Method for preparing molybdenum powder with controllable granularity and molybdenum powder

Abstract

The invention relates to the technical field of nano powder material preparation, in particular to a method for preparing molybdenum powder with controllable granularity and the molybdenum powder. The method for preparing the molybdenum powder with the controllable granularity comprises the steps that molybdenum salt and a pore forming agent are dissolved in water at the room temperature, and a mixed solution is obtained; drying the mixed solution to obtain a nano mixture of molybdenum salt coated with a pore-forming agent; roasting the nano mixture in an oxygen-containing atmosphere to obtain superfine molybdenum trioxide powder; the molybdenum trioxide powder is subjected to first-stage hydrogen reduction treatment, and superfine molybdenum dioxide powder without preferred orientation is obtained by adjusting the hydrogen dew point and the temperature field in the reduction process; and carrying out two-stage hydrogen reduction treatment on the superfine molybdenum dioxide powder to obtain molybdenum powder, and grinding and dispersing the molybdenum powder to obtain the superfine molybdenum powder. According to the preparation method, the superfine molybdenum powder with good uniformity and dispersity and controllable granularity can be prepared.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the technical field of nano-powder material preparation, and more particularly to a method for preparing molybdenum powder with controllable particle size and the molybdenum powder. Background Art

[0002] Molybdenum not only has high elastic modulus, high melting point, good electrical and thermal conductivity, but also has resistance to liquid metal corrosion and low expansion coefficient. Therefore, molybdenum metal and its alloys have broad application prospects in steel, metallurgy, machinery, chemical industry, atomic energy, electronics and aerospace. It is a key material required for the development of green metallurgy, modern electronic information technology and the construction of national defense modernization.

[0003] However, the molybdenum powder obtained by the current traditional process has coarse crystal particle size, wide particle size distribution range, and poor powder dispersibility, which cannot meet the needs of high-performance electronic information technology and other fields.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] The purpose of the present disclosure is to provide a method for preparing molybdenum powder and molybdenum powder, thereby improving the uniformity and dispersibility of ultrafine molybdenum powder at least to a certain extent, and preparing ultrafine molybdenum powder with controllable particle size.

[0006] According to one aspect of the present disclosure, a method for preparing molybdenum powder with controllable particle size is provided, comprising: dissolving a molybdenum salt and a pore-forming agent in water at room temperature to obtain a mixed solution; drying the mixed solution to obtain a nano-mixture of the pore-forming agent-coated molybdenum salt; calcining the nano-mixture in an oxygen-containing atmosphere to obtain an ultrafine molybdenum trioxide powder; subjecting the molybdenum trioxide powder to a one-stage hydrogen reduction treatment to obtain an ultrafine molybdenum dioxide powder without preferential orientation by adjusting the hydrogen dew point and the temperature field of the reduction process; subjecting the ultrafine molybdenum dioxide powder to a two-stage hydrogen reduction treatment to obtain molybdenum powder, and grinding and dispersing the molybdenum powder to obtain an ultrafine molybdenum powder.

[0007] In an exemplary embodiment of the present disclosure, the step of calcining the nano-mixture in an oxygen-containing atmosphere to obtain ultrafine molybdenum trioxide powder includes: a calcination temperature of 400 to 700° C. and a calcination time of 0.5 to 2 hours.

[0008] In an exemplary embodiment of the present disclosure, the reduction temperature of the first stage hydrogen reduction treatment is 400-600°C, the heating rate is less than 20°C / min, the hydrogen flow rate is 0.5-15L / min, and the reaction time is 1-2h.

[0009] In an exemplary embodiment of the present disclosure, the method further comprises: heating and humidifying the hydrogen, with the heating temperature being 40 to 60°C.

[0010] In an exemplary embodiment of the present disclosure, the reduction temperature of the two-stage hydrogen reduction treatment is 700-1000° C., the heating rate is less than 20° C. / min, and the reaction time is 1-3 hours; wherein the hydrogen used is dry hydrogen.

