Ultrafine molybdenum powder and preparation method thereof

Abstract

The invention relates to the technical field of molybdenum powder preparation, and particularly to ultrafine molybdenum powder and a preparation method thereof. The invention comprises the following steps: ball-milling ammonium molybdate and sieving to obtain ammonium molybdate powder, mixing the ammonium molybdate powder with a gluconic acid solution, stirring and dissolving the powder to obtain a suspension solution; adding an azeotropic solution of n-butanol and water to the suspension solution, heating, stirring and dissolving the mixture to obtain a mixed solution; distilling the mixed solution, and cooling the mixture after evaporation to obtain a solid ammonium molybdate precursor; heating and roasting the ammonium molybdate precursor in air to obtain MoO3; first reducing the MoO3 to MoO2 in a hydrogen atmosphere in a first stage, and then reducing the MoO2 in a second stage to obtain super molybdenum powder. The invention comprises the following steps: dispersing the ammonium molybdate precursor through the azeotropic solution, and regulating the mixing ratio of the ammonium molybdate and the azeotropic solution to significantly adjust the morphology and size of the molybdenum powder, thereby preparing molybdenum powder with a single and regular morphology, uniform distribution, high yield, simple preparation process and rapid large-scale production.

Description

Technical Field

[0001] The present invention relates to the technical field of molybdenum powder preparation, and in particular to ultrafine molybdenum powder and a preparation method thereof. Background Art

[0002] Ultrafine molybdenum powder, due to its unique physical and chemical properties, is widely used in many high-tech fields. Compared to ordinary molybdenum powder, ultrafine molybdenum powder has a larger specific surface area, higher activity, and lower sintering temperature. This makes ultrafine molybdenum powder an indispensable material in cutting-edge industries such as electronics, aerospace, military, petrochemical, and nuclear industries.

[0003] At present, the methods for preparing ultrafine molybdenum powder mainly include thermal decomposition and thermal reduction. Thermal decomposition is an early technology used to prepare ultrafine molybdenum powder. By adjusting the carrier gas atmosphere to control the composition of the product, high-purity ultrafine molybdenum powder is obtained. However, this process has high energy consumption and low product collection rate, and is only suitable for producing small batches of high-quality ultrafine molybdenum powder. Thermal reduction methods include hydrogen reduction, metal reduction, mechanical reduction, steam reduction, etc. Among them, the metal reduction method relies on the chemical reaction heat released by the reaction system itself, and it is difficult to achieve fine control of the reaction process. The carbon thermal reduction method has a high carbon content in the product and is not suitable for the production of high-purity molybdenum powder. The mechanical reduction method is prone to introduce impurities, affecting the quality of the powder. The powder of the steam reduction method is easy to stick together and grow, has poor dispersion, and has a low collection rate. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide an ultrafine molybdenum powder and a preparation method thereof. The preparation method of the molybdenum powder provided by the present invention is energy-saving and low-temperature, utilizes a liquid dispersion method, does not produce toxic and harmful gases and other substances, has a simple process, low equipment requirements, is easy to operate, has a short production cycle, and is suitable for large-scale industrial production.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for preparing ultrafine molybdenum powder comprises the following steps:

[0007] Ammonium molybdate is ball-milled and sieved to obtain ammonium molybdate powder, and the ammonium molybdate powder is mixed with a gluconic acid solution and stirred to dissolve to obtain a suspension solution.

[0008] An azeotropic solution of organic alcohol and water is added to the suspension solution, and the mixture is heated and stirred to dissolve the ammonium molybdate in the organic alcohol to obtain a mixed solution.

[0009] The mixed solution is distilled, and the crystal water in the ammonium molybdate can be removed during the heating and evaporation of the organic alcohol and ammonium molybdate, thereby promoting particle refinement. After the mixed solution is evaporated, the temperature is lowered to obtain a solid ammonium molybdate precursor.

[0010] The solid ammonium molybdate precursor is heated and decomposed in air to obtain MoO3, and the MoO3 is first reduced to MoO2 in a hydrogen atmosphere in a first stage, and then reduced in a second stage to obtain super molybdenum powder.

