CN117004256A - Metal electrode for aluminum electrolysis and coating composition and preparation method thereof - Google Patents
Metal electrode for aluminum electrolysis and coating composition and preparation method thereof Download PDFInfo
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- 229910052751 metal Inorganic materials 0.000 title claims abstract description 137
- 239000002184 metal Substances 0.000 title claims abstract description 135
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 49
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 49
- 238000005868 electrolysis reaction Methods 0.000 title claims abstract description 43
- 239000008199 coating composition Substances 0.000 title claims abstract description 38
- 238000002360 preparation method Methods 0.000 title abstract description 12
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 claims abstract description 42
- 239000000758 substrate Substances 0.000 claims abstract description 20
- 239000000126 substance Substances 0.000 claims abstract description 7
- 229910052727 yttrium Inorganic materials 0.000 claims abstract description 7
- 239000000843 powder Substances 0.000 claims description 72
- 239000011248 coating agent Substances 0.000 claims description 35
- 238000000576 coating method Methods 0.000 claims description 35
- 238000000034 method Methods 0.000 claims description 29
- 229910045601 alloy Inorganic materials 0.000 claims description 28
- 239000000956 alloy Substances 0.000 claims description 28
- 239000002245 particle Substances 0.000 claims description 25
- 238000005507 spraying Methods 0.000 claims description 24
- 238000002156 mixing Methods 0.000 claims description 20
- 230000008569 process Effects 0.000 claims description 19
- 239000007921 spray Substances 0.000 claims description 15
- 239000011159 matrix material Substances 0.000 claims description 12
- 238000007750 plasma spraying Methods 0.000 claims description 12
- 229910052759 nickel Inorganic materials 0.000 claims description 9
- 238000003723 Smelting Methods 0.000 claims description 8
- 239000011247 coating layer Substances 0.000 claims description 8
- 239000008367 deionised water Substances 0.000 claims description 8
- 229910021641 deionized water Inorganic materials 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical group O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 238000000889 atomisation Methods 0.000 claims description 6
- 238000001354 calcination Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 5
- 239000002904 solvent Substances 0.000 claims description 5
- 238000005469 granulation Methods 0.000 claims description 4
- 230000003179 granulation Effects 0.000 claims description 4
- 230000007797 corrosion Effects 0.000 abstract description 24
- 238000005260 corrosion Methods 0.000 abstract description 24
- 238000007254 oxidation reaction Methods 0.000 abstract description 12
- 230000003647 oxidation Effects 0.000 abstract description 10
- 239000012535 impurity Substances 0.000 abstract description 7
- 230000001681 protective effect Effects 0.000 abstract description 6
- 150000003839 salts Chemical class 0.000 abstract description 6
- 238000004090 dissolution Methods 0.000 abstract description 4
- 230000001934 delay Effects 0.000 abstract description 2
- 238000007747 plating Methods 0.000 abstract description 2
- 239000011253 protective coating Substances 0.000 abstract description 2
- 238000003756 stirring Methods 0.000 description 18
- 239000000919 ceramic Substances 0.000 description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 16
- 239000011812 mixed powder Substances 0.000 description 14
- 239000010410 layer Substances 0.000 description 11
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 11
- 239000002344 surface layer Substances 0.000 description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 7
- 239000003792 electrolyte Substances 0.000 description 7
- 229910052760 oxygen Inorganic materials 0.000 description 7
- 239000001301 oxygen Substances 0.000 description 7
- 229910052761 rare earth metal Inorganic materials 0.000 description 7
- 238000007873 sieving Methods 0.000 description 6
- 229910003271 Ni-Fe Inorganic materials 0.000 description 5
- 238000009792 diffusion process Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 230000002035 prolonged effect Effects 0.000 description 5
- 238000011160 research Methods 0.000 description 5
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 239000010405 anode material Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- UGKDIUIOSMUOAW-UHFFFAOYSA-N iron nickel Chemical compound [Fe].[Ni] UGKDIUIOSMUOAW-UHFFFAOYSA-N 0.000 description 3
- 239000011698 potassium fluoride Substances 0.000 description 3
- 150000002910 rare earth metals Chemical class 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910003264 NiFe2O4 Inorganic materials 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- NQNBVCBUOCNRFZ-UHFFFAOYSA-N nickel ferrite Chemical compound [Ni]=O.O=[Fe]O[Fe]=O NQNBVCBUOCNRFZ-UHFFFAOYSA-N 0.000 description 2
