CN114843059A - Surface layer aluminum-copper alloyed NdFeB magnet and preparation method thereof - Google Patents

Surface layer aluminum-copper alloyed NdFeB magnet and preparation method thereof Download PDF

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CN114843059A
CN114843059A CN202210532710.3A CN202210532710A CN114843059A CN 114843059 A CN114843059 A CN 114843059A CN 202210532710 A CN202210532710 A CN 202210532710A CN 114843059 A CN114843059 A CN 114843059A
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packing
magnet
furnace
tube
sputtering
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徐光青
陶金
张鹏杰
吴玉程
吕君
李炳山
崔接武
孙威
曹玉杰
刘辉
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Hefei University of Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
    • 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
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/14—Metallic material, boron or silicon
    • C23C14/16—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon
    • C23C14/165—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon by cathodic sputtering
    • 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
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
    • 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
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/58—After-treatment
    • C23C14/5806—Thermal treatment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0572—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes with a protective layer
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    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
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    • H01F41/026—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets protecting methods against environmental influences, e.g. oxygen, by surface treatment
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Abstract

The invention discloses a surface layer aluminum copper alloyed NdFeB magnet and a preparation method thereof, and particularly relates to the technical field of rubidium magnet corrosion prevention, which comprises the following steps: magnet pretreatment: carrying out acid washing on the sintered NdFeB magnet, carrying out ultrasonic washing in deionized water, and then transferring to absolute ethyl alcohol for dehydration treatment; sputtering an Al-Cu alloy film on the surface of the magnet: sputtering an Al-Cu film on the surface of the NdFeB magnet by using a magnetron sputtering coating instrument, wherein the ratio of Al to Cu in the target material is 1: 1; diffusing an Al-Cu alloy layer on the surface of the magnet: putting the NdFeB magnet after coating into a vacuum tube furnace at the vacuum degree of 10 ‑3 ～10 ‑4 Pa, the diffusion temperature is 700-800 ℃, the heating rate is 5 ℃/min, the diffusion is carried out under the condition of heat preservation time of 2h, and the corrosion resistance of the magnet is obviously improved on the premise of ensuring the magnetism of the magnet through the thermal diffusion process after the sputtering coating.

Description

Surface layer aluminum-copper alloyed NdFeB magnet and preparation method thereof
Technical Field
The invention relates to the field of rubidium magnet corrosion prevention, in particular to a surface aluminum copper alloyed NdFeB magnet and a preparation method thereof.
Background
The sintered NdFeB magnet is widely applied to the fields of machinery, electronics, instruments and the like due to excellent magnetic performance, and the NdFeB magnet under the severe environment of wind power generation and the like puts forward the long-term maintenance-free requirement for more than 25 years, but the sintered NdFeB magnet has a multi-phase structure (a main phase Nd) due to the magnet 2 Fe 14 B. Nd-rich phase and B-rich phase) and the difference in electrochemical potential between the phases make the magnet susceptible to corrosion, resulting in failure, and the poor inherent corrosion resistance of the neodymium iron boron magnet has become a benefit for further development of surface protection technology.
The prior art comprises a neodymium iron boron magnet protection method and a surface protection method, wherein the alloying method reduces potential difference, but simultaneously causes a certain loss on the magnetic performance of the magnet; the realization means of the surface protection method is also subjected to the toggle in the aspects of environmental protection, economy and the like, for example, electroplating solution and passivation solution used in the electroplating and passivation process are not environment-friendly, Ni in the Ni layer is a noble metal, and the production cost is high.
Patent application document CN213150565U discloses a neodymium iron boron magnet modification device for metal is oozed in grain boundary diffusion, including feeding cavity, sputtering diffusion process chamber, ejection of compact cavity and base, feeding cavity is provided with three-dimensional work piece revolving rack system, ion source etching system and first heating system, and sputtering diffusion process chamber is provided with sputter source system, high energy ion source system and second heating system, and ejection of compact cavity is provided with third heating system. The neodymium iron boron magnet modification device for grain boundary diffusion metal infiltration is reasonably configured according to the composite process flow of preparing high-coercivity neodymium iron boron, the feeding chamber has the functions of ion etching and preheating, the sputtering diffusion process chamber has the functions of sputtering a metal coating and metal diffusion, the discharging chamber has the function of tempering heat treatment, 3 chambers are separated through valves and work respectively without mutual interference, and the production continuity is realized.