[0011] The addition of the gluconic acid solution in the present invention makes the solution acidic, and the solubility of ammonium molybdate increases under acidic conditions, so that after the subsequent addition of an azeotropic solution of an organic alcohol and water, it can be better dissolved in the organic alcohol. At the same time, the gluconic acid solution is not easy to decompose under heating conditions, and other substances will not be generated to react with the ammonium molybdate. Moreover, its boiling point is lower than that of the corresponding organic alcohol, and it can be subsequently distilled together with the azeotropic solution during the heating process. In addition, gluconic acid is an organic acid that contains multiple hydroxyl groups and can form hydrogen bonds with the surface of solid particles, thereby reducing the attraction between the particles and reducing the aggregation of solid particles. The organic alcohol in the azeotropic solution can reduce the surface tension of the solution, which helps the ammonium molybdate particles to be more evenly dispersed in the solution, reducing mutual adsorption and aggregation between the particles. At the same time, the organic alcohol can remove the crystal water in the ammonium molybdate during the heating and evaporation process with the ammonium molybdate, thereby promoting the refinement of the particles. The present invention disperses ammonium molybdate particles through an azeotropic solution, and simultaneously regulates the mixing ratio of ammonium molybdate and the azeotropic solution to significantly adjust the morphology and size of the molybdenum powder, thereby preparing molybdenum powder with a single and regular morphology, uniform distribution, high yield, simple preparation process, and rapid large-scale production.

[0012] In a preferred embodiment of the present invention, the usage ratio of ammonium molybdate powder to azeotropic solution is 550 g: 2 L to 3 L.

[0013] In a preferred embodiment of the present invention, the azeotropic solution of organic alcohol and water comprises n-butanol, and the volume percentage of n-butanol in the azeotropic solution is 44.55% to 57.5%.

[0014] In a preferred embodiment of the present invention, the ratio of the ammonium molybdate powder to the gluconic acid solution is 550 g:1 L. The gluconic acid solution has a low boiling point and is not easily decomposed when heated, and will not react with ammonium molybdate to generate other substances.

[0015] In a preferred embodiment of the present invention, in the gluconic acid solution, the volume ratio of gluconic acid to water is 1:1.

[0016] In a preferred embodiment of the present invention, the heating and dissolving temperature is 80° C. to 90° C., and the dissolving time is 30 min to 45 min.

[0017] In a preferred embodiment of the present invention, the distillation temperature is 115° C. to 120° C., and the distillation time is 4 h to 5 h.

[0018] In a preferred embodiment of the present invention, the roasting temperature is 500° C. to 600° C., and the roasting time is 2 h to 3 h.

[0019] In a preferred embodiment of the present invention, the first stage reduction temperature is 450°C to 650°C, the first stage reduction time is 4h to 5h, the second stage reduction temperature is 850°C to 950°C, and the second stage reduction time is 8h to 9h.

[0020] In a preferred embodiment of the present invention, the process parameters of ball milling are: ball-to-material ratio of 2:1, rotation speed of 150 r / min to 250 r / min, and ball milling time of 1 h to 2 h.

[0021] Another object of the present invention is to provide an ultrafine molybdenum powder prepared by any of the preparation methods described above, wherein the particle size of the ultrafine molybdenum powder is 0.5 μm to 2 μm.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention comprises mixing, stirring and dissolving ammonium molybdate powder and a gluconic acid solution to obtain a suspension solution; adding an azeotropic solution of an organic alcohol and water to the suspension solution, heating, stirring and dissolving the mixture to obtain a mixed solution; distilling the mixed solution, and cooling the mixed solution after evaporation to obtain a solid ammonium molybdate precursor; heating and roasting the solid ammonium molybdate precursor in air to obtain MoO3, and first reducing the MoO3 to MoO2 in a hydrogen atmosphere in a first stage, and then performing a second stage reduction to obtain super molybdenum powder. In the present invention, the addition of the gluconic acid solution makes the solution acidic, and the solubility of ammonium molybdate increases under acidic conditions, so that the ammonium molybdate can be better dissolved in the organic alcohol after the subsequent addition of the azeotropic solution of the organic alcohol and water. At the same time, the gluconic acid solution is not easily decomposed under heating conditions, and other substances will not be generated to react with the ammonium molybdate. The gluconic acid solution can be subsequently distilled together with the azeotropic solution during the heating process. In addition, gluconic acid is an organic acid containing multiple hydroxyl groups, which can form hydrogen bonds with the surface of solid particles, thereby reducing the attraction between particles and reducing the aggregation of solid particles. The organic alcohol in the azeotropic solution can reduce the surface tension of the solution, which helps the ammonium molybdate particles to be more evenly dispersed in the solution and reduce the mutual adsorption and aggregation between particles. At the same time, the organic alcohol can remove the crystal water in the ammonium molybdate during the heating and evaporation process with ammonium molybdate, thereby promoting the refinement of the particles.

