Preparation method of niobium-tungsten alloy spherical powder

Abstract

The invention provides a preparation method of niobium-tungsten alloy spherical powder. The preparation method comprises the following steps: S1, proportioning and mixing: mixing raw material powder such as niobium powder, tungsten powder, molybdenum powder and zirconium carbide powder into mixed powder according to a proportioning table; s2, pressing and sintering, wherein the mixed powder is pressed into blocks in a mold through pressing equipment, and then the blocks are sintered into blanks in a vacuum state; s3, pulverizing and screening: pulverizing and screening the blank to obtain non-spherical powder with a proper particle size range; and S4, spheroidizing: spheroidizing the non-spherical powder to obtain spherical powder. According to the niobium-tungsten alloy spherical powder prepared through the method, the particle size range of the powder is 15-60 microns, the powder spheroidization rate is larger than or equal to 90%, the powder oxygen content is smaller than or equal to 150 ppm, and the Hall flowability is larger than or equal to 8.0 s / 50 g; the powder prepared by the process is low in oxygen content, appropriate in powder size distribution range and high in fine powder yield, the process flow is short, and a production line is convenient to build.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material manufacturing, and in particular relates to a method for preparing niobium-tungsten alloy spherical powder. Background Art

[0002] Niobium-tungsten alloy has high melting point, high temperature creep resistance, good high temperature strength and acid and alkali corrosion resistance, and is widely used in high temperature resistant complex structural parts and functional parts in aerospace, nuclear power, military industry, etc. However, for niobium-tungsten alloy with a high melting point, the traditional processing method is mainly powder metallurgy process. Powder metallurgy process is difficult to obtain components with complex structures, and additive manufacturing technology has obvious advantages in the molding of complex, thin-walled, integrated components. In the process of additive manufacturing, metal spherical powder has an important influence on the performance of the molded components and is one of the key technologies of additive manufacturing technology.

[0003] At present, the common preparation technology route of niobium-tungsten alloy spherical powder is to obtain niobium-tungsten alloy billet through powder metallurgy or smelting process, then crush it after hydrogenation by hydrogenation method to obtain niobium-tungsten alloy powder, then reduce the hydrogen content by dehydrogenation, and finally obtain spherical powder by induction plasma spheroidization process. This process is easy to increase the oxygen content in the alloy during hydrogenation and dehydrogenation, and high oxygen content may lead to reduced quality of formed components.

[0004] There is another spherical powder preparation process, which is to obtain niobium tungsten alloy billet and then directly obtain spherical powder through plasma rotating electrode powder making equipment. This process has the problem of too large powder particle size (powder suitable for additive manufacturing should be 15-60μm) and low yield (usually ≤20%) during the processing of refractory metals such as niobium tungsten alloy.

[0005] Therefore, those skilled in the art are committed to developing a method for preparing niobium-tungsten alloy spherical powder (15-60 μm) suitable for additive manufacturing and with a high yield. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing niobium-tungsten alloy spherical powder (15-53 μm) suitable for additive manufacturing and with high yield, in view of the corresponding shortcomings of the prior art.

[0007] The purpose of the present invention is to adopt the following scheme to achieve: a method for preparing niobium tungsten alloy spherical powder, comprising the following steps:

[0008] S1. Batching and mixing: mixing raw material powders consisting of niobium powder, tungsten powder, molybdenum powder and zirconium carbide powder into a mixed powder;

[0009] S2. Pressing and sintering: The mixed powder is pressed into a block in a mold and sintered into a blank under vacuum;

[0010] S3. Powdering and sieving: crushing and sieving the blank to obtain a non-spherical powder with a suitable particle size range;

[0011] S4. Spheroidization: Spheroidizing the non-spherical powder to obtain spherical powder.

[0012] Furthermore, in step S1, the raw material powders are calculated by weight percentage, including 4.5-6.6wt% tungsten powder, 1.6-2.8wt% molybdenum powder, 0.8-1.8wt% zirconium carbide powder, and the rest niobium powder.