However, the formation of a film layer on the surface of a rubidium magnet by magnetron sputtering alone results in a certain loss of magnetic properties of the magnet.
Disclosure of Invention
The invention aims to provide an NdFeB magnet with an alloyed surface layer of aluminum and copper and a preparation method thereof, which aim to solve the technical problem of magnetic loss after sputtering coating proposed in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme:
a surface layer aluminum-copper alloyed NdFeB magnet is characterized in that: the surface of the magnet is provided with an aluminum-copper alloy layer which is subjected to thermal diffusion, and the ratio of copper to aluminum is 1: 1
A method for preparing a surface layer aluminum-copper alloyed NdFeB magnet comprises the following steps:
1) magnet pretreatment: carrying out acid washing on the sintered NdFeB magnet, carrying out ultrasonic washing in deionized water, and then transferring to absolute ethyl alcohol for dehydration treatment;
2) sputtering an Al-Cu alloy film on the surface of the magnet: sputtering an Al-Cu film on the surface of the NdFeB magnet by using a magnetron sputtering coating instrument, wherein the ratio of Al to Cu in the target material is 1: 1;
3) diffusing an Al-Cu alloy layer on the surface of the magnet: putting the NdFeB magnet after coating into a vacuum tube furnace at the vacuum degree of 10 -3 ～10 -4 Pa, diffusion temperatureThe temperature is 700-800 ℃, the heating rate is 5 ℃/min, and the diffusion is carried out under the condition of the heat preservation time of 2 h.
The corrosion resistance of the magnet after sputtering and coating is obviously improved on the premise of ensuring the magnetism of the magnet through a thermal diffusion process.
Preferably, in the step 1), the concentration of the adopted nitric acid is 3%, and the pickling time is 20-30 s; the medium ultrasonic time is 3-5 min.
Preferably, in the step 2), an Al-Cu target with the purity of more than 99.99% is selected for sputtering, the sputtering power is 150W, the starting pressure is 1.0Pa, the working pressure is 0.5Pa, and the sputtering coating time is 0.5-1 h.
Meanwhile, a vacuum tube furnace is provided for metal thermal diffusion after magnetron sputtering coating, and the technical scheme is as follows:
vacuum tube furnace, including the control box, the furnace body is connected to the control box top, the furnace body top is connected the bell, fixed connection furnace frame in the furnace body, furnace frame middle part sets up the tube seat, place the furnace chamber on the tube seat, the furnace chamber both ends are connected sealing mechanism respectively, sealing mechanism includes the mounting flange with furnace chamber fixed connection, mounting flange and sealing flange are connected, the sealing flange other end is connected with packing mechanism, sealing flange side connection manometer, sealing flange connects packing mechanism, can last magnet in the thermal diffusion process, the supplementary filler, adopt multi-temperature-zone vacuum tube furnace, realize that a plurality of magnets are thermal diffusion under different conditions simultaneously, improve test efficiency.
Preferably, the packing mechanism comprises a packing pipe communicated with the sealing flange, the end part of the packing pipe is connected with a packing cylinder, a packing wheel is rotatably connected in the packing cylinder, a packing groove is formed in the packing wheel, the side surface of the packing cylinder is respectively connected with an exhaust mechanism, an inflation mechanism and a cooling mechanism, and a transfer mechanism is arranged on the side surface of the furnace chamber.
Preferably, the packing cylinder is hollow and open-sided, the outside of the packing wheel is attached to the inner wall of the packing cylinder, the packing groove is a cylindrical groove with the same inner diameter as the packing pipe, and the packing groove is communicated with the side face of the packing wheel.