[0024] 2. The present invention disperses ammonium molybdate particles through an azeotropic solution of n-butanol and water, and simultaneously regulates the mixing ratio of ammonium molybdate and n-butanol in the azeotropic solution to significantly adjust the morphology and size of the molybdenum powder, thereby preparing molybdenum powder with a single and regular morphology, uniform distribution, high yield, simple preparation process, and rapid large-scale production.

[0025] 3. The particle size of the molybdenum powder prepared by treating the ammonium molybdate precursor in the present invention is 0.5 μm to 2 μm. The preparation method of the molybdenum powder provided by the present invention is energy-saving and low-temperature, utilizes a liquid dispersion method, does not produce toxic and harmful gases and other substances, has a simple process, low equipment requirements, is easy to operate, has a short production cycle, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a scanning electron microscope image of the ultrafine molybdenum powder prepared in Example 1 of the present invention.

[0027] Figure 2 This is a scanning electron microscope image of the ultrafine molybdenum powder prepared in Example 2 of the present invention.

[0028] Figure 3 This is a scanning electron microscope image of the ultrafine molybdenum powder prepared in Example 3 of the present invention.

[0029] Figure 4 This is a scanning electron microscope image of the ultrafine molybdenum powder prepared in Example 4 of the present invention.

[0030] Figure 5 This is a scanning electron microscope image of the ultrafine molybdenum powder prepared in Example 5 of the present invention.

[0031] Figure 6 This is a scanning electron microscope image of the ultrafine molybdenum powder prepared in Example 6 of the present invention.

[0032] Figure 7 This is a scanning electron microscope image of the metallic molybdenum powder prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0033] The following is a detailed description of the technical solutions in the embodiments of the present invention, using preferred embodiments and accompanying drawings in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0035] Example 1

[0036] A method for preparing ultrafine molybdenum powder comprises the following steps:

[0037] (1) 550 g of ammonium molybdate was ball-milled and passed through a 200-mesh sieve to obtain ammonium molybdate powder. The ball-milling process parameters were as follows: ball-to-material ratio of 2:1, rotation speed of 200 r / min, and ball-milling time of 1 h.

[0038] (2) The ammonium molybdate powder obtained in step (1) was mixed with 1 L of gluconic acid solution in a reactor and stirred and dissolved at a stirring rate of 100 r / min for 20 min to obtain a suspension solution, wherein the volume ratio of gluconic acid to deionized water in the gluconic acid solution was 1:1.

[0039] (3) Add 2.5 L of an azeotropic solution of n-butanol and deionized water to the suspension solution obtained in step (2), wherein the volume ratio of n-butanol to deionized water is 44.5:55.5, and heat and stir to dissolve in a reactor. The heating and dissolving temperature is 80° C., the dissolution time is 30 min, and the stirring rate is 150 r / min to obtain a mixed solution.

[0040] (4) The mixed solution obtained in step (3) was heated to 117° C. and distilled for 2 h. After the mixed solution was evaporated, the temperature was lowered to obtain a solid ammonium molybdate precursor.

[0041] (5) The solid ammonium molybdate precursor obtained in step (4) is heated to 550° C. in a muffle furnace and roasted for 2 h to obtain MoO 3 .

[0042] (6) The MoO3 obtained in step (5) is first reduced at 500°C for 4 hours in a hydrogen atmosphere to obtain MoO2, and then secondary reduced at 900°C for 8 hours to obtain ultrafine metallic molybdenum powder.

[0043] Example 2

[0044] A method for preparing ultrafine molybdenum powder comprises the following steps:

[0045] (1) 550 g of ammonium molybdate was ball-milled and passed through a 200-mesh sieve to obtain ammonium molybdate powder. The ball-milling process parameters were as follows: ball-to-material ratio of 2:1, rotation speed of 200 r / min, and ball-milling time of 1 h.

[0046] (2) The ammonium molybdate powder obtained in step (1) was mixed with 1 L of gluconic acid solution in a reactor and stirred and dissolved at a stirring rate of 100 r / min for 20 min to obtain a suspension solution, wherein the volume ratio of gluconic acid to deionized water in the gluconic acid solution was 1:1.

