A kind of molybdenum-rhenium pre-alloyed powder and its preparation method using wet chemical method

Abstract

The present invention relates to the technical field of powder metallurgy, and in particular to a method for preparing molybdenum-rhenium pre-alloyed powder by a wet chemical method. The method specifically comprises the following steps: weighing a Mo source and a Re source respectively according to a designed ratio, and mixing them to form a gel-like precipitate; drying and decomposing the precipitate, and crushing the dried and decomposed product through a 200-mesh sieve to obtain a composite oxide powder; placing the sieved composite oxide powder in a tubular furnace, and performing hydrogen reduction to finally obtain a molybdenum-rhenium pre-alloyed powder. The beneficial effects of the present invention are as follows: the raw materials of the method are mixed at the atomic level by liquid-liquid mixing, and the purity of the pre-alloyed powder can be ensured while improving the uniformity of the powder composition. The raw materials required for the preparation method are easy to obtain, low in cost, simple in process, freely adjustable in composition, and efficient and safe in process, and are very suitable for use in industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, and in particular to a molybdenum-rhenium pre-alloyed powder and a method for preparing the powder by a wet chemical method. Background Art

[0002] Due to the so-called "rhenium effect", molybdenum-rhenium (Mo-Re) alloys have greatly improved the strength, plasticity and machinability of the alloys, and also greatly reduced the ductile-brittle transition temperature of the alloys. Therefore, they have been widely used in aerospace, medical, nuclear industry and other fields. For example, Mo-Re alloys can be used as heat pipe materials for space nuclear reactors due to their excellent radiation resistance; Mo-Re alloys have high tensile strength and ductility, and can be made into very fine wires as good elastic elements; in addition, Mo-Re alloys have good high-temperature properties and can also be used as high-temperature structural parts such as heaters and thermocouples. At present, the industry usually uses powder metallurgy to prepare Mo-Re alloys, that is, molybdenum powder and rhenium powder are first mechanically mixed, and then pressed and high-temperature sintered to obtain molybdenum-rhenium alloy blanks, and finally made into different profiles through a hot plastic deformation process. As we all know, the uniformity and sintering activity of alloy powders prepared by mechanical powder mixing are poor, and the introduction of impurity elements caused by long-term mixing cannot be avoided, thus affecting the purity and performance of the final product. To this end, the industry has tried to use molybdenum oxide powder and ammonium rhenate solid for mechanical mixing, and then decompose and hydrogen reduce to prepare molybdenum-rhenium pre-alloyed powder. This solid-solid mixing method can achieve a certain degree of mutual diffusion of Mo and Re elements through hydrogen reduction, and the uniformity of the prepared powder will be greatly improved, but the preparation process still cannot avoid the introduction of impurities caused by ball milling, resulting in a low purity of the final alloy product. The liquid-liquid mixing method can achieve atomic-level mixing and achieve a high uniformity distribution of Mo and Re elements. Patent CN 111112641 discloses a method for preparing a nano-molybdenum-rhenium composite powder, which uses ammonium molybdate and ammonium rhenate as raw materials, and configures a certain proportion of oxidant and fuel, adds water to fully stir and dissolve to prepare a solution, and stirs at a certain temperature for a period of time until the combustion reaction begins to obtain a precursor powder, and finally prepares Mo-Re pre-alloyed powder by hydrogen reduction. However, when preparing powder in large quantities, its combustion reaction is violent, and there is a certain safety risk; and insufficient combustion is likely to cause oxidant and fuel residues, affecting the purity of the final powder. Summary of the invention

[0003] In order to solve the above-mentioned problems existing in the prior art, the purpose of the present invention is to provide a molybdenum-rhenium pre-alloyed powder and a method for preparing it by a wet chemical method. The method realizes atomic-level mixing of Mo and Re elements without reducing the purity of the molybdenum-rhenium pre-alloyed powder, and fully pre-alloys Mo and Re elements through hydrogen reduction interdiffusion. The process is simple, efficient and safe.

[0004] The present invention achieves the above-mentioned object through the following technical scheme: A method for preparing molybdenum-rhenium pre-alloyed powder by wet chemical method, the method specifically comprising the following steps:

[0005] S1) weighing a Mo source and a Re source according to the designed ratio, mixing them to form a gel precipitate;

[0006] S2) drying and decomposing the precipitate, and crushing the dried and decomposed product through a 200-mesh sieve to obtain a composite oxide powder;

[0007] S3) placing the sieved composite oxide powder into a tubular furnace for hydrogen reduction to finally obtain molybdenum-rhenium pre-alloyed powder.