Preferably, the transfer mechanism comprises a sliding groove which is arranged in a direction parallel to the axis of the furnace chamber and is close to the furnace chamber, an electromagnet is arranged in the sliding groove and is in threaded connection with a screw rod, the electromagnet in the transfer mechanism is electrified to generate magnetic attraction to the magnet in the filling groove, the electromagnet can be moved under the condition that the screw rod rotates, so that the magnet in the filling groove is moved to a specific area in the furnace chamber along with the magnet, and heat diffusion is carried out under the specific temperature condition of the specific area.
Preferably, the exhaust mechanism comprises an exhaust funnel communicated with one end of the packing cylinder, the other end of the packing cylinder is connected with an air guide tube aligned with the exhaust funnel, the outer ends of the exhaust funnel and the air guide tube are respectively connected with a check valve, air in the packing cylinder is exhausted in a mode that one end of the exhaust funnel and one end of the air guide tube are ventilated, and the magnet and a coating film on the magnet are prevented from reacting with components in the air in the thermal diffusion process.
Preferably, the inflation mechanism comprises an inflation pipe communicated with one end of the packing cylinder, the end part of the inflation pipe is connected with an inflation valve, the other end of the packing cylinder is connected with a pressure-measuring pipe in an aligned position with the inflation pipe, the pressure-measuring pipe is connected with a pressure gauge, the other end of the pressure gauge is communicated with the packing pipe, part of inert gas is supplemented through the inflation mechanism, so that the pressure in the packing groove is the same as the pressure in the furnace chamber, and the pressure in the furnace chamber is kept stable after the packing groove rotates to be communicated with the furnace chamber.
Preferably, the cooling mechanism comprises a cooling water pipe connected to one end of the packing cylinder, the cooling water pipe is aligned with a cooling flow channel penetrating through the packing wheel, a water outlet aligned with the cooling flow channel is formed in the other end of the packing cylinder, the cooling mechanism adopts a conduction water cooling mode, the cooling rate is higher compared with natural cooling or inert gas cooling, and the contact between a magnet still in a high-heat state and the outside can be avoided.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention adopts the vacuum diffusion technology based on magnetron sputtering to realize the surface Al-Cu alloying process of the NdFeB magnet, obviously improves the corrosion resistance of the magnet, and compared with the traditional magnet alloying technology, the invention realizes the surface alloying but not the integral alloying of the magnet, greatly improves the intrinsic corrosion resistance of the magnet and ensures that the magnet keeps the magnetism;
2. the vacuum tube furnace is used for a magnet thermal diffusion process, in diffusion, magnets can be supplemented into a furnace chamber or taken out from the furnace chamber at any time through a filling mechanism on the premise of not introducing air, changing the air pressure condition and the temperature condition of the furnace chamber, and the magnets under different process conditions can be simultaneously thermally treated by utilizing the vacuum tube furnace with multiple temperature zones;
3. the packing mechanism adopts a packing wheel which is attached to and rotatably connected with a packing cylinder and is provided with a packing groove on the side surface, the packing cylinder is respectively connected with an exhaust mechanism to realize the vacuum pumping in the packing groove, an inflation mechanism is arranged to ensure that the internal pressure of the packing groove is the same as the internal pressure of the furnace chamber, and a cooling mechanism is arranged to ensure that the taken-out magnet is rapidly cooled under the state of higher vacuum degree, thereby improving the heat treatment efficiency;
4. the exhaust mechanism adopts a mode of introducing inert gas and exhausting at the same time, so that air in the packing groove can be fully extruded out, two ends of a pressure measuring valve in the inflation mechanism are respectively connected with the packing groove and the furnace chamber, and pressure balance is observed while inflating;
5. the cooling mechanism adopts a mode of arranging a through cooling flow channel on the packing wheel, water takes away heat in the flow channel close to the packing groove in the flowing process, and the magnet after the heat treatment is in a high vacuum state to realize rapid cooling through heat conduction.
