Cleaning method for titanium alloy powder

Abstract

The invention relates to a titanium alloy powder cleaning method which comprises the following steps: step 1, putting titanium alloy powder to be cleaned into a ball-milling tank of an ultrasonic-assisted roller ball mill, introducing a water-based cleaning agent into the ball-milling tank, and then sealing the ball-milling tank; 2, the roller ball mill is started, an ultrasonic auxiliary function is started, oil stains and particle impurities on the surface of the titanium alloy powder are removed, and primary cleaning of the titanium alloy powder is achieved; 3, the titanium alloy powder obtained after primary cleaning is aired and put into an ultraviolet light cavity, ultraviolet light is used for irradiating the titanium alloy powder, and secondary cleaning and activation on the surface of the titanium alloy powder are achieved; and 4, the titanium alloy powder subjected to secondary cleaning is put into a vacuum furnace, flowing hydrogen and argon mixed gas is introduced for heat treatment, and the high-purity titanium alloy powder is obtained. According to the cleaning method, oil stains and impurities on the surface of the titanium alloy powder can be cleaned, and the oxygen content of the surface of the titanium alloy powder is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy recycling, and specifically to a method for cleaning titanium alloy powder. Background Art

[0002] Titanium and titanium alloys (hereinafter collectively referred to as Ti alloys) have many applications in the aerospace, biomedical, chemical, construction, and consumer goods industries. Using Ti alloy powder as the raw material for sintering is one of the methods for manufacturing Ti alloy products. In recent years, due to the rapid development of additive manufacturing technology, the demand for spherical Ti alloy powder has been particularly high. Ti alloys are the most promising materials for metal additive manufacturing, especially for the strong demand in 3C consumer electronic products. However, the current market scale of spherical Ti alloy powder is very small, and one of the important reasons is that Ti alloy powder is usually very expensive. The high cost of Ti alloy powder for additive manufacturing is caused by many factors, and two very important factors are: one is that the Ti alloy smelting process is complex and the pre-production cost is relatively high; the other is that high-performance Ti alloys must meet the strict requirements of low oxygen content, and high oxidation will lead to problems such as reduced alloy toughness, poor formability, increased brittleness, and premature failure. Therefore, it is very challenging to both reduce the manufacturing cost of spherical Ti alloy powder and reduce the oxygen content of spherical Ti alloy powder.

[0003] Currently, using recycled titanium alloy powder (i.e., titanium and titanium alloy cutting chips) as raw materials and manufacturing high-performance spherical Ti alloy powder through the hydrogenation and dehydrogenation technology is a very promising technical route. However, the surface of titanium alloy powder adheres very seriously to oil stains and impurities, and how to clean and deoxidize its surface is a very crucial step in the above technical route.

[0004] Patent CN 106319547 A discloses a method for cleaning titanium and titanium alloy scraps, which adopts the methods of soaking, stirring, and drying. This method is a common pre-treatment process in the field of surface treatment of metal materials (including electroplating, electroless plating, vapor deposition, etc.). However, since the thermal conductivity coefficient of Ti alloy is 1 / 16 of that of Al alloy, the cutting point temperature can exceed 1000°C, resulting in relatively high oil stain adhesion and oxygen content of the cutting chips, and it is very difficult to remove them completely by conventional cleaning methods. This will lead to problems such as the inability to pump the vacuum in the furnace during the subsequent hydrogenation process and relatively high oxygen content on the alloy surface. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a method for cleaning titanium alloy powder, which can clean the oil stains and impurities on the surface of titanium alloy powder and reduce the oxygen content on the surface of titanium alloy powder.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions: A cleaning method for titanium alloy powder, comprising the following steps, Step 1: Place the titanium alloy powder to be cleaned into the ball milling tank of an ultrasonic-assisted roller ball mill, introduce a water-based cleaning agent into the ball milling tank, and then seal the ball milling tank; Step 2: Start the roller ball mill and activate the ultrasonic assistance function to remove the oil stains and particulate impurities on the surface of the titanium alloy powder, achieving the primary cleaning of the titanium alloy powder; Step 3: Dry the titanium alloy powder after the primary cleaning and place it in an ultraviolet light chamber. Use ultraviolet light to irradiate the titanium alloy powder to achieve secondary cleaning and activation of its surface; Step 4: Place the titanium alloy powder after the secondary cleaning into a vacuum furnace, introduce a flowing hydrogen-argon mixed gas to perform heat treatment on it, and obtain high-purity titanium alloy powder.

[0007] Furthermore, in Step 2, the ball milling parameters of the ultrasonic-assisted roller ball mill are as follows: the rotation speed of the roller ball mill is 50 rpm - 200 rpm, the ball-to-material ratio is 5:1 - 10:1, the ball milling time is 1 h - 5 h, the ultrasonic frequency is 60 KHz - 120 KHz, the temperature of the water-based cleaning agent is 40°C - 90°C, and the content of the water-based cleaning agent is 3% - 5% by weight percentage.

