CN110026551B - Method for preparing cobalt-coated tungsten carbide powder by freezing - Google Patents
Method for preparing cobalt-coated tungsten carbide powder by freezing Download PDFInfo
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- 229910017052 cobalt Inorganic materials 0.000 title claims abstract description 117
- 239000010941 cobalt Substances 0.000 title claims abstract description 117
- 239000000843 powder Substances 0.000 title claims abstract description 113
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 title claims abstract description 88
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 title claims abstract description 85
- 238000000034 method Methods 0.000 title claims abstract description 78
- 238000007710 freezing Methods 0.000 title claims abstract description 52
- 230000008014 freezing Effects 0.000 title claims abstract description 52
- 239000002243 precursor Substances 0.000 claims abstract description 38
- 230000008569 process Effects 0.000 claims abstract description 36
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims abstract description 33
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 33
- 239000010937 tungsten Substances 0.000 claims abstract description 33
- 238000001816 cooling Methods 0.000 claims abstract description 23
- 150000001868 cobalt Chemical class 0.000 claims abstract description 20
- 238000002425 crystallisation Methods 0.000 claims abstract description 20
- 230000008025 crystallization Effects 0.000 claims abstract description 18
- 238000001035 drying Methods 0.000 claims abstract description 17
- 238000010438 heat treatment Methods 0.000 claims abstract description 17
- 239000002994 raw material Substances 0.000 claims abstract description 17
- 238000003756 stirring Methods 0.000 claims abstract description 6
- 239000000243 solution Substances 0.000 claims description 49
- 239000002245 particle Substances 0.000 claims description 24
- 239000013078 crystal Substances 0.000 claims description 17
- 230000032683 aging Effects 0.000 claims description 10
- 229910052739 hydrogen Inorganic materials 0.000 claims description 10
- 239000001257 hydrogen Substances 0.000 claims description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 9
- 230000009467 reduction Effects 0.000 claims description 8
- 238000006722 reduction reaction Methods 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 8
- 229940011182 cobalt acetate Drugs 0.000 claims description 7
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 claims description 7
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 claims description 7
- 238000000354 decomposition reaction Methods 0.000 claims description 6
- 239000007864 aqueous solution Substances 0.000 claims description 5
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 claims description 4
- 229910001981 cobalt nitrate Inorganic materials 0.000 claims description 4
- 229940044175 cobalt sulfate Drugs 0.000 claims description 4
- 229910000361 cobalt sulfate Inorganic materials 0.000 claims description 4
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 claims description 4
- 239000000956 alloy Substances 0.000 abstract description 19
- 229910045601 alloy Inorganic materials 0.000 abstract description 18
- 239000002131 composite material Substances 0.000 abstract description 17
- 238000004519 manufacturing process Methods 0.000 abstract description 16
- 238000002360 preparation method Methods 0.000 abstract description 8
- 239000000463 material Substances 0.000 abstract description 4
- 238000005272 metallurgy Methods 0.000 abstract description 3
- 239000002667 nucleating agent Substances 0.000 abstract description 3
- 229910052751 metal Inorganic materials 0.000 abstract description 2
- 239000002184 metal Substances 0.000 abstract description 2
- 238000004090 dissolution Methods 0.000 abstract 1
- 239000000203 mixture Substances 0.000 description 21
- 239000007788 liquid Substances 0.000 description 19
- 238000002156 mixing Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 7
- 238000004458 analytical method Methods 0.000 description 6
- 238000003763 carbonization Methods 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 238000000498 ball milling Methods 0.000 description 3
- 239000011247 coating layer Substances 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000001694 spray drying Methods 0.000 description 3
- 229910009043 WC-Co Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- HZLBQBQEGLFWLA-UHFFFAOYSA-N cobalt;oxotungsten Chemical compound [W].[Co]=O HZLBQBQEGLFWLA-UHFFFAOYSA-N 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 150000003657 tungsten Chemical class 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000005255 carburizing Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- QQZGYZFGNGKDOE-UHFFFAOYSA-N cobalt;methanol Chemical compound [Co].OC QQZGYZFGNGKDOE-UHFFFAOYSA-N 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
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- 238000011161 development Methods 0.000 description 1
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- 239000007970 homogeneous dispersion Substances 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000012452 mother liquor Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/17—Metallic particles coated with metal
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
- B22F9/22—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds using gaseous reductors
Abstract
The invention belongs to the field of hard alloy and material metallurgy, and particularly discloses a method for preparing cobalt-coated tungsten carbide powder by freezing. The method takes metal cobalt salt and tungsten carbide powder as raw materials, and realizes the preparation of uniform cobalt-coated tungsten carbide powder through the steps of dissolution, freezing crystallization, three-step heat treatment and the like. Dissolving cobalt salt in the hydrothermal solution to obtain a cobalt-containing precursor solution, adding tungsten carbide powder as a nucleating agent, gradually cooling in the stirring process, separating out the cobalt salt, attaching and wrapping the cobalt salt to the tungsten carbide powder to obtain uniformly wrapped tungsten carbide-cobalt salt composite powder, and then drying, decomposing and reducing at three different temperatures respectively to obtain uniformly mixed cobalt-wrapped tungsten carbide powder. The invention realizes the preparation of uniform tungsten carbide-cobalt coated powder, has simple process flow, can obtain Co contents of different grades, has easily controlled granularity, and effectively solves the problem of non-uniformity of cobalt pools and the like in the current hard alloy production process.
