Method for preparing tungsten molybdenum alloy powder through tungsten molybdate coprecipitation
The preparation of tungsten-molybdenum alloy powder at low temperature by tungsten-molybdate co-precipitation solves the problems of high temperature and high energy consumption in traditional methods, achieves uniform mixing of tungsten and molybdenum and recycling of lead, and reduces preparation cost and energy consumption.
Patent Information
- Application Number
- CN202511182072.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-22
- Publication Date
- 2025-12-12
AI Technical Summary
Traditional methods for preparing tungsten-molybdenum alloys suffer from problems such as high alloying temperature, high energy consumption, large equipment investment, and difficulty in achieving uniform composition.
The tungsten-molybdate coprecipitation method uses lead salt as a precipitant to generate tungsten-molybdenum alloy by high-temperature reduction under a hydrogen atmosphere. The tungsten and molybdenum are then separated and the lead is recovered through vacuum treatment, which reduces the alloying temperature and improves the composition uniformity.
This method achieves efficient alloying of tungsten molybdate co-precipitation at low temperatures, reducing energy consumption, improving the purity and uniformity of tungsten molybdenum alloy powder, and enabling value-added utilization of lead and zero wastewater discharge.
Smart Images
Figure CN121104080A_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 by co-precipitation of tungsten-molybdate. Background Technology
[0002] Tungsten-molybdenum alloys, as important high-temperature resistant materials, combine the high strength and excellent heat resistance of metallic tungsten with the corrosion resistance and ablation resistance of metallic molybdenum. Their high melting point allows them to withstand the erosion of rocket nozzles in the high-temperature propellant combustion environment, making them highly valued in the missile and aerospace fields. Due to their excellent high-temperature strength and low sputtering characteristics, tungsten-molybdenum alloys are one of the ideal structural candidates for high-temperature nuclear reactors. Because of their excellent chemical inertness in corrosive media such as molten zinc and lead, tungsten-molybdenum alloys are suitable component materials for these molten metals.
[0003] Tungsten and molybdenum have melting points of approximately 3380℃ and 2610℃, respectively. Due to their refractory nature, melting and processing tungsten and molybdenum is extremely difficult. Furthermore, the significant difference in their melting points makes it difficult to fully mix the alloy components, leading to segregation and a non-uniform microstructure in the final product. Traditional smelting processes require repeated remelting to achieve compositional homogenization, a time-consuming and costly process. Therefore, current mainstream preparation technologies employ powder metallurgy methods, such as typical hot pressing (HP) and hot isostatic pressing (HIP) sintering processes. High-energy ball milling, as an alternative, can effectively produce nanocrystalline W-Mo alloy powders, while DC magnetron sputtering can prepare W-Mo alloy thin films with different compositions. However, these methods all share common problems: extremely high alloying temperatures, high sintering energy consumption, and large equipment investment. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing tungsten-molybdenum alloy powder by coprecipitation of tungsten-molybdate. This technique uses lead tungsten-molybdate coprecipitate as a precursor, which is reduced at high temperature in a hydrogen atmosphere to generate tungsten-molybdenum alloy, and the tungsten-molybdenum alloy powder is separated from lead by vacuum treatment.
