Device and method for preparing metal powder through gas atomization and capable of improving gas utilization rate

Abstract

The invention discloses a device and method for preparing metal powder through gas atomization and capable of improving the gas utilization rate, and relates to the technical field of metal powder preparation. A liquid outlet is formed in the bottom of a tundish of the device, a middle column is vertically arranged in the tundish, and the bottom end of the middle column is a liquid guide part and extends out of the liquid outlet; a liquid channel for molten metal to flow from the tundish to the atomizing chamber is formed between the liquid guide part and the liquid outlet; the high-pressure gas nozzle is located below the middle column, a gas guide part is formed at the gas outlet, and a gas channel allowing high-pressure gas to flow from the high-pressure gas pipe to the atomizing chamber is formed between the gas guide part and the liquid guide part. The position and the direction of airflow acting on molten metal are changed, the airflow impacts the metal liquid flow outwards from the center of the tubular metal liquid flow, energy loss caused by transverse opposite impact of gas in a traditional structure is avoided, gas energy is more fully utilized, meanwhile, the acting mode of the gas and the metal liquid flow is optimized, and the energy utilization rate is increased. And the gas utilization rate, the production efficiency and the quality of the prepared metal powder are improved.

Description

Technical Field

[0001] This invention relates to the field of metal powder preparation technology, and specifically to an apparatus and method for producing metal powder by gas atomization. Background Technology

[0002] Gas atomization technology is an important method for preparing metal powders. It uses high-speed gas flow to break molten metal into tiny droplets, which are then solidified into powder. Especially in the field of additive manufacturing, the demand for high-performance metal powders is growing.

[0003] In existing devices for producing metal powder via gas atomization, molten metal flows down from the center of an atomizing nozzle, while compressed gas is ejected downwards from the annular gaps of the nozzle towards the center. The kinetic energy of the airflow atomizes the molten metal into small droplets, which then solidify to obtain metal powder. However, in existing technologies, besides the downward impact on the molten metal, the kinetic energy from the lateral decomposition of the airflow is offset, resulting in insufficient utilization of gas energy. To ensure effective atomization, a large gas-liquid ratio is required, increasing the gas consumption cost per unit of metal powder. Furthermore, existing gas atomization methods produce metal powders with numerous satellite powders (small powder particles adhering to large powder particles) and powder adhesion, affecting powder quality and subsequent application performance. This makes it difficult to meet the stringent requirements of metal powder applications regarding particle size, sphericity, and purity, severely hindering the development of gas atomization technology.

[0004] To address these issues, existing technologies have explored various approaches. For example, different nozzle designs have been employed to optimize the airflow field, supersonic gases have been used to enhance atomization, and powder particle size distribution has been adjusted by controlling gas pressure and temperature. However, these methods still have limitations in improving gas utilization and powder quality. Summary of the Invention

[0005] To avoid the shortcomings of the prior art, the present invention provides an apparatus and method for producing metal powder by gas atomization with improved gas utilization.

[0006] The present invention adopts the following technical solution to solve the technical problem: an apparatus for producing metal powder by gas atomization to improve gas utilization, comprising a smelting furnace for melting metal materials and a collection device for collecting metal powder, and equipped with an intermediate ladle, a central column, a high-pressure gas nozzle and an atomization chamber; The liquid inlet of the intermediate ladle is connected to the outlet of the smelting furnace, and a liquid outlet is opened at the bottom of the ladle. The central column is erected inside the tundish, with its bottom end extending from the liquid outlet. The bottom end is radially inclined downward and outward to form a liquid guiding section. A liquid channel is formed between the liquid guiding section and the liquid outlet to allow molten metal to flow from the tundish to the atomization chamber. The high-pressure gas nozzle is located below the central column. Its air inlet is connected to the high-pressure gas pipe, and its air outlet extends radially outward to form a gas guide section. A gas channel is formed between the gas guide section and the liquid guide section to allow high-pressure gas to flow from the high-pressure gas pipe to the atomization chamber. The outlet of the atomizing chamber is connected to the collecting device.

[0007] Furthermore, the gas channel formed between the liquid guiding part and the gas guiding part has a Laval structure.

[0008] Furthermore, the intermediate liner and the central column are made of ceramic, and the high-pressure gas nozzle is made of stainless steel.

