CN114606540A - Rare earth metal electrolytic cathode protection method and cathode - Google Patents

Rare earth metal electrolytic cathode protection method and cathode Download PDF

Info

Publication number
CN114606540A
CN114606540A CN202210078848.0A CN202210078848A CN114606540A CN 114606540 A CN114606540 A CN 114606540A CN 202210078848 A CN202210078848 A CN 202210078848A CN 114606540 A CN114606540 A CN 114606540A
Authority
CN
China
Prior art keywords
cathode
protected
metal coating
tungsten
coating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202210078848.0A
Other languages
Chinese (zh)
Other versions
CN114606540B (en
Inventor
王权
吴忠望
张亚坤
王玉峰
韩帅
赵海营
夏云
杜永亮
杨志鹏
唐永胜
赵良忠
杨丽
李娜
王海燕
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Baotou Xijun Rare Earth Co Ltd
Inner Mongolia University of Science and Technology
Original Assignee
Baotou Xijun Rare Earth Co Ltd
Inner Mongolia University of Science and Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Baotou Xijun Rare Earth Co Ltd, Inner Mongolia University of Science and Technology filed Critical Baotou Xijun Rare Earth Co Ltd
Priority to CN202210078848.0A priority Critical patent/CN114606540B/en
Publication of CN114606540A publication Critical patent/CN114606540A/en
Application granted granted Critical
Publication of CN114606540B publication Critical patent/CN114606540B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/02—Electrodes; Connections thereof
    • C25C7/025—Electrodes; Connections thereof used in cells for the electrolysis of melts
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
    • C23C4/06—Metallic material
    • C23C4/08—Metallic material containing only metal elements
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
    • C23C4/10—Oxides, borides, carbides, nitrides or silicides; Mixtures thereof
    • C23C4/11—Oxides
    • 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
    • C25C3/34—Electrolytic production, recovery or refining of metals by electrolysis of melts of metals not provided for in groups C25C3/02 - C25C3/32

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Electrochemistry (AREA)
  • Electrolytic Production Of Metals (AREA)

Abstract

The invention relates to a rare earth metal electrolytic cathode protection method, which comprises the steps of firstly measuring and counting a large number of invalid tungsten cathode necking positions, determining a position to be protected of a cathode by combining the field production process and the installation condition of equipment, then cleaning the position to be protected, and spraying a nickel metal coating and a zirconium dioxide metal coating by adopting a two-step method, so that the high-temperature oxidation resistance and the corrosion resistance of the cathode are enhanced, the corrosion speed of the cathode is greatly delayed, and the service life of the cathode is prolonged on the premise of not influencing the conductivity of the cathode.