[0008] Further, the specific S1) is:

[0009] S1.1) According to the mass ratio of (1-x)Mo-xRe, x is 3-47.5wt%, weigh the Mo source and Re source respectively;

[0010] S1.2) placing the Mo source and Re source weighed in S1.1) in a stirred tank filled with deionized water to dissolve, and stirring in an oil bath at a certain temperature to form a clear solution;

[0011] S1.3) Add a certain amount of complexing agent to the clear solution and stir thoroughly until it is completely dissolved, and form a gel-like precipitate after the water evaporates.

[0012] Furthermore, the Mo source in S1.1) is ammonium heptamolybdate tetrahydrate, and the Re source is ammonium perrhenate.

[0013] Furthermore, the oil bath stirring temperature in S1.2) is 90-120° C., and the mass fraction of the clear solution is 10%-30%.

[0014] Furthermore, the amount of the complexing agent in S1.3) is added according to a molar ratio of the complexing agent to the metal ion of 0.5 to 2.

[0015] Furthermore, the complexing agent is at least one of oxalic acid, citric acid and malonic acid.

[0016] Furthermore, the drying equipment in S2) adopts a blast drying oven, the drying temperature is 180-250° C., and the drying time is controlled at 7-9 hours.

[0017] Furthermore, the hydrogen reduction in S3) is a three-stage hydrogen reduction method, and the hydrogen flow rate is maintained at 0.5-2 L / min during the entire hydrogen reduction process.

[0018] Further, the three-stage hydrogen reduction method is specifically:

[0019] The first stage reduction temperature is 200-250°C and the holding time is 1-3h;

[0020] The second stage reduction temperature is 400-600°C and the holding time is 1-3h;

[0021] The third stage reduction temperature is 900-1000°C, and the insulation time is 2-4h.

[0022] A molybdenum-rhenium pre-alloyed powder is prepared by the above-mentioned preparation method, and the purity of the molybdenum-rhenium pre-alloyed powder is not less than 99.96%.

[0023] The beneficial effects of the present invention are:

[0024] The method of the present invention realizes atomic-level mixing of Mo and Re elements by liquid-liquid mixing, and realizes pre-alloying of Mo and Re elements by mutual diffusion in a coordinated three-stage hydrogen reduction method, and the prepared molybdenum-rhenium pre-alloyed powder has uniform composition, fine particle size and high purity, thereby solving the problems of uneven mixing and impurity introduction caused by long-term ball milling during solid-solid mechanical mixing, and is conducive to improving the organization and composition uniformity of molybdenum-rhenium alloy and product purity. The process of the present invention is simple and efficient, the composition is freely adjustable, the preparation process can avoid the safety risks and fuel residue problems caused by the combustion method, and can realize the preparation of high-uniformity and high-purity molybdenum-rhenium pre-alloyed powder, which is very suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the morphology and element energy spectrum distribution diagram of the Mo-5wt%Re pre-alloyed powder prepared in Example 1 of the present invention.

[0026] Figure 2 This is the morphology and element energy spectrum distribution diagram of the Mo-14wt%Re pre-alloyed powder prepared in Example 2 of the present invention.

[0027] Figure 3 This is the morphology and element energy spectrum distribution diagram of the Mo-47.5wt%Re pre-alloyed powder prepared in Example 3 of the present invention.

[0028] Figure 4 The present invention is a flowchart of a method for preparing molybdenum-rhenium pre-alloyed powder by a wet chemical method. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0030] like Figure 4 As shown, the present invention provides a method for preparing molybdenum-rhenium pre-alloyed powder by a wet chemical method, and the method specifically comprises the following steps:

[0031] S1) weighing a Mo source and a Re source according to the designed ratio, mixing them to form a gel precipitate;

[0032] S2) drying and decomposing the precipitate, and crushing the dried and decomposed product through a 200-mesh sieve to obtain a composite oxide powder;

[0033] S3) placing the sieved composite oxide powder into a tubular furnace for hydrogen reduction to finally obtain molybdenum-rhenium pre-alloyed powder.

[0034] The specific S1) is:

[0035] S1.1) According to the mass ratio of (1-x)Mo-xRe, x is 3-47.5wt%, weigh the Mo source and Re source respectively;

[0036] S1.2) placing the Mo source and Re source weighed in S1.1) in a stirred tank filled with deionized water to dissolve, and stirring in an oil bath at a certain temperature to form a clear solution;

[0037] S1.3) Add a certain amount of complexing agent to the clear solution and stir thoroughly until it is completely dissolved, and form a gel-like precipitate after the water evaporates.

