Preparation method of fine spherical vanadium and vanadium alloy powder

Abstract

The invention provides a preparation method of fine spherical vanadium and vanadium alloy powder, which comprises the following steps: step 1, compression molding: loading vanadium powder or vanadium alloy powder into a mold, and pressing into a vanadium rod or a vanadium alloy rod; step 2, pre-sintering: putting the vanadium rod or the vanadium alloy rod into a vacuum furnace for pre-sintering, and cooling along with the furnace; 3, vacuum vertical melting sintering is conducted, specifically, the pre-sintered vanadium rod or vanadium alloy rod is placed in a vacuum vertical melting furnace to be sintered, and the vanadium rod or vanadium alloy rod obtained after vacuum vertical melting sintering is obtained; and 4, electrode induction melting gas atomization, wherein the vanadium rod or the vanadium alloy rod subjected to vacuum vertical melting sintering is heated, smelted and atomized into spherical vanadium powder or vanadium alloy powder with the particle size being 0-100 micrometers through an induction coil. The method has the advantages of short process flow, high fine powder yield, high sphericity degree, good fluidity, low production cost and the like.

Description

Technical Field

[0001] The invention relates to the technical field of metal powder preparation, and in particular to a method for preparing fine spherical vanadium and vanadium alloy powder. Background Art

[0002] Vanadium, known as the vitamin of metal, has typical low activation characteristics. High-purity vanadium shows good plasticity and corrosion resistance, and has excellent physical and chemical properties such as low neutron irradiation activity, high heat transfer rate, and high high-temperature strength. Traditional vanadium parts are made by forging + casting, which has problems such as long process, high manufacturing cost, and low raw material utilization. The emergence of 3D printing technology provides a new method for the preparation of vanadium and vanadium alloy materials and the integrated molding of parts. In recent years, with the rapid development of 3D printing, 3D printed vanadium and vanadium alloy materials have been used in many fields such as nuclear power industry, superconducting materials, and aerospace industry, and the market demand for fine vanadium and vanadium alloy powder has increased rapidly.

[0003] At present, there are very few companies in China that produce spherical vanadium and vanadium alloy powders. Due to the high melting point of vanadium, the main method for producing spherical vanadium and vanadium alloy powders is the plasma rotating electrode method. The vanadium and vanadium alloy powders of this method are in the shape of regular spheres and have good powder fluidity. The patent document with publication number CN111644631B discloses a method for preparing spherical vanadium powder, and its production process is vanadium powder pressing and molding → vacuum sintering → electron beam melting → forging → vacuum annealing → plasma rotating electrode atomization. The rotating electrode method has requirements for the mechanical properties of vanadium rods, and the vanadium rod preparation process is long; at the same time, it is limited by the motor speed limit of 19000r / min. The powder prepared by this method has a coarse particle size and a low fine powder yield, resulting in low raw material utilization and high production costs.

[0004] Therefore, it is necessary to develop a method for preparing fine spherical vanadium and vanadium alloy powders with short process flow, high fine powder yield and low production cost. Summary of the invention

[0005] According to the technical problems raised above, a method for preparing fine spherical vanadium and vanadium alloy powder is provided. The present invention adopts vanadium powder pressing and molding, pre-sintering, and then vacuum vertical melting and sintering to prepare vanadium rods or vanadium alloy rods. The vanadium rods or vanadium alloy rods are directly used for gas atomization, with high fine powder yield, short process flow, high raw material utilization rate and low production cost. The present invention solves the problem of low yield and high production cost of fine spherical vanadium and vanadium alloy powders, and the yield of 15-53μm VCr alloy powder is 65%. The vanadium and vanadium alloy powders prepared at the same time have the advantages of high sphericity and good fluidity.