Drawings
FIG. 1 is a SEM image of the surface layer of the Al-Cu alloyed high corrosion resistant magnet after thermal diffusion according to the present invention;
FIG. 2 is a polarization diagram of a surface alloyed high corrosion resistant sintered NdFeB magnet of the invention after thermal diffusion and a comparative example;
FIG. 3 is a schematic view of the structure of a vacuum tube furnace according to the present invention;
FIG. 4 is a schematic structural view of the packing mechanism of the present invention;
FIG. 5 is a half sectional view of the packing cartridge of the present invention;
FIG. 6 is a cross-sectional view of the exhaust mechanism of the present invention;
FIG. 7 is a schematic structural view of the inflation mechanism of the present invention;
FIG. 8 is a schematic view of the packing wheel of the present invention.
In the figure: 1. a control box; 2. a furnace body; 21. a chute; 22. a furnace chamber; 3. a furnace cover; 4. a transfer mechanism; 41. an electromagnet; 42. a screw rod; 43. a transfer motor; 5. a filling mechanism; 51. a packing cylinder; 511. A filling opening; 52. a packing wheel; 521. a packing groove; 522. a cooling flow channel; 53. a stuffing motor; 6. An exhaust mechanism; 61. a gas-guide tube; 62. an exhaust funnel; 7. an inflation mechanism; 71. an inflation tube; 72. a communicating pipe; 73. a pressure gauge; 74. a piezometric tube; 8. a cooling mechanism; 81. a water outlet; 82. a cooling water pipe; 9. a sealing mechanism; 91. a fixed flange; 92. sealing the flange; 93. a filler tube.
Detailed Description
Example 1
S1: carrying out acid washing on the sintered NdFeB magnet for 30s, then carrying out ultrasonic treatment in deionized water, and then transferring to absolute ethyl alcohol for dehydration treatment;
s2: adopting a high-purity (99.999%) Al-Cu target, and sputtering an Al-Cu film on the surface of an NdFeB magnet by using a JGP-450A type magnetron sputtering coating instrument, wherein the sputtering power is 150W, the starting pressure is 1.0Pa, the working pressure is 0.5Pa, and the sputtering coating time is 0.5 h;
s3: the Al-Cu film-plated NdFeB magnet was diffused in a vacuum tube furnace. The vacuum degree is 10 < -3 > to 10 < -4 > Pa, the diffusion temperature is 700 ℃, and the heat preservation time is 2 hours;
in the electrochemical corrosion test of the sintered NdFeB magnet with alloyed surface layer obtained according to the steps, the corrosion potential is-0.79V, the self-corrosion current density is 9.173 multiplied by 10 < -7 > A.cm < -2 >, and the sintered NdFeB magnet is soaked in 3.5 weight percent NaCl solution for 48 hours to cause corrosion, so that the comprehensive corrosion resistance of the sintered NdFeB magnet is obviously better than that of the comparative example.
Example 2:
s1: carrying out acid washing on the sintered NdFeB magnet for 30s, then carrying out ultrasonic treatment in deionized water, and then transferring to absolute ethyl alcohol for dehydration treatment;
s2: adopting a high-purity (99.999%) Al-Cu target, and sputtering an Al-Cu film on the surface of an NdFeB magnet by using a JGP-450A type magnetron sputtering coating instrument, wherein the sputtering power is 150W, the starting pressure is 1.0Pa, the working pressure is 0.5Pa, and the sputtering coating time is 0.5 h;
s3: the Al — Cu film-plated NdFeB magnet was diffused in a vacuum tube furnace. The vacuum degree is 10 < -3 > to 10 < -4 > Pa, the diffusion temperature is 800 ℃, and the heat preservation time is 2 hours;
in the electrochemical corrosion test of the sintered NdFeB magnet with alloyed surface layer obtained according to the steps, the corrosion potential is-1.08V, the self-corrosion current density is 2.138 multiplied by 10 < -6 > A.cm < -2 >, and the sintered NdFeB magnet is soaked in 3.5 weight percent NaCl solution for 30 hours to generate corrosion, so that the comprehensive corrosion resistance of the sintered NdFeB magnet is obviously better than that of the comparative example.