[0008] Furthermore, in Step 3, the irradiation distance between the ultraviolet light and the titanium alloy powder is 2 cm - 15 cm, the power of the ultraviolet light is 200 W - 500 W, and the irradiation time is 6 h - 12 h.

[0009] Furthermore, in Step 3, the titanium alloy powder to be cleaned is placed on a fluidized bed to make it in a fluidized state, and the ultraviolet light is used to irradiate the titanium alloy powder in the fluidized state to achieve secondary cleaning and activation of its surface.

[0010] Furthermore, in Step 4, the vacuum furnace uses an argon cleaning furnace. Continuously introduce a flowing hydrogen-argon mixed gas into the argon cleaning furnace, maintain the pressure at 300 - 500 Pa, the heat treatment temperature is 300°C - 450°C, and the treatment time is 2 h - 5 h.

[0011] Generally speaking, the present invention has the following advantages: (1) During the ball milling process of the ultrasonic-assisted roller ball mill, not only can the oil stains on the surface of the titanium alloy powder be accelerated to peel off by rotation, but also the titanium alloy powder that is lapped together can be opened by the random rotation and stirring of the grinding balls, which is beneficial to the comprehensive cleaning of the titanium alloy powder.

[0012] (2) Since ultraviolet light itself has a high energy density, which is higher than the bond energies of the chemical bonds of most organic substances, metals, and gas molecules. When ultraviolet light irradiates the surface of titanium alloy powder, the organic pollutants that are originally difficult to remove on the surface of the titanium alloy powder will decompose into free atoms and excited molecules due to the photosensitization effect, and thus become easy to remove. At the same time, the oxygen adsorbed on the surface of the titanium alloy powder will generate ozone and atomic oxygen after absorbing vacuum ultraviolet light. They can react with the decomposition products of hydrocarbons generated during the cutting of the titanium alloy to form volatile gases such as CO2 and H2O, which escape from the surface of the object, so as to completely remove the pollutants on the surface of the titanium alloy powder, reduce the oxygen content on the surface of the titanium alloy powder, and achieve the purpose of atomic-level cleaning.

[0013] (3) Heat-treating the titanium alloy powder in a hydrogen-argon mixed gas environment is beneficial to the replacement of oxygen on the surface of the Ti alloy by hydrogen, so as to achieve the purpose of reducing the oxygen content to a certain extent. Brief Description of the Drawings

[0014] Figure 1 It is a schematic flow chart of the cleaning method of the present invention.

[0015] Figure 2 It is a schematic diagram of irradiating the titanium alloy powder on the ultraviolet light irradiation cleaning fluidized bed with ultraviolet light. Detailed Description of the Invention

[0016] The following will further describe the present invention in detail.

[0017] As Figure 1 shown, a cleaning method for titanium alloy powder includes the following steps. Step 1: Put the titanium alloy powder to be cleaned into the ball milling tank of the ultrasonic-assisted drum ball mill, introduce a water-based cleaning agent into the ball milling tank, and then seal the ball milling tank. Step 2: Start the drum ball mill and activate the ultrasonic-assisted function to remove the oil stains and particulate impurities on the surface of the titanium alloy powder, and achieve the primary cleaning of the titanium alloy powder. During the ball milling process of the ultrasonic-assisted drum ball mill, the oil stains on the surface of the titanium alloy powder can be accelerated to peel off by rotation, and the titanium alloy powder that is lapped together can be opened by the disordered rotation and stirring of the grinding balls, increasing the contact area between the titanium alloy powder and the water-based cleaning agent, which is beneficial to the comprehensive cleaning of the titanium alloy powder.

[0018] Step 3: Dry the titanium alloy powder after the primary cleaning, and put it into the ultraviolet light cavity, and irradiate the titanium alloy powder with ultraviolet light to achieve the secondary cleaning and activation of its surface, as Figure 2As shown; since ultraviolet light itself has a relatively high energy density and is higher than the bond energies of the chemical bonds of most organic substances, metals, and gas molecules, when ultraviolet light irradiates the surface of titanium alloy powder, the organic pollutants that are originally difficult to remove on the surface of the titanium alloy powder will, due to the photosensitization effect, decompose into free atoms, excited molecules, etc. and become easier to remove. At the same time, the oxygen adsorbed on the surface of the titanium alloy powder will generate ozone and atomic oxygen after absorbing vacuum ultraviolet light, and they can react with the decomposition products of hydrocarbons to form volatile gases such as CO2 and H2O, which escape from the surface of the object, so as to completely remove the pollutants on the surface of the titanium alloy powder, reduce the oxygen content on the surface of the titanium alloy powder, and achieve the purpose of atomic-level cleaning.

