WO2024000919A1

WO2024000919A1 - Preparation method and system for titanium or titanium alloy powder having high degree of sphericity and low oxygen increment

Info

Publication number: WO2024000919A1
Application number: PCT/CN2022/124577
Authority: WO
Inventors: 王健; 赵博深; 任志豪; 李永华; 张生滨; 陈小龙
Original assignee: 南京尚吉增材制造研究院有限公司
Priority date: 2022-07-01
Filing date: 2022-10-11
Publication date: 2024-01-04

Abstract

The present invention provides a preparation method and system for titanium or titanium alloy powder having a high degree of sphericity and a low oxygen increment. A high-cleanliness titanium alloy wire material and bar material are used as raw materials; a high-energy plasma heat source heats the wire material under the protection of an inert atmosphere; molten metal droplets drop to an end surface of the high-speed rotating bar material and are thrown out by centrifugal force, and sequentially undergo stages such as a spheroidization stage, a solidification stage, and a cooling stage along a flying track, so that defects such as satellite powder, special-shaped powder, and hollow powder caused by rapid cooling of particles and interference of secondary gas flow are effectively avoided without impact of high-speed jet flow. The whole process of powder preparation and screening post-treatment is performed under the protection of an inert atmosphere, and the powder oxygen increment is effectively limited, thereby facilitating obtaining of the titanium or titanium alloy powder having a high degree of sphericity and a low oxygen increment.

Description

Preparation method and system for titanium or titanium alloy powder with high sphericity and low oxygen increment

Technical field

The present invention relates to the technical field of powder metallurgy, and specifically to a method and system for preparing titanium or titanium alloy powder with high sphericity and low oxygen increment.

Background technique

Titanium alloy additive manufacturing and powder metallurgy near net shape technology have received increasing attention, especially in the field of processing and manufacturing of large and complex structural parts. Spherical titanium alloy powder is the key raw material for the above technologies. Its quality is fundamentally determined. It determines the performance of titanium alloy parts.

The commonly used preparation method for spherical titanium alloy powder is the gas atomization method, represented by the electrode induction melting inert gas atomization method (EIGA). The powder produced has a wide particle size distribution, a high fine powder yield, and a relatively low manufacturing cost. It has lower advantages, but under this method, the powder in the middle particle size section (53-150μm or 53-250μm) has a relatively high proportion of defects such as satellite powder, special-shaped powder, and hollow powder, which deteriorates the powder process performance and limits its use in laser fusion deposition. and applications in powder metallurgy hot isostatic pressing processes.

The Chinese patent with the publication number CN114192790A discloses a device and method for preparing spherical titanium and titanium alloy powder. The large-diameter high-speed rotating wheel contacts the titanium and titanium alloy molten pool, relies on centrifugal force to throw out the melt, and solidifies into spherical titanium. mineral powder. This method uses a rotating wheel to throw out the melt for heat exchange to produce spherical titanium or titanium alloy powder with fine particle size, low hollowness, high sphericity, and low oxygen content. It solves the existing preparation method of spherical titanium and titanium alloys. The powder contains The problem of high oxygen content, hollow content and impurity content. However, the sphericity of titanium and titanium alloy powder obtained by this method can only reach up to 93%. For fields with strict requirements on component quality, the sphericity of this kind of powder cannot meet the needs.

Contents of the invention

According to a first aspect of the present invention, a preparation system for titanium or titanium alloy powder with high sphericity and low oxygen increment is provided, including:

The transmission system is provided with a feed transmission chamber. The side wall of the feed transmission chamber is provided with a ventilation pipeline for continuously introducing inert gas into the transmission system and atomization system to maintain the stability of the transmission system and atomization system. pressure needs;

The feed transmission chamber is provided with a titanium alloy bar material and a driving mechanism for driving the titanium alloy bar material to rotate. The titanium alloy bar material is provided with a penetrating through hole along the center direction as a feed channel for the titanium alloy wire material;

One end of the titanium alloy bar is located in the feed transmission chamber, and the other end of the titanium alloy bar extends into the atomization system. The titanium alloy wire is fed to the atomization system through the wire feeding mechanism through the through hole. Inside, reaching the working end face of the titanium alloy bar;

The atomization system is provided with an atomization chamber, and the other end of the titanium alloy bar extends into the atomization chamber as a working end face and corresponds to the plasma generating device provided in the atomization chamber;

The plasma generating device has a plasma gun disposed in the atomization chamber for forming a plasma torch inside the atomization chamber, and the center of the plasma gun is located at the same level as the through hole;

The side wall of the atomization chamber is equipped with a pressure relief device. The inert gas enters the transmission system and the atomization system through the ventilation pipeline and the plasma generating device, and passes through the pressure relief device to form gas in the feed transmission chamber and the atomization chamber. circulation, and keep the pressure in the feed transmission chamber and atomization chamber within the preset range;

The titanium alloy wire fed into the atomization chamber is melted by the plasma torch to produce molten metal. After it reaches the working end face of the high-speed rotating titanium alloy bar, it moves along all directions under the action of centrifugal force and the set pressure. The edge of the working end face is thrown out to obtain fine metal droplets, which fly under the inert atmosphere in the atomization chamber to obtain powder with high sphericity and low oxygen increment.