[0006] The technical means adopted by the present invention are as follows:

[0007] A method for preparing fine spherical vanadium and vanadium alloy powders comprises the following steps:

[0008] Step 1: Pressing and molding: putting vanadium powder or vanadium alloy powder into a mold and pressing it into a vanadium rod or vanadium alloy rod;

[0009] Step 2: Pre-sintering: placing the vanadium rod or vanadium alloy rod in a vacuum furnace for pre-sintering and cooling with the furnace;

[0010] Step 3: Vacuum vertical melting sintering: placing the pre-sintered vanadium rod or vanadium alloy rod in a vacuum vertical melting furnace for sintering to obtain a vacuum vertical melting sintered vanadium rod or vanadium alloy rod;

[0011] Step 4: Electrode induction melting and gas atomization: The vanadium rod or vanadium alloy rod after vacuum vertical melting and sintering is heated by an induction coil to melt and atomize into spherical vanadium powder or vanadium alloy powder with a particle size of 0 to 100 microns.

[0012] Furthermore, in the step 1, the pressing pressure is 300-320 MPa, and the holding time is 150-200 s.

[0013] Furthermore, in the step 1, a hydraulic press is used to press and shape the vanadium powder or vanadium alloy powder into a circular steel mold sleeve, and after the pressing is completed, the vanadium rod or vanadium alloy rod is removed from the mold.

[0014] Furthermore, in the step 2, the pre-sintering temperature is 850-950°C.

[0015] Furthermore, in the step three, the method of vacuum vertical melting sintering is: raising the temperature to 1600°C to 1700°C at a heating rate of 6-8°C / min for sintering, keeping the temperature for 0.4-1h, and then cooling with the furnace.

[0016] Furthermore, in the step 4, the melting power of the electrode induction melting gas atomization is 60-70kw, the induction coil adopts an induction heating copper coil, the distance between the uppermost inner diameter of the induction heating copper coil and the outer surface of the vanadium and vanadium alloy rod is 15-25mm, the angle of the nozzle used for atomization is 80-100°, the nozzle sprays the atomizing medium, the atomizing medium adopts high-temperature argon gas, and the temperature of the high-temperature argon gas is 80°C.

[0017] Furthermore, in step 4, the vanadium rod or vanadium alloy rod is suspended in a rotary feeding device and can be raised and lowered, a high-power induction coil is used as a heat source, the tip of the slowly descending vanadium rod or vanadium alloy rod is continuously melted, and an atomizing medium is sprayed through a large-angle nozzle for atomization, thereby reducing the descending stroke of the vanadium droplets.

[0018] Furthermore, in step 4, the spherical vanadium powder or vanadium alloy powder has a spherical or nearly spherical shape, a sphericity of 0.93-0.94, and a powder particle size of 0-100 μm, of which fine powder within 53 μm accounts for 55%-65%.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The present invention uses vacuum vertical melting sintering to prepare vanadium rods. In the vacuum vertical melting sintering furnace, a low-voltage high current is added to both ends of the rod-shaped blank, and the high temperature is generated by the resistance of the strip blank itself, so that the powdered metal is sintered into dense vanadium and vanadium alloy rods. The vanadium and vanadium alloy rods are directly used as raw materials for gas atomization powder making. The plasma rotating electrode raw material preparation process requires the vanadium ingot after electron beam melting, forging to prepare vanadium rods, and vacuum annealing the residual processing stress in the vanadium rods to obtain vanadium rods with mechanical properties that meet the requirements. The process flow of the present invention is short.

[0021] 2. The present invention adopts a gas atomization method to prepare vanadium and vanadium alloy powders, with a high fine powder yield, and fine powders within 53μm account for 55%-65%. The rotating electrode prepares fine powders within 53μm, accounting for 15%-25%. The present invention improves the utilization rate of raw materials and greatly reduces production costs.

[0022] 3. The present invention adopts a large-angle spray disc and cooperates with ultra-high power smelting to increase the superheat of vanadium and vanadium alloy droplets during breakage. At the same time, heated argon gas is used as an atomizing medium to increase the breakage energy. The spheroidization time after the droplets are broken is less than the solidification time. The powder is spheroidized under the action of surface tension before solidification. The sphericity of the prepared powder is as high as 0.93-0.95, which is close to the sphericity of spherical vanadium powder prepared by plasma rotating electrode atomization at 0.95-0.96.