[0011] In an exemplary embodiment of the present disclosure, the grinding and dispersing of the molybdenum powder to obtain ultrafine molybdenum powder includes: dispersing the molybdenum powder by ball milling, with a ball-to-material ratio of 5 to 10:1, and a ball milling treatment time of 2 to 5 hours.

[0012] In an exemplary embodiment of the present disclosure, the molybdenum salt is selected from at least one of ammonium molybdate dihydrate, ammonium molybdate tetrahydrate and ammonium molybdate heptahydrate, and the pore-forming agent is at least one of polyethylene glycol, hexadecyltrimethylammonium bromide and polyvinylpyrrolidone.

[0013] In an exemplary embodiment of the present disclosure, the method of drying the mixed solution is selected from any one of air drying, freeze drying, spray drying, and rotary evaporation; wherein the drying time is greater than 12 hours.

[0014] In an exemplary embodiment of the present disclosure, the mass of the pore former is 0.1% to 2.0% of the mass of the molybdenum salt; wherein, when the molybdenum salt and the pore former are dissolved in water, the total mass percentage of the molybdenum salt and the pore former in the solid-liquid mixture is 1.0% to 5.0%.

[0015] According to one aspect of the present disclosure, a molybdenum powder is provided, which is prepared by any one of the above methods.

[0016] In the technical solution provided in the embodiments of the present disclosure, molybdenum salt is used as a raw material, and a pore-forming agent is added to synthesize ultrafine molybdenum trioxide powder with good dispersibility, high porosity and uniform particle size through a roasting process, which provides a basis for subsequently obtaining molybdenum dioxide and molybdenum powder with controllable particle size and good dispersibility. Then, a relatively low-cost two-stage hydrogen reduction process is adopted, and high-purity molybdenum dioxide powder with uniform and controllable particle size is obtained by regulating the hydrogen dew point during the first reduction. Subsequently, through two-stage dry hydrogen reduction and further dispersion treatment, ultrafine molybdenum powder with uniform and controllable particle size and high dispersion can be obtained, which solves the problems of abnormal growth, uneven particle size, and poor dispersibility of molybdenum dioxide and molybdenum powder obtained by the traditional molybdenum powder preparation process.

[0017] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0019] Figure 1 A flow chart of preparing molybdenum powder with controllable particle size according to an embodiment of the present disclosure is schematically shown.

[0020] Figure 2 A scanning electron microscope image (SEM image) of the ultrafine molybdenum dioxide powder obtained in step 4 of the preparation process of Example 1 of the present embodiment is schematically shown.

[0021] Figure 3 The SEM image of molybdenum powder prepared by the preparation method of Example 1 according to an embodiment of the present disclosure is schematically shown.

[0022] Figure 4 An X-ray diffraction analysis (XRD) diagram of molybdenum powder prepared by the preparation method of Example 1 according to an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0023] The following is an explanation of the implementation of the present disclosure by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification.

[0024] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0025] In addition, it should be understood that one or more method steps mentioned in the present disclosure do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present disclosure does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these explicitly mentioned two devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. Changes or adjustments in their relative relationships, without substantial changes in the technical content, should also be regarded as the scope of the present disclosure.

[0026] In the implementation process, it was found that during the hydrogen reduction of molybdenum trioxide (MoO3), molybdenum dioxide (MoO2) and Mo4O 11First, nucleation is formed on the surface of molybdenum trioxide, and the growth of MoO2 crystals has obvious preferential orientation characteristics and presents a flaky morphology. During the hydrogen reduction process, there is a chemical vapor transport (CVT) process, and the gaseous MoO2(OH)2 promotes the agglomeration of Mo powder and the abnormal growth of grains. Therefore, the embodiment of the present disclosure provides a method for preparing ultrafine molybdenum dioxide and molybdenum powder with good dispersibility, uniform particle size distribution and no obvious preferential orientation through a hydrogen reduction process.

[0027] It should be noted that the molybdenum powder prepared by the method for preparing molybdenum powder according to the embodiment of the present disclosure can be applied to the fields of steel, metallurgy, machinery, chemical industry, atomic energy, electronics and aerospace, etc. Of course, the molybdenum powder prepared by the embodiment of the present disclosure can also be applied to other application fields requiring molybdenum processed products, without limitation.