Preferably, the driving mechanism includes a first transmission roller set, through which the titanium alloy bar is driven to rotate.

Preferably, the wire feeding mechanism includes a second transmission roller set, through which the titanium alloy wire is fed to the titanium alloy bar and fed through the through hole to the interior of the atomization system. .

Preferably, the second transmission roller group includes a steering roller and a power straightening roller. The titanium alloy wire is converted in the feeding direction through the steering roller, and the power straightening roller ensures smooth and stable feeding of the wire.

Preferably, a sealing device is provided at the entrance of the titanium alloy wire into the feed transmission chamber.

According to a second aspect of the present invention, a method for preparing titanium or titanium alloy powder with high sphericity and low oxygen increment is provided, including the following steps:

After the titanium alloy bar is placed at the designated position of the transmission system, one end of the titanium alloy wire for powder milling is passed through the inner hole of the titanium alloy bar. The preparation system is then sealed and evacuated until the target vacuum level is reached. , add inert gas and maintain the preparation system in the first pressure range;

The titanium alloy bar is driven to rotate to drive the titanium alloy wire to the smelting starting position in the atomization chamber. When the titanium alloy bar reaches the preset speed and there is no abnormality, the parameters of the plasma heat source are set according to the predetermined parameters and the plasma is started. Generate device and complete arc starting;

When the plasma torch reaches a stable state, adjust the feed speed of the titanium alloy wire according to the predetermined process and start the atomization powder making process;

Among them, the viscosity of the melt is reduced by feeding the wire for melting. After the molten metal droplets drop onto the working end face of the high-speed rotating titanium alloy bar, they move under the combined force of gravity and centrifugal force, and under the conditions of the first pressure range After completing the spheroidization, heat exchange with the inert atmosphere is carried out to achieve cooling, and finally titanium alloy powder with high sphericity and low oxygen increment is obtained.

Preferably, the sphericity of the prepared titanium alloy powder is ≥0.97.

Preferably, the first pressure range is between 0.15-0.25 bar.

Preferably, the titanium alloy rod and titanium alloy wire have the same composition.

Preferably, the diameter of the titanium alloy wire is between 1-3 mm, and the surface roughness is not greater than Ra1.6 μm.

Preferably, the inert gas is argon or an argon-helium mixture, and in the argon-helium mixture, the volume ratio of argon and helium is between (1:9) and (9:1).

Compared with the existing technology, the beneficial effects of the above technical solution are:

1. The present invention uses wire feeding for melting, which effectively reduces the melt volume generated per unit time. Compared with melting the bar, a melt with a higher degree of superheat can be obtained, which is beneficial to the rotary atomization process, reduces the viscosity of the melt, and achieves a more stable process. Full crushing, refining and spheroidization will help to increase the fine powder yield and reduce the oxygen increment of the powder while ensuring the sphericity of the powder.

2. Molten metal droplets drop onto the working end face of the high-speed rotating titanium alloy bar, and are thrown out by centrifugal force. The droplets thrown out at the same time have close to the same initial speed, and the droplets are thrown out in different directions, with intersecting trajectories. At the same time, it ensures that the atomization system is at low pressure, effectively limiting the interference of the air flow field on the core area of the centrifugal atomization, effectively maintaining the initial movement trajectory of the droplets, and avoiding contact between droplets or particles due to turbulence in the air flow field. The rapid cooling of the high-speed air flow causes the particles to have no time to spheroidize, which is beneficial to ensuring the sphericity of the powder particles; and combined with convective cooling in an inert atmosphere, the droplets are fully cooled and solidified into solid particles before settling, effectively avoiding adhesion between particles. Compared with traditional The aerosolization process significantly reduces the proportion of satellite powder.

3. The present invention effectively ensures the continuity and consistency of the powdering process through continuous wire feeding, melting and atomization, and avoids process and powder quality fluctuations caused by bar shaking or component segregation during the atomization process of large-diameter bars, and has It is conducive to improving the comprehensive performance of the powder. At the same time, through the control of wire diameter and feed speed, more precise control of the powdering process can be achieved, which facilitates targeted process adjustments according to the needs of the target particle size section, thereby increasing the discharge rate of the target section and optimizing the target section. particle size distribution to obtain better powder processing characteristics.

Description of drawings

Figure 1 is a schematic structural diagram of the preparation system of high sphericity and low oxygen increment titanium or titanium alloy powder according to the present invention.

Figure 2 is a partial structural diagram of the transmission system and atomization system of the present invention.

Fig. 3 is a schematic structural diagram of a driving mechanism for driving the titanium alloy bar to rotate according to the present invention.