Description

Rare earth metal electrolytic cathode protection method and cathode
Technical Field
The invention relates to the technical field of rare earth metal electrolysis, in particular to a rare earth metal electrolysis cathode protection method and a cathode.
Background
Rare earth (Rare earth) is a group of novel functional materials with various characteristics such as electricity, magnetism, light, superconduction, catalysis and biology, comprises seventeen metal elements including lanthanide elements, scandium and yttrium in a periodic table of elements, is an important basic material for the high-tech fields such as information technology, biotechnology, new material and new energy technology and national defense construction, and plays an important role in reforming certain traditional industries such as agriculture, chemical industry, building materials and the like.
At present, a molten salt electrolysis method is one of the main methods for producing mixed and single rare earth metals and alloys in China, and the method is divided into two electrolyte systems, wherein one electrolyte system is a rare earth chloride electrolyte system, namely a binary system; the second is a rare earth oxide electrolyte system, namely a ternary system. In the process of rare earth electrolysis, a rare earth metal electrolytic furnace is needed, referring to fig. 1, an open type electrolytic graphite tank is arranged in the electrolytic furnace 1, a cathode 3 and an anode 2 are inserted into the graphite tank, and the oxide is electrolyzed under the action of direct current. It can be seen that the cathode 3 is an important component of the electrolysis apparatus. In the ternary system, the cathode 3 for rare earth electrolysis is usually prepared by using a high-price tungsten material, and a local area of the cathode 3 generates a necking phenomenon under the action of high-temperature oxidation and a corrosive medium in the electrolysis process, referring to fig. 2, the necking area 4 is in an irregular funnel shape, and the tungsten cathode in the liquid surface of the electrolytic furnace 1 is hardly corroded. The necking phenomenon causes the service life of the cathode 3 to be reduced, the general service life is 6 months in a single direction, the two directions are less than one year, and the production cost and the cathode replacement frequency of enterprises are invisibly increased.
The Chinese utility model patent publication No. CN 202011912U, tungsten cathode for fused salt electrolysis, proposes to use water cooling protection, and the method is to cover a cooling protection ring outside the tungsten cathode, and the cooling protection ring adopts water cooling mode. In the chinese utility model publication No. CN 202671678U, the "tungsten electrode bar protection device" is a method in which a stainless steel protective cover is added on the upper part of the tungsten cathode to make the bottom end of the protective cover flush with the liquid level of the electrolyte. Although the service life of the tungsten cathode is prolonged by the two technical schemes, the necking problem is still not well solved.
In view of the above, how to avoid or delay the corrosion rate of the cathode without affecting the current efficiency and the thermal efficiency of the electrolytic furnace, so as to prolong the service life of the cathode, is a technical problem that needs to be solved at present.
Disclosure of Invention
The invention discloses a rare earth metal electrolytic cathode protection method and a cathode manufactured by using the same, and aims to solve the technical problems in the prior art.
The invention adopts the following technical scheme:
in one aspect, the invention provides a rare earth metal electrolytic cathodic protection method, comprising:
determining a position to be protected of a cathode, wherein the length of the cathode is 800mm, the center of the position to be protected of the cathode is apart from the bottom of the cathode by 570-580mm, and the width of the position to be protected of the cathode is 180 mm;
cleaning an oxide layer and a corrosion layer at the position to be protected of the cathode;
heating the position to be protected of the cathode, and spraying a nickel metal coating;
heating the position to be protected of the cathode, and spraying a zirconium dioxide metal coating;
cooling to room temperature and inspecting the final coating formed, porosity of less than 5% is required.
Preferably, the cathode comprises a tungsten cathode.
Preferably, the position of the cathode to be protected comprises a necking region of the cathode.
In the step of cleaning the oxidation layer and the corrosion layer of the position to be protected of the cathode, the position to be protected of the cathode is treated by shot blasting or shot blasting.
As a preferable technical scheme, in the step of heating the position to be protected of the cathode and spraying the nickel metal coating, the position to be protected of the cathode is heated to 1200-1500 ℃ through a thermal induction coil, and the molten metal nickel is uniformly sprayed on the heating position to form the nickel metal coating.
As a preferred technical scheme, the thickness of the nickel metal coating is 0.1 mm.
As a preferable technical scheme, in the step of heating the position to be protected of the cathode and spraying the zirconium dioxide metal coating, the position to be protected of the cathode is heated to 800-.
As a preferred technical scheme, the thickness of the zirconium dioxide metal coating is 0.2-0.5 mm.
In another aspect, the present invention also provides a rare earth metal electrolytic cathode comprising:
-a tungsten cathode, the tungsten cathode being rod-shaped;
a protective coating, the central position of which is arranged at 580mm apart from the bottom 570 of the cathode, the width of which is 180mm apart from the bottom of the cathode; the protective coating comprises a nickel metal coating on the inner layer and a zirconium dioxide metal coating on the outer layer.