[0013] Furthermore, in step S1, the raw material powders are calculated by weight percentage, including 5.0wt% tungsten powder, 2.0wt% molybdenum powder, 1.1wt% zirconium carbide powder, and the rest niobium powder.

[0014] Furthermore, in step S1, the raw material powders are calculated by weight percentage, including 4.5wt% tungsten powder, 1.6wt% molybdenum powder, 0.8wt% zirconium carbide powder, and the rest niobium powder.

[0015] Furthermore, in step S1, the particle size of the raw material powder is ≤5 μm.

[0016] Furthermore, in step S1, a ball mill is used for mixing, and the mixing time is 12 to 16 hours.

[0017] Furthermore, in step S2, the mixed powder is pressed by isostatic pressing, the pressing die sleeve is cylindrical, the diameter is 30-50 mm, and the pressing pressure is 150-180 MPa.

[0018] Furthermore, in step S2, vacuum sintering is performed in a vacuum induction furnace at a temperature of 1200-1350°C and a vacuum degree of ≤0.1Pa.

[0019] Furthermore, in step S3, the non-spherical powder with a suitable particle size range includes non-spherical powder with a particle size of 20 to 70 μm, and the mass of the non-spherical powder with a particle size of 20 to 70 μm accounts for ≥ 65% of the total mass of the non-spherical powder.

[0020] Furthermore, in step S4, spheroidization is performed using an induction plasma spheroidization device.

[0021] The advantages of the present invention are:

[0022] 1) The temperature during sintering is low, so mechanical crushing can be performed directly without hydrogenation process, thus avoiding the increase of oxygen content in the alloy during hydrogenation and dehydrogenation;

[0023] 2) The particle size distribution of the powder can be flexibly controlled during the powder making and screening process, thereby increasing the yield of powder within the appropriate particle size range;

[0024] 3) The process has fewer steps, shorter processes and shorter cycles, which can reduce production costs.

[0025] 4) The niobium tungsten alloy spherical powder prepared by the method of the present invention has a powder particle size range of 15 to 60 μm, a powder spheroidization rate of ≥90%, a powder oxygen content of ≤150 ppm, a Hall fluidity of ≥8.0 s / 50 g, a high powder yield, and a powder particle size suitable for additive manufacturing requirements of 15 to 60 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a production process flow chart of the present invention;

[0027] Figure 2 This is a scanning electron microscope image of the niobium-tungsten alloy spherical powder prepared in Example 1;

[0028] Figure 3 This is a scanning electron microscope image of the niobium-tungsten alloy spherical powder prepared in Example 2;

[0029] Figure 4 Scanning electron microscope image of the niobium-tungsten alloy spherical powder prepared in Example 3;

[0030] Figure 5 This is a scanning electron microscope image of the niobium-tungsten alloy spherical powder prepared in Example 4. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to understand the characteristics and effects of the present application, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein have the common meanings understood by those skilled in the art for the present application. In case of conflict, the definitions in this specification shall prevail.

[0032] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present application in any way, that is, the content of the present application can be implemented without being limited by any specific theory or mechanism.

[0033] As used herein, "this application" means "the present invention" or "the present disclosure".

[0034] The use of "one", "an", "a kind" or similar expressions to describe the components and technical features described in this application is merely for the convenience of expression and to provide a general meaning to the scope of this application. Therefore, such description should be understood to include one or at least one, and the singular also includes the plural, unless it is obvious that it refers to another meaning.

[0035] In this document, "or its combination" means "or any combination thereof", and "any one", "any one" means "any one", "any one" or "any one".

[0036] As used herein, the terms "comprises," "including," "having," "containing," or any other similar terms are open-ended transitional phrases that are intended to cover non-exclusive inclusions. For example, a composition or article containing multiple elements is not limited to the elements listed herein, but may also include other elements that are not explicitly listed but are generally inherent to the composition or article. In addition, unless otherwise expressly stated, the term "or" refers to an inclusive "or" rather than an exclusive "or." For example, any of the following situations satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist). In addition, in this article, the terms "comprising", "including", "having", and "containing" should be interpreted as being specifically disclosed and simultaneously covering closed connections such as "consisting of", "consisting of", "the remainder of", and "substantially consisting of", "mainly consisting of", "mainly consisting of", "basically containing", "essentially consisting of", "essentially consisting of", "essentially containing", and other connecting words.

