A method for preparing a tungsten-molybdenum alloy powder based on coprecipitated precursors
By using the method of co-precipitating tungsten-molybdenum salt precursors, tungsten-molybdenum alloy powder is generated under hydrogen reduction conditions using zinc or cadmium salts. This solves the problems of high energy consumption and expensive equipment in the traditional high-temperature sintering preparation of tungsten-molybdenum alloys, and achieves energy saving, consumption reduction and preparation of uniform alloy powder.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGXI UNIV OF SCI & TECH
- Filing Date
- 2025-08-22
- Publication Date
- 2026-06-02
AI Technical Summary
Existing tungsten-molybdenum alloy preparation processes and equipment are expensive, the process conditions are harsh, high-temperature sintering consumes a lot of energy, and traditional methods are difficult to obtain alloy products in powder or particle form.
Using tungsten-molybdate coprecipitation precursors and zinc or cadmium salts as precipitants, tungsten-molybdenum alloy powder is generated under hydrogen reduction conditions. Combined with the evaporation and concentration of the precipitate mother liquor and the freeze crystallization process, uniform mixing and alloying of tungsten and molybdenum are achieved.
The alloying reaction temperature was lowered, saving energy and simplifying the preparation process. Uniform tungsten-molybdenum alloy powder with dispersed tungsten and molybdenum elements was obtained, and no wastewater was produced.
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Figure CN120940653B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of materials preparation technology, and specifically to a method for preparing tungsten-molybdenum alloy powder based on a co-precipitation precursor. Background Technology
[0002] Tungsten, with its high melting point, high tensile strength, low sputtering properties, and trace tritium retention, is considered one of the most promising plasma-oriented candidate materials for fusion reactors. However, the inherent defects of pure tungsten, such as poor high-temperature radiation stability, low oxidation resistance, poor room-temperature ductility, and high ductile-brittle transition temperature, limit its practical applications. Therefore, it is urgent to improve its service reliability under the extreme conditions of magnetic confinement fusion through material modification. Alloying has proven to be an important way to overcome its performance bottlenecks. Among all tungsten alloys, tungsten-molybdenum alloys have attracted attention due to their high melting temperature, good thermal conductivity, and low tritium retention, making them promising for engineering applications in fields such as nuclear fusion reactors.
[0003] Currently, most tungsten-molybdenum alloys are prepared using powder metallurgy: tungsten and molybdenum powders are mechanically mixed, and then solidified using techniques such as pressing-sintering, hot pressing-sintering, and hot isostatic pressing. High-energy ball milling is also used as an alternative method for preparing nanocrystalline tungsten-molybdenum alloy powders. DC magnetron sputtering is another technique that can be used to prepare tungsten-molybdenum alloy thin films with different compositions. Regardless of the pretreatment method used, the resulting tungsten-molybdenum mixture usually needs to be sintered at a high temperature of 1200 to 2000°C to achieve alloying. However, the above techniques generally suffer from drawbacks such as expensive equipment and demanding process conditions: for example, hot isostatic pressing equipment requires high investment, and magnetron sputtering systems require maintaining an ultra-high vacuum environment. Because tungsten (melting point 3380°C) and molybdenum (melting point 2610°C) have extremely high melting points, the high-temperature sintering process required for alloying consumes a huge amount of energy. Furthermore, tungsten-molybdenum alloys prepared by traditional mechanical mixing-pressing-sintering are dense bulk materials, and it is impossible to directly obtain alloy products in powder particle form. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing tungsten-molybdenum alloy powder based on a co-precipitation precursor, which aims to use tungsten-molybdenate co-precipitation as a precursor to generate tungsten-molybdenum alloy under hydrogen reduction conditions.
[0005] To achieve the above objectives, the present invention proposes a method for preparing tungsten-molybdenum alloy powder based on a co-precipitation precursor, comprising the following steps:
[0006] (1) Prepare a tungsten-molybdenum mixed solution by mixing sodium tungstate, sodium molybdate and water; mix the tungsten-molybdenum mixed solution with a precipitant solution containing zinc salt or cadmium salt or the regenerated precipitant solution returned from step (3), wherein the molar amount of zinc or cadmium in the precipitant solution is 1.2 to 1.5 times the total molar amount of tungsten and molybdenum in the tungsten-molybdenum mixed solution, and allow the tungsten and molybdenum to coprecipitate under stirring; after the reaction slurry is filtered and washed, the precipitate obtained is a wet residue of tungsten-molybdate coprecipitate, and the filtrate is the mother liquor of the precipitate;
[0007] (2) The wet residue of tungsten molybdate coprecipitate obtained in step (1) is dried and ground to obtain tungsten molybdate coprecipitate powder; the tungsten molybdate coprecipitate powder is reduced in a hydrogen stream at 700~1000℃ to obtain tungsten molybdenum alloy powder and zinc or cadmium vapor; the zinc or cadmium vapor is carried out by the hydrogen stream and condenses in the condensation section at 500℃ and below to obtain solid metal;
[0008] (3) The precipitate mother liquor obtained in step (1) is evaporated and concentrated to obtain a concentrated liquid. The condensate recovered by evaporation is returned to step (1) for use. The concentrated liquid is frozen and crystallized to precipitate sodium salt. Sodium salt crystals and crystallization mother liquor are obtained by solid-liquid separation. Zinc salt or cadmium salt is added to the crystallization mother liquor to obtain a regenerated precipitant solution.