[0009] A method for producing metal powder by gas atomization with improved gas utilization efficiency, using the above-mentioned apparatus to produce metal powder by gas atomization, includes the following processes: The first step is to adjust the apparatus for producing metal powder. Adjust the size of the annular gap in the liquid channel formed between the liquid guide section and the gas guide section according to actual needs; The second step is the preparation of molten metal. Metal materials are heated and melted in a smelting furnace into molten metal, which flows into the tundish through the outlet of the smelting furnace and the inlet of the tundish. Step 3: Liquid metal guidance Molten metal flows into the atomization chamber through the liquid channel under the guidance of the liquid guiding part, forming a uniform tubular liquid metal flow around the liquid guiding part; Step 4: Gas atomization High-pressure gas flows through a high-pressure gas pipe to a high-pressure gas nozzle and is blown out. The airflow is accelerated in a gas channel with a Laval structure and then flows into the atomization chamber. It acts at high speed on the liquid metal flow and blows the liquid metal flow into tiny droplets. Step 5, Powder Collection Tiny droplets are cooled and solidified into metal powder, which then flows in with the airflow and is collected in the collection device. Step 6, Follow-up processing Metal powders are sieved, graded, and / or surface-treated to obtain metal powder products with specific parameters.

[0010] Furthermore, in the first step, the size of the annular gap in the liquid channel formed between the liquid guiding part and the gas guiding part is 0.5mm~3mm.

[0011] Furthermore, in the third step, the high-pressure gas is an inert gas.

[0012] This invention provides an apparatus and method for producing metal powder by gas atomization to improve gas utilization, which has the following beneficial effects: 1. This invention changes the position and direction of the airflow acting on the molten metal, causing the airflow to impact the molten metal flow from the core of the tubular molten metal flow outward, avoiding the energy loss caused by the lateral collision of gas in the traditional structure, so that the gas energy can be utilized more fully. At the same time, it optimizes the interaction between gas and molten metal flow, which is conducive to improving gas utilization, production efficiency and the quality of the produced metal powder.

[0013] 2. This invention achieves supersonic acceleration of high-pressure gas through the Laval structure gas channel formed between the liquid guiding part and the gas guiding part, so as to make fuller use of gas energy, reduce gas consumption, and reduce production costs; at the same time, the high-speed airflow can more effectively break up molten metal, reduce satellite powder and powder adhesion, and improve the sphericity and uniformity of powder.

[0014] 3. The present invention can adaptively adjust structural parameters such as Laval structure parameters and liquid metal flow diameter, as well as process parameters such as gas pressure, heating temperature, and high-pressure gas type, according to actual needs. It can achieve precise control of powder particle size, sphericity, and other characteristics, and meet the customized needs of different application scenarios. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a device for producing metal powder by gas atomization in the prior art; Figure 2 This is a schematic diagram of the structure of the present invention.

[0016] In the picture: 1. Intermediate jar; 2. Central column; 21. Liquid guiding section; 3. High-pressure gas nozzle; 31. Gas guiding section; 4. Ceramic nozzle; 5. High-pressure gas flow chamber; 51. Gas flow chamber outlet; a. Molten metal; b. High-pressure gas; c. Tiny droplets. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The structure of the device for atomizing metal powder in the prior art is as follows: Figure 1As shown, the high-pressure airflow chamber 5 is evenly distributed around the ceramic nozzle 4 in the circumferential direction. The airflow chamber outlet 51 of the high-pressure airflow chamber 5 faces the center of the ceramic nozzle 4 at an inclined downward position. The high-pressure gas b is blown out from the airflow chamber outlet 51 towards the molten metal a, causing the molten metal a to disperse into tiny droplets c.

[0019] An apparatus for producing metal powder by gas atomization to improve gas utilization, such as... Figure 2 As shown, its structural relationship is as follows: it includes a smelting furnace for melting metal materials and a collection device for collecting metal powder, and is equipped with an intermediate ladle 1, a central column 2, a high-pressure gas nozzle 3 and an atomization chamber; The liquid inlet of the intermediate ladle 1 is connected to the outlet of the smelting furnace, and a liquid outlet is opened at its bottom; The central column 2 is erected inside the tundish 1, with its bottom end extending from the liquid outlet. The bottom end is radially inclined downward and outward to form a liquid guiding part 21. A liquid channel is formed between the liquid guiding part 21 and the liquid outlet to allow molten metal to flow from the tundish 1 to the atomization chamber. The high-pressure gas nozzle 3 is located below the central column 2. Its air inlet is connected to the high-pressure gas pipe, and its air outlet extends radially outward to form a gas guide 31. A gas channel is formed between the gas guide 31 and the liquid guide 21 to allow high-pressure gas to flow from the high-pressure gas pipe to the atomization chamber. The outlet of the atomization chamber is connected to the collection device.

[0020] Preferably, the gas channel formed between the liquid guiding part 21 and the gas guiding part 31 has a Laval structure.

[0021] The Laval structure design can effectively improve the kinetic energy utilization of gas. By precisely controlling the contraction and expansion angles of the Laval structure, supersonic acceleration of the airflow can be achieved, thereby effectively improving atomization efficiency.