[0047] (3) Add 2.5 L of an azeotropic solution of n-butanol and deionized water to the suspension solution obtained in step (2), wherein the volume ratio of n-butanol to deionized water is 47:53, and heat and stir to dissolve in a reactor. The heating and dissolving temperature is 80° C., the dissolution time is 30 min, and the stirring rate is 160 r / min to obtain a mixed solution.

[0048] (4) The mixed solution obtained in step (3) was heated to 117° C. and distilled for 5 h. After the mixed solution was evaporated, the temperature was lowered to obtain a solid ammonium molybdate precursor.

[0049] (5) The solid ammonium molybdate precursor obtained in step (4) is heated to 550° C. in a muffle furnace and roasted for 2 h to obtain MoO 3 .

[0050] (6) The MoO3 obtained in step (5) is first reduced at 500°C for 4 hours in a hydrogen atmosphere to obtain MoO2, and then secondary reduced at 900°C for 8 hours to obtain ultrafine metallic molybdenum powder.

[0051] Example 3

[0052] A method for preparing ultrafine molybdenum powder comprises the following steps:

[0053] (1) 550 g of ammonium molybdate was ball-milled and passed through a 200-mesh sieve to obtain ammonium molybdate powder. The ball-milling process parameters were as follows: ball-to-material ratio of 2:1, rotation speed of 200 r / min, and ball-milling time of 1 h.

[0054] (2) The ammonium molybdate powder obtained in step (1) was mixed with 1 L of gluconic acid solution in a reactor and stirred and dissolved at a stirring rate of 100 r / min for 20 min to obtain a suspension solution, wherein the volume ratio of gluconic acid to deionized water in the gluconic acid solution was 1:1.

[0055] (3) Add 2.5 L of an azeotropic solution of n-butanol and deionized water to the suspension solution obtained in step (2), wherein the volume ratio of n-butanol to deionized water is 49.5:50.5, and heat and stir to dissolve in a reactor. The heating and dissolving temperature is 80° C., the dissolution time is 30 min, and the stirring rate is 170 r / min to obtain a mixed solution.

[0056] (4) The mixed solution obtained in step (3) was heated to 117° C. and distilled for 5 h. After the mixed solution was evaporated, the temperature was lowered to obtain a solid ammonium molybdate precursor.

[0057] (5) The solid ammonium molybdate precursor obtained in step (4) is heated to 550° C. in a muffle furnace and roasted for 2 h to obtain MoO 3 .

[0058] (6) The MoO3 obtained in step (5) is first reduced at 500°C for 4 hours in a hydrogen atmosphere to obtain MoO2, and then secondary reduced at 900°C for 8 hours to obtain ultrafine metallic molybdenum powder.

[0059] Example 4

[0060] A method for preparing ultrafine molybdenum powder comprises the following steps:

[0061] (1) 550 g of ammonium molybdate was ball-milled and passed through a 200-mesh sieve to obtain ammonium molybdate powder. The ball-milling process parameters were as follows: ball-to-material ratio of 2:1, rotation speed of 200 r / min, and ball-milling time of 1 h.

[0062] (2) The ammonium molybdate powder obtained in step (1) was mixed with 1 L of gluconic acid solution in a reactor and stirred and dissolved at a stirring rate of 100 r / min for 20 min to obtain a suspension solution, wherein the volume ratio of gluconic acid to deionized water in the gluconic acid solution was 1:1.

[0063] (3) Add 2.5 L of an azeotropic solution of n-butanol and deionized water to the suspension solution obtained in step (2), wherein the volume ratio of n-butanol to deionized water is 52:48, and heat and stir to dissolve in a reactor. The heating and dissolving temperature is 80° C., the dissolution time is 30 min, and the stirring rate is 180 r / min to obtain a mixed solution.

[0064] (4) The mixed solution obtained in step (3) was heated to 117° C. and distilled for 5 h. After the mixed solution was evaporated, the temperature was lowered to obtain a solid ammonium molybdate precursor.

[0065] (5) The solid ammonium molybdate precursor obtained in step (4) is heated to 550° C. in a muffle furnace and roasted for 2 h to obtain MoO 3 .

[0066] (6) The MoO3 obtained in step (5) is first reduced at 500°C for 4 hours in a hydrogen atmosphere to obtain MoO2, and then secondary reduced at 900°C for 8 hours to obtain ultrafine metallic molybdenum powder.