[0028] Figure 1 A flow chart of preparing molybdenum powder with controllable particle size is shown, which may include:

[0029] In step S110, a molybdenum salt and a pore-forming agent are dissolved in water at room temperature to obtain a mixed solution.

[0030] In step S120, the mixed solution is dried to obtain a nano-mixture of pore-forming agent-coated molybdenum salt.

[0031] In step S130, the nano-mixture is calcined in an oxygen-containing atmosphere to obtain ultrafine molybdenum trioxide powder.

[0032] In step S140, the molybdenum trioxide powder is subjected to a hydrogen reduction treatment to obtain ultrafine molybdenum dioxide powder without preferential orientation by adjusting the hydrogen dew point and the temperature field of the reduction process.

[0033] In step S150, ultrafine molybdenum dioxide powder is subjected to a two-stage hydrogen reduction treatment to obtain molybdenum powder, and the molybdenum powder is ground and dispersed to obtain ultrafine molybdenum powder.

[0034] Next, the method for preparing molybdenum powder with controllable particle size in the embodiment of the present disclosure is specifically described.

[0035] In step S110, a molybdenum salt and a pore-forming agent are dissolved in water at room temperature to obtain a mixed solution.

[0036] In the embodiment of the present disclosure, optionally, the molybdenum salt is selected from at least one of ammonium molybdate dihydrate, ammonium molybdate tetrahydrate and ammonium molybdate heptahydrate. Optionally, the pore-forming agent is selected from at least one of polyethylene glycol (PEG), hexadecyltrimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVP). Among them, water can be ultrapure water, deionized water, etc., which is not limited in the embodiment of the present disclosure and can be flexibly selected according to needs.

[0037] Optionally, the mass of the pore former is 0.1% to 2.0% of the mass of the molybdenum salt, wherein when the molybdenum salt and the pore former are dissolved in water, the total mass percentage of the molybdenum salt and the pore former in the solid-liquid mixture is 1.0% to 5.0%.

[0038] Mixing molybdenum salt and pore-forming agent and calcining them can prepare molybdenum trioxide with higher defects, increase the activity of molybdenum trioxide, and lower the subsequent reduction temperature, which is beneficial to improving the reaction efficiency. The lower reduction temperature can inhibit the abnormal growth of grains. Therefore, by controlling the ratio of pore-forming agent to molybdenum salt, the nucleation and growth process of molybdenum trioxide can be regulated, thereby controlling its particle size, morphology, porosity and dispersity.

[0039] In step S120, the mixed solution is dried to obtain a nano-mixture of pore-forming agent-coated molybdenum salt.

[0040] In the disclosed embodiment, optionally, the mixed solution is dried in a manner selected from any one of forced air drying, freeze drying, spray drying, and rotary evaporation, wherein the drying time is greater than 12 hours.

[0041] By adjusting the drying method, the complexation mode of the molybdenum salt and the pore-forming agent and the morphology of the mixed powder after drying can be effectively controlled.

[0042] In step S130, the nano-mixture is calcined in an oxygen-containing atmosphere to obtain ultrafine molybdenum trioxide powder.

[0043] In the disclosed embodiment, optionally, the calcination temperature is 400-700°C and the calcination time is 0.5-2h. This condition is suitable for the nucleation growth of MoO3 with high porosity and uniform particle size distribution. There is no special restriction on the concentration of the oxygen atmosphere and the calcination furnace.

[0044] In step S140, the molybdenum trioxide powder is subjected to a hydrogen reduction treatment to obtain ultrafine molybdenum dioxide powder by adjusting the hydrogen dew point and the temperature field of the reduction process.