[0019] (4) Step 4: Put the titanium alloy powder after secondary cleaning into a vacuum furnace, and introduce a flowing hydrogen-argon mixed gas to perform heat treatment on it to obtain titanium alloy powder with high purity. Heat treatment of the titanium alloy powder in a hydrogen-argon mixed gas environment is beneficial to the replacement of oxygen on the surface of the Ti alloy by hydrogen, so as to achieve the purpose of reducing the oxygen content to a certain extent.

[0020] Further, in step 2, the ball milling parameters of the ultrasonic-assisted drum ball mill are: the rotational speed of the drum ball mill is 50 rpm - 200 rpm, the ball-to-material ratio is 5:1 - 10:1, the ball milling time is 1 h - 5 h, the ultrasonic frequency is 60 KHz - 120 KHz, the temperature of the water-based cleaning agent is 40 °C - 90 °C, and the content of the water-based cleaning agent is 3% - 5% by weight percentage.

[0021] Further, in step 3, the irradiation distance between the ultraviolet light and the titanium alloy powder is 2 cm - 15 cm, the power of the ultraviolet light is 200 W - 500 W, and the irradiation time is 6 h - 12 h.

[0022] Further, in step 3, the titanium alloy powder to be cleaned is placed on a fluidized bed to make it in a fluidized state, and the fluidized titanium alloy powder is irradiated with ultraviolet light to achieve secondary cleaning and activation of its surface.

[0023] In the fluidized state, the titanium alloy powder particles can be fully exposed to ultraviolet light, ensuring uniform irradiation of the powder surface by ultraviolet light and improving the cleaning efficiency. At the same time, the fluidized state is also conducive to timely removing the pollutants desorbed and volatilized from the powder surface, avoiding the re-adsorption of pollutants on the powder surface, and further enhancing the cleaning effect.

[0024] Further, in step 4, the vacuum furnace uses an argon cleaning furnace. Continuously introduce a flowing hydrogen-argon mixed gas into the argon cleaning furnace, the pressure is maintained at 300 - 500 Pa, the heat treatment temperature is 300 °C - 450 °C, and the treatment time is 2 h - 5 h.

[0025] The present invention combines methods such as primary cleaning through an ultrasonic-assisted roller ball milling process, secondary cleaning and surface activation by ultraviolet light irradiation, and heat treatment in a hydrogen-argon mixed gas environment. This not only achieves the cleaning of oil stains and impurities on the surface of titanium alloy powder but also effectively reduces its surface oxygen content. The method of the present invention has the advantages of thorough cleaning, low energy consumption, low-temperature deoxidation, and high efficiency. The prepared titanium alloy powder is suitable for its subsequent hydrogenation and dehydrogenation process flows.

[0026] The above embodiments are preferred embodiments of the present invention. However, the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A cleaning method for titanium alloy powder, characterized in that: It includes the following steps: Step 1: Put the titanium alloy powder to be cleaned into the ball milling tank of the ultrasonic-assisted drum ball mill. Inject the water-based cleaning agent into the ball milling tank, and then seal the ball milling tank. Step 2: Start the drum ball mill and activate the ultrasonic-assisted function to remove the oil stains and particulate impurities on the surface of the titanium alloy powder, achieving the primary cleaning of the titanium alloy powder. Step 3: Dry the titanium alloy powder after the primary cleaning and put it into the ultraviolet light cavity. Use ultraviolet light to irradiate the titanium alloy powder to achieve the secondary cleaning and activation of its surface. Step 4: Put the titanium alloy powder after the secondary cleaning into a vacuum furnace, and introduce a flowing hydrogen-argon mixed gas to conduct heat treatment on it to obtain a titanium alloy powder with high purity.

2. The cleaning method according to claim 1, characterized in that: In Step 2, the ball milling parameters of the ultrasonic-assisted drum ball mill are as follows: the rotational speed of the drum ball mill is 50 rpm - 200 rpm, the ball-to-material ratio is 5:1 - 10:1, the ball milling time is 1 h - 5 h, the ultrasonic frequency is 60 KHz - 120 KHz, the temperature of the water-based cleaning agent is 40°C - 90°C, and the content of the water-based cleaning agent is 3% - 5% by weight percentage.

3. The cleaning method according to claim 1, wherein: In Step 3, the irradiation distance between the ultraviolet light and the titanium alloy powder is 2 cm - 15 cm, the power of the ultraviolet light is 200 W - 500 W, and the irradiation time is 6 h - 12 h.

4. The cleaning method according to claim 1, characterized in that: In Step 3, the titanium alloy powder to be cleaned is placed on a fluidized bed to make it in a fluidized state, and the ultraviolet light is used to irradiate the titanium alloy powder in the fluidized state to achieve the secondary cleaning and activation of its surface.

5. The cleaning method according to claim 1, characterized in that: In Step 4, the vacuum furnace uses an argon cleaning furnace. Continuously introduce a flowing hydrogen-argon mixed gas into the argon cleaning furnace, maintain the pressure at 300 - 500 Pa, the heat treatment temperature is 300°C - 450°C, and the treatment time is 2 h - 5 h.

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