Example 3:
s1: carrying out acid washing on the sintered NdFeB magnet for 30s, then carrying out ultrasonic treatment in deionized water, and then transferring to absolute ethyl alcohol for dehydration treatment;
s2: sputtering an Al-Cu film on the surface of an NdFeB magnet by adopting a high-purity (99.999%) Al-Cu target and using a JGP-450A type magnetron sputtering coating instrument, wherein the sputtering power is 150W, the starting pressure is 1.0Pa, the working pressure is 0.5Pa, and the sputtering coating time is 1 h;
s3: the Al-Cu film-plated NdFeB magnet was diffused in a vacuum tube furnace. The vacuum degree is 10 < -3 > to 10 < -4 > Pa, the diffusion temperature is 700 ℃, and the heat preservation time is 2 hours.
In the electrochemical corrosion test of the sintered NdFeB magnet with alloyed surface layer obtained according to the steps, the corrosion potential is-1.91V, the self-corrosion current density is 3.159 multiplied by 10 < -6 > A cm < -2 >, the sintered NdFeB magnet is soaked in 3.5 wt% NaCl solution for 24 hours to generate corrosion, and the comprehensive corrosion resistance of the sintered NdFeB magnet is obviously superior to that of a comparison example.
Example 4:
s1: carrying out acid washing on the sintered NdFeB magnet for 30s, then carrying out ultrasonic treatment in deionized water, and then transferring to absolute ethyl alcohol for dehydration treatment;
s2: sputtering an Al-Cu film on the surface of an NdFeB magnet by adopting a high-purity (99.999%) Al-Cu target and using a JGP-450A type magnetron sputtering coating instrument, wherein the sputtering power is 150W, the starting pressure is 1.0Pa, the working pressure is 0.5Pa, and the sputtering coating time is 1 h;
s3: the Al-Cu film-plated NdFeB magnet was diffused in a vacuum tube furnace. The vacuum degree is 10 < -3 > to 10 < -4 > Pa, the diffusion temperature is 800 ℃, and the heat preservation time is 2 hours.
In the electrochemical corrosion test of the sintered NdFeB magnet with alloyed surface layer obtained according to the steps, the corrosion potential is-1.12V, the self-corrosion current density is 1.211 multiplied by 10 < -5 > A.cm < -2 >, and the sintered NdFeB magnet is soaked in 3.5 weight percent NaCl solution for 18 hours to generate corrosion, so that the comprehensive corrosion resistance of the sintered NdFeB magnet is obviously better than that of a control example, as shown in a figure 1-2.
Example 5
As shown in fig. 3-4, the vacuum tube furnace comprises a control box 1, a furnace body 2 is connected above the control box 1, a furnace cover 3 is connected above the furnace body 2, a furnace frame is fixedly connected in the furnace body 2, a tube slot is arranged in the middle of the furnace frame, a furnace chamber 22 is arranged on the tube slot, two ends of the furnace chamber 22 are respectively connected with a sealing mechanism 9, the sealing mechanism 9 comprises a fixed flange 91 fixedly connected with the furnace chamber 22, the fixed flange 91 is connected with a sealing flange 92, the other end of the sealing flange 92 is connected with a packing mechanism 5, the side surface of the sealing flange 92 is connected with a pressure gauge 73, the packing mechanism 5 comprises a packing tube 93 communicated with the sealing flange 92, the end part of the packing tube 93 is connected with a packing cylinder 51, a packing wheel 52 is rotatably connected in the packing cylinder 51, a packing slot 521 is arranged on the packing wheel 52, the side surface of the packing cylinder 51 is respectively connected with an exhaust mechanism 6 and an inflation mechanism 7, the cooling mechanism 8 is provided with a transfer mechanism 4 on the side of the furnace chamber 22.
