mbar;

[0067] The heating power of the induction melting is 25kW; the frequency of the induction melting is 75kHz;

[0068] The pressure of the supersonic inert gas is 4.5 MPa; the flow velocity of the supersonic inert gas is 1200 m / s; and the angle between the flow direction of the supersonic inert gas and the axis of the titanium alloy rod is 75°.

[0069] Example 3

[0070] This embodiment provides a method for preparing titanium alloy powder, the method comprising:

[0071] In an inert environment (argon), titanium alloy rods are induction melted, and at the same time, supersonic inert gas is used to blow the liquid titanium alloy to disperse and atomize the liquid titanium alloy, thus obtaining titanium alloy powder.

[0072] The absolute pressure of the inert gas in the inert environment is 0.9 bar;

[0073] The titanium alloy rod has a diameter of 40 mm; before induction melting, the titanium alloy is subjected to ultrasonic cleaning (HFE-347 cleaning solution) and drying; the ultrasonic cleaning time is 10 min; the drying temperature is 100℃; and the drying time is 3 h.

[0074] The absolute value of the difference between the ambient air pressure for induction melting and the ambient air pressure for atomization is 0 mbar;

[0075] The heating power of the induction melting is 12kW; the frequency of the induction melting is 80kHz;

[0076] The pressure of the supersonic inert gas is 3 MPa; the flow velocity of the supersonic inert gas is 1000 m / s; and the angle between the flow direction of the supersonic inert gas and the axis of the titanium alloy rod is 45°.

[0077] Example 4

[0078] This embodiment provides a method for preparing titanium alloy powder, the method comprising:

[0079] In an inert environment (argon), titanium alloy rods are induction melted, and at the same time, supersonic inert gas is used to blow the liquid titanium alloy to disperse and atomize the liquid titanium alloy, thus obtaining titanium alloy powder.

[0080] The absolute pressure of the inert gas in the inert environment is 1.3 bar;

[0081] The titanium alloy rod has a diameter of 60 mm; before induction melting, the titanium alloy is subjected to ultrasonic cleaning (HFE-347 cleaning solution) and drying; the ultrasonic cleaning time is 20 min; the drying temperature is 120℃; and the drying time is 2 h.

[0082] The absolute value of the difference between the ambient air pressure for induction melting and the ambient air pressure for atomization is 20 mbar;

[0083] The heating power of the induction melting is 30kW; the frequency of the induction melting is 60kHz;

[0084] The pressure of the supersonic inert gas is 5 MPa; the flow velocity of the supersonic inert gas is 1300 m / s; and the angle between the flow direction of the supersonic inert gas and the axis of the titanium alloy rod is 90°.

[0085] Example 5

[0086] The only difference from Example 1 is that the frequency of induction melting is 50 kHz.

[0087] Example 6

[0088] The only difference from Example 1 is that the frequency of induction melting is 90 kHz.

[0089] Example 7

[0090] The only difference from Example 1 is that the pressure of the supersonic inert gas is 2 MPa.

[0091] Example 8

[0092] The only difference from Example 1 is that the pressure of the supersonic inert gas is 6 MPa.

[0093] Example 9

[0094] The only difference from Example 1 is that the angle between the direction of the supersonic inert gas flow and the axis of the titanium alloy rod is 30°.

[0095] Comparative Example 1

[0096] The only difference from Example 1 is that the heating power for induction melting is 10kW.

[0097] Comparative Example 2

[0098] The only difference from Example 1 is that the heating power for induction melting is 60kW.

[0099] The titanium alloy powders obtained in the above examples and comparative examples were subjected to performance tests. The particle size distribution of the powder was tested using a laser particle size analyzer. The sphericity of the powder was evaluated and analyzed according to the morphology description clause in ASTM B822-20 "Standard Method for Determination of Particle Size Distribution of Metal Powders". The flowability was tested according to GB / T 1482-2022 "Standard Funnel Method (Hall Flowmeter) for Determination of Flowability of Metal Powders". The results are shown in Table 1 below.

[0100] Table 1

[0101]

[0102] As shown in Table 1, the solution provided by the present invention can significantly improve the properties of the obtained titanium alloy powder by optimizing the preparation process of titanium alloy powder. It has the advantages of narrow particle size distribution, high sphericity and high flowability. Among them, particles of 40-50μm account for more than 85% of the total powder mass, sphericity ≥0.98, and Hall flow rate ≤20s / 50g.

[0103] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0104] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0105] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing titanium alloy powder, characterized in that, The preparation method includes: In an inert environment, titanium alloy rods are induction melted, and at the same time, supersonic inert gas is used to blow the liquid titanium alloy to disperse and atomize the liquid titanium alloy, thus obtaining titanium alloy powder. The heating power for induction melting is 12-30kW.

2. The preparation method according to claim 1, characterized in that, The absolute pressure of the inert gas in the inert environment is 0.9-1.3 bar.

3. The preparation method according to claim 1, characterized in that, The absolute value of the difference between the ambient air pressure for induction melting and the ambient air pressure for atomization is ≤300mbar.

4. The preparation method according to claim 1, characterized in that, The diameter of the titanium alloy rod is 40-60 mm.

5. The preparation method according to claim 1, characterized in that, The frequency of the induction melting is 60-80kHz.

6. The preparation method according to claim 1, characterized in that, The pressure of the supersonic inert gas is 3-5 MPa.

7. The preparation method according to claim 1, characterized in that, The flow rate of the supersonic inert gas is 1000-1300 m / s.

8. The preparation method according to claim 1, characterized in that, The angle between the direction of the supersonic inert gas flow and the axis of the titanium alloy rod is 45-90°.

9. The preparation method according to claim 1, characterized in that, The titanium alloy is subjected to ultrasonic cleaning and drying sequentially before induction melting.

10. The preparation method according to claim 9, characterized in that, The ultrasonic cleaning time is 10-20 minutes; Preferably, the drying temperature is 100-120℃; Preferably, the drying time is 2-3 hours.

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