- NROKBHXJSPEDAR-UHFFFAOYSA-M potassium fluoride Chemical compound [F-].[K+] NROKBHXJSPEDAR-UHFFFAOYSA-M 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 235000013024 sodium fluoride Nutrition 0.000 description 2
- 239000011775 sodium fluoride Substances 0.000 description 2
- 238000012876 topography Methods 0.000 description 2
- IRPGOXJVTQTAAN-UHFFFAOYSA-N 2,2,3,3,3-pentafluoropropanal Chemical compound FC(F)(F)C(F)(F)C=O IRPGOXJVTQTAAN-UHFFFAOYSA-N 0.000 description 1
- 229910016569 AlF 3 Inorganic materials 0.000 description 1
- KLZUFWVZNOTSEM-UHFFFAOYSA-K Aluminum fluoride Inorganic materials F[Al](F)F KLZUFWVZNOTSEM-UHFFFAOYSA-K 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005234 chemical deposition Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 229910001610 cryolite Inorganic materials 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000001513 hot isostatic pressing Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 235000013980 iron oxide Nutrition 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 229910000480 nickel oxide Inorganic materials 0.000 description 1
- 239000011224 oxide ceramic Substances 0.000 description 1
- 229910052574 oxide ceramic Inorganic materials 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 235000003270 potassium fluoride Nutrition 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D1/00—Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/08—Anti-corrosive paints
- C09D5/10—Anti-corrosive paints containing metal dust
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/24—Electrically-conducting paints
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
- C25C3/08—Cell construction, e.g. bottoms, walls, cathodes
- C25C3/12—Anodes
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Metallurgy (AREA)
- Electrolytic Production Of Metals (AREA)
Abstract
The application relates to a metal electrode for aluminum electrolysis, a coating composition thereof and a preparation method thereof, belonging to the technical field of aluminum electrolysis; the coating composition comprises the following components in percentage by mass: niFe 2 O 4 :65% -75% and metal components: 25% -35%; wherein the chemical components of the metal component comprise: ni, fe and Y; the corrosion-resistant NiFe-based metal anode can be applied to the surface of the existing corrosion-resistant NiFe-based metal anode, can effectively reduce direct corrosion of high-temperature electrolytic molten salt to a metal anode substrate, and can regenerate a protective film layer by the substrate and a plating layer when the surface of the protective coating is dissolved, so that dynamic relative balance of metal anode corrosion oxidation and dissolution is achieved, and the film layer thickness is kept in the service cycle of the protective film layerThe internal relative stability greatly delays the consumption of the metal anode, the content of the metal impurities in the electrolytic raw aluminum can be stably lower than 0.7% for a long time, and the problems of short electrolytic time and shorter stable time of the low content of the metal impurities in the electrolytic raw aluminum in the prior art are solved.
Description
Technical Field
The application relates to the technical field of aluminum electrolysis, in particular to a metal electrode for aluminum electrolysis, a coating composition thereof and a preparation method thereof.
Background
The inert anode aluminum electrolysis technology does not consume carbon anode and discharge CO 2 The electrolysis process discharges O 2 The method has the advantages that the electrode replacement is not needed, the labor intensity of workers is greatly reduced, the working environment of the workers is improved, a large amount of carbon resources are saved, the environment is friendly, the green development concept is met, and the green aluminum electrolysis technology taking the inert anode as the core is an important strategic support for upgrading and upgrading of the aluminum industry.
At present, the inert anode material is mainly concentrated in three aspects of metal alloy anode, oxide ceramic anode and metal ceramic anode, and the research of the article "research current situation of aluminum electrolysis inert anode" indicates that the metal inert anode is suitable for processing, forming and preparing parts with complex shapes due to excellent conductivity and mechanical property, is easy to connect with a metal guide rod, is easy to obtain raw materials, has low processing cost, and becomes one of the inert anode materials with the most development prospect, and is valued by various research institutions and enterprises. However, alloy anodes have the fatal disadvantages of poor high-temperature molten salt corrosion resistance, a compact oxide layer can be formed on the surface of the anode in the metal anode electrolysis process, otherwise, the metal anode can be directly corroded by electrolyte, and when the anode is polarized and not passivated, the corrosion can be aggravated, and the anode metal is directly electrically peeled off, so that the disastrous result of abnormal interruption of electrolysis is caused.