[0009] Preferably, in step (1), the molar ratio of tungsten to molybdenum in the tungsten-molybdenum mixed solution is between 0.1 and 10; the zinc salt includes one or more of zinc chloride, zinc nitrate, zinc acetate, and zinc sulfate; and the cadmium salt includes one or more of cadmium chloride, cadmium nitrate, cadmium acetate, and cadmium sulfate.
[0010] Preferably, when the precipitant solution in step (1) is a cadmium salt solution, the temperature of the coprecipitation reaction is 5~100℃ and the reaction time is 0.5~2 hours; when the precipitant solution in step (1) is a zinc salt solution, the temperature of the coprecipitation reaction is 95~100℃ and the reaction time is 3~5 hours.
[0011] Preferably, when the tungsten-molybdenum coprecipitated powder in step (2) contains zinc, the reduction temperature is 850~1000℃ and the reduction time is 1~2 hours; when the tungsten-molybdenum coprecipitated powder in step (2) contains cadmium, the reduction temperature is 700~850℃ and the reduction time is 0.5~1 hour.
[0012] Preferably, the freezing temperature in step (3) is -5~5℃.
[0013] The technical principles employed in this invention are as follows:
[0014] This invention first involves a co-precipitation reaction between tungstate and molybdate to obtain a tungstomolybdate coprecipitate. The precipitant used is a zinc salt or a cadmium salt. The coprecipitation reaction is shown in equations (1) and (2).
[0015]
[0016] After hydrogen reduction of the tungsten-molybdate coprecipitate, zinc or cadmium will be reduced to elemental form and volatilize, thus separating it from tungsten and molybdenum. Tungsten and molybdenum are then reduced to tungsten-molybdenum alloy powder. The reduction process is shown in equations (3) and (4), and x + y = 1 in equations (1-4).
[0017]
[0018] Zinc or cadmium vapors condense at low temperatures to obtain the corresponding solid metals. The reactions are shown in equations (5) and (6).
[0019]
[0020] This invention uses a co-precipitate of tungsten and molybdenum at the atomic level as a precursor, followed by a one-step hydrogen reduction process to obtain a homogeneous tungsten-molybdenum alloy powder. Compared to the traditional process of mixing tungsten and molybdenum powders and sintering them at high temperatures for an extended period to prepare tungsten-molybdenum alloy powder, this invention combines the reduction and alloying reactions into one, with a reaction temperature below 1000℃, thus shortening the tungsten-molybdenum alloy powder preparation process and significantly reducing energy consumption. This invention uses zinc or cadmium salts as precipitants, which can be reduced during hydrogen reduction and volatilized and condensed to obtain solid metals. The purity of zinc and cadmium can reach over 99.9%, achieving value-added utilization of zinc and cadmium salts. Combined with the evaporation and concentration of the precipitate mother liquor and the freeze crystallization process, the tungsten-molybdenum alloy powder preparation process produces no wastewater. Attached Figure Description
[0021] Figure 1 The image shows the XRD pattern of the tungsticoline coprecipitate of Example 1 of this invention.
[0022] Figure 2 This is a SEM image of the tungsten-molybdate coprecipitate of Example 1 of the present invention.
[0023] Figure 3 The image shows the XRD pattern of the tungsten-molybdenum alloy powder of Example 1 of the present invention.
[0024] Figure 4 This is a SEM image of the tungsten-molybdenum alloy powder of Example 1 of the present invention.
[0025] Figure 5 The following are EDS images of the tungsten-molybdenum alloy powder of Example 1 of the present invention: (a) EDS layered image; (b) EDS electron image; (c) EDS surface scan tungsten element distribution map; (d) EDS surface scan molybdenum element distribution map.
[0026] Figure 6 The image shows the XRD pattern of the tungsten molybdate coprecipitate of Example 2 of the present invention.
[0027] Figure 7This is a SEM image of the tungsten-molybdate coprecipitate of Example 2 of the present invention.
[0028] Figure 8 This is the XRD pattern of the tungsten-molybdenum alloy powder of Example 2 of the present invention.