Description
Technical Field
The invention belongs to the field of hard alloy and material metallurgy, and particularly relates to a method for preparing cobalt-coated tungsten carbide powder by freezing.
Background
The WC/Co hard alloy material is widely applied to the fields of mechanical processing, electronic light textile, national defense war industry, geological metallurgy and the like. The existing production method of WC/Co hard alloy is to perform solid-solid ball milling and mixing on tungsten carbide and cobalt powder to obtain a tungsten carbide-cobalt mixture, and the tungsten carbide-cobalt mixture is formed by pressing, sintering and molding. In the method, tungsten carbide and cobalt are difficult to be uniformly mixed, the performance of a hard alloy product is influenced, and a cobalt pool is controlled to form a common problem in production. With the development of ultra-fine and low cobalt cemented carbide, the requirement for mixing tungsten carbide and cobalt is higher. The traditional production method of tungsten carbide-cobalt composite powder is difficult to meet the requirements, and a plurality of solid-liquid and liquid-liquid production methods of tungsten carbide-cobalt composite powder are researched.
In the aspect of solid-liquid mixing, Chinese patent CN103056376A and Chinese CN102198514A take waste hard alloy as raw materials, the waste hard alloy is oxidized and crushed and then mixed with a water-soluble carburizing and nodulizing agent to prepare a mixed aqueous solution, and the mixed aqueous solution is subjected to rapid spray drying, reduction synthesis and carbon regulation to obtain the tungsten carbide-cobalt composite powder. Chinese patent CN102198514A is a method of mixing a cobalt salt methanol solution with tungsten carbide powder to obtain a planar daub, and then reducing the daub to obtain a tungsten carbide cobalt composite powder, wherein the organic system limits the preparation of the composite powder with high cobalt content.
In the aspect of liquid-liquid mixing, Chinese patent CN201010104957, Chinese patent CN103056382A, Chinese patent CN103056377A, Chinese patent CN105290413A and article, "ultra-fine grain tungsten carbide-cobalt composite powder short-process preparation process research" all mix liquid tungsten salt and cobalt salt to obtain an aqueous solution, prepare tungsten-cobalt oxide composite powder by spray drying, and then carbonize the tungsten-cobalt oxide composite powder into carbonized metal-cobalt composite powder, which is a method researched more at present, but impurities are easily introduced in the carbonization process, the reduction and the carbonization are incomplete, the process flow is complex, impurities are easily introduced in the carbonization process, and the method has no good application at present.
Meanwhile, in the production process, the Co coating powder is uniformly covered on the surface of WC particles, so that the uniform distribution of WC and Co can be realized, and the coating layer plays a role in protecting the WC particles in the ball milling process. Therefore, the integrity of the WC particles is ensured, and the method has important significance for producing the ultra-high performance hard alloy product.
In conclusion, the existing solid-solid production process has the problem that cobalt segregation causes a cobalt pool, and both solid and liquid do not form simple and universal WC-Co uniform powder production so as to solve the problem of raw materials for producing high-performance hard alloys.