The metal on the working surface of the metal anode is easy to generate oxidation reaction with the newly generated oxygen of the electrolytic reaction, the oxide and the alloy matrix are dissolved into electrolyte and are reduced into aluminum liquid after being diffused into cathode aluminum liquid, so that the service life of the metal anode is shortened, and the problems of high pollution of newly generated aluminum and the like are caused. Therefore, the research of the alloy anode is mainly focused on how to reduce the corrosion rate of the alloy and prolong the service life of the anode, and the research of the alloy anode mainly adopts the following two ways, namely optimizing an alloy anode material system and a microstructure, adding alloy elements and improving the corrosion resistance of the alloy in a cryolite high-temperature molten salt system. Secondly, a layer of compact corrosion-resistant oxide film or coating is formed on the surface of the alloy anode in advance through surface modification technologies such as pre-oxidation, surface spraying and chemical deposition, so that the metal matrix is prevented from being in direct contact with electrolyte, and the alloy matrix is protected.
Disclosure of Invention
The application provides a metal electrode for aluminum electrolysis, a coating composition and a preparation method thereof, which are used for solving the problem of short service life of a metal anode.
In a first aspect, the present application provides a coating composition for a metal electrode for aluminum electrolysis, the coating composition comprising the following components in mass fraction: niFe 2 O 4 :65% -75% and metal components: 25% -35%; wherein the chemical components of the metal component comprise: ni, fe and Y.
As an alternative embodiment, the chemical composition of the metal component includes, in mass fraction: ni:55% -65%, fe:35% -45% and Y:0.5% -1.5%.
As an alternative embodiment, the coating composition is in the form of particles;
optionally, the coating composition has a volume particle size of 55-70 μm.
In a second aspect, the present application provides a metal electrode for aluminium electrolysis, the metal electrode comprising a substrate and a coating layer attached to the substrate, the components of the coating layer comprising the coating composition of the first aspect.
As an alternative embodiment, the thickness of the coating is 250-350 μm; and/or
The matrix is a NiFe metal anode.
In a third aspect, the present application provides a method for producing a metal electrode for aluminum electrolysis, the method comprising:
obtaining NiFe 2 O 4 Powder;
obtaining metal component powder;
the NiFe is processed 2 O 4 Mixing the powder with the metal component powder to obtain a coating composition;
the coating composition is coated on the surface of a substrate to obtain the metal electrode for aluminum electrolysis.
As an alternative embodiment, the NiFe is obtained 2 O 4 The powder comprises:
NiO and Fe 2 O 3 Mixing, calcining to obtain NiFe 2 O 4 Powder;
optionally, the NiO and Fe 2 O 3 The molar ratio of (2) is 1:1, a step of;
optionally, the calcining temperature is 900-1050 ℃;
optionally, the calcined atmosphere is an air atmosphere.
As an alternative embodiment, the obtaining metal component powder includes:
smelting Ni, fe and Fe-Y intermediate alloy, and granulating to obtain metal component powder;
optionally, the granulating adopts a vacuum atomization mode;
optionally, the volume particle size of the metal component powder is 44-60 μm.
As an alternative embodiment, the step of bringing the NiFe into contact with the surface of the substrate 2 O 4 Mixing the powder with the metal component powder to obtain a coating composition comprising:
the NiFe is processed 2 O 4 The powder and the metal component powder are dispersed in a solvent,then spray granulating to obtain a coating composition;
optionally, the solvent is deionized water;
optionally, the coating composition has a volume particle size of 55-70 μm;
optionally, the technological parameters of spray granulation include: the treatment capacity is 45-55kg/h, the atomization pressure is 3-5MPa, and the discharge temperature is 85-95 ℃.
As an alternative embodiment, the coating is by spraying;
optionally, a plasma spraying process is adopted for spraying;
optionally, the process parameters of the plasma spraying process include: the flow rate of the powder feeding gas is 0.5-0.6m 3 And/h, the moving speed of the spray gun is 900-1000mm/min, and the spraying distance is 80-100mm.