[0005] To achieve this goal, the proposed preparation method includes the following steps: (1) Mix sodium tungstate, sodium molybdate and water to prepare a tungsten-molybdenum mixed solution; mix the tungsten-molybdenum mixed solution with lead salt precipitant or the regenerated precipitant solution returned from step (2), wherein the number of moles of lead contained in the precipitant is 1.05 to 1.15 times the total number of moles of tungsten and molybdenum in the mixed solution; react for a certain time under stirring to allow the tungsten and molybdenum to undergo a co-precipitation reaction; after the reaction, the slurry is subjected to solid-liquid separation and washing, and the obtained solid is the wet residue of lead tungsten-molybdate co-precipitate, and the liquid is the mother liquor of precipitation; (2) The precipitate mother liquor obtained in step (1) is evaporated and concentrated, and the resulting condensate is reused in step (1); the concentrated liquid is frozen and crystallized to precipitate sodium salt, and sodium salt crystals and crystallization mother liquor are obtained after separation; lead salt is added to the crystallization mother liquor to obtain a regenerated precipitant solution; (3) Dry and grind the wet slag obtained in step (1) to obtain lead tungsten molybdate coprecipitate powder; place the lead tungsten molybdate coprecipitate powder in a hydrogen gas flow and reduce it at 700~800℃ for 0.5~1 hours to convert the lead tungsten molybdate coprecipitate powder into a mixture of tungsten molybdenum alloy powder and elemental lead; then stop the hydrogen gas flow and start the vacuum pump to keep the vacuum degree of the furnace body below 50Pa, and vacuum treat it at 1000~1100℃ for 1~2 hours to make the elemental lead volatilize and condense into liquid lead in the condensation zone at 350~450℃ for recovery. At the same time, lead-free tungsten molybdenum alloy powder is obtained.
[0006] Preferably, in step (1), the molar ratio of tungsten to molybdenum in the tungsten-molybdenum mixed solution is between 0.05 and 20. The lead salt includes one or both of lead nitrate and lead acetate.
[0007] Preferably, the temperature of the coprecipitation reaction in step (1) is 30~100℃ and the reaction time is 0.5~2 hours.
[0008] Preferably, the freezing temperature in step (2) is -10 to -5°C.
[0009] The technical principles employed in this invention are as follows: This invention first uses lead salt as a precipitant to induce a coprecipitation reaction between tungstate and molybdate to obtain lead tungsomolybdate coprecipitate. The coprecipitation reaction is shown in equation (1).
[0010] Lead tungsticomol coprecipitate is reduced by hydrogen, and then reduced to elemental form and volatilized under vacuum, thus separating it from tungstic and molybdenum. Tungstic and molybdenum are reduced to obtain tungstic-molybdenum alloy powder. The overall reaction of the reduction process and the vacuum volatilization step is shown in equation (2), and x+y=1 in equations (1) and (2).
[0011] Lead vapor condenses at low temperature to obtain the corresponding liquid metal. The reaction is shown in equation (3).
[0012] This invention utilizes atomically mixed lead tungstate-molybdate co-precipitate as a precursor to prepare homogeneous tungstate-molybdenum alloy powder during hydrogen reduction. Compared to traditional processes that require high-temperature, long-term sintering after mixing tungstate and molybdenum powders, this method integrates reduction and alloying in a single reaction. Using lead salt as a precipitant allows for the quantitative precipitation of tungstates and molybdates, yielding co-precipitates with a wide tungstate-molybdenum ratio. Furthermore, the gasification and separation properties of lead in a high-temperature vacuum environment enable the separation of lead from tungstate and molybdenum, resulting in high-purity metallic lead (greater than 99.9%) in the condensation zone, achieving value-added utilization from lead salt to metallic lead. Excess lead salt is recycled within the system through evaporation and concentration of the precipitate mother liquor and freeze-crystallization, achieving zero wastewater discharge. The high-temperature stages of the entire process do not exceed 1100℃, significantly reducing energy consumption compared to the traditional sintering process of tungstate and molybdenum powders at temperatures above 1300℃. Attached Figure Description
[0013] Figure 1 The image shows the XRD pattern of lead tungsticomolybdate coprecipitate in Example 1 of this invention.
[0014] Figure 2 This is a SEM image of lead tungsticomolybdate coprecipitation in Example 1 of the present invention.
[0015] Figure 3 The image shows the XRD pattern of the hydrogen reduction product without vacuum treatment in Example 1 of this invention.
[0016] Figure 4 The image shows the XRD pattern of the tungsten-molybdenum alloy powder after vacuum treatment in Example 1 of this invention.
[0017] Figure 5 This is a SEM image of the tungsten-molybdenum alloy powder after vacuum treatment in Example 1 of the present invention.