Disclosure of Invention
The invention provides a method for preparing cobalt-coated tungsten carbide powder by freezing, aiming at the technical problem of uniform tungsten carbide-cobalt coating powder required by the current high-performance hard alloy production, the method is a novel solid-liquid mixing method, tungsten carbide is directly adopted as a raw material and is frozen and crystallized in saline solution to realize uniform cobalt deposition, and a three-section heat treatment process is subsequently adopted to ensure the stabilization and sufficient reduction of a coating layer so as to realize the economical, efficient, controllable and stable production of the tungsten carbide-cobalt coating powder.
The purpose of the invention is realized by the following technical scheme:
a method for preparing cobalt-coated tungsten carbide powder by freezing comprises the following steps:
s1, preparing a cobalt precursor solution: dissolving cobalt salt in an aqueous solution to prepare 10-80 g/L cobalt precursor solution;
s2, freezing and crystallizing: adding the cobalt precursor solution of the step S1 into a solution-solid ratio of 3: 1-6: 1, adding tungsten carbide powder by calculation, transferring the tungsten carbide powder into a cold bath, stirring the tungsten carbide powder to perform freezing crystallization, cooling the tungsten carbide powder to the end point temperature of 10-5 ℃ at the cooling speed of 0.2-3 ℃/min, aging the tungsten carbide powder for a certain time, separating the solution from crystals, and returning the separated solution to the step S1 to prepare a cobalt precursor solution;
s3, heat treatment: and (4) respectively and sequentially drying, decomposing and reducing the crystal obtained in the step (S2) at the temperature of 50-100 ℃, 200-350 ℃ and 400-550 ℃ to obtain tungsten carbide-cobalt coated powder.
The method takes metal cobalt salt and tungsten carbide powder as raw materials, and realizes the preparation of uniform cobalt-coated tungsten carbide powder through the steps of cobalt precursor solution preparation, freezing crystallization, three-step heat treatment and the like. Dissolving cobalt salt in the hydrothermal solution to obtain a cobalt-containing precursor solution, adding tungsten carbide powder as a nucleating agent, gradually cooling in the stirring process, separating out the cobalt salt, attaching and wrapping the cobalt salt on the tungsten carbide powder to obtain uniformly-wrapped tungsten carbide-cobalt salt composite powder, and then respectively drying, decomposing and reducing at three different temperatures to obtain uniformly-mixed cobalt-wrapped tungsten carbide powder. The method realizes the preparation of uniform tungsten carbide-cobalt coated powder, has simple process flow, can obtain Co contents of different grades, has easily controlled granularity, and effectively solves the problem of non-uniformity of cobalt pools and the like in the current hard alloy production process.
The method for preparing the cobalt-coated tungsten carbide powder by freezing also comprises the following preferred scheme.
Preferably, in step S1, the cobalt salt is one of cobalt acetate, cobalt chloride, cobalt nitrate and cobalt sulfate, and is further preferably cobalt acetate or cobalt chloride.
Preferably, the concentration of the cobalt precursor solution in step S1 is set according to the cobalt content in the required grade, and the heating temperature is adjusted.
Preferably, in step S2, the particle size of the tungsten carbide is 0.4 to 5 μm, and the tungsten carbide is used as a nucleating agent, and the particle size of the tungsten carbide has a direct influence on the size of the tungsten carbide-cobalt coating powder, and is further preferably 0.4 to 2 μm.
Preferably, the adding amount of the tungsten carbide in the step S2 is as follows: WC mass is 3: 1-6: 1 is added according to the calculation of the liquid-solid ratio.
Preferably, the stirring speed of crystallization in step S2 is 300-800 rpm, which can ensure the sufficient and uniform dispersion of heavy WC powder.
Preferably, in the step S2, the cooling rate of the crystallization is 0.2-1 ℃/min, the cooling rate can affect the precipitation rate of the cobalt salt, the precipitation rate is higher, the crystal nucleus is finer, the obtained coated powder is finer, and the cobalt salt is directly precipitated at an excessively high cooling rate and cannot be coated with the tungsten carbide powder.
Preferably, the crystallization end point temperature in the step S2 is 2-2 ℃, the low end point temperature is beneficial to fully separating out cobalt phase, the crystallized mother liquor can be returned to the cobalt salt dissolving solution for use, and no waste water is discharged.