Optionally, the coating thickness of the coating is 250-350 μm.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
the coating composition provided by the embodiment of the application can be applied to the surface of the existing corrosion-resistant NiFe-based metal anode, can effectively reduce direct corrosion of high-temperature electrolytic molten salt to a metal anode substrate, can regenerate a protective film layer from the substrate and a coating layer while protecting the surface dissolution of the coating, achieves dynamic relative balance of metal anode corrosion oxidation and dissolution, keeps the relative stability of the film layer thickness in the service period, greatly delays the consumption of the metal anode, prolongs the service life from a few hours to tens of hours to 35-45 weeks, ensures that the content of metal impurities in electrolytic raw aluminum is also stable to be lower than 0.7% for a long time, and solves the problems of short electrolytic time and shorter stable time of the low content of metal impurities in electrolytic raw aluminum in the prior art.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.
In order to more clearly illustrate the embodiments of the application or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.
FIG. 1 is a surface topography of an uncoated metal anode provided by an embodiment of the application;
FIG. 2 is a surface topography of a coated metal anode according to an embodiment of the present application;
FIG. 3 is a cross-sectional SEM of a coating of a metal electrode according to an embodiment of the present application;
FIG. 4 is an SEM image of a metal electrode after electrolysis provided in an embodiment of the present application;
fig. 5 is a flowchart of a method according to an embodiment of the present application.
Reference numerals: 1-oxide layer, 2-substrate, 3-surface layer and substrate infiltration zone, 4-coating.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Unless otherwise specifically indicated, the various raw materials, reagents, instruments, equipment and the like used in the present application are commercially available or may be prepared by existing methods.
As shown in fig. 1, an embodiment of the present application provides a coating composition for a metal electrode for aluminum electrolysis, comprising, in mass fraction: niFe 2 O 4 :65% -75% and metal components: 25% -35%; wherein the chemical components of the metal component comprise: ni, fe and Y.
In some embodiments, the chemical composition of the metal component comprises, in mass fraction: ni:55% -65%, fe:35% -45% and Y:0.5% -1.5%.
The metal on the working surface of the alloy anode is easy to generate oxidation reaction with the newly generated oxygen of the electrolytic reaction, the oxide and the alloy matrix are dissolved into electrolyte, and are reduced into aluminum liquid after being diffused into cathode aluminum liquid to cause high pollution of newly generated aluminum, etc., the coating is used for avoiding the contact of the metal matrix with high-temperature molten salt directly, protecting the metal anode of the matrix, the service environment of the electrolytic anode requires that the coating has good conductivity, thermal stability, oxidation resistance and corrosion resistance, and NiFe 2 O 4 The ceramic has good conductivity, thermal stability, strong corrosion resistance and strong high-temperature oxidation resistance relative to the electrolyte, so the coating component is selected from NiFe 2 O 4 As a basic raw material for preparing the coating, the content of the NiFe2O4 ceramic phase is controlled to be 65-75%, and the balance is a metal phase, so that the coating has a due protective effect and can further improve the conductivity of the coating. NiFe 2 O 4 When the ceramic phase mass fraction is too large, the thermal vibration property of the ceramic phase is poor, the conductivity of the ceramic phase is reduced, the reactive power consumption is increased, and when the ceramic phase mass fraction is too small, the protection performance is insufficient, so that the service life of the inert electrode is influenced.