Figure 4 is a schematic structural diagram of the wire feeding mechanism of the present invention.

Figure 5 is a process flow chart of the preparation method of titanium or titanium alloy powder with high sphericity and low oxygen increment of the present invention.

Detailed ways

In order to better understand the technical content of the present invention, specific embodiments are described below along with the accompanying drawings.

Aspects of the invention are described in this disclosure with reference to the accompanying drawings, in which a number of illustrated embodiments are shown. The embodiments of the present disclosure are not necessarily intended to include all aspects of the invention. It is to be understood that the various concepts and embodiments introduced above, and those described in greater detail below, can be implemented in any of numerous ways.

Preparation system for titanium or titanium alloy powder with high sphericity and low oxygen increment

With reference to Figures 1-4, the present invention provides a preparation system for titanium or titanium alloy powder with high sphericity and low oxygen increment, including:

The transmission system 100 is provided with a feed transmission chamber 110. The side wall of the feed transmission chamber 110 is provided with at least one set of ventilation pipes 111 for continuously introducing inert gas into the feed transmission chamber and the atomization system to maintain Pressure requirements for transmission and atomization systems.

The feed transmission chamber is provided with a titanium alloy bar 200 and a driving mechanism 300 for driving the titanium alloy bar to rotate. The titanium alloy bar 200 is provided with a through hole along the center direction as a feed channel for the titanium alloy wire 400 .

One end of the titanium alloy bar 200 is located in the feed transmission chamber 110, the other end of the titanium alloy bar 200 extends into the atomization system, and the titanium alloy wire 400 is fed to the mist through the through hole through the wire feeding mechanism 500. Inside the chemical system, it reaches the working end face of the titanium alloy bar.

The atomization system 600 is provided with a spray chamber 610. The other end of the titanium alloy bar 200 extends into the spray chamber 610 as a working end surface and corresponds to the plasma generating device 700 provided in the spray chamber 610.

In an optional embodiment, the atomization chamber 610 is in the shape of a horizontal cylinder, and water-cooling interlayers are provided at both ends and side walls of the atomization chamber 610, and the atomization preparation process is cooled through cooling medium circulation.

The plasma generating device 700 has a plasma gun 710 disposed in the atomization chamber for forming a plasma torch 720 inside the atomization chamber. The center of the plasma gun is located at the same level as the through hole of the titanium alloy bar.

As shown in Figure 2, the side wall of the atomization chamber 610 is provided with a pressure relief device 611, preferably a pressure relief valve, and the inert gas enters the feed transmission chamber 110 and the atomization chamber 610 through the ventilation pipeline 111 and the plasma generating device 700. And through the pressure relief device 611, the gas in the feed transmission chamber and the atomization chamber is circulated, and the pressure in the feed transmission chamber and the atomization chamber is maintained within the preset range, thereby ensuring that the metal droplet particles move into the cabin. In front of the edge, the gas interference is minimal, which effectively limits the interference of the air flow field to the core area of centrifugal atomization, effectively maintains the initial motion trajectory of the droplets, and avoids contact between droplets or particles due to turbulent air flow fields and rapid cooling by high-speed air flow. As a result, the particles have no time to spheroidize, which is beneficial to ensuring the sphericity of the powder particles.

As shown in FIG. 1 , the titanium alloy wire 400 fed into the atomization chamber 610 is melted by the plasma torch 720 to generate molten metal 800 , and after reaching the working end surface of the high-speed rotating titanium alloy bar 200 , under the action of centrifugal force and are thrown out along the edge of the working end face under a set pressure condition to obtain fine metal droplets 900, which fly under the inert atmosphere in the atomization chamber to obtain powder with high sphericity and low oxygen increment. .

As shown in FIG. 3 , in a preferred embodiment, the driving mechanism 300 includes a first transmission roller set 310 , and the titanium alloy bar is driven to rotate through the first transmission roller set 310 .

In a more specific embodiment, the first drive roller set 310 includes a set of drive rollers 311 and a set of pressure rollers 312. The drive rollers 311 are located on the lower end of the titanium alloy bar, and the pressure rollers 312 are located on the upper surface of the titanium alloy bar. The end face, while maintaining the stability of the titanium alloy bar, works together with the transmission roller to drive the titanium alloy bar to rotate.

As shown in FIG. 4 , in a preferred embodiment, the wire feeding mechanism 500 includes a second transmission roller set 510 , through which the titanium alloy wire is fed to the titanium alloy bar and passes through the second transmission roller set 510 . The through hole feeds into the interior of the atomization system.

In a more preferred embodiment, the second transmission roller set 510 includes a steering roller 511 and a power straightening roller 512. The titanium alloy wire changes the feeding direction through the steering roller 511, and the power straightening roller 512 ensures the smoothness of the wire. Stable feed.