[0038] The Mo source in S1.1) is ammonium heptamolybdate tetrahydrate, and the Re source is ammonium perrhenate.

[0039] The oil bath stirring temperature in S1.2) is 90-120° C., and the mass fraction of the clear solution is 10%-30%.

[0040] The amount of the complexing agent in S1.3) is added according to a molar ratio of the complexing agent to the metal ion of 0.5 to 2.

[0041] The complexing agent is at least one of oxalic acid, citric acid and malonic acid.

[0042] The drying equipment in S2) adopts a blast drying oven, the drying temperature is 180-250° C., and the drying time is controlled at 7-9 hours.

[0043] The hydrogen reduction in S3) is a three-stage hydrogen reduction method, and the hydrogen flow rate is maintained at 0.5-2 L / min during the entire hydrogen reduction process.

[0044] Further, the three-stage hydrogen reduction method is specifically:

[0045] The first stage reduction temperature is 200-250°C and the holding time is 1-3h;

[0046] The second stage reduction temperature is 400-600°C and the holding time is 1-3h;

[0047] The third stage reduction temperature is 900-1000°C, and the insulation time is 2-4h.

[0048] A molybdenum-rhenium pre-alloyed powder is prepared by the above-mentioned preparation method, and the purity of the molybdenum-rhenium pre-alloyed powder is not less than 99.96%.

[0049] Example 1

[0050] The Mo-5wt%Re pre-alloyed powder is prepared in the following steps:

[0051] (1) According to the calculation of preparing 1 kg Mo-5wt%Re pre-alloyed powder, 1747.93 g ammonium heptamolybdate tetrahydrate and 72.03 g ammonium perrhenate powder were weighed and dissolved in a stirred kettle filled with deionized water, and stirred in an oil bath at 90°C to form a solution with a mass fraction of 30%; then 75.75 g oxalic acid and 176.8 g citric acid were added and stirred thoroughly until completely dissolved; after the water evaporated, a gelatinous precipitate was formed,

[0052] (2) placing the precipitate in a 180° C. forced air drying oven for drying and decomposition, and crushing the dried product and passing it through a 200-mesh sieve to obtain a composite oxide powder;

[0053] (3) The sieved composite oxide powder is placed in a tubular furnace and reduced in three stages under a flowing hydrogen atmosphere of 0.5 L / min. The first stage reduction temperature is 200°C and the insulation time is 1 h; the second stage reduction temperature is 400°C and the insulation time is 1 h; the third stage reduction temperature is 900°C and the insulation time is 2 h; after cooling in the furnace, Mo-5wt%Re pre-alloyed powder is obtained.

[0054] After testing, the purity of the prepared powder is 99.96%, and the powder morphology is as follows Figure 1 As shown, the EDS surface scanning spectrum proves that the Mo and Re elements in the powder are evenly distributed.

[0055] Example 2

[0056] The Mo-14wt%Re pre-alloyed powder is prepared in the following steps:

[0057] (1) According to the calculation of preparing 1 kg Mo-14wt%Re pre-alloyed powder, 1582.34 g ammonium heptamolybdate tetrahydrate and 201.67 g ammonium perrhenate powder were weighed and dissolved in a stirred kettle filled with deionized water, and stirred in an oil bath at 100°C to form a solution with a mass fraction of 20%; then 89.75 g oxalic acid and 231.1 g malonic acid were added and stirred thoroughly until completely dissolved; after the water evaporated, a gelatinous precipitate was formed,

[0058] (2) placing the precipitate in a 220° C. forced air drying oven for drying and decomposition, and crushing the dried product and passing it through a 200-mesh sieve to obtain a composite oxide powder;

[0059] (3) The sieved composite oxide powder is placed in a tubular furnace and subjected to three-stage reduction in a flowing hydrogen atmosphere at a flow rate of 1 L / min. The first stage reduction temperature is 230°C and the holding time is 1.5 h; the second stage reduction temperature is 500°C and the holding time is 2 h; the third stage reduction temperature is 950°C and the holding time is 3 h. After cooling in the furnace, a Mo-14wt%Re pre-alloyed powder is obtained.

[0060] After testing, the purity of the prepared powder is 99.97%, and the powder morphology is as follows Figure 2 As shown, the EDS surface scanning spectrum proves that the Mo and Re elements in the powder are evenly distributed.

