Method for preparing titanium-aluminum alloy powder based on plasma rotating electrode atomization method

Abstract

The invention discloses a method for preparing titanium-aluminum alloy powder based on a plasma rotating electrode atomization method, and relates to a preparation method of titanium-aluminum alloy powder. The method aims at solving the technical problems that titanium-aluminum alloy powder prepared through an existing method is uneven in particle size, poor in sphericity degree and high in oxygen content, and comprises the steps that firstly, metal raw materials are weighed according to the target titanium-aluminum alloy chemical component proportion, and a uniform cast ingot is obtained through smelting of a vacuum arc smelting furnace; processing the cast ingot into an electrode bar with a smooth surface, mounting the electrode bar on plasma rotating electrode atomization equipment, enabling the electrode bar to rotate at a high speed, melting alloy at the end part of the electrode bar by utilizing a plasma beam generated by a plasma generator, atomizing the alloy into liquid drops under the action of centrifugal force, and cooling and solidifying the liquid drops in a high-purity argon protection atmosphere to form powder; and finally, the powder is collected and screened, finished powder is obtained, the sphericity degree of the powder reaches 95% or above, the oxygen content is lower than 500 ppm, particle size distribution is uniform, and the powder can be used in the fields of aerospace, the automobile industry, energy and the like.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, and in particular to a method for preparing titanium-aluminum alloy powder. Background Art

[0002] Titanium aluminum alloy has many advantages such as low density, high specific strength, good high temperature mechanical properties and anti-oxidation performance, and has extremely broad and important application prospects in many high-end manufacturing fields such as aerospace, automobile industry, and energy. However, the preparation of high-quality powder has always been a key link restricting its further expansion of application. Traditional powder preparation methods often have problems such as uneven powder particle size, poor sphericity, and high oxygen content, which makes it difficult to meet the high quality and high performance requirements of titanium aluminum alloy powder. Summary of the invention

[0003] The present invention aims to solve the technical problems of uneven particle size, poor sphericity and high oxygen content of titanium-aluminum alloy powder prepared by existing methods, and provides a method for preparing titanium-aluminum alloy powder based on plasma rotating electrode atomization. It utilizes plasma rotating electrode atomization to efficiently and stably prepare high-quality titanium-aluminum alloy powder, so as to solve the quality deficiencies of titanium-aluminum alloy powder in the prior art and meet the demand for high-quality titanium-aluminum alloy powder in the high-end manufacturing field.

[0004] The method for preparing titanium aluminum alloy powder based on plasma rotating electrode atomization method of the present invention is carried out according to the following steps:

[0005] 1. Raw material preparation: According to the chemical composition ratio of the target titanium aluminum alloy, accurately weigh the metal raw materials and mix them evenly, then place them in a vacuum arc melting furnace and evacuate to 1×10 - 3Pa or less, and then high-purity argon is filled as a protective gas to maintain the pressure in the furnace at 0.03-0.05MPa, and multiple smelting is performed, and the alloy is melted and stirred evenly during each smelting process to obtain a titanium-aluminum alloy ingot with uniform composition;

[0006] 2. Electrode preparation: The titanium-aluminum alloy ingot is processed into an electrode rod by mechanical processing, and the surface of the electrode rod is finely polished to make its surface roughness Ra reach less than 0.8 μm; this step makes the surface of the electrode rod smooth, without obvious defects and oxide layer, ready for subsequent plasma rotary atomization;

[0007] 3. Plasma rotating electrode atomization process:

[0008] Install the prepared electrode rod on the rotating electrode shaft of the plasma rotating electrode atomization equipment; ensure that the installation is firm and the electrode rod can rotate at high speed around the shaft; turn on the equipment, drive the electrode rod to rotate, and set the rotation speed to 10000-50000r / min. At the same time, turn on the plasma generator arranged at the end of the electrode rod to generate a high-temperature, high-energy density plasma beam, and adjust the working power of the plasma to 10-50kW, so that the titanium aluminum alloy at the end of the electrode rod is heated by the plasma beam under high-speed rotation to quickly melt to form a liquid metal film, and under the action of centrifugal force, the liquid metal film is thrown out and atomized and broken into tiny droplets; set a protective gas hood around the atomization area, and introduce high-purity argon gas as a protective gas, and control the gas flow rate to 5-20L / min to prevent the droplets from being oxidized during the atomization process, so that the atomized droplets are quickly cooled and solidified in the protective gas atmosphere to obtain primary powder;