As shown in Figure 3, in another preferred embodiment, a sealing device 111 is provided at the entrance of the titanium alloy wire 400 into the feed transmission chamber 110 to ensure the sealing of the feed transmission chamber and the atomization chamber.

The titanium alloy wire 400 is driven by the power straightening roller 512, enters the feed transmission chamber 110 through the steering roller 511 and the sealing device 111, and is fed through the axial through hole of the titanium alloy bar to the inside of the atomization system, arriving at Working end face of titanium alloy bar.

The relationship between the diameter of the through hole of the titanium alloy bar and the diameter of the titanium alloy wire only requires that the titanium alloy wire does not rotate with the rotation of the titanium alloy bar, thereby ensuring smooth feeding of the wire.

In embodiments of the present invention, the diameter of the through hole of the titanium alloy rod is between 5-10 mm, and the diameter of the titanium alloy wire is between 1-3 mm.

Preparation method of titanium or titanium alloy powder with high sphericity and low oxygen increment

For fields with high requirements on part quality, such as the aerospace field, in order to meet the quality requirements of molded parts, titanium and titanium alloy powder raw materials are required to have higher quality and consistency. Therefore, it is necessary to obtain high composition uniformity and impurity content. Extremely low, high density, precisely dimensioned powder raw material.

Therefore, in conjunction with the process shown in Figure 5, the aforementioned preparation system of titanium or titanium alloy powder with high sphericity and low oxygen increment of the present invention is provided to provide a preparation of titanium or titanium alloy powder with high sphericity and low oxygen increment. method, including the following steps:

The titanium alloy bar is driven to rotate and feed the wire to the starting position of the smelting in the atomization chamber. When the titanium alloy bar reaches the preset speed and there is no abnormality, the parameters of the plasma heat source are set according to the predetermined parameters and the plasma generating device is started. and complete arc starting;

In one specific embodiment, a method for preparing titanium or titanium alloy powder with high sphericity and low oxygen increment includes the following specific steps:

S1. Preparation and acceptance of raw materials for milling: Prepare titanium alloy wires and bars for milling. Their compositions are consistent and meet the standards or design ratios. Test and verify that the size and surface quality of the above wires and bars meet the usage requirements.

S2. Pre-installation of powder-making raw materials: Place the titanium alloy bar at the designated position of the transmission system, pass one end of the titanium alloy wire through the inner hole of the titanium alloy bar, and then seal the powder-making system.

S3. Gas replacement: Vacuum the milling environment. After reaching the target vacuum degree, add inert gas to normal pressure.

S4. Bar rotation: Start the transmission device and drive the titanium alloy bar to rotate at high speed until the predetermined speed.

S5. Arc ignition smelting: Continuously introduce inert gas through the plasma generation system and ventilation pipeline and open the pressure relief device, maintain the atomization system in the first pressure range, set the initial and target parameters of the plasma heat source and start, and complete the plasma arc ignition. Arc to normal melting.

S6. Rotary atomization: Adjust the feed speed of the wire and start normal atomization. This process is that the high-temperature plasma arc flame melts the end of the wire to form a local molten pool or liquid flow and drips to the end face of the bar. Under the action of centrifugal force generated by high-speed rotation, the molten state is broken, producing tiny droplets and being thrown out simultaneously within a 360° range along the edge of the bar. They move along a specific trajectory under the combined force of gravity and centrifugal force, and the process is completed by surface tension. Spheroidization, and heat exchange with the inert atmosphere to achieve rapid cooling.

S7. Powder cooling and collection: The powder produced by atomization moves to the edge of the annular spray chamber. Driven by the cooling air flow, it accelerates further cooling, and enters the bottom collection tank along the edge of the spray chamber to be enriched.

S8. Powder screening: Screen and post-process the obtained powder to obtain powder in the target particle size range.

In a preferred embodiment, the first pressure range is between 0.15-0.25 bar.

In a preferred embodiment, the sphericity of the titanium alloy powder prepared is ≥0.97.

In an optional embodiment, the size specifications of the titanium alloy bar are that the diameter is between 30-60mm, the length is between 200-400mm, the straightness of the bar is not greater than 0.05mm, the cylindricity is not greater than 0.025mm, and the verticality is not greater than 0.2 mm, the end surface roughness is not greater than Ra3.2μm, the side roughness is not greater than Ra1.6μm, and the through hole diameter of the titanium alloy bar is between 5-10mm.

The diameter of the titanium alloy wire is between 1-3 mm, the surface is bright, and the roughness is no more than 1.6 μm.

In an optional embodiment, the closed range of the preparation system includes a transmission chamber, a spray chamber, and a powder collection tank. The powder collection tank is disposed at the bottom end of the spray chamber and communicates with the inside of the spray chamber.

During the atmosphere replacement process, the pre-evacuation degree of the system is below 3*10 ^-2 Pa. The inert gas added is argon or an argon-helium mixture, and the volume ratio of the argon-helium mixture is between (1:9 )-(9:1), gas purity is not less than 99.99%.