[0061] Example 3

[0062] The Mo-47.5wt%Re pre-alloyed powder is prepared in the following steps:

[0063] (1) According to the calculation of preparing 1 kg Mo-47.5wt%Re pre-alloyed powder, 965.96 g ammonium heptamolybdate tetrahydrate and 684.24 g ammonium perrhenate powder were weighed and dissolved in a stirred kettle filled with deionized water, and stirred in an oil bath at 120°C to form a solution with a mass fraction of 10%; then 722.2 g oxalic acid was added and stirred thoroughly until it was completely dissolved; after the water evaporated, a gelatinous precipitate was formed,

[0064] (2) placing the precipitate in a 250° C. forced air drying oven for drying and decomposition, and crushing the dried product and passing it through a 200-mesh sieve to obtain a composite oxide powder;

[0065] (3) The sieved composite oxide powder is placed in a tubular furnace and subjected to three-stage reduction in a flowing hydrogen atmosphere at 2 L / min. The first stage reduction temperature is 250°C and the holding time is 2 h; the second stage reduction temperature is 600°C and the holding time is 2 h; the third stage reduction temperature is 1000°C and the holding time is 4 h. After cooling in the furnace, Mo-47.5wt%Re pre-alloyed powder is obtained.

[0066] After testing, the purity of the prepared powder is 99.98%, and the powder morphology is as follows Figure 3 As shown, the EDS surface scanning spectrum proves that the Mo and Re elements in the powder are evenly distributed.

[0067] In summary, the molybdenum-rhenium pre-alloyed powder prepared by the embodiment of the present invention has the characteristics of fine particle size, uniform composition, high purity, etc., and the raw materials used in the method of the present invention are easy to obtain and low in cost. At the same time, the process is simple, the composition is freely adjustable, the process is efficient and safe, and it is very suitable for large-scale industrial production.

[0068] The above is an embodiment of the present invention with better effects, which is non-limiting to the present invention and is only used to illustrate the detailed sample preparation process of the present invention, but does not mean that the present invention is limited to the above sample preparation process. It should be noted that any simple improvement and content modification of the technology of the present invention, without departing from the technical scope of the present invention, belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing molybdenum-rhenium pre-alloyed powder by wet chemical method, characterized in that: The method specifically comprises the following steps: S1) weighing a Mo source and a Re source according to the designed ratio, mixing them to form a gel precipitate; The specific steps of S1) are: S1.1) weighing a Mo source and a Re source respectively according to a mass ratio of (1-x)Mo-xRe, where x is 3 to 47.5wt%; The Mo source is ammonium heptamolybdate tetrahydrate, and the Re source is ammonium perrhenate; S1.2) The Mo source and Re source weighed in S1.1) are placed in a stirred tank filled with deionized water to dissolve, and stirred in an oil bath at a temperature of 90-120°C to form a clear solution; the mass fraction of the clear solution is 10%-30%; S1.3) Add a certain amount of complexing agent to the clear solution and stir thoroughly until it is completely dissolved, and form a gelatinous precipitate after the water evaporates; The amount of the complexing agent is added according to a molar ratio of the complexing agent to the metal ion of 0.5 to 2; The complexing agent is at least two of oxalic acid, citric acid and malonic acid; S2) drying and decomposing the precipitate, and crushing the dried and decomposed product through a 200-mesh sieve to obtain a composite oxide powder; S3) placing the sieved composite oxide powder into a tubular furnace for hydrogen reduction to finally obtain molybdenum-rhenium pre-alloyed powder.

2. The method according to claim 1, characterized in that: The drying equipment in S2) adopts a blast drying oven, the drying temperature is 180-250° C., and the drying time is controlled at 7-9 hours.

3. The method according to claim 1, characterized in that: The hydrogen reduction in S3) is a three-stage hydrogen reduction method, and the hydrogen flow rate is maintained at 0.5-2 L / min during the entire hydrogen reduction process.

4. The method according to claim 3, characterized in that The three-stage hydrogen reduction method is specifically as follows: the first stage reduction temperature is 200-250°C, and the insulation time is 1-3h; the second stage reduction temperature is 400-600°C, and the insulation time is 1-3h; the third stage reduction temperature is 900-1000°C, and the insulation time is 2-4h.

5. A molybdenum-rhenium pre-alloyed powder, wherein the molybdenum-rhenium pre-alloyed powder is prepared by the preparation method according to any one of claims 1 to 4, and the purity of the molybdenum-rhenium pre-alloyed powder is not less than 99.96%.

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