[0045] In the embodiments of the present disclosure, the hydrogen dew point refers to the temperature at which water vapor in hydrogen condenses. Specifically, the hydrogen dew point is the temperature at which water vapor begins to condense under a specific pressure of hydrogen, and the temperature value is affected by the temperature, pressure and water content of the hydrogen. The embodiments of the present disclosure adjust the hydrogen dew point by controlling the heating temperature of the hydrogen being heated and humidified, the hydrogen flow rate, etc.

[0046] Optionally, the reduction temperature of the first stage hydrogen reduction treatment is 400-600°C, the heating rate is less than 20°C / min, the hydrogen flow rate is 0.5-15L / min, and the reaction time is 1-2h.

[0047] Optionally, the hydrogen is heated and humidified at a heating temperature of 40 to 60°C, thereby adjusting the dew point of the hydrogen to 20 to 50°C.

[0048] Considering that Mo4O is first generated during the reduction of MoO3 11 The intermediate phase is further deoxidized to generate the MoO2 phase. The reaction follows a continuous reaction mechanism, that is, MoO3 is first reduced to Mo4O 11 phase, while Mo4O 11 The transformation process to MoO2 also occurs. By regulating the hydrogen dew point, the reaction rate can be effectively controlled, and then the morphology and particle size of MoO2 can be regulated. Among them, the reaction rate can be slowed down by increasing the hydrogen dew point, and MoO2 has sufficient time for nucleation and growth, while avoiding the preferential growth of its grains, and the resulting grain size is also larger. On the contrary, using dry hydrogen or reducing the hydrogen dew point can obtain ultrafine nanocrystalline MoO2.

[0049] Optionally, during the one-stage atmosphere reduction treatment, a two-stage reduction process can also be adopted. The total processing time of the two-stage reduction process is controlled by the processing time of the one-stage atmosphere reduction treatment. The specific processing time of the two stages can be flexibly adjusted according to actual needs.

[0050] In step S150, ultrafine molybdenum dioxide powder is subjected to a two-stage hydrogen reduction treatment to obtain molybdenum powder, and the molybdenum powder is ground and dispersed to obtain ultrafine molybdenum powder.

[0051] In the disclosed embodiment, the reduction temperature of the second-stage hydrogen reduction treatment is 700-1000° C., the heating rate is less than 20° C. / min, and the reaction time is 1-3 hours. The hydrogen is dry hydrogen.

[0052] By regulating the reduction temperature and the reaction atmosphere, it is possible to ensure that Mo maintains the particle size corresponding to MoO2. The preferred hydrogen reduction process can ensure that the MoO2 phase is reduced to Mo powder.

[0053] Optionally, the molybdenum powder is ground and dispersed to obtain ultrafine molybdenum powder. The molybdenum powder can be dispersed by ball milling, with a ball-to-material ratio of 5 to 10:1 and a ball milling treatment time of 2 to 5 hours. The dispersibility of the Mo powder can be further improved by reasonably selecting the grinding conditions.

[0054] Furthermore, the embodiment of the present disclosure also provides a molybdenum powder, which is prepared by the method for preparing molybdenum powder with controllable particle size according to the embodiment of the present disclosure, and the specific details are not repeated here.

[0055] In the technical solution provided in the embodiments of the present disclosure, on the one hand, a high-purity and high-porosity MoO3 powder is prepared by calcining a molybdenum salt with a pore-forming agent. By screening a suitable molybdenum salt and adding a pore-forming agent, the reaction system and reaction conditions are regulated to achieve precise control of the MoO3 nucleation and growth process, and obtain a MoO3 powder with controllable particle size and high porosity. Compared with the MoO3 obtained by the traditional air calcination method, it has the characteristics of good dispersibility, high porosity, controllable particle size and uniform size, which lays the foundation for the subsequent preparation of ultrafine MoO2 and molybdenum powder with highly dispersed and controllable particle size. On the other hand, the oxygen vacancies and reaction rate can be adjusted by the low-temperature wet hydrogen reduction process to achieve the MoO3→Mo4O 11 →MoO2 reduction process, realize the gas phase dissolution migration and deposition growth process of uniform and highly dispersed MoO3, and achieve effective regulation of MoO2 particle size and morphology by optimizing wet hydrogen reduction conditions, solving the problems of MoO2 agglomeration, poor size uniformity and preferential growth of crystal surface in the traditional MoO3 reduction process. On the other hand, through "MoO3→Mo4O 11 →MoO2" topological chemical transformation and confined gas phase transport growth synergistically regulate the structure of MoO2 and molybdenum powder. The prepared MoO2 has high activity, good particle size uniformity, high dispersibility and good sphericity, which reduces the energy barrier and reduction temperature of subsequent hydrogen reduction to prepare Mo powder, improves the reaction efficiency, and solves the problems of MoO2 and molybdenum powder agglomeration and abnormal growth of some particles in traditional preparation methods. Subsequently, through further reduction deoxidation and ball milling treatment, highly dispersed ultrafine molybdenum powder with uniform and controllable particle size is obtained. In addition, the embodiment of the present disclosure uses molybdenum salt as raw material, which has a wide source, low cost, simple operation, and easy production and scale-up, and has a high industrial application prospect.