[0022] Preferably, the tundish 1 and the central column 2 are made of ceramic, which has good high temperature resistance and chemical stability, and can effectively prevent the molten metal from reacting with the central column 2; the high-pressure gas nozzle 3 is made of 316 stainless steel.

[0023] A method for producing metal powder by gas atomization with improved gas utilization efficiency, using the above-mentioned apparatus to produce metal powder by gas atomization, includes the following processes: The first step is to adjust the apparatus for producing metal powder. Adjust the size of the annular gap in the liquid channel formed between the liquid guiding part 21 and the gas guiding part 31 according to actual needs; To regulate the flow rate of the molten metal and ensure its uniformity; The second step is the preparation of molten metal. The metal material is heated and melted into molten metal in a smelting furnace. The molten metal flows into the tundish 1 through the outlet of the smelting furnace and the inlet of the tundish 1. The heating temperature of the smelting furnace should be set reasonably according to the characteristics of the metal material to ensure that the molten metal has good fluidity; Step 3: Liquid metal guidance Molten metal flows into the atomization chamber through the liquid channel under the guidance of the liquid guiding part 21, forming a uniform tubular liquid metal flow around the liquid guiding part 21; Step 4: Gas atomization High-pressure gas flows through the high-pressure gas pipe to the high-pressure gas nozzle 3 and is blown out. The airflow is accelerated in the gas channel with a Laval structure and then flows into the atomization chamber. It acts at high speed on the liquid metal flow and blows the liquid metal flow into tiny droplets. Step 5, Powder Collection Tiny droplets are cooled and solidified into metal powder, which then flows in with the airflow and is collected in the collection device. Step 6, Follow-up processing Metal powders are sieved, graded, and / or surface-treated to obtain metal powder products with specific parameters.

[0024] Surface treatments, including passivation, are used to improve the oxidation resistance of the powder.

[0025] Preferably, in the first step, the size of the annular gap of the liquid channel formed between the liquid guiding part 21 and the gas guiding part 31 is 0.5mm to 3mm.

[0026] Preferably, in the third step, the high-pressure gas is an inert gas to protect the metal powder during the collection process and prevent the metal powder from oxidizing.

[0027] Example 1: Preparation of AlSi10Mg aluminum alloy powder The first step is to empirically adjust the size of the annular gap of the liquid channel formed between the liquid guide section 21 and the gas guide section 31 to 3mm according to actual needs.

[0028] The second step is the preparation of molten metal. The AlSi10Mg aluminum alloy was heated to 750°C in a melting furnace and kept in a molten state. Step 3: Liquid metal guidance Molten AlSi10Mg aluminum alloy flows into the atomization chamber through the liquid channel under the guidance of the liquid guiding part 21, forming a uniform tubular AlSi10Mg aluminum alloy liquid metal flow with a diameter of 5mm around the liquid guiding part 21. Step 4: Gas atomization High-pressure argon gas at 4MPa is blown out through the high-pressure gas pipe from gas nozzle 3. The gas flow is accelerated to supersonic speed in the gas channel with a Laval structure, and then flows into the atomization chamber to act on the AlSi10Mg aluminum alloy liquid metal flow at high speed, blowing the AlSi10Mg aluminum alloy liquid metal flow into AlSi10Mg aluminum alloy tiny droplets. Step 5, Powder Collection Tiny droplets of AlSi10Mg aluminum alloy are cooled and solidified into AlSi10Mg aluminum alloy metal powder under the protection of argon gas. The powder is then carried by the airflow and collected in a cyclone separator, which serves as the collection device.

[0029] Step 6, Follow-up processing The collected AlSi10Mg aluminum alloy powder was sieved using a cyclone separator to obtain AlSi10Mg aluminum alloy powder products with a particle size range of 20-60μm.

[0030] The AlSi10Mg aluminum alloy powder prepared in Example 1 has good sphericity and uniformity, significantly reduces satellite powder and powder adhesion, and improves gas utilization by 25% compared with traditional methods.

[0031] Example 2: Preparation of Fe85Si9.6Al5.4 alloy powder The first step is to empirically adjust the size of the annular gap of the liquid channel formed between the liquid guide section 21 and the gas guide section 31 to 0.5 mm according to actual needs.