In another optional embodiment, the target rotation speed of the titanium alloy bar is between 20,000-35,000 r/min, and the feed speed of the titanium alloy wire is between 3,000-6,000 mm/min.

In another optional embodiment, the initial current of the plasma heat source is 200-300A, and the current during normal operation is between 1400-2000A.

In another optional embodiment, during the smelting and atomization process, the titanium alloy wire is melted by a high-temperature plasma heat source, and the molten metal drips onto the end face of the high-speed rotating bar and is thrown out by centrifugal force. During the flight, it interacts with the atomization system. The inert atmosphere inside performs heat exchange and contacts the water cooling wall at the boundary of the flight trajectory to achieve cooling. The ambient temperature at the edge of the system is controlled not to exceed 50°C through circulating air replacement, and water cooling is controlled through the cooling water volume and flow channel design. The temperature measured inside the wall is not higher than 40℃.

In another optional embodiment, during the powder screening process, an ultrasonic vibrating screen with atmosphere protection is used. The protective atmosphere is argon or nitrogen, and the gas purity is not less than 99.99%, to sequentially separate larger particles (above 180 μm) and Fine particles (below 75 μm) are obtained to obtain intermediate powder.

By prefabricating high-quality titanium alloy wire, the present invention obtains powder-making raw materials with high composition uniformity, extremely low impurity content, high density, and precise dimensions. It provides guarantee for the powder-making process and powder quality from the source, and cooperates with the powder-making process. The atmosphere is controlled to achieve clean self-consumable powdering, effectively limiting the oxygen increase in the powder (not higher than 200ppm) and the introduction of other impurities, and well restoring the design ingredients.

At the same time, by controlling the matching relationship between the feed speed of the titanium alloy wire and the electrical parameters of the plasma heat source, the melting speed of the bar can be controlled, the rotation speed of the titanium alloy bar can be assisted, and the number and size of particles produced per unit time can be controlled. The control is conducive to improving the discharge rate of powder in the target particle size range.

The continuous feeding of titanium alloy wire also enables continuous and high-precision titanium alloy powder preparation, which is beneficial to ensuring powder quality and production efficiency.

The technical solution of the present invention will be further described below in conjunction with the process flow chart and preparation system diagram of the present invention, taking TC4 titanium alloy, TC11 titanium alloy, and TA15 titanium alloy as examples respectively.

Example 1

TC4 powder

First, prepare the wire and bar according to the TC4 alloy composition standard. The tested composition results are Al: 6.04%, V: 4.04%, Fe: 0.062%, C: 0.0046%, N: 0.0030%, H: 0.0008%, O :0.1125%.

The specifications of TC4 bar are 40mm in diameter, 400mm in length, and the inner hole diameter is 6mm. After testing, the straightness of TC4 bar is 0.03mm, the cylindricity is 0.025mm, the verticality is 0.03mm, and the end surface roughness is not greater than Ra3.2μm. The side roughness is not greater than Ra1.6μm; the diameter of TC4 wire is 3mm.

Place the TC4 bar material between the transmission rollers and lower the pressure roller to ensure that the bar material can rotate smoothly; the TC4 wire material completes the direction change through the steering roller, and uses the power straightening roller to guide the wire material through the inner hole of the TC4 bar material .

The feed transmission chamber and atomization chamber are sealed and evacuated to 1*10 ^-2 Pa, and then high-purity argon is supplied through the plasma generator and ventilation pipeline. The purity of argon is 99.999%, and the pressure in the atomization chamber reaches After 0.15bar, the pressure relief valve opens to maintain the pressure in the feed transmission chamber and atomization chamber between 0.15-0.25bar.

Set the target rotation speed of the transmission roller to 24000r/min and start it to drive the TC4 bar to rotate; set the starting current of the plasma generation system to 200A and the working current to 1400A to start and generate high-temperature plasma arc flame.

Set the TC4 wire feed speed to 4000mm/min, start the fuse atomization powder making, the molten metal flow drips to the end face of the high-speed rotating TC4 bar, and is thrown out by centrifugal force. The tiny droplets move along the edge under the inert atmosphere. The flight path gradually cools, solidifies and is enriched in the powder collecting device.

The collected TC4 powder is screened and processed using an ultrasonic vibrating screen with atmosphere protection. The protective atmosphere uses high-purity argon with a purity of 99.999%. It is passed through 80 mesh and 200 mesh screens in sequence to separate larger particles (above 180 μm) and fine particles (below 75 μm) to obtain TC4 powder in the middle particle size range.

Example 2

TC11 powder

First, prepare the wire and bar according to the TC11 alloy composition standard. The tested composition results are Al: 6.42%, Si: 0.26%, Zr: 1.76%, Mo: 3.44%, Fe: 0.23%, C: 0.0111%, N :0.0038%, H: 0.0023%, O: 0.0841%.