When the magnet after magnetron sputtering needs thermal diffusion, the magnet is sent into a packing groove 521 on the side surface of a packing wheel 52 rotationally connected with a packing cylinder 51 through a packing mechanism 5, the packing wheel 52 is firstly driven to rotate in the rotating process of the packing groove 521 until the side surface of the packing groove 521 is attached to the inner wall of the packing cylinder 51, the end part of the packing groove 521 is communicated with an exhaust mechanism 6, inert gas is filled into the packing groove 521 through the exhaust mechanism 6 to expel the internal air, then the packing wheel 52 rotates under the driving of a packing motor 53 until the end part of the packing groove 521 is communicated with an inflation mechanism 7, gas is supplemented or exhausted from the inflation mechanism 7, the internal pressure of the packing groove 521 carrying the magnet is the same as the internal pressure of a furnace chamber 22, the packing wheel 52 rotates again until the packing groove 521 is communicated with a packing pipe 93, an electromagnet 41 of a transfer mechanism 4 is electrified, and the electromagnet 41 moves under the driving of a screw rod 42, the magnet is moved to a specific position along the furnace chamber 22 under the adsorption force of the magnet and the electromagnet 41, and the vacuum tube furnace is a multi-temperature-zone vacuum tube furnace, so that the heat diffusion of a plurality of magnets under different conditions is realized simultaneously.
Example 6
As shown in fig. 3-8, the vacuum tube furnace comprises a control box 1, a furnace body 2 is connected above the control box 1, a furnace cover 3 is connected above the furnace body 2, a furnace frame is fixedly connected in the furnace body 2, a tube slot is arranged in the middle of the furnace frame, a furnace chamber 22 is arranged on the tube slot, two ends of the furnace chamber 22 are respectively connected with a sealing mechanism 9, the sealing mechanism 9 comprises a fixed flange 91 fixedly connected with the furnace chamber 22, the fixed flange 91 is connected with a sealing flange 92, the other end of the sealing flange 92 is connected with a packing mechanism 5, the side surface of the sealing flange 92 is connected with a pressure gauge 73, the packing mechanism 5 comprises a packing tube 93 communicated with the sealing flange 92, the end part of the packing tube 93 is connected with a packing cylinder 51, a packing wheel 52 is rotatably connected in the packing cylinder 51, a packing slot 521 is arranged on the packing wheel 52, the side surface of the packing cylinder 51 is respectively connected with an exhaust mechanism 6 and an inflation mechanism 7, a cooling mechanism 8, a transfer mechanism 4 is arranged on the side surface of the furnace chamber 22;
the packing tube 51 is hollow and has a side surface opened, the outside of the packing wheel 52 is attached to the inner wall of the packing tube 51, the packing groove 521 is a cylindrical groove having the same inner diameter as the packing tube 93, and the packing groove 521 is communicated with the side surface of the packing wheel 52.
The transfer mechanism 4 comprises a chute 21 which is arranged along the direction parallel to the axial line of the furnace chamber 22 and is close to the furnace chamber 22, an electromagnet 41 is arranged in the chute 21, and the electromagnet 41 is in threaded connection with a screw rod 42.
The exhaust mechanism 6 comprises an exhaust cylinder 62 communicated with one end of the packing cylinder 51, the other end of the packing cylinder 51 is connected with an air duct 61 aligned with the exhaust cylinder 62, and the outer ends of the exhaust cylinder 62 and the air duct 61 are respectively connected with a check valve.
The inflation mechanism 7 comprises an inflation tube 71 communicated with one end of the filling tube 51, the end part of the inflation tube 71 is connected with an inflation valve, the other end of the filling tube 51 is connected with a pressure measurement tube 74 aligned with the inflation tube 71, the pressure measurement tube 74 is connected with a pressure gauge 73, and the other end of the pressure gauge 73 is communicated with a filling tube 93.
The cooling mechanism 8 includes a cooling water pipe 82 connected to one end of the packing cylinder 51, the cooling water pipe 82 is aligned with a cooling flow passage 522 passing through the packing wheel 52, and the other end of the packing cylinder 51 is provided with a water discharge port 81 aligned with the cooling flow passage 522.