The incorporation of the metal component can improve NiFe 2 O 4 The ceramic phase has the main function of improving the conductivity of the coating, and the coating reacts with oxygen newly generated by electrolytic aluminum oxide in an electrolytic environment to produce nickel and iron oxides, reduce the corrosion diffusion speed and further improve the protective performance of the coating. The mass fraction of the metal component is controlled to be 25% -35%, the corrosion rate can be improved when the mass fraction is too high, the protection period of the coating is shortened, and the improvement of the conductivity can be limited when the mass fraction is too low. Wherein nickel and iron can form new oxide with oxygen newly generated by electrolytic alumina on the surface of the coating in the electrolytic environment, play a role in protecting, reduce the corrosion diffusion speed of the coating, control the two to be in a specific mass fraction range, and have the role of forming an oxygen-containing atmosphere microenvironment by self in the high-temperature electrolytic environment, wherein the two oxides can be partially formed into NiFe 2 O 4 The ceramic phase further improves the corrosion resistance effect of the coating. The added rare earth element Y is mainly enriched in phase boundaries and grain boundaries, and large-atom rare earth existing in a large amount at the interfaces prevents outward diffusion channels of metal elements such as Fe, ni and the like, and simultaneously prevents inward diffusion of atoms such as oxygen, fluorine and the like in an electrolysis environment, so that the corrosion diffusion speed of the metal elements is effectively inhibited, the service cycle of a coating is prolonged, and the oxidation resistance of the alloy and the bonding strength of the film layer and a matrix can be improved due to strong affinity of the rare earth element and oxygen and special pinning effect of the rare earth element, and an oxidation resistant film layer which is more resistant to corrosion of electrolyte molten liquid is generated. The rare earth Y content of the coating is controlled within the range of 0.5-1.5%, the effect is not obvious when the rare earth Y content is too low, and the preparation cost is increased when the rare earth Y content is too high, so that the coating is not beneficial to industrial large-scale application.
In some embodiments, the coating composition is in the form of a granule; optionally, the coating composition has a volume particle size of 55-70 μm.
The volume particle size of the coating composition is controlled to be 55-70 mu m, the particle size range has good spraying quality, good powder fluidity, easy dispersion and proper spraying temperature, the particle size is excessively large, the spraying temperature is increased, the binding force between a spraying layer and a substrate is poor, the surface smoothness is reduced, the particle size is excessively small, the powder fluidity is poor, agglomeration is easy, and a nozzle is easy to block in the spraying process.
Based on one general inventive concept, an embodiment of the present application also provides a metal electrode for aluminum electrolysis, the metal electrode including a substrate and a coating layer attached to the substrate, the composition of the coating layer including the coating composition provided above.
In some embodiments, the thickness of the coating is 250-350 μm and the substrate is a NiFe metal anode.
The reason for controlling the thickness of the coating to be 250-350 mu m is that the bonding strength of the coating and the matrix cannot be adversely affected on the basis of ensuring that the protection period of the metal inert anode is prolonged as much as possible, the bonding strength of the coating and the matrix becomes low due to the fact that the coating is seriously cracked or even falls off, and the adverse effect of the fact that the bonding strength of the coating and the matrix is too small due to the fact that the protection effect is reduced and the service life of the inert metal anode is shortened.
The plasma spraying oxidation-resistant corrosion-resistant layer on the surface of the existing corrosion-resistant NiFe-based metal anode can effectively reduce direct corrosion of high-temperature electrolytic molten salt to a metal anode substrate, and can regenerate a protective film layer from the substrate and a plating layer while dissolving the surface of a protective coating, so that the dynamic relative balance of metal anode corrosion oxidation and dissolution is achieved, the film thickness is kept stable relatively in the service period, the consumption of the metal anode is greatly delayed, the service life is prolonged from the existing hours to tens of hours to 35-45 weeks, the content of metal impurities in electrolytic raw aluminum can be stably lower than 0.7% for a long time, and the problems of short electrolytic time and shorter stable time of low content of metal impurities in electrolytic raw aluminum in the prior art are solved. In addition, in the process of using the metal anode, the service life of the inert anode can be further prolonged along with the perfection of an electrolysis process, so that the universal application of the inert anode in industrial electrolysis production is realized.
As shown in fig. 5, based on a general inventive concept, an embodiment of the present application further provides a method for preparing a metal electrode for aluminum electrolysis, the method comprising:
s1, obtaining NiFe 2 O 4 Powder;
in some embodiments, the resulting NiFe 2 O 4 The powder comprises: niO and Fe 2 O 3 Mixing, calcining to obtain NiFe 2 O 4 And (5) powder.
Specifically, in this embodiment, the molar ratio is 1: niO, fe of 1 2 O 3 Stirring uniformly by a kneader, and calcining at 900-1050 ℃ under the air atmosphere to obtain NiFe2O4 ceramic powder.
S2, obtaining metal component powder;
in some embodiments, the obtaining the metal component powder comprises: smelting the intermediate alloy of Ni, fe and Fe-Y, and granulating to obtain metal component powder.