[0023] Based on the above reasons, the present invention can be widely promoted in the fields of preparation of metal powders. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 Flow chart of the method of the present invention.

[0026] Figure 2 This is a scanning electron microscope image of the spherical vanadium powder prepared in Example 1 of the present invention.

[0027] Figure 3 This is a scanning electron microscope image of the spherical vanadium powder prepared in Example 2 of the present invention.

[0028] Figure 4 This is a scanning electron microscope image of the spherical vanadium-chromium alloy powder prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0032] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be clear that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0033] The invention provides a method for preparing fine spherical vanadium and vanadium alloy powders. The spherical vanadium and vanadium alloy powders prepared by the method of the invention have the advantages of short process flow, high fine powder yield, high sphericity, good fluidity, low production cost, etc.

[0034] The invention presses high-purity vanadium or vanadium alloy powder into rods, pre-sinters them in a vacuum furnace, and then sinters them in a vacuum vertical melting furnace to obtain vanadium and vanadium alloy rods with uniform composition. Spherical vanadium and vanadium alloy powders with a particle size of 0 to 100 microns are prepared by electrode induction melting atomization method. A high-power induction coil is used as a heat source to continuously melt the tip of the slowly descending vanadium metal rod material. A large-angle spray plate (nozzle) is used to reduce the descending stroke of vanadium droplets, reduce heat loss, and improve the superheat of molten droplets. At the same time, high-temperature argon gas is used as an atomizing medium to increase the energy of argon gas, increase the fine powder yield, and improve the sphericity of powder.

[0035] The process of the preparation method of fine spherical vanadium and vanadium alloy powder of the present invention is: vanadium and vanadium alloy powder pressing molding → vacuum sintering → vacuum vertical melting furnace sintering → electrode induction melting atomization, specifically including the following steps:

[0036] Step 1: Compression molding:

[0037] The vanadium powder or vanadium alloy powder is loaded into a mold and pressed into a vanadium rod or a vanadium alloy rod;

[0038] Step 2: Pre-sintering:

[0039] The vanadium rod or vanadium alloy rod is placed in a vacuum furnace for pre-sintering;

[0040] Step 3: Vacuum vertical melting and sintering:

[0041] The pre-sintered vanadium rod or vanadium alloy rod is placed in a vacuum vertical melting furnace for sintering to obtain a vacuum vertical melting sintered vanadium rod or vanadium alloy rod;

[0042] Step 4: Electrode induction melting gas atomization:

[0043] The vanadium rod or vanadium alloy rod sintered in step 3 is heated, melted and atomized by an induction coil to form spherical vanadium powder or vanadium alloy powder with a particle size of 0 to 100 microns.

[0044] In step 1, the pressing pressure is 300-320 MPa, and the holding time is 150-200 s.

[0045] In step 2, the pre-sintering temperature is 850-950°C.

[0046] In step three, the vacuum vertical melting sintering system is a heating rate of 6-8°C / min, a sintering temperature of 1600°C to 1700°C, a holding time of 0.4-1h, and cooling with the furnace.

[0047] In step 4, electrode induction melting gas atomization: melting power is 60-70kw; the distance between the uppermost inner diameter of the induction heating copper coil and the outer surface of the vanadium and vanadium alloy rod is 15-25mm; the nozzle angle is 80-100°; the atomizing gas argon temperature is 80°C.

[0048] In a vacuum vertical melting sintering furnace, a low-voltage high current is applied to both ends of the rod-shaped billet, relying on the resistance of the strip billet itself to generate high temperature, so that the powdered metal is sintered into dense vanadium and vanadium alloy rods. The vanadium and vanadium alloy rods are directly used as raw materials for gas atomization powder making.