[0037] In this article, all features or conditions such as numerical values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are only for simplicity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be deemed to have covered and specifically disclosed all possible sub-ranges and individual values ​​within the range (including integers and fractions), especially integer values. For example, the range description of "1.0 to 8.0" or "between 1.0 and 8.0" or "between 1.0 and 8.0" should be deemed to have specifically disclosed all sub-ranges such as 1.0 to 8.0, 1.0 to 7.0, 2.0 to 8.0, 2.0 to 6.0, 3.0 to 6.0, 4.0 to 8.0, 3.0 to 8.0, etc., and should be deemed to cover endpoint values, especially sub-ranges defined by integer values, and should be deemed to have specifically disclosed individual values ​​such as 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, etc. Unless otherwise indicated, the foregoing method of interpretation applies to all contents of the entire application, regardless of whether the scope is broad or not.

[0038] If the quantity, concentration or other numerical value or parameter is expressed as a range, a preferred range (or a better range) or a series of upper and lower limits, it should be understood that all ranges consisting of any pair of the upper limit or preferred value (or a better value) of the range and the lower limit or preferred value (or a better value) of the range have been specifically disclosed herein, regardless of whether these ranges are disclosed separately. In addition, if a numerical range is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.

[0039] In this document, numerical values ​​should be understood to have the accuracy of the number of significant digits of the numerical value, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover the range of 39.50 to 40.49.

[0040] It should be understood that the features disclosed in the various embodiments herein may be arbitrarily combined to form the technical solution of the present application, as long as there is no contradiction in the combination of these features.

[0041] The present application will be described below with specific implementations and examples. It should be understood that these specific implementations and examples are merely illustrative and are not intended to limit the scope of the present application and its use.

[0042] Unless otherwise specified, the methods, reagents and conditions used in the preparation examples, comparative examples and examples below are conventional methods, reagents and conditions in the art. The vacuum induction furnace in the following examples is produced by Xi'an Chenghang Furnace Industry Co., Ltd., model Z / Q-ZGS25-350 / 2.5-500 / 700 (S); the induction plasma spheroidization equipment is produced by Tekna, model TekSphero-80kW.

[0043] Example 1

[0044] A method for preparing niobium-tungsten alloy spherical powder comprises the following steps:

[0045] S1. Batching and mixing: Mix raw material powders consisting of niobium powder, tungsten powder, molybdenum powder and zirconium carbide powder into mixed powders. The purity of the raw material powders is ≥99.99%, and the particle size of the raw material powders is ≤5μm. The raw material ratio is 5%wt% of tungsten powder, 2wt% of molybdenum powder, 1.1wt% of zirconium carbide powder, and the rest is niobium powder. After batching, the powders are placed in a stainless steel ball mill for mixing, and the mixing time in the ball mill is 12h.

[0046] S2. Pressing and sintering: The mixed powder is pressed by isostatic pressing. The pressing die sleeve is cylindrical, with a diameter of 30 mm and a length of 500 mm. The pressing pressure is 150 MPa. The diameter of the pressed blank is 22.5 mm and the length is 460 mm. The pressed blank is placed in a vacuum induction furnace for sintering. The sintering temperature is 1200°C. The blank is heated with the furnace at a heating rate of 10°C / min. It is kept at 1200°C for 2 hours. The vacuum degree of the induction furnace is ≤0.1Pa.