[0018] Figure 6 The images shown are EDS images of the tungsten-molybdenum alloy powder after vacuum treatment in Example 1 of the present invention, specifically (a) EDS layered image; (b) EDS electron image; (c) EDS surface scan tungsten element distribution map; and (d) EDS surface scan molybdenum element distribution map. Detailed Implementation
[0019] The present invention will be further illustrated by the following examples, but is not limited thereto.
[0020] Example 1 Prepare a 0.4 L tungsten-molybdenum mixed solution by dissolving 0.5 mol of sodium tungstate, 0.5 mol of sodium molybdate and water. Dissolve 1.1 mol of lead nitrate in 0.3 L of water to prepare a lead salt precipitant solution. Mix the tungsten-molybdenum mixed solution and the lead salt precipitant solution under stirring, and react with stirring at 100 °C for 2 hours. The slurry after the reaction is filtered by suction and washed with water to obtain wet residue of lead tungstate-molybdate co-precipitate and precipitation mother liquor. Evaporate and concentrate the precipitation mother liquor, and perform freeze crystallization at -10 °C. After solid-liquid separation, the obtained crystal is sodium nitrate crystal.
[0021] Dry and grind the wet residue of lead tungstate-molybdate co-precipitate to obtain a lead tungstate-molybdate co-precipitate powder. The XRD pattern and SEM image of the lead tungstate-molybdate co-precipitate are respectively as attached Figure 1 and attached Figure 2 shown. By Figure 1 it can be seen that the XRD diffraction pattern of the lead tungstate-molybdate co-precipitate has a high degree of conformity with the standard diffraction cards of lead tungstate and lead molybdate. Divide the lead tungstate-molybdate co-precipitate powder into two equal parts. Among them, the first part of the lead tungstate-molybdate co-precipitate powder is reduced in a hydrogen stream at 750 °C for 1 hour, then the temperature is raised to 1100 °C and hydrogen is continuously introduced, and heat preservation is carried out for 1 hour. The XRD pattern of the obtained product is as attached Figure 3 shown, and its phase is a mixture of tungsten-molybdenum alloy and lead, indicating that the volatilization of lead is incomplete. The second part of the lead tungstate-molybdate co-precipitate powder is reduced in a hydrogen stream at 750 °C for 1 hour, then the reducing gas is turned off, the vacuum pump is turned on, the vacuum degree of the furnace body is made lower than 50 Pa, and the temperature is raised to 1100 °C for vacuum treatment for 1 hour. The XRD pattern of the obtained product is as attached Figure 4 shown, and its phase is tungsten-molybdenum alloy. The SEM image and EDS image of the obtained product are respectively as attached Figure 5 and attached Figure 6 shown. As attached Figure 5 , the particle size distribution of the tungsten-molybdenum alloy powder is uniform. From attached Figure 6 it can be seen that there is no residual lead element in the tungsten-molybdenum alloy powder, and the elements of tungsten and molybdenum are in a uniformly dispersed state.
[0022] Example 2 Prepare a 0.5 L tungsten-molybdenum mixed solution by dissolving 1 mol of sodium tungstate, 0.05 mol of sodium molybdate and water. Dissolve 1.11 mol of lead nitrate in 0.5 L of water to prepare a lead salt precipitant. Mix the tungsten-molybdenum mixed solution and the lead salt precipitant under stirring, and react with stirring at 30 °C for 1 hour. The slurry after the reaction is filtered by suction and washed with water to obtain wet residue of lead tungstate-molybdate co-precipitate and precipitation mother liquor. Evaporate and concentrate the precipitation mother liquor, and perform freeze crystallization at -5 °C. After solid-liquid separation, the obtained crystal is sodium nitrate crystal.
[0023] The wet residue of lead tungsticomolybdate coprecipitate was dried and ground to obtain lead tungsticomolybdate coprecipitate powder. The lead tungsticomolybdate coprecipitate powder was reduced in a hydrogen stream at 700℃ for 0.5 hours. Then the reducing gas was turned off, the vacuum pump was turned on to make the vacuum degree of the furnace body lower than 50 Pa, and the temperature was raised to 1000℃ for vacuum treatment for 2 hours to obtain tungsten-molybdenum alloy powder. Metallic lead was collected in the condensation section at a temperature of 350~400℃. The purity of the metallic lead obtained by chemical determination was 99.93%, and the lead content in the tungsten-molybdenum alloy powder was 0.0002%.