In the filling, the magnet after magnetron sputtering enters the corresponding filling groove 521 from a filling opening 511 on the side surface of a filling cylinder 51, when a filling wheel 52 rotates to be communicated with an exhaust mechanism 6, a gas guide pipe 61 is communicated with an inert gas storage tank, the inert gas can enter the filling groove 521 by opening a valve, the inert gas passes through the filling groove 521 and extrudes the internal air and carries a fixed amount of air to be exhausted from one end of an exhaust cylinder 62, and under the condition of continuously introducing the inert gas, the air in the filling groove 521 can be basically expelled, so that the influence on the performance of the magnet due to the oxidation of a coating on the surface of the magnet in the thermal diffusion process is avoided;
then the packing wheel 52 rotates to communicate with the inflating mechanism 7, the inflating pipe 71 in the inflating mechanism 7 is connected with the inert gas tank through the air supply and exhaust device in the prior art, at this time, one end of the pressure measuring pipe 74 is communicated with the packing groove 521, the other end is communicated with the inside of the furnace chamber 22 connected with the fixed flange 91 through the communicating pipe 72, when the pressure in the packing groove 521 is large, the inner gas is exhausted, when the pressure in the packing groove 521 is smaller than the pressure in the furnace chamber 22, the inert gas is supplemented to the inside, when the pressure in the packing groove 521 is the same as the pressure in the furnace chamber 22, the pointer of the pressure gauge 73 points to display the pressure balance at the two ends, then the packing wheel 52 can be controlled to rotate to the packing groove 521 carrying the magnet to communicate with the packing pipe 93, and after the communication, the pressure in the furnace chamber 22 is kept stable, the heat diffusion is carried out stably, the packing can be realized at any time, and the magnet which needs different heating time can be subjected to the heat diffusion treatment under the same condition by adopting the same vacuum tube furnace, compared with a mode of heating treatment one by one, the method saves more time.
When the magnets in the stuffing groove 521 are moved, the electromagnet 41 is electrified to have magnetism, the electromagnet 41 is in threaded connection with the screw rod 42 connected with the transfer motor 43, the electromagnet 41 can be axially moved relative to the screw rod 42 when the screw rod 42 rotates, and the magnets in the stuffing groove 521 can move to the characteristic position of a specific temperature zone in the furnace chamber 22 under the action of the adsorption force of the electromagnet 41, so that different magnets can be subjected to thermal diffusion treatment under different temperature conditions at the same time.
After the heating of the individual magnets is completed, the electromagnet 41 in the transfer mechanism 4 is moved to the position under the control of the transfer motor 43, then the electromagnet 41 is electrified to adsorb the magnets and then moves into the packing groove 521 on the packing wheel 52 aligned with the packing pipe 93, then the packing wheel 52 rotates until the cooling flow channel 522 on the side surface of the packing groove 521 is communicated with the cooling water pipe 82, the valve connected with the cooling water pipe 82 is opened, cooling water flows through the cooling water pipe 82 and is discharged from the water outlet 81, the magnets in the packing groove 521 are rapidly cooled through heat conduction, and in the cooling process, the heat-treated magnets are still in the closed packing groove 521, so that the phenomenon that the surface is contacted with air or a cooling medium due to overheating of the temperature to cause reaction and the surface corrosion resistance is affected is avoided.
The vacuum tube furnace is used for the research of the surface heat treatment conditions of the magnets to determine the optimal heat treatment conditions, such as air pressure, temperature and time, and can add other magnets during the heat treatment process of one magnet in the furnace chamber 22 and add the magnets under the condition of not changing the internal environmental conditions of the furnace chamber 22, thereby greatly shortening the experimental time.

Claims (10)

1. A surface layer aluminum-copper alloyed NdFeB magnet is characterized in that: the surface of the magnet is provided with an aluminum-copper alloy layer which is subjected to thermal diffusion, and the ratio of copper to aluminum is 1: 1.