As a preferred technical scheme, the porosity of the protective coating is less than 5 percent; the thickness of the nickel metal coating is 0.1 mm; the thickness of the zirconium dioxide metal coating is 0.2-0.5 mm.
The technical scheme adopted by the invention can achieve the following beneficial effects:
(1) according to the rare earth metal electrolytic cathode protection method provided by the invention, firstly, measurement statistics needs to be carried out on a large number of invalid tungsten cathode necking positions, the positions to be protected of the cathode are determined by combining the field production process and the installation condition of equipment, then the positions to be protected are cleaned, and the nickel metal coating and the zirconium dioxide metal coating are sprayed by adopting a two-step method, so that the high-temperature oxidation resistance and the corrosion resistance of the cathode are enhanced, the corrosion speed of the cathode is greatly delayed, and the service life of the cathode is prolonged on the premise of not influencing the conductivity of the cathode.
(2) The protective coating coated outside the cathode comprises an inner nickel metal coating and an outer zirconium dioxide metal coating, and the expansion coefficient of tungsten and the expansion coefficient of zirconium dioxide are different greatly, so that the nickel metal coating is firstly sprayed between the nickel metal coating and the zirconium dioxide metal coating, the nickel metal coating and the zirconium dioxide metal coating are combined more tightly, and the zirconium dioxide metal coating is prevented from peeling off after being heated and heated to influence the protection effect on the tungsten cathode.
(3) When the nickel metal coating is sprayed, the penetration effect of the nickel metal coating is enhanced by controlling the heating temperature, so that the nickel metal coating is combined with the cathode more tightly; when the zirconium dioxide metal coating is sprayed, the heating temperature is controlled again, so that the porosity of the finally formed coating is controlled to be less than 5%, and the corrosion resistance effect is further improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below to form a part of the present invention, and the exemplary embodiments and the description thereof illustrate the present invention and do not constitute a limitation of the present invention. In the drawings:
FIG. 1 is a schematic view of a rare earth metal electrolytic furnace according to the prior art;
FIG. 2 is a schematic structural view showing the failure of a tungsten cathode after 6 months of use in the prior art;
FIG. 3 is a schematic structural diagram of a corrosion-resistant rare earth metal electrolytic cathode disclosed in example 2 of the present invention.
Description of reference numerals:
electrolytic furnace 1, anode 2, cathode 3, necking zone 4, protective coating 5.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. In the description of the present invention, it is noted that the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
In order to solve the problems in the prior art, embodiments of the present application mainly provide a method for protecting a rare earth metal cathode, including the steps of: 1) determining the position of the cathode to be protected; 2) cleaning an oxide layer and a corrosion layer at the position to be protected of the cathode; 3) heating the position to be protected of the cathode, and spraying a nickel metal coating; 4) heating the position to be protected of the cathode, and spraying a zirconium dioxide metal coating; 5) cooling to room temperature, and inspecting the finally formed coating, wherein the porosity is required to be less than 5%.
Example 1
Referring to fig. 1 to 2, fig. 1 is a schematic structural view of a rare earth metal electrolytic furnace in the prior art, and fig. 2 is a schematic structural view of a tungsten cathode which fails after 6 months of use.
In the prior art, the diameter of a tungsten cathode used for rare earth electrolysis is about 75 mm-80 mm, the length is about 800mm, and the tungsten cathode is connected with a power supply through a conductive plate and then inserted into an electrolyte melt at the central position (1050 +/-20) DEG C of an electrolytic furnace 1. During the production process, the rare earth oxide and the fluoride electrolyte respectively generate electrochemical reaction on the cathode 3 and the anode 2 of the electrolytic furnace 1 under the action of current to generate anode gas and cathode rare earth metal, so that the tungsten cathode is influenced by factors such as temperature, corrosive gas, volatile electrolyte and high-temperature convective air, and as can be seen from fig. 1 and 2, when the ternary system molten salt electrolysis method is used, a necking region 4 appears between the tungsten cathode and a cathode chuck above the furnace mouth of the electrolytic furnace 1, which indicates that the corrosion is serious, and the necking region 4 usually has a deformed double-funnel shape.
In a preferred embodiment, 6 failed tungsten cathodes are selected and the necking area 4 of the tungsten cathodes is measured, and the result shows that the maximum necking point occurs 53-67 mm above the upper surface of the furnace mouth of the electrolytic furnace 1, and the average height is 60.5 mm; the diameter of the maximum part of the necking is 50.4-55.5 mm, the average diameter is 53.2mm, and the average necking rate is calculated to be 0.121 mm/day; the length of the necking zone 4 is 84 mm-96 mm, and the average length is 90 mm; the average service temperature of the necking zone 4 is 735 to 800 ℃.
In a preferred embodiment, 4 metallographic samples are taken of the necking region of a failed tungsten cathode, and the surfaces of the metallographic samples are observed to have pits formed by cracks and grain shedding distributed along the crystal from the surface to the inside, wherein the pits along the crystal are the most serious at the maximum position of the necking and begin to become lighter away from the maximum position of the necking. In addition, in the whole necking process of the tungsten cathode which is symmetrical in the axial direction, the cracks on two sides are different in number and depth, namely, the corrosion is not uniform in the circumferential direction of the necking area. According to the detection result of a scanning electron microscope, the cracks contain elements such as O, W, F, Nd, S, Fe and the like, and particularly the content of the element O is high.