[0047] S3. Powder making and screening: The sintered blank is crushed to less than 0.5 mm by mechanical crushing, and then ground to a non-spherical powder with a powder particle size of less than 100 μm, and then screened in an electric screening equipment, and sieved with 200-mesh and 800-mesh sieves to obtain a non-spherical powder with a particle size of 20 to 70 μm. The mass of the non-spherical powder with a particle size of 20 to 70 μm accounts for 72% of the total mass of the non-spherical powder. The remaining powder can be recovered and ground and reused in the batching.

[0048] S4. Spheroidization: The non-spherical powder of 20 to 70 μm obtained by screening is spheroidized in an induction plasma spheroidization equipment. The spheroidization atmosphere is argon, the spheroidization power is 50 kW, the feeding rate is 50 g / min, and the carrier gas flow rate is 5 L / min.

[0049] Example 2

[0050] A method for preparing niobium-tungsten alloy spherical powder comprises the following steps:

[0051] S1. Batching and mixing: Mix raw material powders consisting of niobium powder, tungsten powder, molybdenum powder and zirconium carbide powder into mixed powders, the purity of the raw material powders is ≥99.99%, the particle size of the raw material powders is ≤5μm, the raw material ratio is 5.0%wt% tungsten powder, 2.0wt% molybdenum powder, 1.1wt% zirconium carbide powder, and the rest is niobium powder. After batching, the powders are placed in a stainless steel ball mill for mixing, and the mixing time in the ball mill is 16h.

[0052] S2. Pressing and sintering: The mixed powder is pressed by isostatic pressing. The pressing die sleeve is cylindrical, with a diameter of 50 mm and a length of 500 mm. The pressing pressure is 180 MPa. The diameter of the pressed blank is 41.6 mm and the length is 463 mm. The pressed blank is placed in a vacuum induction furnace for sintering. The sintering temperature is 1300°C. The blank is heated with the furnace at a heating rate of 10°C / min. It is kept at 1300°C for 2.5 hours. The vacuum degree of the induction furnace is ≤0.1Pa.

[0053] S3. Powder making and screening: The sintered blank is crushed to less than 0.5 mm by mechanical crushing, and then ground to a non-spherical powder with a powder particle size of less than 100 μm, and then screened in an electric screening device. The non-spherical powder with a particle size of 20 to 70 μm is obtained by screening with 200-mesh and 800-mesh sieves. The mass of the non-spherical powder with a particle size of 20 to 70 μm accounts for 70% of the total mass of the non-spherical powder. The remaining powder can be recovered and ground and reused in the batching.

[0054] S4. Spheroidization: The non-spherical powder of 20 to 70 μm obtained by screening is spheroidized in an induction plasma spheroidization equipment. The spheroidization atmosphere is argon, the spheroidization power is 60 kW, the feeding rate is 80 g / min, and the carrier gas flow rate is 5 L / min.

[0055] Example 3

[0056] A method for preparing niobium-tungsten alloy spherical powder comprises the following steps:

[0057] S1. Batching and mixing: Mix raw material powders consisting of niobium powder, tungsten powder, molybdenum powder and zirconium carbide powder into mixed powders, the purity of the raw material powders is ≥99.99%, the particle size of the raw material powders is ≤5μm, the raw material ratio is 4.5wt% tungsten powder, 1.6wt% molybdenum powder, 0.8wt% zirconium carbide powder, and the rest is niobium powder. After batching, the powders are placed in a stainless steel ball mill for mixing, and the mixing time in the ball mill is 14h.

[0058] S2. Pressing and sintering: The mixed powder is pressed by isostatic pressing. The pressing die sleeve is cylindrical, with a diameter of 30 mm and a length of 450 mm. The pressing pressure is 160 MPa. The diameter of the pressed blank is 41.6 mm and the length is 463 mm. The pressed blank is placed in a vacuum induction furnace for sintering. The sintering temperature is 1350°C. The blank is heated with the furnace at a heating rate of 10°C / min. It is kept at 1350°C for 2.5 hours. The vacuum degree of the induction furnace is ≤0.1Pa.