Specifically, in this embodiment, ni, fe and Fe-Y intermediate alloy is vacuum melted to prepare Ni-Fe-Y ternary master alloy, and metal powder with a particle size of 44-60 μm is obtained by vacuum atomization.
S3, the NiFe is processed 2 O 4 Mixing the powder with the metal component powder to obtain a coating composition;
in some embodiments, said bringing said NiFe 2 O 4 Mixing the powder with the metal component powder to obtain a coating composition comprising: the NiFe is processed 2 O 4 The powder and the metal component powder are dispersed in a solvent and then spray granulated to obtain the coating composition.
Specifically, in this embodiment, calcined NiFe 2 O 4 Mixing ceramic powder and metal powder in proportion, adding deionized water, stirring thoroughly by using a stirring mill, granulating by using a spray granulator, and sieving to obtain mixed powder with the particle size of 55-70 mu m. Further, the technological parameters of spray granulation include: the treatment capacity is 45-55kg/h, the atomization pressure is 3-5MPa, and the discharge temperature is 85-95 ℃.
S4, coating the coating composition on the surface of a substrate to obtain the metal electrode for aluminum electrolysis.
In some embodiments, the coating is by spraying.
Specifically, in the implementation, the mixed powder is uniformly sprayed on the surface layer of the NiFe metal anode by adopting a plasma spraying process, and the thickness of the mixed powder is 250-350 mu m. Further, the process parameters of the plasma spraying process include: the flow rate of the powder feeding gas is 0.5-0.6m 3 And/h, the moving speed of the spray gun is 900-1000mm/min, and the spraying distance is 80-100mm.
The application will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present application and are not intended to limit the scope of the present application. The experimental procedures, which are not specified in the following examples, are generally determined according to national standards. If the corresponding national standard does not exist, the method is carried out according to the general international standard, the conventional condition or the condition recommended by the manufacturer.
Example 1
A preparation method of a metal electrode for aluminum electrolysis comprises the following steps:
NiO with the molar ratio of 1:1 is mixed,Fe 2 O 3 stirring uniformly by a kneader, and presintering at 900-1050 ℃ under the air atmosphere to synthesize NiFe 2 O 4 Ceramic powder is prepared through vacuum smelting Ni, fe and Fe-Y intermediate alloy to obtain ternary Ni-Fe-Y mother alloy, vacuum atomizing to obtain metal powder of 44-60 microns particle size, and mixing NiFe with Fe powder 2 O 4 Mixing the powder and the metal powder according to the mass ratio of 75 percent to 25 percent, adding deionized water, using a stirring mill to fully stir, granulating by a spray granulator, sieving to obtain mixed powder with the particle size of 55-70 mu m, and uniformly spraying the mixed powder to the surface layer of the Ni-Fe-based metal anode with the size of 180-150-30 mm by adopting a plasma spraying process, wherein the spraying thickness is 250 mu m, thereby being used as an electrolytic anode to be used.
Example 2
A preparation method of a metal electrode for aluminum electrolysis comprises the following steps:
NiO and Fe in a molar ratio of 1:1 are mixed 2 O 3 Stirring uniformly by a kneader, and presintering at 900-1050 ℃ under the air atmosphere to synthesize NiFe 2 O 4 Ceramic powder is prepared through vacuum smelting Ni, fe and Fe-Y intermediate alloy to obtain ternary Ni-Fe-Y mother alloy, vacuum atomizing to obtain metal powder of 44-60 microns particle size, and mixing NiFe with Fe powder 2 O 4 Mixing the powder and the metal powder according to the proportion of 72 percent to 28 percent, adding deionized water, using a stirring mill to fully stir, granulating by a spray granulator, sieving to obtain mixed powder with the particle size of 55-70 mu m, and uniformly spraying the mixed powder to the surface layer of the Ni-Fe-based metal anode with the size of 180-150-30 mm by adopting a plasma spraying process, wherein the spraying thickness is 280 mu m, thereby being used as an electrolytic anode to be used.