The specifications of TC11 bar are 30mm in diameter, 300mm in length, and the inner hole diameter is 5mm. After testing, the straightness of TC11 bar 2 is 0.02mm, the cylindricity is 0.03mm, the verticality is 0.02mm, and the end surface roughness is not greater than Ra3.2μm. , the side roughness is not greater than Ra1.6μm; the diameter of TC11 wire is 2mm.

Place the TC11 bar between the transmission rollers, and put down the pressure roller to ensure that the bar can rotate smoothly; the TC11 wire changes the feeding direction through the steering roller, and uses the power straightening roller to guide the wire through the TC11 bar Bore.

After sealing the pulverizing system, evacuate it to 1*10 ^-2 Pa, and then add high-purity argon gas to normal pressure. The purity of argon gas is 99.999%. Start the transmission roller to drive the TC11 bar to rotate, and set the target rotation speed to 26000r/min.

Continuously supply high-purity argon gas into the pulverizing system through the plasma generation system and ventilation pipeline, with a purity of 99.999%. At the same time, open the pressure relief device to maintain the pressure in the atomization system at 0.15-0.20Bar; set the starting current of the plasma generation system is 200A, start and complete arcing, and gradually increase the current to 1600A.

Set the TC11 wire feed speed to 5000mm/min, start the fuse atomization powder making, the molten metal flow drips to the end face of the high-speed rotating TC11 bar, and is thrown out by the centrifugal force. The tiny droplets move along the edge under the inert atmosphere. The flight trajectory gradually cools, solidifies, and is enriched in the powder collecting device.

The collected TC11 powder was screened and processed using an ultrasonic vibrating screen with atmosphere protection. The protective atmosphere used high-purity argon with a purity of 99.999%. It was passed through 80 mesh and 200 mesh screens in sequence, and the larger particles were separated. Large particles (above 180 μm) and fine particles (below 75 μm) were used to obtain TC11 powder in the middle particle size range.

Example 3

TA15 powder

First, prepare the wire and bar according to the TA15 alloy composition standard. The tested composition results are Al: 6.40%, V: 1.54%, Si: 0.014%, Zr: 1.90%, Mo: 1.60%, Fe: 0.11%, C :0.0061%, N: 0.0039%, H: 0.0017%, O: 0.0950%.

The specifications of TA15 bar are 50mm in diameter, 400mm in length, and the inner hole diameter is 8mm. After testing, the straightness of TA15 bar is 0.02mm, the cylindricity is 0.02mm, the verticality is 0.02mm, the end surface roughness is not greater than Ra3.2μm, and the side surface roughness is not greater than Ra3.2μm. The roughness is not greater than Ra1.6μm; the diameter of TA15 wire is 3mm.

Place the TA15 bar between the transmission rollers, and put down the pressure roller to ensure that the bar can rotate smoothly; the TA15 wire changes the feeding direction through the steering roller, and uses the power straightening roller to guide the wire through the TA15 bar Bore.

After sealing the pulverizing system, evacuate it to 1*10 ^-2 Pa, and then add high-purity argon gas to normal pressure. The purity of argon gas is 99.999%. Start the transmission roller to drive the TA15 bar to rotate, and set the target rotation speed to 25000r/min.

High-purity argon gas is continuously supplied into the pulverizing system through the plasma generation system and ventilation pipeline, with a purity of 99.999%. At the same time, the pressure relief device is opened to maintain the pressure in the atomization system at 0.15-0.20Bar. Set the initial current of the plasma generation system to 200A, start and complete arcing, and gradually increase the current to 1500A.

Set the TA15 wire feed speed to 4500mm/min, start the fuse atomization powder making, the molten metal flow drips to the end face of the high-speed rotating TA15 bar, and is thrown out by centrifugal force. The tiny droplets move along the edge under the inert atmosphere. The flight trajectory gradually cools, solidifies, and is enriched in the powder collecting device.

The collected TA15 powder is screened and processed using an ultrasonic vibrating sieve with atmosphere protection. The protective atmosphere uses high-purity argon with a purity of 99.999%. It is passed through 80 mesh and 200 mesh screens in sequence to separate the larger ones. particles (above 180 μm) and fine particles (below 75 μm) to obtain TA15 powder in the middle particle size range.

Example 4

Based on the GB/T 23942-2009, GB/T 3620.1-2016, GB/T 4698-2017, GB/T 31981-2015 standards, the inductively coupled plasma optical emission spectrometer (ICP-OES) in Examples 1-3 The main components and trace elements of wire and powder, as well as TC4 powder using conventional EIGA process were measured.

Based on the GB/T 14265-2017 standard, the content of O, N, H, C and other impurity elements in wire materials, rods and powders passed ONH analyzer.

Based on the GB/T 19077-2016 and GB/T21649.2-2017 standards, the particle size distribution and sphericity of the powder are tested through a laser particle size and shape analyzer.