Preferably, the aging is continued for 1 to 4 hours, and more preferably for 2 to 3 hours after the crystallization in step S2.
Preferably, the three steps of heat treatment, drying, decomposition and reduction in step S3 are all carried out in a rotary furnace, and the same furnace operation reduces equipment investment and material transfer times.
Preferably, the drying time, the decomposition time and the reduction time of the three-step heat treatment in the step S3 are respectively 3-10 hours, 2-5 hours and 0.5-3 hours.
Preferably, the furnace body rotating speed in the step S3 is 1-20rpm, and a faster rotating speed can reduce material agglomeration and improve uniformity, and further preferably 5-10 rpm.
Preferably, the drying process and the decomposition process in step S3 are both carried out in air, the reduction process is carried out in hydrogen, and the hydrogen flow rate is more preferably 2-5 m3/h。
Compared with the prior art, the invention has the beneficial effects that:
(1) the method comprises the steps of taking tungsten carbide powder and cobalt salt as raw materials, firstly preparing a cobalt precursor solution, then adding tungsten carbide as a nucleation center in a freezing process, carrying out freezing crystallization in the cobalt salt solution to obtain tungsten carbide-cobalt salt wrapping powder, and then drying, decomposing and reducing to obtain the tungsten carbide-cobalt wrapping powder. Has the following advantages: (a) the cobalt amount is controllable, the cobalt salt solubility is greatly changed along with the temperature, and the cobalt content in the tungsten carbide-cobalt coating powder can be controlled by adjusting the cobalt salt concentration, so that the production requirements of hard alloys of different grades are met; (b) the components are uniform, and the molecular-level wrapping and homogeneous dispersion of cobalt on tungsten carbide are realized through crystallization separation and liquid-solid mixing; (c) compared with the existing production method of the composite wrapping powder, the method has the advantages that a tungsten precursor is not adopted, tungsten carbide is directly adopted as a raw material, and the problems of incomplete carbonization, impurity introduction, non-metered compounds and the like of tungsten salt in the carbonization process are solved; (d) the granularity is easy to control, and the problem of non-uniformity of a cobalt pool and the like in the current hard alloy production process is effectively solved.
(2) The invention utilizes a freezing crystallization method to efficiently and quickly wrap the tungsten carbide powder so as to prepare the cobalt-wrapped tungsten carbide composite powder, does not have the processes of spray drying, fluidized carbonization and the like, and has the advantages of low capital construction cost, simple process, high production efficiency, wide raw material selectivity and uniform wrapping of components.
(3) The invention adopts a freezing crystallization method to realize the preparation of cobalt-coated tungsten carbide powder, achieves uniform mixing and effective coating, forms effective protection to WC particles, avoids the defects of the lattice structure in the subsequent ball milling process, and is particularly suitable for the production of ultra-coarse hard alloy products.
(4) The invention adopts liquid-solid reaction synthesis, so that the particle size of the tungsten carbide-cobalt composite powder is more uniform, the particle size distribution is narrow, and the requirements of the hard alloy on the performance of the tungsten carbide-cobalt composite powder are met.
(5) The method scientifically sets the process flow, strictly selects the process parameters, realizes the directional control of the cobalt content and the granularity by the mutual matching of the process and the parameters, finally produces the WC-Co composite powder which is uniform in dispersion, controllable in granularity and capable of meeting the requirements of different hard alloy grades, and ensures the stable performance of hard alloy devices, thereby improving the quality of hard alloys.
Drawings
FIG. 1 is a process flow diagram of a method for preparing cobalt-coated tungsten carbide powder by freezing.
FIG. 2 is an SEM photograph of the composite powder obtained in example 1.