[0059] S3. Powder making and screening: The sintered blank is crushed to less than 0.5 mm by mechanical crushing, and then ground to a non-spherical powder with a powder particle size of less than 100 μm, and then screened in an electric screening device. The non-spherical powder with a particle size of 20 to 70 μm is obtained by screening with 200-mesh and 800-mesh sieves. The mass of the non-spherical powder with a particle size of 20 to 70 μm accounts for 70% of the total mass of the non-spherical powder. The remaining powder can be recovered and ground and reused in the batching.

[0060] S4. Spheroidization: The non-spherical powder of 20 to 70 μm obtained by screening is spheroidized in an induction plasma spheroidization equipment. The spheroidization atmosphere is argon, the spheroidization power is 60 kW, the feeding rate is 70 g / min, and the carrier gas flow rate is 5 L / min.

[0061] Example 4

[0062] A method for preparing niobium-tungsten alloy spherical powder comprises the following steps:

[0063] S1. Batching and mixing: Mix raw material powders consisting of niobium powder, tungsten powder, molybdenum powder and zirconium carbide powder into mixed powders, the purity of the raw material powders is ≥99.99%, the particle size of the raw material powders is ≤5μm, the raw material ratio is 6.6%wt% tungsten powder, 2.8wt% molybdenum powder, 1.8wt% zirconium carbide powder, and the rest is niobium powder. After batching, the powders are placed in a stainless steel ball mill for mixing, and the mixing time in the ball mill is 16h.

[0064] S2. Pressing and sintering: The mixed powder is pressed by isostatic pressing. The pressing die sleeve is cylindrical, with a diameter of 50 mm and a length of 450 mm. The pressing pressure is 180 MPa. The diameter of the pressed blank is 41.6 mm and the length is 463 mm. The pressed blank is placed in a vacuum induction furnace for sintering. The sintering temperature is 1300°C. The blank is heated with the furnace at a heating rate of 10°C / min. It is kept at 1300°C for 2.5 hours. The vacuum degree of the induction furnace is ≤0.1Pa.

[0065] S3. Powder making and screening: The sintered blank is crushed to less than 0.5 mm by mechanical crushing, and then ground to a non-spherical powder with a powder particle size of less than 100 μm, and then screened in an electric screening device. The non-spherical powder with a particle size of 20 to 70 μm is obtained by screening with 200-mesh and 800-mesh sieves. The mass of the non-spherical powder with a particle size of 20 to 70 μm accounts for 70% of the total mass of the non-spherical powder. The remaining powder can be recovered and ground and reused in the batching.

[0066] S4. Spheroidization: The non-spherical powder of 20 to 70 μm obtained by screening is spheroidized in an induction plasma spheroidization equipment. The spheroidization atmosphere is argon, the spheroidization power is 60 kW, the feeding rate is 75 g / min, and the carrier gas flow rate is 5 L / min.

[0067] The spherical powders in Examples 1-4 were tested using the following method:

[0068] 1. Detection of spheroidization rate: Under FEI Inspect F50 scanning electron microscope, magnify 200 times, randomly select 3 fields of view of the same size, and count the number of spherical and non-spherical particles in them respectively. The spheroidization rate is the ratio of the number of spherical particles to the total number of particles. The average of the spheroidization rates of the three fields of view is the final detection spheroidization rate.

[0069] 2. Detect the powder yield: Use the Microtrac S3500 laser particle size analyzer to detect the particle size distribution of the spherical powder, obtain the mass percentage of the 15-60μm powder, calculate the mass of the 15-60μm powder, and the ratio of the powder mass to the mass of the blank after the sintering process in the preparation process is the 15-60μm powder yield.

[0070] 3. Detect the oxygen content of the powder using the test standard: GB / T 15076.14-2008 "Chemical analysis method for tantalum and niobium - Determination of oxygen content".

[0071] 4. To test the powder Hall flowability, the test standard is: GB / T 1482-1984 "Standard funnel method for determination of metal powder flowability (Hall flowmeter)".