[0067] Example 5

[0068] A method for preparing ultrafine molybdenum powder comprises the following steps:

[0069] (1) 550 g of ammonium molybdate was ball-milled and passed through a 200-mesh sieve to obtain ammonium molybdate powder. The ball-milling process parameters were as follows: ball-to-material ratio of 2:1, rotation speed of 200 r / min, and ball-milling time of 1 h.

[0070] (2) The ammonium molybdate powder obtained in step (1) was mixed with 1 L of gluconic acid solution in a reactor and stirred and dissolved at a stirring rate of 100 r / min for 20 min to obtain a suspension solution, wherein the volume ratio of gluconic acid to deionized water in the gluconic acid solution was 1:1.

[0071] (3) Add 2.5 L of an azeotropic solution of n-butanol and deionized water to the suspension solution obtained in step (2), wherein the volume ratio of n-butanol to deionized water is 54.5:45.5, and heat and stir to dissolve in a reactor. The heating and dissolving temperature is 80° C., the dissolution time is 30 min, and the stirring rate is 190 r / min to obtain a mixed solution.

[0072] (4) The mixed solution obtained in step (3) was heated to 117° C. and distilled for 5 h. After the mixed solution was evaporated, the temperature was lowered to obtain a solid ammonium molybdate precursor.

[0073] (5) The solid ammonium molybdate precursor obtained in step (4) is heated to 550° C. in a muffle furnace and roasted for 2 h to obtain MoO 3 .

[0074] (6) The MoO3 obtained in step (5) is first reduced at 500°C for 4 hours in a hydrogen atmosphere to obtain MoO2, and then secondary reduced at 900°C for 8 hours to obtain ultrafine metallic molybdenum powder.

[0075] Example 6

[0076] A method for preparing ultrafine molybdenum powder comprises the following steps:

[0077] (1) 550 g of ammonium molybdate was ball-milled and passed through a 200-mesh sieve to obtain ammonium molybdate powder. The ball-milling process parameters were as follows: ball-to-material ratio of 2:1, rotation speed of 200 r / min, and ball-milling time of 1 h.

[0078] (2) The ammonium molybdate powder obtained in step (1) was mixed with 1 L of gluconic acid solution in a reactor and stirred and dissolved at a stirring rate of 100 r / min for 20 min to obtain a suspension solution, wherein the volume ratio of gluconic acid to deionized water in the gluconic acid solution was 1:1.

[0079] (3) Add 2.5 L of an azeotropic solution of n-butanol and deionized water to the suspension solution obtained in step (2), wherein the volume ratio of n-butanol to deionized water is 57.5:42.5, and heat and stir to dissolve in a reactor. The heating and dissolving temperature is 80° C., the dissolution time is 30 min, and the stirring rate is 200 r / min to obtain a mixed solution.

[0080] (4) The mixed solution obtained in step (3) was heated to 117° C. and distilled for 5 h. After the mixed solution was evaporated, the temperature was lowered to obtain a solid ammonium molybdate precursor.

[0081] (5) The solid ammonium molybdate precursor obtained in step (4) is heated to 550° C. in a muffle furnace and roasted for 2 h to obtain MoO 3 .

[0082] (6) The MoO3 obtained in step (5) is first reduced at 500°C for 4 hours in a hydrogen atmosphere to obtain MoO2, and then secondary reduced at 900°C for 8 hours to obtain ultrafine metallic molybdenum powder.

[0083] Example 7

[0084] A method for preparing ultrafine molybdenum powder comprises the following steps:

[0085] (1) 550 g of ammonium molybdate was ball-milled and passed through a 200-mesh sieve to obtain ammonium molybdate powder. The ball-milling process parameters were as follows: ball-to-material ratio of 2:1, rotation speed of 200 r / min, and ball-milling time of 1 h.

[0086] (2) The ammonium molybdate powder obtained in step (1) was mixed with 1.5 L of gluconic acid solution in a reactor and stirred and dissolved at a stirring rate of 100 r / min and a dissolution time of 20 min to obtain a suspension solution, wherein the volume ratio of gluconic acid to deionized water in the gluconic acid solution was 1:1.