Further, mechanical stripping is used to obtain corrosion products in the non-necked region and the necked region 4, and the composition phases of the corrosion products are analyzed by XRD. According to the analysis of the XRD diffraction experiment result, the substance of the failed tungsten cathode on the surface of the uncrimped area is NdF3、Nd2O3LiF, which is caused by volatilization of high-temperature molten salt and raw material dust deposited by a feeding system in the process of producing metal neodymium by the electrolytic furnace 1; the failed tungsten cathode has NdF on the surface of the necking zone 43、Nd2O3Besides LiF, WO appears3W and NdOF, etc., which show that the necking zone 4 of the tungsten cathode is oxidized at high temperature during the use process, and oxygen firstly enters into the interior of the tungsten cathode from the surface of the tungsten cathode along grain boundaries during the high-temperature oxidation process, so that the cathode 3 is oxidized along the grains to form WO3As the corrosion time is prolonged, the crystal grains are separated to form a simple substance W metal phase.
On the one hand, in the process of producing rare earth metal by adopting the rare earth oxide electrolysis method, the graphite anode 2 of the electrolytic furnace 1 is subjected to reduction reaction to generate O2、CO、CO2、F2HF, CF and CF4When the gas overflows from the molten pool, the gas is adsorbed on the surface of the tungsten cathode under the action of cold air at the upper part of the furnace mouth to generate WO3And WF6And oxidation products and corrosion products. These oxidation and corrosion products can grow in thickness over time, flaking off the tungsten cathode surface, and causing the tungsten cathode to taper and fail.
On the other hand, LiF and part of NdF in the electrolyte in the electrolytic furnace 13Volatilizing at high temperature, and adsorbing on the surface of the tungsten cathode to form a wrapping layer with a certain thickness; the electrolytic furnace 1 is added in the production processDuring feeding, a certain amount of raw material dust can be formed to float in the air due to the vibration effect in the feeding process and be adsorbed on the surface of the tungsten cathode under the action of external cold air and an electric field to form a wrapping layer with a certain thickness. The electrolyte and the raw material wrapped on the surface of the tungsten cathode react with tungsten metal at a high temperature to generate tungsten oxide and fluoride, so that the tungsten cathode is gradually thinned, and finally the cathode fails.
In addition, the furnace mouth of the electrolytic furnace 1 is open. In the production process, anode gas generated in the furnace overflows from the furnace opening in a cylindrical mode with certain density under the action of high temperature and high pressure in the furnace, and an anode gas flow wall is formed at the furnace opening. The cold air outside the furnace mouth flows from outside to center in a convection mode, when the cold air meets the anode gas in a high-temperature state, the cold air is heated and flows upwards along with the anode gas, when the cold air flows upwards to about 60mm above the furnace mouth (namely the most serious part of the necking of the tungsten cathode), the heated air and the cold air above the heated air penetrate through a gas wall formed by the anode gas, the wrapped anode gas is adsorbed on the surface of the tungsten cathode or the surface of a wrapping layer, and O in the adsorbed gas2CO, HF, etc. reach the surface of the tungsten cathode by diffusing from the surface of the tungsten rod inwards along the grain boundary or diffusing from the surface of the wrapping layer inwards, and then diffusing inwards along the grain boundary to oxidize and corrode the tungsten metal grain boundary to form WO3、WC、WC2And WF6And the oxidation and corrosion products destroy the bonding force of the grain boundary, and cause the falling of tungsten metal grains to form a falling pit on the surface of the tungsten rod. The tungsten cathode is continuously oxidized, corroded and peeled along the crystal grains through the process, so that the diameter of the tungsten cathode is thinned, and finally the cathode fails.
As can be seen from the above, the cause of the necking region 4 of the tungsten cathode is mainly high temperature oxidation and high temperature corrosion. For the above reasons, in a preferred embodiment, a rare earth metal cathode protection method is provided, and referring to fig. 3, the high-temperature electrolyte and the high-temperature oxidizing gas are isolated without affecting the current efficiency and the thermal efficiency of the electrolytic furnace 1, so as to prolong the service life of the tungsten cathode. The method mainly comprises the following steps:
s1, determining a position to be protected of a cathode.
Preferably, as is clear from the above experimental results, the maximum point at which necking of the tungsten cathode occurs is not located in the middle of the entire necking region 4, but is located at a position lower than the middle, on average, 60.5mm above the furnace opening of the electrolytic furnace 1, and the length of the entire necking region 4 is on average 90 mm. Based on the measurement of the necking position of the failed tungsten cathode and the combination of the field production process and the installation condition of equipment, the distance between the center of the position to be protected of the cathode and the bottom of the cathode 3 is 570-.
And S2, cleaning an oxide layer and a corrosion layer at the position to be protected of the cathode.