[0056] The method for preparing molybdenum powder disclosed in the present invention is specifically described below through specific examples.

[0057] Example 1

[0058] The method for preparing molybdenum powder with controlled particle size comprises the following steps:

[0059] Step 1: Place 300 mL of deionized water on a magnetic stirrer and slowly add 3.7 g of ammonium molybdate tetrahydrate and 0.025 g of PEG, and stir at a speed of 300 r / min until the dispersant is completely dissolved to obtain a uniform and transparent mixed solution.

[0060] Step 2: Pre-freeze the mixed solution obtained in step 1 and place it in a freeze dryer with a cold trap temperature of -70°C and a sample chamber vacuum degree of 2Pa. After treating for 12 hours, a nano-mixture of pore-forming agent-coated ammonium molybdate is obtained.

[0061] Step 3: calcining the nano-mixture obtained in step 2 in an air atmosphere at a temperature of 560° C. for 1.5 h to obtain ultrafine molybdenum trioxide powder.

[0062] Step 4: The ultrafine molybdenum trioxide powder obtained in step 3 is subjected to a stage atmosphere reduction treatment at 400-480°C and 500-550°C in sections, the reducing gas is wet hydrogen, the heating temperature of the hydrogen is 50°C, the hydrogen flow rate is 0.8L / min, the heating rate is 10°C / min, the treatment time is 2h, and ultrafine molybdenum dioxide powder is obtained.

[0063] Step 5: The ultrafine molybdenum dioxide powder in step 4 is subjected to a two-stage atmosphere reduction treatment at 900°C, the reducing gas is dry hydrogen, the heating rate is 5°C / min, the hydrogen flow rate is 1L / min, and the treatment time is 1h to obtain ultrafine molybdenum powder. In order to further improve the dispersibility of the molybdenum powder, the product is subjected to low-energy ball milling at a speed of 180r / min for 4h and passed through a 200-mesh sieve to obtain the final highly dispersed ultrafine molybdenum powder.

[0064] Example 2

[0065] The method for preparing molybdenum powder with controlled particle size comprises the following steps:

[0066] Step 1: Place 300 mL of deionized water on a magnetic stirrer and slowly add 7.4 g of ammonium molybdate tetrahydrate and 0.01 g of PVP, and stir at a speed of 400 r / min until the dispersant is completely dissolved to obtain a uniform and transparent mixed solution.

[0067] Step 2: Place the mixed solution obtained in step 1 in a forced air drying oven at a drying temperature of 70° C. After 24 hours, a nano-mixture of pore-forming agent-coated ammonium molybdate is obtained.

[0068] Step 3: calcine the nano-mixture obtained in step 2 in an air atmosphere at a temperature of 600° C. for 2 h to obtain ultrafine molybdenum trioxide powder.

[0069] Step 4: The ultrafine molybdenum trioxide powder obtained in step 3 is subjected to a staged atmosphere reduction treatment at 400-450°C and 480-530°C in sections, the reducing gas is wet hydrogen, the heating temperature of the hydrogen is 40°C, the hydrogen flow rate is 1L / min, the heating rate is 5°C / min, the treatment time is 3h, and ultrafine molybdenum dioxide powder is obtained.