Detailed Description
In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
Example 1
The embodiment provides a method for preparing cobalt-coated tungsten carbide powder by freezing, which takes tungsten carbide powder and cobalt acetate as raw materials, the particle size of the tungsten carbide powder is 0.8 μm (fsss), the attached figure 1 is a process diagram of the embodiment, and the specific steps are as follows:
s1, preparing a cobalt precursor solution: preparing precursor solution with the concentration of 30g/L by using cobalt acetate, and taking 1000mL of the solution;
s2, freezing and crystallizing: adding 200g of tungsten carbide powder into the cobalt precursor liquid obtained in the step S1, transferring the mixture into a cold bath, adjusting the rotating speed of a stirrer to be 500rpm, carrying out freezing crystallization, cooling the mixture to the end point temperature of 2 ℃ at the cooling speed of 0.5 ℃/min, aging the mixture for 2 hours, separating a solution and a crystal, and returning the separated solution to the step S1 to prepare the cobalt precursor liquid;
s3, heat treatment: drying the crystal obtained in the step S2 in a rotary furnace for 6h at 80 ℃/air atmosphere, decomposing for 3h at 260 ℃/air atmosphere and decomposing for 3m at 480 ℃/3m3Reducing for 2h in a hydrogen atmosphere, and keeping the rotating speed of the furnace body at 8rpm in the whole process to finally obtain the tungsten carbide-cobalt coated powder.
The SEM image of the obtained tungsten carbide-cobalt coated powder is shown in fig. 2, and it can be seen from the figure that a cobalt coating layer with a uniform thickness is formed on the surface of the WC particles, the cobalt particles are small, and the content analysis thereof shows that the cobalt content is 7.63% and the Fsss particle size is 0.91 μm.
Example 2
The embodiment provides a method for preparing cobalt-coated tungsten carbide powder by freezing, which takes tungsten carbide powder and cobalt acetate as raw materials, the particle size of the tungsten carbide powder is 0.8 μm (fsss), the attached figure 1 is a process diagram of the embodiment, and the specific steps are as follows:
s1, preparing a cobalt precursor solution: preparing a precursor solution with the concentration of 45g/L by using cobalt acetate, and taking 1000mL of the solution;
s2, freezing and crystallizing: adding 200g of tungsten carbide powder into the cobalt precursor liquid obtained in the step S1, transferring the mixture into a cold bath, adjusting the rotating speed of a stirrer to 800rpm, carrying out freezing crystallization, cooling the mixture to the end point temperature of 0 ℃ at the cooling speed of 1.0 ℃/min, aging the mixture for 3 hours, separating a solution and a crystal, and returning the separated solution to the step S1 to prepare the cobalt precursor liquid;
s3, heat treatment: drying the crystal obtained in the step S2 in a rotary furnace for 8h at a temperature of 80 ℃/air atmosphere, decomposing for 3h at a temperature of 300 ℃/air atmosphere and decomposing for 500 ℃/3m3Reducing for 2h in hydrogen atmosphere, and keeping the rotating speed of the furnace body at 10rpm in the whole process to obtain the tungsten carbide-cobalt coated powder.
The content analysis of the obtained tungsten carbide-cobalt coated powder shows that the cobalt content is 14.20 percent, and the Fsss particle size is 0.94 mu m.
Example 3
The embodiment provides a method for preparing cobalt-coated tungsten carbide powder by freezing, which takes tungsten carbide powder and cobalt chloride as raw materials, the particle size of the tungsten carbide powder is 0.6 μm (fsss), the attached figure 1 is a process diagram of the embodiment, and the specific steps are as follows:
s1, preparing a cobalt precursor solution: preparing a precursor solution with the concentration of 20g/L by using cobalt chloride, and taking 1000mL of the solution;
s2, freezing and crystallizing: adding 200g of tungsten carbide powder into the cobalt precursor liquid obtained in the step S1, transferring the mixture into a cold bath, adjusting the rotating speed of a stirrer to be 300rpm, carrying out freezing crystallization, cooling the mixture to the end temperature of-1 ℃ at the cooling speed of 0.8 ℃/min, aging the mixture for 4 hours, separating the solution and crystals, and returning the separated solution to the step S1 to prepare the cobalt precursor liquid;
s3, heat treatment: drying the crystal obtained in the step S2 in a rotary furnace for 10h at 60 ℃/air atmosphere, decomposing for 4h at 330 ℃/air atmosphere and decomposing for 430 ℃/2m3And reducing for 3h in a hydrogen atmosphere, and keeping the rotating speed of the furnace body at 15rpm in the whole process to obtain the tungsten carbide-cobalt coated powder.
The content analysis of the obtained tungsten carbide-cobalt coated powder shows that the cobalt content is 4.83 percent, and the Fsss particle size is 0.63 mu m.