Example 3
A preparation method of a metal electrode for aluminum electrolysis comprises the following steps:
NiO and Fe in a molar ratio of 1:1 are mixed 2 O 3 Stirring uniformly by a kneader, and presintering at 900-1050 ℃ under the air atmosphere to synthesize NiFe 2 O 4 Ceramic powder is prepared through vacuum smelting Ni, fe and Fe-Y intermediate alloy to obtain ternary Ni-Fe-Y mother alloy, vacuum atomizing to obtain metal powder of 44-60 microns particle size, and mixing NiFe with Fe powder 2 O 4 Mixing the powder and the metal powder according to the proportion of 70 percent to 30 percent, adding deionized water, using a stirring mill to fully stir, granulating by a spray granulator, sieving to obtain mixed powder with the particle size of 55-70 mu m, and uniformly spraying the mixed powder to the surface layer of the Ni-Fe-based metal anode with the size of 180-150-30 mm by adopting a plasma spraying process, wherein the spraying thickness is 300 mu m, thereby being used as an electrolytic anode to be used.
Example 4
A preparation method of a metal electrode for aluminum electrolysis comprises the following steps:
NiO and Fe in a molar ratio of 1:1 are mixed 2 O 3 Stirring uniformly by a kneader, and presintering at 900-1050 ℃ under the air atmosphere to synthesize NiFe 2 O 4 Ceramic powder is prepared through vacuum smelting Ni, fe and Fe-Y intermediate alloy to obtain ternary Ni-Fe-Y mother alloy, vacuum atomizing to obtain metal powder of 44-60 microns particle size, and mixing NiFe with Fe powder 2 O 4 Mixing the powder and the metal powder according to the proportion of 68 percent to 32 percent, adding deionized water, using a stirring mill to fully stir, granulating by a spray granulator, sieving to obtain mixed powder with the particle size of 55-70 mu m, and uniformly spraying the mixed powder to the surface layer of the Ni-Fe-based metal anode with the size of 180-150-30 mm by adopting a plasma spraying process, wherein the spraying thickness is 330 mu m, thereby being used as an electrolytic anode to be used.
Example 5
A preparation method of a metal electrode for aluminum electrolysis comprises the following steps:
NiO and Fe in a molar ratio of 1:1 are mixed 2 O 3 Stirring uniformly by a kneader, and presintering at 900-1050 ℃ under the air atmosphere to synthesize NiFe 2 O 4 Ceramic powder is prepared through vacuum smelting Ni, fe and Fe-Y intermediate alloy to obtain ternary Ni-Fe-Y mother alloy, vacuum atomizing to obtain metal powder of 44-60 microns particle size, and mixing NiFe with Fe powder 2 O 4 Mixing powder and metal powder according to the proportion of 65 percent to 35 percent, adding deionized water, using a stirring mill to fully stir, granulating by a spray granulator, sieving to obtain mixed powder with the particle size of 55-70 mu m, uniformly spraying the mixed powder to the surface layer of the Ni-Fe-based metal anode with the size of 180-150-30 mm by adopting a plasma spraying process, and using the mixed powder with the spraying thickness of 350 mu m as the standby electrolysisAnd an anode.
Comparative example 1
Nickel-iron-based metal with a size of 180 x 150 x 30mm is used as the electrolytic anode.
Comparative example 2
A preparation method of a metal electrode for aluminum electrolysis comprises the following steps:
and (3) placing the nickel-iron-based metal anode with the size of 180-150-30 mm into a heat treatment furnace for pre-oxidation treatment under the condition of 1000 ℃, preserving heat for 10 hours, and forming a protective layer with the thickness of about 100 mu m on the surface layer of the nickel-iron-based metal anode to serve as an electrolytic anode.
The metal electrodes provided in examples 1 to 5 and comparative examples 1 to 2 were assembled as anodes into an electrolytic device for performance testing by the following procedure: tiB using hot isostatic pressing 2 The cathode and the anode adopt a vertical structure, and the electrolysis current density is 0.5A/cm 2 KF-NaF-AlF is adopted in the electrolytic test 3 The electrolyte system has a KF content of about 20wt%, a molecular ratio of 1.4-1.5 (sum of sodium fluoride and potassium fluoride moles divided by aluminum fluoride moles ([ NaF)]+[KF])/[AlF 3 ]) The alumina content is 4.2-5.2 wt% and the temperature is 820 ℃. The test results are shown in the following table:
as shown in the table above, the service life of the metal electrode prepared by the method provided by the embodiment of the application is prolonged from the existing hours to tens of hours to 35-45 weeks, and the content of the metal impurities in the electrolytic raw aluminum can be stably lower than 0.7% for a long time.