The test results are as follows :

(1) The composition of the TC4 powder in Example 1 is: Al; 6.03%, V; 4.09%, Fe: 0.061%, C: 0.0020%, N: 0.0161%, H: 0.0009%, O: 0.1206%.

The oxygen increment was calculated from the difference in O content between TC4 powder and wire, and the oxygen increment was 81 ppm.

The particle size distribution results of TC4 powder are: D10: 98.47 μm, D50: 131.9 μm, D90: 180.4 μm, and the sphericity is 0.97.

(2) The composition results of the TC11 powder in Example 2 are as follows: Al: 6.18%, Si: 0.26%, Zr: 1.83%, Mo: 3.39%, Fe: 0.23%, C: 0.0118%, N: 0.0099%, H: 0.0017%, O: 0.0936%.

The oxygen increment was calculated from the difference in O content between TC11 powder and wire, and the oxygen increment was 95 ppm.

The particle size distribution results of TC11 powder are as follows: D10: 90.95 μm, D50: 125.1 μm, D90: 168.0 μm, and the sphericity is 0.97.

(3) The composition results of the TA15 powder in Example 3 are as follows: Al: 6.37%, V: 1.52%, Si: 0.016%, Zr: 1.92%, Mo: 1.58%, Fe: 0.12%, C: 0.0057%, N: 0.0088%, H: 0.0013%, O: 0.0993%.

The oxygen increment was calculated from the difference in O content between TA15 powder and wire, and the oxygen increment was 43 ppm.

The particle size distribution results of TA15 powder are as follows: D10: 97.55 μm, D50: 130.0 μm, D90: 168.4 μm, and the sphericity is 0.97.

(4) TC4 powder under conventional EIGA process, the oxygen increment is 160ppm, the particle size distribution is D10: 60.37μm, D50: 85.40μm, D90: 147.2μm, and the sphericity is 0.92.

It can be seen from the above that the preparation method of the present invention can obtain titanium or titanium alloy powder with high sphericity and low oxygen increment. The sphericity can be as high as 0.97 and above, the oxygen increment is not higher than 200ppm, and the minimum can reach 43ppm. The powder quality is good. , thus providing guarantee for the quality of subsequent formed components.

Example 5

Using the TC4 powder obtained in Example 1 and the TC4 powder obtained under the conventional EIGA process, the laser fused deposition process is used to print components.

A special powder feeding device is used to transport the powder to the bottom of the laser head through turntable feeding and pneumatic conveying (preset powder feeding parameters, turntable speed, and gas pressure). The powder and substrate surface are melted and deposited by the laser to form a metallurgical bond. Through the laser melting and deposition of metal powder materials layer by layer, according to the preset printing process (power, scanning speed, etc.), the forming of the part is directly completed according to the model.

Among them, the powder feeding parameters are: 0.8r/min, and the air flow is 6.5L/min.

Printing parameters: laser power 1600W, scanning pitch 1.6mm, zigzag cycle, spot diameter 3mm, scanning speed 600mm/min.

Through the above printing, it was found that when printing using the TC4 powder obtained in Example 1:

a) When the powder feeding system is preset at 0.8r/min, the measured powder feeding amount is 5.53, 5.55, 5.55, 5.54, 5.52, 5.56, 5.54, 5.56, 5.52, 5.55g/min, and the powder feeding amount fluctuates less than 0.05g/min. min.

b) The test results of the formed samples show that there are no visually visible shrinkage cavities, cracks, or block defects. The tensile strength of the (deposited) formed parts is 1025±25MPa, the yield strength is 920±25MPa, and the elongation is 13±2%. .

When printing with TC4 powder obtained by conventional EIGA process:

a) When the powder feeding system is preset at 0.8r/min, the measured powder feeding amount is 4.88, 5.08, 4.99, 5.04, 5.10, 4.86, 5.07, 5.01, 5.05, 4.90g/min, and the powder feeding amount fluctuates by more than 0.2g/min. min.

b) (As deposited) The tensile strength of the formed part is 985±50MPa, the yield strength is 908±50MPa, and the elongation after fracture is 11±2%.

By comparison, it was found that the TC4 powder prepared by our method has better powder feeding stability, and under the same powder feeding parameters, the powder feeding amount per unit time is nearly 10% higher, and the surface of the formed part has no holes. In terms of defects, the surface finish is high and there is less sticky powder. At the same time, the mechanical properties of the parts are not lower than those of conventional EIGA powder parts and have higher stability.

Although the present invention has been disclosed above in terms of preferred embodiments, these are not intended to limit the present invention. Those with ordinary skill in the technical field to which the present invention belongs can make various modifications and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the claims.