Preferably, the position to be protected of the cathode determined in S1 is cleaned by a shot blasting machine or a shot blasting machine to eliminate an oxide layer and other surface defects formed on the surface of the tungsten cathode during the forming process, so as to prepare for the subsequent spraying step.
And S3, heating the position to be protected of the cathode, and spraying a nickel metal coating.
Preferably, the metal nickel is firstly put into a thermal spraying device for heating and melting, meanwhile, a position to be protected of the cathode is heated by a thermal induction coil, after the position to be protected of the cathode turns red and is heated to 1200-1500 ℃, the molten metal nickel is evenly sprayed on the heating position to form the nickel metal coating. Preferably, the thickness of the nickel metal coating is 0.1 mm.
And S4, spraying a zirconium dioxide metal coating after the cathode is cooled.
Preferably, after the tungsten cathode is cooled to room temperature and the nickel metal coating is guaranteed to be continuously compact, the zirconium dioxide is placed in a thermal spraying device to be heated and melted, the position of the cathode to be protected is heated again by a thermal induction coil, and after the position turns red and is heated to 800-1000 ℃, the melted zirconium dioxide is uniformly sprayed on the surface of the nickel metal coating to form the zirconium dioxide metal coating. Preferably, the zirconium dioxide metal coating is 0.2-0.5 mm.
S5, when the cathode is cooled to the room temperature, detecting the finally formed coating, wherein the porosity is required to be less than 5%, and if the porosity is not required to be sprayed again.
Preferably, in the above steps S3-S5, since the expansion coefficient of the tungsten and the expansion coefficient of the zirconium dioxide are greatly different, a nickel metal coating is firstly sprayed between the tungsten and the zirconium dioxide, and the nickel metal coating has the functions of oxidation resistance and corrosion resistance, so that the tungsten cathode and the zirconium dioxide metal coating can be more tightly combined, and the zirconium dioxide metal coating is prevented from peeling off after being heated to increase the temperature, and the protection effect on the tungsten cathode is prevented from being affected. Meanwhile, the thickness of the nickel metal coating is controlled to be about 0.1mm and cannot be too thick, so that the peeling and falling of the tungsten cathode after heating are avoided. Furthermore, when the nickel metal coating is sprayed, the penetration effect of the nickel metal coating is enhanced by controlling the heating temperature, so that the nickel metal coating can be combined with the tungsten cathode more tightly.
Preferably, when the zirconium dioxide metal coating is sprayed, the heating temperature is controlled again to control the porosity of the finally formed coating to be less than 5%, so as to further improve the corrosion resistance. The zirconium dioxide has stable chemical property, high temperature resistance and stability in an oxidizing atmosphere, and can resist the erosion of acid or neutral slag, so the zirconium dioxide can be used as a preferable material for oxidation resistance and corrosion resistance of the tungsten cathode. The thickness of the zirconium dioxide coating is controlled to be 0.2-0.5mm, so that the zirconium dioxide coating has enough corrosion resistance and can be prevented from peeling off due to over-thickness.
Preferably, the porosity of the finally formed coating is ensured to be less than 5%, and the optimal corrosion resistance effect can be achieved under the condition that the production process allows.
Example 2
Based on the tungsten cathodic protection method disclosed in example 1, in this example, a corrosion-resistant rare earth metal electrolytic cathode manufactured using the method disclosed in example 1 is disclosed, as shown in fig. 3, which comprises a cathode 3 itself and a protective coating 5.
In a preferred embodiment, the cathode 3 is a rod-shaped tungsten cathode having a length of about 800 mm. Preferably, the protective coating 5 comprises a nickel metal coating layer as an inner layer and a zirconium dioxide metal coating layer as an outer layer, wherein the thickness of the nickel metal coating layer is preferably 0.1mm, and the thickness of the zirconium dioxide metal coating layer is preferably 0.2-0.5 mm; further, the central position of the protective coating 5 is arranged at 580mm away from the bottom 570-180 mm of the cathode 3, and the width of the protective coating 5 is 180 mm-120 mm. Preferably, the porosity of the protective coating 5 is less than 5%.
Preferably, the tungsten cathode sprayed with the protective coating 5 in this embodiment is tested on different electrolytic furnaces 1 such as praseodymium-neodymium metal, lanthanum-cerium metal, lanthanum metal, cerium metal, etc., and it is verified by the test that the tungsten cathode with the protective coating 5 is also lossy, and the loss is extremely small compared with the tungsten cathode without the protective coating.
When the residual diameter of the tungsten cathode reaches 40mm, the tungsten cathode needs to be replaced and scrapped in order to ensure the safety and reliability of production equipment. The tungsten cathode sprayed with the protective coating 5 in this example had a residual diameter of 1 year after use
Figure BDA0003485243430000071
When the un-sprayed tungsten cathode is used for 6 months, the residual diameter of the tungsten cathode reaches 40mm, and the rejection requirement is met. Therefore, the sprayed tungsten cathode can be continuously used, and according to the results of 'study on corrosion behavior of tungsten metal in NdF3-LiF molten salt environment at different temperatures', the tungsten thinning rate is 6.50mm/mon at 850 ℃, and the tungsten cathode in the embodiment can be continuously used for 3 to 4 months, and the service life of the tungsten cathode reaches 15 months.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (10)