[0009] 4. Powder collection and post-processing: The primary powder formed by atomization is collected by combining a cyclone collector with a bag dust collector. The collected powder is screened by a screening device, and the powder that meets the particle size range requirements is screened out as the finished powder, which is collected and packaged to obtain titanium-aluminum alloy powder; the coarse powder and fine powder that do not meet the particle size requirements are returned for remelting and reprocessing.

[0010] Furthermore, the titanium aluminum alloy described in step 1 is Ti-48Al-2Cr-2Nb.

[0011] Furthermore, the purity of the metal raw material in step 1 is not less than 99.99% by mass.

[0012] Furthermore, the smelting times described in step 1 are no less than 3 times.

[0013] Furthermore, the electrode rod described in step 2 has a diameter of 20-25 mm and a length of 300 mm.

[0014] Furthermore, the particle size range of the titanium aluminum alloy powder described in step 4 is required to be 10 to 150 μm.

[0015] Furthermore, the purity of the high-purity argon gas in step 3 is not less than 99.999% by mass.

[0016] The titanium aluminum alloy powder prepared by the plasma rotating electrode atomization method of the present invention has uniform particle size and high sphericity, which can effectively improve the fluidity and loose density of the powder, is more conducive to processing operations in subsequent powder metallurgy forming and other processes, and can improve the density and performance uniformity of formed parts. With the help of strict raw material preparation and the use of high-purity protective gas during the atomization process, the impurity content such as oxygen content in the powder can be effectively controlled, so that it can meet the stringent requirements of various industries for material purity. The entire preparation method has stable process and strong controllability. The process parameters can be flexibly adjusted according to the actual performance requirements of the titanium aluminum alloy powder, which is convenient for industrial large-scale production and lays a good production technology foundation for the wide application of titanium aluminum alloy powder.

[0017] The present invention uses a plasma rotating electrode atomization method to prepare metal powders with uniform particle size, high sphericity and low impurity content. The finished powder has a sphericity of more than 95%, an oxygen content of less than 500ppm, and a uniform particle size distribution, which can be used in high-end manufacturing fields such as aerospace, automotive industry, and energy. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is further described in detail below through specific embodiments, but the present invention is not limited thereto.

[0019] Example 1: The method for preparing titanium aluminum alloy powder based on plasma rotating electrode atomization method of this embodiment is carried out according to the following steps:

[0020] 1. Raw material preparation: According to the chemical composition ratio of the target titanium-aluminum alloy Ti-45Al-5Nb, accurately weigh titanium, aluminum, and niobium metal raw materials with a purity of 99.8%, mix them evenly, and then place them in a vacuum arc melting furnace and evacuate to 8×10 - 4Pa, and then high-purity argon is filled as a protective gas to maintain the pressure in the furnace at 0.04MPa, and smelting is performed three times, during each smelting process, the alloy is melted and stirred evenly to obtain a titanium-aluminum alloy ingot with uniform composition;

[0021] 2. Electrode preparation: The titanium-aluminum alloy ingot is machined into an electrode rod with a diameter of 30 mm and a length of 200 mm, and the surface of the electrode rod is finely polished to a surface roughness Ra of 0.6 μm. This step makes the surface of the electrode rod smooth without obvious defects and oxide layer, preparing for subsequent plasma rotary atomization;

[0022] 3. Plasma rotating electrode atomization process:

[0023] Install the prepared electrode rod on the rotating electrode shaft of the plasma rotating electrode atomization equipment; ensure that the installation is firm and the electrode rod can rotate at high speed around the shaft; turn on the equipment, drive the electrode rod to rotate, and set the rotation speed to 20000r / min. At the same time, turn on the plasma generator set at the end of the electrode rod to generate a high-temperature, high-energy density plasma beam, and adjust the working power of the plasma to 30kW, so that the titanium aluminum alloy at the end of the electrode rod is heated by the plasma beam under high-speed rotation to quickly melt to form a liquid metal film. Under the action of centrifugal force, the liquid metal film is thrown out and atomized and broken into tiny droplets; set a protective gas hood around the atomization area, and introduce high-purity argon gas as a protective gas. The gas flow rate is controlled at 15L / min to prevent the droplets from being oxidized during the atomization process, so that the atomized droplets are quickly cooled and solidified in the protective gas atmosphere to obtain primary powder;