[0032] The second step is the preparation of molten metal. The Fe85Si9.6Al5.4 alloy was heated to 1450℃ in a melting furnace and kept in a molten state; Step 3: Liquid metal guidance Molten Fe85Si9.6Al5.4 alloy flows into the atomization chamber through the liquid channel under the guidance of the liquid guiding part 21, forming a uniform tubular Fe85Si9.6Al5.4 alloy liquid metal flow with a diameter of 6mm around the liquid guiding part 21. Step 4: Gas atomization High-pressure argon gas at a pressure of 5.2 MPa is blown out through a high-pressure gas pipe from gas nozzle 3. The gas flow is accelerated to supersonic speed in a gas channel with a Laval structure, and then flows into the atomization chamber to act on the Fe85Si9.6Al5.4 alloy liquid metal flow at high speed, which disperses the Fe85Si9.6Al5.4 alloy liquid metal flow into tiny Fe85Si9.6Al5.4 alloy droplets. Step 5, Powder Collection Tiny droplets of Fe85Si9.6Al5.4 alloy are cooled and solidified into Fe85Si9.6Al5.4 alloy metal powder under the protection of argon gas. The powder is then carried by the airflow into and collected in a cyclone separator, which serves as the collection device.

[0033] Step 6, Follow-up processing The collected Fe85Si9.6Al5.4 alloy metal powder was sieved using a cyclone separator to obtain Fe85Si9.6Al5.4 alloy metal powder products with a particle size range of 10-70μm.

[0034] The Fe85Si9.6Al5.4 alloy metal powder prepared in Example 2 has good sphericity and uniformity, significantly reduces satellite powder and powder adhesion, and improves gas utilization by 20% compared with the traditional method.

[0035] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An apparatus for producing metal powder by gas atomization with improved gas utilization, comprising a smelting furnace for melting metal materials and a collecting device for collecting the metal powder, characterized in that: It is equipped with an intermediate package (1), a central column (2), a high-pressure gas nozzle (3), and an atomizing chamber; The liquid inlet of the intermediate ladle (1) is connected to the outlet of the smelting furnace, and a liquid outlet is opened at its bottom; The central column (2) is erected inside the intermediate tundish (1), with its bottom end extending out from the liquid outlet. The bottom end is radially inclined downward and outward to form a liquid guiding part (21). A liquid channel is formed between the liquid guiding part (21) and the liquid outlet to allow molten metal to flow from the intermediate tundish (1) to the atomizing chamber. The high-pressure gas nozzle (3) is located below the central column (2), its air inlet is connected to the high-pressure gas pipe, and its air outlet extends radially outward to form a gas guide (31). A gas channel is formed between the gas guide (31) and the liquid guide (21) to allow high-pressure gas to flow from the high-pressure gas pipe to the atomizing chamber. The outlet of the atomizing chamber is connected to the collecting device.

2. The apparatus for producing metal powder by gas atomization to improve gas utilization according to claim 1, characterized in that: The gas channel formed between the liquid guiding part (21) and the gas guiding part (31) has a Laval structure.

3. The apparatus for producing metal powder by gas atomization with improved gas utilization rate according to claim 2, characterized in that: The intermediate liner (1) and the central column (2) are made of ceramic, and the high-pressure gas nozzle (3) is made of 316 stainless steel.

4. A method for producing metal powder by gas atomization with improved gas utilization, comprising producing metal powder by gas atomization using the apparatus as described in claim 2 or 3, characterized in that, The process includes the following: The first step is to adjust the apparatus for producing metal powder. Adjust the size of the annular gap of the liquid channel formed between the liquid guiding part (21) and the gas guiding part (31) according to actual needs; The second step is the preparation of molten metal. The metal material is heated and melted in the smelting furnace into molten metal, and the molten metal flows into the tundish (1) through the outlet of the smelting furnace and the inlet of the tundish (1); Step 3: Liquid metal guidance Molten metal flows into the atomization chamber through the liquid channel under the guidance of the liquid guiding part (21), forming a uniform tubular liquid metal flow around the liquid guiding part (21); Step 4: Gas atomization High-pressure gas flows through the high-pressure gas pipe to the high-pressure gas nozzle (3) and is blown out. The airflow is accelerated in the gas channel with a Laval structure and then flows into the atomization chamber. It acts on the liquid metal flow at high speed and blows the liquid metal flow into tiny droplets. Step 5, Powder Collection Tiny droplets are cooled and solidified into metal powder, which then flows in with the airflow and is collected in the collection device. Step 6, Follow-up processing Metal powders are sieved, graded, and / or surface-treated to obtain metal powder products with specific parameters.

5. The method for producing metal powder by gas atomization with improved gas utilization rate according to claim 4, characterized in that: In the first step, the size of the annular gap of the liquid channel formed between the liquid guiding part (21) and the gas guiding part (31) is 0.5mm~3mm.

6. The method for producing metal powder by gas atomization with improved gas utilization rate according to claim 4, characterized in that: In the third step, the high-pressure gas is an inert gas.

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