[0024] Example 3 A 0.5 L tungstate-molybdenum mixed solution was prepared by dissolving 0.05 mol sodium tungstate, 1 mol sodium molybdate, and water. A lead salt precipitant was prepared by dissolving 1.2 mol lead acetate in 0.4 L of water. The tungstate-molybdenum mixed solution and the lead salt precipitant were mixed under stirring and reacted at 60 °C for 0.5 hours. The resulting slurry was filtered and washed with water to obtain a wet residue of lead tungstate-molybdenum co-precipitate and a mother liquor. The mother liquor was evaporated and concentrated, and then frozen at -8 °C for crystallization. After solid-liquid separation, the obtained crystals were sodium acetate crystals.
[0025] The wet residue of lead tungsticomolybdate coprecipitate was dried and ground to obtain lead tungsticomolybdate coprecipitate powder. The powder was reduced in a hydrogen stream at 800℃ for 0.75 hours. The reducing gas was then turned off, and the vacuum pump was turned on to achieve a furnace vacuum of less than 50 Pa. The temperature was then raised to 1100℃ for vacuum treatment for 1.2 hours to obtain tungsten-molybdenum alloy powder. Metallic lead was collected in the condensation section at 400-450℃. Chemical analysis showed that the lead content in the tungsten-molybdenum alloy powder was ≤0.0001%, and the purity of the metallic lead obtained from condensation was 99.95%.
Claims
1. A method for producing a tungsten-molybdenum alloy powder from a tungstomolybdate co-precipitate, characterized by, The method comprises the following steps: (1) mixing sodium tungstate and sodium molybdate with water to prepare a tungsten-molybdenum mixed solution; mixing the tungsten-molybdenum mixed solution with a lead salt precipitant or a regenerated precipitant solution returned from step (2), wherein the lead salt precipitant contains lead in a molar amount of 1.05-1.15 times the total molar amount of tungsten and molybdenum in the mixed solution; allowing the tungsten and molybdenum to undergo a co-precipitation reaction under stirring for a certain period of time; and performing solid-liquid separation and washing on the slurry after the reaction, to obtain a lead tungstate-molybdate co-precipitation wet residue and a precipitate mother liquor; (2) evaporating and concentrating the precipitate mother liquor obtained in step (1) to obtain condensed water, which is returned to step (1); freezing and crystallizing the concentrated solution to separate sodium salt crystals and a crystallization mother liquor; and adding a lead salt to the crystallization mother liquor to obtain a regenerated precipitant solution; (3) drying and grinding the wet residue obtained in step (1) to obtain lead tungstate-molybdate co-precipitation powder; placing the lead tungstate-molybdate co-precipitation powder in a hydrogen stream, and allowing the lead tungstate-molybdate co-precipitation powder to be converted into a mixture of tungsten-molybdenum alloy powder and elemental lead by reduction reaction at 700-800℃ for 0.5-1 hour; then stopping the hydrogen flow, starting a vacuum pump, and maintaining the vacuum degree of the furnace body below 50 Pa, to allow the elemental lead to volatilize and condense into liquid lead at 350-450℃, while obtaining lead-depleted tungsten-molybdenum alloy powder.
2. The method of claim 1, wherein, The molar ratio of tungsten to molybdenum in the tungsten-molybdenum mixed solution in step (1) is between 0.05 and 20.
3. The method of claim 1, wherein, The lead salt includes one or both of lead nitrate and lead acetate.
4. The method of claim 1, wherein, The temperature of the co-precipitation reaction in step (1) is 30-100℃, and the reaction time is 0.5-2 hours.
5. The method of claim 1, wherein, The freezing and crystallization temperature in step (2) is -10 to -5℃.