1. A rare earth metal electrolytic cathodic protection method is characterized by comprising the following steps:
determining a position to be protected of a cathode, wherein the length of the cathode is 800mm, the center of the position to be protected of the cathode is apart from the bottom of the cathode by 570-580mm, and the width of the position to be protected of the cathode is 180 mm;
cleaning an oxidation layer and a corrosion layer at the position to be protected of the cathode;
heating the position to be protected of the cathode, and spraying a nickel metal coating;
heating the position to be protected of the cathode, and spraying a zirconium dioxide metal coating;
cooling to room temperature and inspecting the final coating formed, porosity of less than 5% is required.
2. The method of claim 1, wherein the cathode comprises a tungsten cathode.
3. The cathodic protection method as recited in claim 2, wherein the location at which the cathode is to be protected comprises a necked down region of the cathode.
4. The method of claim 2, wherein the locations to be protected of the cathodes are treated by shot blasting or ball blasting in the step of cleaning the oxide and corrosion layers of the locations to be protected of the cathodes.
5. The method as claimed in claim 2, wherein in the step of heating the position to be protected of the cathode and spraying the nickel metal coating, the position to be protected of the cathode is heated to 1200-1500 ℃ by a thermal induction coil, and the molten metal nickel is uniformly sprayed on the heated position to form the nickel metal coating.
6. The cathodic protection method as recited in claim 5, wherein the nickel metal coating has a thickness of 0.1 mm.
7. The method as claimed in claim 2, wherein in the step of heating the position to be protected of the cathode and spraying the zirconium dioxide metal coating, the position to be protected of the cathode is heated to 800-100 ℃ by a thermal induction coil, and molten zirconium dioxide is uniformly sprayed on the surface of the nickel metal coating to form the zirconium dioxide metal coating.
8. The method of claim 7, wherein the zirconia metal coating has a thickness of 0.2 to 0.5 mm.
9. A rare earth metal electrolytic cathode, comprising:
-a tungsten cathode in the shape of a rod;
a protective coating, the central position of which is arranged at 580mm from the bottom 570-570 of the cathode, and the width of which is 180 mm; the protective coating comprises a nickel metal coating on the inner layer and a zirconium dioxide metal coating on the outer layer.
10. The rare earth metal electrolytic cathode of claim 9 wherein the protective coating has a porosity of less than 5%; the thickness of the nickel metal coating is 0.1 mm; the thickness of the zirconium dioxide metal coating is 0.2-0.5 mm.
CN202210078848.0A 2022-01-24 2022-01-24 Rare earth metal electrolytic cathode protection method and cathode Active CN114606540B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210078848.0A CN114606540B (en) 2022-01-24 2022-01-24 Rare earth metal electrolytic cathode protection method and cathode