[0070] Step 5: The ultrafine molybdenum dioxide powder in step 4 is subjected to a two-stage atmosphere reduction treatment at 850°C, the reducing gas is dry hydrogen, the heating rate is 5°C / min, the hydrogen flow rate is 2L / min, and the treatment time is 2h to obtain ultrafine molybdenum powder. In order to further improve the dispersibility of the molybdenum powder, the product is subjected to low-energy ball milling at a speed of 200r / min for 3h and passed through a 200-mesh sieve to obtain the final highly dispersed ultrafine molybdenum powder.

[0071] Example 3

[0072] The method for preparing molybdenum powder with controlled particle size comprises the following steps:

[0073] Step 1: Place 300 mL of deionized water on a magnetic stirrer and slowly add 11.1 g of ammonium molybdate heptahydrate and 0.05 g of CTAB, and stir at a speed of 600 r / min until the dispersant is completely dissolved to obtain a uniform and transparent mixed solution.

[0074] Step 2: Pre-freeze the mixed solution obtained in step 1 and place it in a freeze dryer with a cold trap temperature of -70°C and a sample chamber vacuum degree of 2Pa. After 24 hours, a nano-mixture of ammonium molybdate coated with a pore-forming agent is obtained.

[0075] Step 3: calcine the nano-mixture obtained in step 2 in an oxygen atmosphere at a temperature of 500° C. for 2 h to obtain ultrafine molybdenum trioxide powder.

[0076] Step 4: The ultrafine molybdenum trioxide powder obtained in step 3 is subjected to a stage atmosphere reduction treatment at 400-500°C and 510-600°C in sections, the reducing gas is wet hydrogen, the heating temperature of the hydrogen is 60°C, the hydrogen flow rate is 2L / min, the heating rate is 10°C / min, the treatment time is 3h, and ultrafine molybdenum dioxide powder is obtained.

[0077] Step 5: The ultrafine molybdenum dioxide powder in step 4 is subjected to a two-stage atmosphere reduction treatment at 1000°C, the reducing gas is dry hydrogen, the heating rate is 5°C / min, the hydrogen flow rate is 1.5L / min, and the treatment time is 3h to obtain ultrafine molybdenum powder. In order to further improve the dispersibility of the molybdenum powder, the product is subjected to low-energy ball milling at a speed of 220r / min for 6h and passed through a 200-mesh sieve to obtain the final highly dispersed ultrafine molybdenum powder.

[0078] After the molybdenum powder was prepared by the preparation method of Examples 1 to 3, the particle size and particle distribution of the molybdenum dioxide powder and the molybdenum powder in the preparation process were analyzed by scanning electron microscopy, and X-ray diffraction analysis was performed.

[0079] like Figure 2 The SEM image (SEM image) of the ultrafine molybdenum dioxide powder obtained in step 4 of the preparation process of Example 1 is shown. Figure 2As shown, the obtained molybdenum dioxide powder has a blocky, non-oriented morphology, and the molybdenum dioxide powder has good dispersibility and uniform particle size distribution. Based on this, by subjecting molybdenum dioxide to a two-stage hydrogen reduction treatment, ultrafine molybdenum powder with good dispersibility and uniform particle size distribution can be obtained.

[0080] like Figure 3 Shown is a SEM image of the molybdenum powder prepared by the preparation method of Example 1, as shown in Figure 3 As shown, the obtained nano molybdenum powder has good dispersibility and uniform size. Figure 4 The X-ray diffraction analysis (XRD) diagram of the molybdenum powder prepared by the preparation method of Example 1 is shown. Figure 4 As shown, the ultrafine molybdenum powder has the same structure as the Mo with the JCPDS (also called PDF card, a standard diffraction card) number of 42-1120, and has high purity without other impurities, indicating that a high-purity molybdenum powder is prepared.