[0049] In step 4, electrode induction melting gas atomization: the vanadium and vanadium alloy fine spherical powder has a spherical or nearly spherical shape, a sphericity of 0.93-0.94, a powder particle size of 0-100 μm, of which fine powder within 53 μm accounts for 55%-65%.

[0050] Example 1

[0051] A method for preparing fine spherical vanadium and vanadium alloy powders comprises the following steps:

[0052] (1) Vanadium powder pressing and molding: The vanadium powder is pressed and molded by a hydraulic press. The vanadium powder is loaded into a circular steel mold sleeve with a pressing pressure of 320 MPa and a holding time of 180 seconds. The powder is then taken out after demolding.

[0053] (2) Vacuum sintering: The pressed vanadium rod is placed in a vacuum sintering furnace for sintering, with a vacuum degree of 1.0×10 - 3 pa, sintering system is 900℃, keep warm for 60min, and cool with the furnace.

[0054] (3) Vacuum vertical melting sintering: The heating rate of vacuum vertical melting sintering is 8°C / min, the sintering temperature is 1700°C, the insulation time of vacuum vertical melting sintering is 1h, and the furnace is cooled.

[0055] (4) Electrode induction melting gas atomization: The vanadium rod is hung in a rotary feed device, and the induction heating copper coil is wrapped around the vanadium rod. The melting power is 70kw; the distance between the inner diameter of the top layer of the induction heating copper coil and the outer surface of the vanadium rod is 25mm; the nozzle angle is 80°, and the temperature of the atomizing gas argon is 80°C. Spherical vanadium powder with a particle size of 0 to 100 microns is formed.

[0056] The 0-53 μm vanadium powder was obtained by ultrasonic sieve screening. The yield of 0-53 μm vanadium powder was 55.3%, the sphericity was 0.93, the fluidity was 42s / 50g, and the scanning electron microscope image was shown in Figure 2 , the particle size distribution is shown in Table 1.

[0057] Example 2

[0058] A method for preparing fine spherical vanadium and vanadium alloy powders. The difference between this embodiment and embodiment 1 is that in step (4), the distance between the inner diameter of the uppermost layer of the induction heating copper coil and the outer surface of the chromium rod alloy rod is 20 mm; the nozzle angle is 100°, and the remaining preparation steps and process parameters are the same as those of embodiment 1. 0-53 μm vanadium powder is obtained by ultrasonic sieve screening. The yield of 0-53 μm vanadium powder is 59.6%, the sphericity is 0.94, the fluidity is 38s / 50g, and the scanning electron microscope image is shown in FIG. Figure 3 , the particle size distribution is shown in Table 1.

[0059] Example 3

[0060] In this embodiment, a method for preparing fine spherical vanadium and vanadium alloy powder comprises the following steps:

[0061] (1) Pressing and molding: Vanadium powder and chromium powder are mixed evenly in a ratio of 96:4, and pressed and molded by a hydraulic press. The vanadium-chromium alloy powder is loaded into a circular steel mold sleeve, the pressing pressure is 300 MPa, the pressure holding time is 200 s, and the mold is removed.

[0062] (2) Vacuum sintering: The pressed vanadium rod is placed in a vacuum sintering furnace for sintering, with a vacuum degree of 2.0×10 - 3 pa, sintering system is 850℃, keep warm for 80min, and cool with the furnace.

[0063] (3) Vacuum vertical melting sintering: The heating rate of vacuum vertical melting sintering is 7°C / min, the sintering temperature is 1600°C, the holding time of vacuum vertical melting sintering is 0.6h, and it cools with the furnace.

[0064] (4) Electrode induction melting gas atomization: Hang the vanadium-chromium rod in a rotary feed device with a melting power of 60 kW; the distance between the inner diameter of the top layer of the induction heating copper coil and the outer surface of the chromium rod alloy rod is 15 mm; the nozzle angle is 100°, and the temperature of the atomizing gas argon is 80°C. Spherical vanadium-chromium powder with a particle size of 0 to 100 microns is formed.