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210078848.0A CN114606540B (en) 2022-01-24 2022-01-24 Rare earth metal electrolytic cathode protection method and cathode

Publications (2)

Publication Number Publication Date
CN114606540A true CN114606540A (en) 2022-06-10
CN114606540B CN114606540B (en) 2023-07-14

Family

ID=81857913

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210078848.0A Active CN114606540B (en) 2022-01-24 2022-01-24 Rare earth metal electrolytic cathode protection method and cathode

Country Status (1)

Country Link
CN (1) CN114606540B (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB773491A (en) * 1952-08-27 1957-04-24 Ernst Adalbert Pokorny Process for the manufacture of cerium mischmetal with low contents of iron, silicon, aluminium, copper, lead
CN105986266A (en) * 2015-12-26 2016-10-05 包头市三隆稀有金属材料有限责任公司 Tungsten cathode laser multilayer cladding repairing method
CN107190260A (en) * 2017-05-24 2017-09-22 中国船舶重工集团公司第七二五研究所 A kind of anti-corrosion heat insulating coat system and preparation method thereof
CN110753987A (en) * 2017-05-23 2020-02-04 普兰西股份有限公司 Cathode material
CN113481544A (en) * 2021-07-07 2021-10-08 西安建筑科技大学 Fused salt non-electrolytic infiltration local treatment method for prolonging service life of tungsten and molybdenum cathodes of rare earth fused salt electrode
CN113897642A (en) * 2021-09-29 2022-01-07 内蒙金属材料研究所 Tungsten cathode for molten salt electrolysis, preparation method thereof and application of laser cladding technology

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB773491A (en) * 1952-08-27 1957-04-24 Ernst Adalbert Pokorny Process for the manufacture of cerium mischmetal with low contents of iron, silicon, aluminium, copper, lead
CN105986266A (en) * 2015-12-26 2016-10-05 包头市三隆稀有金属材料有限责任公司 Tungsten cathode laser multilayer cladding repairing method
CN110753987A (en) * 2017-05-23 2020-02-04 普兰西股份有限公司 Cathode material
CN107190260A (en) * 2017-05-24 2017-09-22 中国船舶重工集团公司第七二五研究所 A kind of anti-corrosion heat insulating coat system and preparation method thereof
CN113481544A (en) * 2021-07-07 2021-10-08 西安建筑科技大学 Fused salt non-electrolytic infiltration local treatment method for prolonging service life of tungsten and molybdenum cathodes of rare earth fused salt electrode
CN113897642A (en) * 2021-09-29 2022-01-07 内蒙金属材料研究所 Tungsten cathode for molten salt electrolysis, preparation method thereof and application of laser cladding technology