Example 4
The embodiment provides a method for preparing cobalt-coated tungsten carbide powder by freezing, which takes tungsten carbide powder and cobalt chloride as raw materials, the particle size of the tungsten carbide powder is 0.6 μm (fsss), the attached figure 1 is a process diagram of the embodiment, and the specific steps are as follows:
s1, preparing a cobalt precursor solution: preparing a precursor solution with the concentration of 60g/L by using cobalt chloride, and taking 1000mL of the solution;
s2, freezing and crystallizing: adding 250g of tungsten carbide powder into the cobalt precursor liquid obtained in the step S1, transferring the mixture into a cold bath, adjusting the rotating speed of a stirrer to 600rpm, carrying out freezing crystallization, cooling the mixture to the end temperature of-1 ℃ at the cooling speed of 1.5 ℃/min, aging the mixture for 2 hours, separating the solution and crystals, and returning the separated solution to the step S1 to prepare the cobalt precursor liquid;
s3, heat treatment: drying the crystal obtained in the step S2 in a rotary furnace for 10h at 60 ℃/air atmosphere, decomposing for 4h at 330 ℃/air atmosphere and decomposing for 550 ℃/3m3And reducing for 3h in a hydrogen atmosphere, and keeping the rotating speed of the furnace body at 5rpm in the whole process to obtain the tungsten carbide-cobalt coated powder.
The content analysis of the obtained tungsten carbide-cobalt coated powder shows that the cobalt content is 17.26 percent, and the Fsss particle size is 0.72 mu m.
Example 5
The embodiment provides a method for preparing cobalt-coated tungsten carbide powder by freezing, which takes tungsten carbide powder and cobalt nitrate as raw materials, the particle size of the tungsten carbide powder is 1.6 μm (fsss), the attached figure 1 is a process diagram of the embodiment, and the specific steps are as follows:
s1, preparing a cobalt precursor solution: preparing cobalt nitrate into precursor solution with the concentration of 40g/L, and taking 1000mL of the solution;
s2, freezing and crystallizing: adding 250g of tungsten carbide powder into the cobalt precursor liquid obtained in the step S1, transferring the mixture into a cold bath, adjusting the rotating speed of a stirrer to 600rpm, carrying out freezing crystallization, cooling the mixture to the end temperature of-2 ℃ at the cooling speed of 2.0 ℃/min, aging the mixture for 2 hours, separating the solution and crystals, and returning the separated solution to the step S1 to prepare the cobalt precursor liquid;
s3, heat treatment: drying the crystal obtained in the step S2 in a rotary furnace for 10h at 60 ℃/air atmosphere, decomposing for 4h at 240 ℃/air atmosphere and decomposing for 500 ℃/3m3Reducing for 2h in hydrogen atmosphere, and keeping the rotating speed of the furnace body at 10rpm in the whole process to obtain the tungsten carbide-cobalt coated powder.
The content analysis of the obtained tungsten carbide-cobalt coated powder shows that the cobalt content is 14.38%, and the Fsss particle size is 1.88 μm.
Example 6
The embodiment provides a method for preparing cobalt-coated tungsten carbide powder by freezing, which takes tungsten carbide powder and cobalt sulfate as raw materials, the particle size of the tungsten carbide powder is 1.6 μm (fsss), the attached figure 1 is a process diagram of the embodiment, and the specific steps are as follows:
s1, preparing a cobalt precursor solution: preparing precursor solution with the concentration of 30g/L by taking cobalt sulfate, and taking 1000mL of the solution;
s2, freezing and crystallizing: adding 200g of tungsten carbide powder into the cobalt precursor liquid obtained in the step S1, transferring the mixture into a cold bath, adjusting the rotating speed of a stirrer to 600rpm, carrying out freezing crystallization, cooling the mixture to the end point temperature of 0 ℃ at the cooling speed of 2.0 ℃/min, aging the mixture for 2 hours, separating a solution and a crystal, and returning the separated solution to the step S1 to prepare the cobalt precursor liquid;
s3, heat treatment: drying the crystal obtained in the step S2 in a rotary furnace for 5h at a temperature of 80 ℃/air atmosphere, decomposing for 5h at a temperature of 350 ℃/air atmosphere and decomposing for 550 ℃/3m3Reducing for 3h in hydrogen atmosphere, and keeping the rotating speed of the furnace body at 18rpm in the whole process to obtain the tungsten carbide-cobalt coated powder.