[0087] (3) Add 2 L of an azeotropic solution of n-butanol and deionized water to the suspension solution obtained in step (2), wherein the volume ratio of n-butanol to deionized water is 57.5:42.5, and heat and stir to dissolve in a reactor. The heating and dissolving temperature is 85° C., the dissolution time is 45 min, and the stirring rate is 200 r / min to obtain a mixed solution.

[0088] (4) The mixed solution obtained in step (3) was heated to 117° C. and distilled for 5.5 h. After the mixed solution was evaporated, the temperature was lowered to obtain a solid ammonium molybdate precursor.

[0089] (5) The solid ammonium molybdate precursor obtained in step (4) is heated to 550° C. in a muffle furnace and roasted for 3 h to obtain MoO 3 .

[0090] (6) The MoO3 obtained in step (5) is first reduced at 450°C for 5 hours in a hydrogen atmosphere to obtain MoO2, and then reduced again at 850°C for 9 hours to obtain ultrafine metallic molybdenum powder.

[0091] Example 8

[0092] A method for preparing ultrafine molybdenum powder comprises the following steps:

[0093] (1) 550 g of ammonium molybdate was ball-milled and passed through a 200-mesh sieve to obtain ammonium molybdate powder. The ball-milling process parameters were as follows: ball-to-material ratio of 2:1, rotation speed of 200 r / min, and ball-milling time of 1 h.

[0094] (2) The ammonium molybdate powder obtained in step (1) was mixed with 2 L of gluconic acid solution in a reactor and stirred and dissolved at a stirring rate of 100 r / min and a dissolution time of 20 min to obtain a suspension solution, wherein the volume ratio of gluconic acid to deionized water in the gluconic acid solution was 1:1.

[0095] (3) Add 3 L of an azeotropic solution of n-butanol and deionized water to the suspension solution obtained in step (2), wherein the volume ratio of n-butanol to deionized water is 57.5:42.5, and heat and stir to dissolve in a reactor. The heating and dissolving temperature is 90° C., the dissolution time is 40 min, and the stirring rate is 200 r / min to obtain a mixed solution.

[0096] (4) The mixed solution obtained in step (3) was heated to 117° C. and distilled for 4 h. After the mixed solution was evaporated, the temperature was lowered to obtain a solid ammonium molybdate precursor.

[0097] (5) The solid ammonium molybdate precursor obtained in step (4) is heated to 600° C. in a muffle furnace and roasted for 2.5 h to obtain MoO 3 .

[0098] (6) The MoO3 obtained in step (5) is first reduced at 650°C for 4.5 hours in a hydrogen atmosphere to obtain MoO2, and then reduced again at 950°C for 8.5 hours to obtain ultrafine metallic molybdenum powder.

[0099] Comparative Example 1

[0100] A method for preparing metallic molybdenum powder comprises the following steps:

[0101] (1) 550 g of ammonium molybdate was ball-milled and passed through a 200-mesh sieve to obtain ammonium molybdate powder. The ball-milling process parameters were as follows: ball-to-material ratio of 2:1, rotation speed of 200 r / min, and ball-milling time of 1 h.

[0102] (2) The ammonium molybdate powder obtained in step (1) and 2.5 L of deionized water azeotropic solution were heated and stirred in a reactor to dissolve at a heating and dissolving temperature of 80° C., a dissolving time of 30 min, and a stirring rate of 200 r / min to obtain a mixed solution.

[0103] (3) heating the mixed solution obtained in step (2) to 117° C. and distilling for 5 h. After the mixed solution is evaporated, cooling is performed to obtain a solid ammonium molybdate precursor.

[0104] (4) The solid ammonium molybdate precursor obtained in step (3) is heated to 550° C. in a muffle furnace and roasted for 2 h to obtain MoO 3 .

[0105] (6) The MoO3 obtained in step (5) is first reduced at 500°C for 4 hours in a hydrogen atmosphere to obtain MoO2, and then secondary reduced at 900°C for 8 hours to obtain ultrafine metallic molybdenum powder.