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
WENJIN DING 等: "Molten chloride salts for high-temperature thermal energy storage: Continuous electrolytic salt purification with two Mg-electrodes and alternating voltage for corrosion control", 《SOLAR ENERGY MATERIALS AND SOLAR CELLS》, pages 1 - 10 *
王权 等: "稀土电解炉钨阴极失效原因分析", 《稀土》, vol. 40, no. 5, pages 106 - 114 *
邓汝富 等: "电解金属钕过程中阴极钼(钨)棒的腐蚀与防护", 《稀有金属》, vol. 21, no. 2, pages 105 - 108 *

Also Published As

Publication number Publication date
CN114606540B (en) 2023-07-14

Similar Documents

Publication Publication Date Title
EP0306099B1 (en) A ceramic/metal composite material
KR101383524B1 (en) Method for forming an electrocatalytic surface on an electrode and the electrode
JP5562962B2 (en) Oxygen generating metal anode operating at high current density for aluminum reduction cells
US6248227B1 (en) Slow consumable non-carbon metal-based anodes for aluminium production cells
CA2339095C (en) Nickel-iron alloy-based anodes for aluminium electrowinning cells
Choi et al. Electrolytic reduction runs of 0.6 kg scale-simulated oxide fuel in a Li2O-LiCl molten salt using metal anode shrouds
CN103820816A (en) Surface treatment method for aluminum electrolyzing inert anode
Vishnu et al. Corrosion of high density graphite anodes during direct electrochemical de-oxidation of solid oxides in molten CaCl2 medium
US4354918A (en) Anode stud coatings for electrolytic cells
EP1102874B1 (en) Nickel-iron alloy-based anodes for aluminium electrowinning cells
US6521116B2 (en) Cells for the electrowinning of aluminium having dimensionally stable metal-based anodes
CN114606540B (en) Rare earth metal electrolytic cathode protection method and cathode
Soral et al. A pilot-scale trial of an improved galvanic deoxidation process for refining molten copper
CN108754395B (en) Preparation method of anticorrosive coating on surface of electrolytic zinc anode plate
CA1113427A (en) Silicon carbide-valve metal borides-carbon electrodes
KR20140108211A (en) Conductor of high electrical current at high temperature in oxygen and liquid metal environment
US6436274B2 (en) Slow consumable non-carbon metal-based anodes for aluminium production cells
Zhang et al. Electrochemical derusting in molten Na 2 CO 3-K 2 CO 3
CN114561671A (en) Rare earth metal electrolytic cathode protection method and cathode
CN102925921B (en) A kind of method strengthening Top-blown Lead Smelting
US6913682B2 (en) Cells for the electrowinning of aluminium having dimensionally stable metal-based anodes
US20220042189A1 (en) Anodes comprising transition metal and platinum group metal as alloys, and related methods and systems
JP2007119296A (en) Heat-resistant container made of iridium
CN117966217A (en) Preparation method of nickel-based alloy surface corrosion-resistant film
Meunier et al. An electrochemical study of the anode effect in the aluminium smelting process

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
CB03 Change of inventor or designer information

Inventor after: Wang Quan

Inventor after: Tang Yongsheng

Inventor after: Zhao Liangzhong

Inventor after: Yang Li

Inventor after: Li Na

Inventor after: Wang Haiyan

Inventor after: Wu Zhongwang

Inventor after: Zhang Yakun

Inventor after: Wang Yufeng

Inventor after: Han Shuai

Inventor after: Zhao Haiying

Inventor after: Xia Yun

Inventor after: Du Yongliang

Inventor after: Yang Zhipeng

Inventor before: Wang Quan

Inventor before: Tang Yongsheng

Inventor before: Zhao Liangzhong

Inventor before: Yang Li

Inventor before: Li Na

Inventor before: Wang Haiyan

Inventor before: Wu Zhongwang

Inventor before: Zhang Yakun

Inventor before: Wang Yufeng

Inventor before: Han Shuai

Inventor before: Zhao Haiying

Inventor before: Xia Yun

Inventor before: Du Yongliang

Inventor before: Yang Zhipeng

CB03 Change of inventor or designer information
GR01 Patent grant
GR01 Patent grant