[0065] The 0-53 μm vanadium-chromium powder was obtained by ultrasonic sieve screening. The yield of 0-53 μm vanadium powder was 64.8%, the sphericity was 0.95, the fluidity was 26s / 50g, and the scanning electron microscope image was shown in Figure 4 , the particle size distribution is shown in Table 1.

[0066] Table 1 Preparation properties of 0-53 μm vanadium and vanadium-chromium alloy powders

[0067]

[0068] The present invention solves the problem of low yield and high production cost of fine spherical vanadium and vanadium alloy powder. With a 15-53μmV powder yield of 55% and a 15-53μmV powder price of 6,000 yuan / kg, after adopting the technology of the present invention, according to the estimated output of 15-53μmV powder of 2t / a, the output value can be 12 million yuan / year.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing fine spherical vanadium and vanadium alloy powders, characterized in that: The steps include: Step 1: Pressing and molding: putting vanadium powder or vanadium alloy powder into a mold and pressing it into a vanadium rod or vanadium alloy rod; Step 2: Pre-sintering: placing the vanadium rod or vanadium alloy rod in a vacuum furnace for pre-sintering and cooling with the furnace; Step 3: Vacuum vertical melting sintering: placing the pre-sintered vanadium rod or vanadium alloy rod in a vacuum vertical melting furnace for sintering to obtain a vacuum vertical melting sintered vanadium rod or vanadium alloy rod; Step 4: Electrode induction melting and gas atomization: The vanadium rod or vanadium alloy rod after vacuum vertical melting and sintering is heated by an induction coil to melt and atomize into spherical vanadium powder or vanadium alloy powder with a particle size of 0 to 100 microns.

2. The method for preparing fine spherical vanadium and vanadium alloy powder according to claim 1, characterized in that: In the step 1, the pressing pressure is 300-320 MPa, and the holding time is 150-200 s.

3. The method for preparing fine spherical vanadium and vanadium alloy powder according to claim 1 or 2, characterized in that: In the step 1, a hydraulic press is used to press and shape the vanadium powder or vanadium alloy powder into a circular steel mold sleeve, and after the pressing is completed, the vanadium rod or vanadium alloy rod is removed from the mold.

4. The method for preparing fine spherical vanadium and vanadium alloy powder according to claim 1, characterized in that: In the step 2, the pre-sintering temperature is 850-950°C.

5. The method for preparing fine spherical vanadium and vanadium alloy powder according to claim 1, characterized in that: In the step three, the vacuum vertical melting sintering method is: using a heating rate of 6-8°C / min to increase the temperature to 1600°C to 1700°C for sintering, keeping the temperature for 0.4-1h, and then cooling with the furnace.

6. The method for preparing fine spherical vanadium and vanadium alloy powder according to claim 1, characterized in that: In the step 4, the melting power of the electrode induction melting gas atomization is 60-70kw, the induction coil adopts an induction heating copper coil, the distance between the uppermost inner diameter of the induction heating copper coil and the outer surface of the vanadium and vanadium alloy rod is 15-25mm, the angle of the nozzle used for atomization is 80-100°, the nozzle sprays the atomizing medium, the atomizing medium adopts high-temperature argon gas, and the temperature of the high-temperature argon gas is 80°C.

7. The method for preparing fine spherical vanadium and vanadium alloy powder according to claim 6, characterized in that: In the step 4, the vanadium rod or vanadium alloy rod is suspended in the rotary feeding device and can be raised and lowered. A high-power induction coil is used as a heat source to continuously melt the tip of the slowly descending vanadium rod or vanadium alloy rod, and atomization medium is sprayed through a large-angle nozzle for atomization to reduce the descending distance of the vanadium droplets.

8. The method for preparing fine spherical vanadium and vanadium alloy powder according to claim 1, characterized in that: In the step 4, the spherical vanadium powder or vanadium alloy powder has a spherical or nearly spherical shape, a sphericity of 0.93-0.94, and a powder particle size of 0-100 μm, of which fine powder within 53 μm accounts for 55%-65%.

Images