2. A method for preparing a surface layer aluminum-copper alloyed NdFeB magnet is characterized by comprising the following steps: the method comprises the following steps:
1) magnet pretreatment: after acid washing, the sintered NdFeB magnet is ultrasonically washed in deionized water, and then is transferred to absolute ethyl alcohol for dehydration treatment;
2) sputtering an Al-Cu alloy film on the surface of the magnet: sputtering an Al-Cu film on the surface of the NdFeB magnet by using a magnetron sputtering coating instrument, wherein the ratio of Al to Cu in the target material is 1: 1;
3) diffusing an Al-Cu alloy layer on the surface of the magnet: putting the NdFeB magnet after coating into a vacuum tube furnace at the vacuum degree of 10 -3 ～10 -4 Pa, the diffusion temperature is 700-800 ℃, the heating rate is 5 ℃/min, and the diffusion is carried out under the condition of the heat preservation time of 2 h.
3. A surface aluminum copper alloyed NdFeB magnet according to claim 2: the method is characterized in that: in the step 1), the concentration of the adopted nitric acid is 3%, and the pickling time is 20-30 s; the medium ultrasonic time is 3-5 min, the Al-Cu target with the purity of more than 99.99% is selected for medium sputtering, the sputtering power is 150W, the starting pressure is 1.0Pa, the working pressure is 0.5Pa, and the sputtering coating time is 0.5-1 h.
4. Vacuum tube furnace, its characterized in that: the furnace comprises a control box, a furnace body is connected above the control box, the furnace cover is connected above the furnace body, a furnace frame is fixedly connected in the furnace body, a pipe groove is arranged in the middle of the furnace frame, a furnace chamber is placed on the pipe groove, two ends of the furnace chamber are respectively connected with a sealing mechanism, the sealing mechanism comprises a fixing flange fixedly connected with the furnace chamber, the fixing flange is connected with a sealing flange, the other end of the sealing flange is connected with a packing mechanism, and the side surface of the sealing flange is connected with a pressure gauge.
5. The vacuum tube furnace according to claim 4, wherein: the packing mechanism comprises a packing pipe communicated with a sealing flange, the end part of the packing pipe is connected with a packing cylinder, a packing wheel is rotationally connected in the packing cylinder, a packing groove is formed in the packing wheel, the side surface of the packing cylinder is respectively connected with an exhaust mechanism, an inflation mechanism and a cooling mechanism, and a transfer mechanism is arranged on the side surface of the furnace chamber.
6. The vacuum tube furnace of claim 5, wherein: the packing tube is hollow and open-sided, the outside of the packing wheel is attached to the inner wall of the packing tube, the packing groove is a cylindrical groove with the same inner diameter as the packing tube, and the packing groove is communicated with the side face of the packing wheel.
7. The vacuum tube furnace of claim 5, wherein: the transfer mechanism comprises a chute which is arranged in the direction parallel to the axis of the furnace chamber and is close to the furnace chamber, an electromagnet is arranged in the chute, and the electromagnet is in threaded connection with a screw rod.
8. The vacuum tube furnace of claim 5, wherein: the exhaust mechanism comprises an exhaust funnel communicated with one end of the packing cylinder, the other end of the packing cylinder is connected with an air guide tube aligned with the exhaust funnel, and the outer ends of the exhaust funnel and the air guide tube are respectively connected with a check valve.
9. The vacuum tube furnace of claim 5, wherein: the inflation mechanism comprises an inflation tube communicated with one end of the filling tube, the end of the inflation tube is connected with an inflation valve, the other end of the filling tube is connected with a pressure measuring tube aligned with the inflation tube, the pressure measuring tube is connected with a pressure gauge, and the other end of the pressure gauge is communicated with the filling tube.
10. The vacuum tube furnace of claim 5, wherein: the cooling mechanism comprises a cooling water pipe connected to one end of the packing cylinder, the cooling water pipe is aligned with a cooling flow channel penetrating through the packing wheel, and a water outlet aligned with the cooling flow channel is formed in the other end of the packing cylinder.
CN202210532710.3A 2022-05-16 2022-05-16 Surface layer aluminum-copper alloyed NdFeB magnet and preparation method thereof Pending CN114843059A (en)

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CN202210532710.3A CN114843059A (en) 2022-05-16 2022-05-16 Surface layer aluminum-copper alloyed NdFeB magnet and preparation method thereof

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