[0029] Figure 9 This is a SEM image of the tungsten-molybdenum alloy powder of Example 2 of the present invention.
[0030] Figure 10 The following are EDS images of the tungsten-molybdenum alloy powder of Example 2 of the present invention: (a) EDS layered image; (b) EDS electron image; (c) EDS surface scan tungsten element distribution map; (d) EDS surface scan molybdenum element distribution map. Detailed Implementation
[0031] The present invention will be further illustrated by the following examples, but is not limited thereto.
[0032] Example 1
[0033] A 0.5 L mixed solution of tungstate and molybdate was prepared by dissolving 0.5 mol sodium tungstate, 0.5 mol sodium molybdate, and water. A precipitant solution was prepared by dissolving 1.3 mol cadmium chloride in 0.25 L of water. The tungstate and molybdate mixed solution and the precipitant solution were mixed under stirring and reacted at 100°C for 2 hours. The resulting slurry was filtered and washed with water to obtain a wet residue of tungstate and molybdate coprecipitate and a mother liquor. The wet residue of tungstate and molybdate coprecipitate was dried and ground to obtain tungstate and molybdate coprecipitate powder. The XRD and SEM morphology images of the tungstate and molybdate coprecipitate are attached. Figure 1 With appendix Figure 2 As shown, by appendix Figure 2 SEM images show that the tungsten-molybdate coprecipitate obtained using cadmium chloride as a precipitant solution exhibits a plate-like stacked structure with a particle size of approximately 80 nm. The tungsten-molybdate coprecipitate powder was reduced in a hydrogen stream at 850 °C for 1 hour to obtain tungsten-molybdenum alloy powder. Metallic cadmium was collected in the condensation section at 350–450 °C. The XRD pattern of the obtained tungsten-molybdenum alloy powder is shown in the attached figure. Figure 3 As shown in the attached SEM image. Figure 4 As shown, its EDS plot is attached. Figure 5 As shown. (From the appendix) Figure 4 As can be seen, the obtained tungsten-molybdenum alloy powder has a uniform particle size. (The last sentence appears to be incomplete and possibly refers to an error.) Figure 5 It can be seen that tungsten and molybdenum are uniformly dispersed in the alloy powder. Chemical analysis showed that the purity of the cadmium metal obtained after condensation was 99.98%. The precipitate mother liquor was evaporated and concentrated, then frozen and crystallized at -5℃. After solid-liquid separation, the obtained crystals were sodium chloride crystals.
[0034] Example 2
[0035] A 0.5 L mixed solution of tungstate and molybdate was prepared by dissolving 0.5 mol sodium tungstate, 0.5 mol sodium molybdate, and water. A precipitant solution was prepared by dissolving 1.3 mol zinc nitrate in 0.3 L of water. The tungstate-molybdate mixed solution and the precipitant solution were mixed under stirring and reacted at 95°C for 5 hours. The resulting slurry was filtered and washed with water to obtain a wet residue of tungstate-molybdate coprecipitate and a mother liquor. The wet residue of tungstate-molybdate coprecipitate was dried and ground to obtain tungstate-molybdate coprecipitate powder. The XRD and SEM morphology images of the tungstate-molybdate coprecipitate are attached. Figure 6 With appendix Figure 7 As shown, by appendix Figure 7 SEM images show that the tungsten-molybdate coprecipitate obtained using zinc nitrate as a precipitant solution has a fine granular structure with a particle size of approximately 10 nm. The tungsten-molybdate coprecipitate powder was reduced in a hydrogen stream at 850 °C for 2 hours to obtain tungsten-molybdenum alloy powder. Metallic zinc was collected in the condensation section at 400–500 °C. The XRD pattern of the obtained tungsten-molybdenum alloy powder is shown in the attached figure. Figure 8 As shown in the attached SEM image. Figure 9 As shown, its EDS plot is attached. Figure 10 As shown. (From the appendix) Figure 9 As can be seen, the obtained tungsten-molybdenum alloy powder has a uniform particle size. (The last sentence appears to be incomplete and possibly refers to an error.) Figure 10 It can be seen that tungsten and molybdenum are uniformly dispersed in the alloy powder. Chemical analysis showed that the purity of the zinc obtained after condensation was 99.95%. The precipitate mother liquor was evaporated and concentrated, then frozen and crystallized at -5℃. After solid-liquid separation, the obtained crystals were sodium nitrate crystals.