Various embodiments of the application may exist in a range of forms; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the application; it is therefore to be understood that the range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that a description of a range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, wherever applicable. In addition, whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the indicated range.
In the present application, unless otherwise specified, terms such as "upper" and "lower" are used specifically to refer to the orientation of the drawing in the figures. In addition, in the description of the present specification, the terms "include", "comprising" and the like mean "including but not limited to".
Relational terms such as "first" and "second", and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Herein, "and/or" describing an association relationship of an association object means that there may be three relationships, for example, a and/or B, may mean: a alone, a and B together, and B alone. Wherein A, B may be singular or plural. Herein, "at least one" means one or more, and "a plurality" means two or more. "at least one", "at least one" or the like refer to any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
The foregoing is only a specific embodiment of the application to enable those skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A coating composition for a metal electrode for aluminum electrolysis, characterized in that the coating composition comprises the following components in mass fraction: niFe 2 O 4 :65% -75% and metal components: 25% -35%; wherein the chemical components of the metal component comprise: ni, fe and Y.
2. The coating composition of a metal electrode for aluminum electrolysis according to claim 1, wherein the chemical composition of the metal component comprises, in mass fraction: ni:55% -65%, fe:35% -45% and Y:0.5% -1.5%.
3. The coating composition for a metal electrode for aluminum electrolysis according to claim 1, wherein the coating composition is in the form of particles;
optionally, the coating composition has a volume particle size of 55-70 μm.
4. A metal electrode for electrolysis of aluminum, characterized in that the metal electrode comprises a substrate and a coating layer attached to the substrate, the composition of the coating layer comprising the coating composition according to any one of claims 1 to 3.
5. The metal electrode for aluminum electrolysis according to claim 4, wherein the thickness of the coating layer is 250 to 350 μm; and/or
The matrix is a NiFe metal anode.
6. A method for preparing a metal electrode for aluminum electrolysis, comprising the steps of:
obtaining NiFe 2 O 4 Powder;
obtaining metal component powder;
the NiFe is processed 2 O 4 Mixing the powder with the metal component powder to obtain a coating composition;
the coating composition is coated on the surface of a substrate to obtain the metal electrode for aluminum electrolysis.
7. The method for producing a metal electrode for aluminum electrolysis according to claim 6, wherein NiFe is obtained 2 O 4 The powder comprises:
NiO and Fe 2 O 3 Mixing, calcining to obtain NiFe 2 O 4 Powder;
optionally, the NiO and Fe 2 O 3 The molar ratio of (2) is 1:1, a step of;
optionally, the calcining temperature is 900-1050 ℃;
optionally, the calcined atmosphere is an air atmosphere.
8. The method for producing a metal electrode for aluminum electrolysis according to claim 6, wherein the obtaining of the metal component powder comprises:
smelting Ni, fe and Fe-Y intermediate alloy, and granulating to obtain metal component powder;
optionally, the granulating adopts a vacuum atomization mode;
optionally, the volume particle size of the metal component powder is 44-60 μm.
9. The method for producing a metal electrode for aluminum electrolysis according to claim 6, wherein said NiFe is deposited on said metal electrode 2 O 4 Mixing the powder with the metal component powder to obtain a coating composition comprising:
the NiFe is processed 2 O 4 Dispersing the powder and the metal component powder in a solvent, and then carrying out spray granulation to obtain a coating composition;
optionally, the solvent is deionized water;
optionally, the coating composition has a volume particle size of 55-70 μm;
optionally, the technological parameters of spray granulation include: the treatment capacity is 45-55kg/h, the atomization pressure is 3-5MPa, and the discharge temperature is 85-95 ℃.
10. The method for producing a metal electrode for aluminum electrolysis according to claim 6, wherein the coating is by spraying;
optionally, a plasma spraying process is adopted for spraying;
optionally, the process parameters of the plasma spraying process include: the flow rate of the powder feeding gas is 0.5-0.6m 3 And/h, the moving speed of the spray gun is 900-1000mm/min, and the spraying distance is 80-100mm;
optionally, the coating thickness of the coating is 250-350 μm.
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