Claims

A preparation system for titanium or titanium alloy powder with high sphericity and low oxygen increment, which is characterized by including:

The transmission system (100) is provided with a feed transmission chamber (110), and a ventilation pipeline (111) is provided on the side wall of the feed transmission chamber for continuously introducing inert gas into the transmission system and atomization system. , maintain the pressure requirements of the transmission system and atomization system;

The feed transmission chamber is provided with a titanium alloy bar (200) and a driving mechanism (300) for driving the titanium alloy bar to rotate. The titanium alloy bar (200) is provided with a through hole along the center direction. As a feed channel for titanium alloy wire (400);

One end of the titanium alloy bar (200) is located in the feed transmission chamber, the other end of the titanium alloy bar (200) extends into the atomization system, and the titanium alloy wire (400) passes through the wire feeding mechanism (500) Feed through the through hole to the inside of the atomization system and reach the working end face of the titanium alloy bar;

The atomization system (600) is provided with an atomization chamber (610). The other end of the titanium alloy bar (200) extends into the atomization chamber as a working end surface and is connected with the plasma generating device (610) provided in the atomization chamber. 700) corresponding;

The plasma generating device (700) has a plasma gun (710) disposed in the atomization chamber for forming a plasma torch (720) inside the atomization chamber, and the center of the plasma gun is located at the same level as the through hole;

The side wall of the atomization chamber (610) is provided with a pressure relief device (611), and the inert gas enters the transmission system (100) and atomization system (600) through the ventilation pipeline (111) and the plasma generating device (700). And through the pressure relief device (611), the gas in the feed transmission chamber (110) and the atomization chamber (610) is circulated, and the pressure in the feed transmission chamber (110) and the atomization chamber (610) is maintained within the preset range;

The titanium alloy wire (400) fed into the atomization chamber (610) is melted by the plasma torch (720) to generate molten metal (800), and after reaching the working end surface of the high-speed rotating titanium alloy bar (200), Under the action of centrifugal force and under set pressure conditions, they are thrown out along the edge of the working end surface to obtain fine metal droplets (900), which fly under the inert atmosphere in the atomization chamber to obtain high sphericity and Hypoxic augmentation powder.
The preparation system of titanium or titanium alloy powder with high sphericity and low oxygen increment according to claim 1, characterized in that the driving mechanism (300) includes a first transmission roller group (310), which is The transmission roller set (310) drives the titanium alloy bar (200) to rotate.
The preparation system of titanium or titanium alloy powder with high sphericity and low oxygen increment according to claim 1, characterized in that the wire feeding mechanism (500) includes a second transmission roller group (510), which is The two transmission roller sets (510) feed the titanium alloy wire (400) to the titanium alloy bar (200), and feed it through the through hole to the inside of the atomization system.
The preparation system for titanium or titanium alloy powder with high sphericity and low oxygen increment according to claim 3, characterized in that the second transmission roller group (510) includes a steering roller (511) and a power straightening roller ( 512), the titanium alloy wire (400) switches the feeding direction through the steering roller (511), and the power straightening roller (512) ensures smooth and stable feeding of the wire.
The preparation system for titanium or titanium alloy powder with high sphericity and low oxygen increment according to claim 1, characterized in that a sealing device (111) is provided at the entrance of the titanium alloy wire into the feed transmission chamber.
A method for preparing titanium or titanium alloy powder using the high sphericity and low oxygen increment titanium or titanium alloy powder preparation system described in any one of claims 1 to 5, characterized in that the method includes the following steps :

After the titanium alloy bar is placed at the designated position of the transmission system, one end of the titanium alloy wire for powder milling is passed through the inner hole of the titanium alloy bar. The preparation system is then sealed and evacuated until the target vacuum level is reached. , add inert gas and maintain the preparation system in the first pressure range;

The titanium alloy bar is driven to rotate to drive the titanium alloy wire to the smelting starting position in the atomization chamber. When the titanium alloy bar reaches the preset speed and there is no abnormality, the parameters of the plasma heat source are set according to the predetermined parameters and the plasma is started. Generate device and complete arc starting;

When the plasma torch reaches a stable state, adjust the feed speed of the titanium alloy wire according to the predetermined process and start the atomization powder making process;

Among them, the viscosity of the melt is reduced by feeding the wire for melting. After the molten metal droplets drop onto the working end face of the high-speed rotating titanium alloy bar, they move under the combined force of gravity and centrifugal force, and under the conditions of the first pressure range After completing the spheroidization, heat exchange with the inert atmosphere is carried out to achieve cooling, and finally titanium alloy powder with high sphericity and low oxygen increment is obtained.
The method according to claim 6, characterized in that the sphericity of the titanium alloy powder prepared is ≥0.97.
The method of claim 6, wherein the first pressure range is between 0.15-0.25 bar.
The method according to claim 6, characterized in that the titanium alloy bar material and the titanium alloy wire material have the same composition.
The method according to claim 6, characterized in that the diameter of the titanium alloy wire is between 1-3 mm, and the surface roughness is not greater than Ra1.6 μm.
The method according to claim 6, wherein the inert gas is argon or an argon-helium mixture, and in the argon-helium mixture, the volume ratio of argon and helium is between (1:9)-( 9:1).