[0036] Example 3
[0037] A 0.5 L mixed solution of tungstate and molybdate was prepared by dissolving 1 mol sodium tungstate, 0.1 mol sodium molybdate, and water. A precipitant solution was prepared by dissolving 1.2 mol cadmium acetate in 0.4 L of water. The tungstate and molybdate mixed solution and the precipitant solution were mixed under stirring and reacted at 5°C for 0.5 hours. The resulting slurry was filtered and washed with water to obtain a wet residue of tungstate and molybdate coprecipitate and a mother liquor. The wet residue of tungstate and molybdate coprecipitate was dried and ground to obtain tungstate and molybdate coprecipitate powder. The tungstate and molybdate coprecipitate powder was reduced in a hydrogen stream at 700°C for 0.5 hours to obtain tungstate and molybdate alloy powder. Metallic cadmium was collected in the condensation section at 400-500°C. The purity of the metallic cadmium obtained after condensation was determined to be 99.93% by chemical methods. The mother liquor was evaporated and concentrated, and then frozen and crystallized at -3°C. After solid-liquid separation, the obtained crystals were sodium acetate crystals.
[0038] Example 4
[0039] A 0.5 L mixed solution of tungstate and molybdate was prepared by dissolving 0.1 mol sodium tungstate, 1 mol sodium molybdate, and water. A precipitant solution was prepared by dissolving 1.5 mol zinc sulfate in 1 L of water. The tungstate and molybdate mixed solution and the precipitant solution were mixed under stirring and reacted at 100°C for 3 hours. The resulting slurry was filtered and washed with water to obtain a wet residue of tungstate and molybdate coprecipitate and a mother liquor. The wet residue of tungstate and molybdate coprecipitate was dried and ground to obtain tungstate and molybdate coprecipitate powder. The tungstate and molybdate coprecipitate powder was reduced in a hydrogen stream at 1000°C for 1 hour to obtain tungstate and molybdate alloy powder. Metallic zinc was collected in the condensation section at 400-500°C. The purity of the metallic zinc obtained by condensation was determined to be 99.96% by chemical methods. The mother liquor was evaporated and concentrated, and then frozen to crystallize at 5°C. After solid-liquid separation, the obtained crystals were sodium sulfate crystals.
Claims
1. A method for preparing tungsten-molybdenum alloy powder based on a co-precipitation precursor, characterized in that, Includes the following steps: (1) Prepare a tungsten-molybdenum mixed solution by mixing sodium tungstate, sodium molybdate and water; mix the tungsten-molybdenum mixed solution with a precipitant solution containing zinc salt or cadmium salt or the regenerated precipitant solution returned from step (3), wherein the molar amount of zinc or cadmium in the precipitant solution is 1.2 to 1.5 times the total molar amount of tungsten and molybdenum in the tungsten-molybdenum mixed solution, and allow the tungsten and molybdenum to coprecipitate under stirring; after the reaction slurry is filtered and washed, the precipitate obtained is a wet residue of tungsten-molybdate coprecipitate, and the filtrate is the mother liquor of the precipitate; (2) The wet residue of tungsten molybdate coprecipitate obtained in step (1) is dried and ground to obtain tungsten molybdate coprecipitate powder; the tungsten molybdate coprecipitate powder is reduced in a hydrogen stream at 700~1000℃ to obtain tungsten molybdenum alloy powder and zinc or cadmium vapor; the zinc or cadmium vapor is carried out by the hydrogen stream and condenses in the condensation section at 500℃ and below to obtain solid metal; (3) The precipitate mother liquor obtained in step (1) is evaporated and concentrated to obtain a concentrated liquid. The condensate recovered by evaporation is returned to step (1) for use. The concentrated liquid is frozen and crystallized to precipitate sodium salt. Sodium salt crystals and crystallization mother liquor are obtained by solid-liquid separation. Zinc salt or cadmium salt is added to the crystallization mother liquor to obtain a regenerated precipitant solution. When the tungsten molybdate coprecipitate powder in step (2) contains cadmium, the reduction temperature is 700~850℃ and the reduction time is 0.5~1 hour; the freezing crystallization temperature in step (3) is -5~5℃; when the tungsten molybdate coprecipitate powder in step (2) contains zinc, the reduction temperature is 850~1000℃ and the reduction time is 1~2 hours.
2. The method as described in claim 1, characterized in that, In step (1), the molar ratio of tungsten to molybdenum in the tungsten-molybdenum mixed solution is between 0.1 and 10.
3. The method as described in claim 1, characterized in that, Zinc salts include one or more of zinc chloride, zinc nitrate, zinc acetate, and zinc sulfate.
4. The method as described in claim 1, characterized in that, Cadmium salts include one or more of cadmium chloride, cadmium nitrate, cadmium acetate, and cadmium sulfate.
5. The method as described in claim 1, characterized in that, When the precipitant solution in step (1) is a cadmium salt solution, the temperature of the coprecipitation reaction is 5~100℃ and the reaction time is 0.5~2 hours.
6. The method as described in claim 1, characterized in that, When the precipitant solution in step (1) is a zinc salt solution, the temperature of the coprecipitation reaction is 95~100℃ and the reaction time is 3~5 hours.