[0024] 4. Powder collection and post-processing: The primary powder formed by atomization is collected by combining a cyclone collector with a bag dust collector. The collected powder is sifted through a screening device, and the powder with a particle size range of 20 to 100 μm is screened out as the finished powder, which is collected and packaged to obtain titanium-aluminum alloy powder; the coarse powder and fine powder that do not meet the particle size requirements are returned for remelting and reprocessing.

[0025] The titanium aluminum alloy powder prepared in this embodiment was tested, and the sphericity of the finished powder reached 96%, the oxygen content was 450 ppm, and the particle size distribution was uniform, meeting the performance requirements of the titanium aluminum alloy powder for aircraft engine blades.

Claims

1. A method for preparing titanium aluminum alloy powder based on plasma rotating electrode atomization method, characterized in that The method proceeds as follows:

1. Raw material preparation: According to the chemical composition ratio of the target titanium aluminum alloy, accurately weigh the metal raw materials and mix them evenly, then place them in a vacuum arc melting furnace and evacuate to 1×10 - 3Pa or less, and then high-purity argon is filled as a protective gas to maintain the pressure in the furnace at 0.03-0.05MPa, and multiple smelting is performed, and the alloy is melted and stirred evenly during each smelting process to obtain a titanium-aluminum alloy ingot with uniform composition; 2. Electrode preparation: The titanium-aluminum alloy ingot is processed into an electrode rod by mechanical processing, and the surface of the electrode rod is finely polished to make its surface roughness Ra reach less than 0.8μm; 3. Plasma rotating electrode atomization process: the prepared electrode rod is installed on the rotating electrode shaft of the plasma rotating electrode atomization equipment; the equipment is turned on to drive the electrode rod to rotate, and the rotation speed is set at 10000-50000r / min. At the same time, the plasma generator arranged at the end of the electrode rod is turned on, and the working power of the plasma is adjusted to 10-50kW, so that the titanium aluminum alloy at the end of the electrode rod is quickly melted by the heating of the plasma beam under high-speed rotation to form a liquid metal film, and under the action of centrifugal force, the liquid metal film is thrown out and atomized and broken into tiny droplets; a protective gas hood is set around the atomization area, and high-purity argon gas is introduced as a protective gas, and the gas flow rate is controlled at 5-20L / min, so that the atomized droplets are cooled and solidified in the protective gas atmosphere to obtain primary powder; 4. Powder collection and post-processing: The primary powder formed by atomization is collected by combining a cyclone collector with a bag dust collector. The collected powder is screened by a screening device, and the powder that meets the particle size range requirements is screened out as the finished powder, which is collected and packaged to obtain titanium-aluminum alloy powder; the coarse powder and fine powder that do not meet the particle size requirements are returned for remelting and reprocessing.

2. The method for preparing titanium aluminum alloy powder based on plasma rotating electrode atomization method according to claim 1, characterized in that: The titanium aluminum alloy described in step 1 is Ti-48Al-2Cr-2Nb.

3. The method for preparing titanium aluminum alloy powder based on plasma rotating electrode atomization method according to claim 1 or 2, characterized in that: The purity of the metal raw material in step 1 is not less than 99.99% by mass.

4. The method for preparing titanium aluminum alloy powder based on plasma rotating electrode atomization method according to claim 1 or 2, characterized in that: The smelting times described in step 1 are no less than 3 times.

5. The method for preparing titanium aluminum alloy powder based on plasma rotating electrode atomization method according to claim 1 or 2, characterized in that: The electrode rod described in step 2 has a diameter of 20-25 mm and a length of 300 mm.

6. The method for preparing titanium aluminum alloy powder based on plasma rotating electrode atomization method according to claim 1 or 2, characterized in that: The particle size range of the titanium aluminum alloy powder described in step 4 is required to be 10 to 150 μm.