[0081] From the above, it can be seen that the technical solution of the embodiment of the present disclosure uses molybdenum salt as raw material, adopts the method of adding pore-forming agent, and synthesizes ultrafine molybdenum trioxide powder with good dispersibility, high porosity and uniform particle size through a roasting process, which provides a basis for the subsequent acquisition of molybdenum dioxide and molybdenum powder with controllable particle size and good dispersibility, and then adopts a relatively low-cost two-stage hydrogen reduction process. By regulating the hydrogen dew point during the first reduction, high-purity molybdenum dioxide powder with uniform and controllable particle size is obtained. Subsequently, through two-stage dry hydrogen reduction and further dispersion treatment, ultrafine molybdenum powder with uniform and controllable particle size and high dispersion can be obtained, which solves the problems of abnormal growth, uneven particle size and poor dispersibility of molybdenum dioxide and molybdenum powder obtained by the traditional molybdenum powder preparation process.

[0082] It should be noted that the above embodiments are only illustrative of the principles and effects of the present disclosure, and are not intended to limit the present disclosure. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present disclosure. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the present disclosure should still be covered by the claims of the present disclosure.

Claims

1. A method for preparing molybdenum powder with controllable particle size, characterized in that: include: dissolving the molybdenum salt and the pore-forming agent in water at room temperature to obtain a mixed solution; Drying the mixed solution to obtain a nano-mixture of pore-forming agent-coated molybdenum salt; The nano-mixture is placed in an oxygen-containing atmosphere and calcined to obtain ultrafine molybdenum trioxide powder; The molybdenum trioxide powder is subjected to a hydrogen reduction treatment to obtain ultrafine molybdenum dioxide powder without preferential orientation by adjusting the hydrogen dew point and the temperature field of the reduction process; The ultrafine molybdenum dioxide powder is subjected to a two-stage hydrogen reduction treatment to obtain molybdenum powder, and the molybdenum powder is ground and dispersed to obtain ultrafine molybdenum powder.

2. The method according to claim 1, characterized in that The step of placing the nano-mixture in an oxygen-containing atmosphere and calcining it to obtain ultrafine molybdenum trioxide powder comprises: The calcination temperature is 400-700°C, and the calcination time is 0.5-2h.

3. The method according to claim 1, characterized in that The reduction temperature of the one-stage hydrogen reduction treatment is 400-600°C, the heating rate is less than 20°C / min, the hydrogen flow rate is 0.5-15L / min, and the reaction time is 1-2h.

4. The method according to claim 3, characterized in that The method further comprises: The hydrogen gas is heated and humidified at a heating temperature of 40 to 60°C.

5. The method according to claim 1, characterized in that The reduction temperature of the two-stage hydrogen reduction treatment is 700-1000° C., the heating rate is less than 20° C. / min, and the reaction time is 1-3 hours; wherein the hydrogen used is dry hydrogen.

6. The method according to claim 5, characterized in that The method of grinding and dispersing the molybdenum powder to obtain ultrafine molybdenum powder comprises: The molybdenum powder is dispersed by ball milling, the ball-to-material ratio is 5-10:1, and the ball milling treatment time is 2-5 hours.

7. The method according to claim 1, characterized in that The molybdenum salt is selected from at least one of ammonium molybdate dihydrate, ammonium molybdate tetrahydrate and ammonium molybdate heptahydrate, and the pore-forming agent is selected from at least one of polyethylene glycol, hexadecyltrimethylammonium bromide and polyvinylpyrrolidone.

8. The method according to claim 1, characterized in that The mixed solution is dried by any one of forced air drying, freeze drying, spray drying and rotary evaporation; wherein the drying time is greater than 12 hours.

9. The method according to claim 1, characterized in that: The mass of the pore former is 0.1% to 2.0% of the mass of the molybdenum salt; Wherein, when the molybdenum salt and the pore-forming agent are dissolved in water, the total amount of the molybdenum salt and the pore-forming agent in the solid-liquid mixture is 1.0% to 5.0% by mass.

10. A molybdenum powder, characterized in that: The molybdenum powder is prepared by the method according to any one of claims 1 to 9.

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