[0072] Through the above tests, the powder in Example 1 with a particle size range of 15 to 60 μm after spheroidization accounts for more than 95%, the powder spheroidization rate is 92%, the powder oxygen content is 120 ppm, and the Hall flowability is 8.0 s / 50 g. Figure 2 shown.

[0073] In Example 2, the powder with a particle size range of 15 to 60 μm after spheroidization accounts for more than 95%, the powder spheroidization rate is 90%, the powder oxygen content is 100 ppm, and the Hall flowability is 8.2 s / 50 g. Figure 3 shown.

[0074] In Example 3, the powder with a particle size range of 15 to 60 μm after spheroidization accounts for more than 95%, the powder spheroidization rate is 92%, the powder oxygen content is 110 ppm, and the Hall flowability is 8.1 s / 50 g. Figure 4 shown.

[0075] In Example 4, the powder with a particle size range of 15 to 60 μm after spheroidization accounts for more than 95%, the powder spheroidization rate is 90%, the powder oxygen content is 100 ppm, and the Hall flowability is 8.2 s / 50 g. Figure 5 shown.

[0076] In summary, the spherical powder prepared by the method of the present invention has low powder oxygen content, appropriate powder particle size distribution range, high fine powder yield, and the process flow is short and the production line is easy to build.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing niobium-tungsten alloy spherical powder, characterized in that: The following steps are involved: S1. Batching and mixing: mixing raw material powders consisting of niobium powder, tungsten powder, molybdenum powder and zirconium carbide powder into a mixed powder; S2. Pressing and sintering: The mixed powder is pressed into a block in a mold and sintered into a blank under vacuum; S3. Powdering and sieving: crushing and sieving the blank to obtain a non-spherical powder with a suitable particle size range; S4. Spheroidization: Spheroidizing the non-spherical powder to obtain spherical powder.

2. The method for preparing niobium-tungsten alloy spherical powder according to claim 1, characterized in that: In step S1, the raw material powders are calculated by weight percentage, including 4.5-6.6wt% tungsten powder, 1.6-2.8wt% molybdenum powder, 0.8-1.8wt% zirconium carbide powder, and the rest niobium powder.

3. The method for preparing niobium-tungsten alloy spherical powder according to claim 2, characterized in that: In step S1, the raw material powders are calculated by weight percentage, including 5.0wt% tungsten powder, 2.0wt% molybdenum powder, 1.1wt% zirconium carbide powder, and the rest niobium powder.

4. The method for preparing niobium-tungsten alloy spherical powder according to claim 2, characterized in that: In step S1, the raw material powders are calculated by weight percentage, including 4.5wt% tungsten powder, 1.6wt% molybdenum powder, 0.8wt% zirconium carbide powder, and the rest niobium powder.

5. The method for preparing niobium-tungsten alloy spherical powder according to claim 1, characterized in that: In step S1, the particle size of the raw material powder is ≤5 μm.

6. The method for preparing niobium-tungsten alloy spherical powder according to claim 1, characterized in that: In step S1, a ball mill is used for mixing, and the mixing time is 12 to 16 hours.

7. The method for preparing niobium-tungsten alloy spherical powder according to claim 1, characterized in that: In step S2, the mixed powder is pressed by isostatic pressing, the pressing die sleeve is cylindrical, the diameter is 30-50 mm, and the pressing pressure is 150-180 MPa.

8. The method for preparing niobium-tungsten alloy spherical powder according to claim 1, characterized in that: In step S2, vacuum sintering is performed in a vacuum induction furnace at a temperature of 1200-1350°C and a vacuum degree of ≤0.1Pa.

9. The method for preparing niobium-tungsten alloy spherical powder according to claim 1, characterized in that: In step S3, the non-spherical powder with a suitable particle size range includes non-spherical powder with a particle size of 20 to 70 μm, and the mass of the non-spherical powder with a particle size of 20 to 70 μm accounts for ≥65% of the total mass of the non-spherical powder.

10. The method for preparing niobium-tungsten alloy spherical powder according to claim 1, characterized in that: In step S4, spheroidization is performed using an induction plasma spheroidization device.

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