The content analysis of the obtained tungsten carbide-cobalt coated powder shows that the cobalt content is 5.16%, and the Fsss particle size is 1.73 μm.
Claims (13)
1. A method for preparing cobalt-coated tungsten carbide powder by freezing is characterized by comprising the following steps:
s1, preparing a cobalt precursor solution: dissolving cobalt salt in an aqueous solution to prepare 10-80 g/L cobalt precursor solution;
s2, freezing and crystallizing: adding the cobalt precursor solution of the step S1 into a solution-solid ratio of 3: 1-6: 1, adding tungsten carbide powder, transferring the tungsten carbide powder into a cold bath, stirring the tungsten carbide powder and the cold bath for freezing crystallization, cooling the tungsten carbide powder to the end temperature of 10 to-5 ℃ at the cooling speed of 0.2 to 3 ℃/min, aging the tungsten carbide powder for a certain time, separating a solution and a crystal, and returning the separated solution to the step S1 to prepare a cobalt precursor solution;
s3, heat treatment: and (4) respectively and sequentially drying, decomposing and reducing the crystal obtained in the step (S2) at the temperature of 50-100 ℃, 200-350 ℃ and 400-550 ℃ to obtain tungsten carbide-cobalt coated powder.
2. The method for preparing cobalt-coated tungsten carbide powder by freezing as claimed in claim 1, wherein in step S1, the cobalt salt is one of cobalt acetate, cobalt chloride, cobalt nitrate or cobalt sulfate.
3. The method for preparing cobalt-coated tungsten carbide powder by freezing as claimed in claim 1, wherein in step S2, the particle size of the tungsten carbide raw material is 0.4-5 μm.
4. The method for preparing cobalt-coated tungsten carbide powder by freezing according to claim 3, wherein in step S2, the particle size of the tungsten carbide raw material is 0.4-2 μm.
5. The method for preparing cobalt-coated tungsten carbide powder by freezing as claimed in claim 1, wherein in step S2, the stirring speed is kept at 300-800 rpm during the freezing crystallization process.
6. The method for preparing cobalt-coated tungsten carbide powder by freezing as claimed in claim 1, wherein in step S2, the aging time is 1-4 h.
7. The method for preparing cobalt-coated tungsten carbide powder by freezing as claimed in any one of claims 1, 5 and 6, wherein in step S2, the cooling rate in the freezing crystallization process is 0.2-1 ℃/min.
8. The method for preparing the cobalt-coated tungsten carbide powder by freezing as claimed in any one of claims 1, 5 and 6, wherein the cooling end point of the freezing and crystallizing process in step S2 is 2-2 ℃.
9. The method for preparing cobalt-coated tungsten carbide powder by freezing as claimed in claim 1, wherein in step S3, the drying and decomposition heat treatment processes are both performed in an air atmosphere, and the reduction heat treatment process is performed in a hydrogen atmosphere.
10. The method for preparing cobalt-coated tungsten carbide powder by freezing as claimed in claim 9, wherein in step S3, the hydrogen flow rate is 2-5 m3/h。
11. The method for preparing cobalt-coated tungsten carbide powder by freezing as claimed in claim 1, wherein the three steps of heat treatment, drying, decomposition and reduction in step S3 are all performed in a rotary furnace, and the rotating speed of the rotary furnace is set to 1-20 rpm.
12. The method for preparing cobalt-coated tungsten carbide powder by freezing according to claim 11, wherein the rotating speed of the furnace body of the rotary furnace is set to 5-10 rpm.
13. The method for preparing cobalt-coated tungsten carbide powder by freezing as claimed in any one of claims 1 and 9 to 12, wherein in step S3, the drying time, the decomposition time and the reduction time are respectively 3-10 h, 2-5 h and 0.5-3 h.
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Denomination of invention: A method for preparing cobalt coated tungsten carbide powder by freezing Granted publication date: 20210219 Pledgee: China Co. truction Bank Corp Yiyang branch Pledgor: HUNAN JINDIAO ENERGY TECHNOLOGY Co.,Ltd. Registration number: Y2024980009894 |