[0106] Result Analysis

[0107] The morphology of the ultrafine metal molybdenum powder obtained in Examples 1 to 6 is as follows: Figures 1-6 As shown, the average Fischer-Strauss particle size of the molybdenum powder of Example 1 is 1.9 μm, the average Fischer-Strauss particle size of the molybdenum powder of Example 2 is 1.6 μm, the average Fischer-Strauss particle size of the molybdenum powder of Example 3 is 1.3 μm, the average Fischer-Strauss particle size of the molybdenum powder of Example 4 is 1.1 μm, the average Fischer-Strauss particle size of the molybdenum powder of Example 5 is 0.75 μm, and the average Fischer-Strauss particle size of the molybdenum powder of Example 6 is 0.5 μm. This is mainly due to the fact that, on the one hand, the addition of the gluconic acid solution makes the solution acidic, and the solubility of ammonium molybdate increases under acidic conditions, so that after the subsequent addition of the azeotropic solution, it can be better dissolved in n-butanol. On the other hand, gluconic acid is an organic acid that contains multiple hydroxyl groups and can form hydrogen bonds with the surface of solid particles, thereby reducing the attraction between the particles and reducing the aggregation of solid particles. The n-butanol in the azeotropic solution can reduce the surface tension of the solution, which helps the ammonium molybdate particles to be more evenly dispersed in the solution and reduces the mutual adsorption and aggregation between the particles. At the same time, the n-butanol can remove the crystal water in the ammonium molybdate during the heating and evaporation process with ammonium molybdate, thereby promoting the refinement of the particles.

[0108] The morphology of the molybdenum powder obtained in Comparative Example 1 is as follows: Figure 7 As shown, the average Fisher particle size of the molybdenum powder in Comparative Example 1 is 5.2 μm. Without adding the gluconic acid solution and the azeotropic solution, the size of the obtained molybdenum powder is relatively large. By comparison, it can be clearly concluded that the gluconic acid solution and the azeotropic solution have a good dispersion effect and refine the particle size of the ammonium molybdate precursor, so that the molybdenum powder obtained by the subsequent two-stage hydrogen reduction has a smaller size.

[0109] It should be noted that when numerical ranges are mentioned in the present invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints may be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes preferred embodiments. Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0110] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing ultrafine molybdenum powder, characterized in that, The following steps are involved: ball-milling ammonium molybdate and sieving to obtain ammonium molybdate powder, and mixing the ammonium molybdate powder with a gluconic acid solution, stirring and dissolving the mixture to obtain a suspension solution; adding an azeotropic solution of an organic alcohol and water to the suspension solution, heating and stirring to dissolve the ammonium molybdate in the organic alcohol to obtain a mixed solution; The mixed solution is distilled, and the organic alcohol and ammonium molybdate are heated and evaporated to remove crystal water in the ammonium molybdate, thereby promoting particle refinement. After the mixed solution is evaporated, the temperature is lowered to obtain a solid ammonium molybdate precursor; The solid ammonium molybdate precursor is heated and calcined to obtain MoO3, and the MoO3 is first reduced to MoO2 in a hydrogen atmosphere in a first stage, and then reduced in a second stage to obtain super molybdenum powder.

2. The method for preparing ultrafine molybdenum powder according to claim 1, wherein The usage ratio of ammonium molybdate powder to azeotropic solution is 550g:2L~3L.

3. The method for preparing ultrafine molybdenum powder according to claim 1, wherein In the azeotropic solution of organic alcohol and water, the organic alcohol is n-butanol, and the volume percentage of n-butanol in the azeotropic solution is 44.55% to 57.5%.

4. The method for preparing ultrafine molybdenum powder according to claim 1, wherein The usage ratio of the ammonium molybdate powder to the gluconic acid solution is 550g:1L-2L.

5. The method for preparing ultrafine molybdenum powder according to claim 1, wherein In the gluconic acid solution, the volume ratio of gluconic acid to water is 1-1.5:1-2.

6. The method for preparing ultrafine molybdenum powder according to claim 1, wherein The heating dissolution temperature is 80℃~90℃, and the dissolution time is 30min~45min.

7. The method for preparing ultrafine molybdenum powder according to claim 1, wherein The distillation temperature is 115℃~120℃, and the distillation time is 4h~5h.

8. The method for preparing ultrafine molybdenum powder according to claim 1, wherein The roasting temperature is 500°C to 600°C, and the roasting time is 2h to 3h.

9. The method for preparing ultrafine molybdenum powder according to claim 1, wherein The first stage reduction temperature is 450℃~650℃, the first stage reduction time is 4h~5h, the second stage reduction temperature is 850℃~950℃, and the second stage reduction time is 8h~9h.

10. An ultrafine molybdenum powder obtained by the preparation method according to any one of claims 1 to 9, characterized in that: The particle size of the ultrafine molybdenum powder is 0.5 μm to 2 μm.

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