CN114990652A - Electroplated layer structure of sintered neodymium-iron-boron magnet and preparation method - Google Patents

Electroplated layer structure of sintered neodymium-iron-boron magnet and preparation method Download PDF

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CN114990652A
CN114990652A CN202210706503.5A CN202210706503A CN114990652A CN 114990652 A CN114990652 A CN 114990652A CN 202210706503 A CN202210706503 A CN 202210706503A CN 114990652 A CN114990652 A CN 114990652A
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copper
terbium
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郝志平
黄书林
魏佳祥
张旭辉
薛文陶
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Baotou Maigelong Technology Co ltd
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Abstract

The invention discloses an electroplated layer structure of a sintered neodymium-iron-boron magnet and a preparation method thereof, wherein the electroplated layer structure comprises the sintered neodymium-iron-boron magnet, the sintered neodymium-iron-boron magnet sequentially comprises a terbium-copper alloy particle composite layer, a copper layer, a zinc layer and a trivalent chromium passivation layer from inside to outside, and the zinc layer can be replaced by a high-phosphorus nickel chemical plating layer; the copper layer is positioned on the codeposition layer and is used as an intermediate layer; the zinc layer is positioned on the copper layer, trivalent chromium passivation treatment is carried out on the zinc layer to generate a trivalent chromium passivation film layer as a surface layer, and the surface with the roughness of Ra6.3-12.5 mu m is formed on the magnet substrate of the sintered neodymium-iron-boron magnet by adopting an automatic sand blasting method; the terbium copper alloy particle composite layer is composed of terbium copper alloy fine powder particles, the fine powder particles and copper are co-deposited, and the terbium copper alloy particle composite layer is in direct contact with the sintered neodymium iron boron magnet substrate.

Description

Electroplated layer structure of sintered neodymium-iron-boron magnet and preparation method
Technical Field
The invention belongs to the technical field of electromagnetism, and particularly relates to an electroplated layer structure of a sintered neodymium-iron-boron magnet and a preparation method of the electroplated layer structure.
Background
In the sintered neodymium iron boron industry, electroplating is generally carried out by adopting electroplated layer structures of nickel, copper and nickel, nickel and nickel, zinc-nickel alloy, copper and nickel, and the main purposes of the electroplating are corrosion resistance. However, the above-mentioned electroplated layer structure has a negative effect of the magnetic shielding effect of nickel, which weakens the magnetic flux of the magnet and increases the thermal demagnetization rate.
The sintered Nd-Fe-B magnet is a functional material, the main function is to provide permanent magnetic energy, wherein the intrinsic coercive force Hcj is a key index item of magnetic performance, and Hcj represents the performance level of the magnetic material.
Traditionally, the work of improving the performance of the sintered neodymium iron boron permanent magnet is a work task completed by material factories and material engineers.
It is well known that dysprosium and terbium can increase the intrinsic coercivity of a magnet, how can dysprosium and terbium be driven into the main phase and grain boundary phase of the magnet? In a material factory, material engineers adopt a variety of methods, including a melting method, a magnetron sputtering method HR method, a hot-dip HR method, a screen printing HR method, a spray coating fluorination HR method, a spray coating hydrogenation HR method, and the like. The process comprises the following steps: the alloy is added with heavy rare earth dysprosium or terbium, a fine grain process, a double alloy process and a grain boundary diffusion technology to improve Hcj. The above-mentioned processes are all that the terbium metal is fed into the interior of magnet, or fed into main phase, or fed into grain boundary phase, or infiltrated along the edges of main phase and grain boundary phase to form shell layer, and all the shell layer is fed into the interior of magnet.
Up to now, no method for improving the intrinsic coercive force Hcj of the magnet by electroplating has been known. The electroplating method does not leave terbium which is a metal, and for the ultrathin small magnet, terbium is adhered to the surface of the magnet through electroplating to form a shell layer to wrap the magnet, and the small magnet anisotropy field Ha is increased by using the shell layer to improve the intrinsic coercive force Hcj, so that the thermal demagnetization rate of the magnet is reduced.
Disclosure of Invention
The invention aims to provide an electroplated layer structure of a sintered neodymium-iron-boron magnet and a preparation method thereof, so as to solve the problems in the background technology.
The purpose of the invention is realized by the following technical scheme: an electroplated layer structure of a sintered neodymium-iron-boron magnet comprises the sintered neodymium-iron-boron magnet, wherein the sintered neodymium-iron-boron magnet sequentially comprises a terbium-copper alloy particle composite layer, a copper layer, a zinc layer and a trivalent chromium passivation layer from inside to outside, wherein the zinc layer can be replaced by a high-phosphorus nickel chemical plating layer;
the copper layer is positioned on the codeposition layer and is used as an intermediate layer;
the zinc layer is positioned on the copper layer;
and carrying out trivalent chromium passivation treatment on the zinc layer to generate a trivalent chromium passivation film layer as a surface layer.
Further, the magnet substrate of the sintered neodymium-iron-boron magnet is provided with a surface with the roughness of Ra6.3-12.5 mu m by adopting an automatic sand blasting method;
the terbium copper alloy particle composite layer is composed of terbium copper alloy fine powder particles, the fine powder particles and copper are co-deposited, and the terbium copper alloy particle composite layer is in direct contact with the sintered neodymium iron boron magnet substrate.
Further, the fine powder particles of terbium copper alloy are co-deposited with copper to a thickness of about 10 to 20 μm to fill the sandblasted rough surface.
And further, on the basis of the composite coating of the terbium-copper alloy particle composite layer, a simple substance copper layer is additionally coated, the thickness of the simple substance copper layer is 1-5 mu m, and the simple substance copper layer is used as an intermediate layer.
Further, on the basis of the simple substance copper layer, a simple substance zinc + passivation film layer coating is electroplated, the thickness of the simple substance zinc + passivation film layer coating is 5-10 mu m, and the simple substance zinc + passivation film layer coating is used as a surface layer.
Further, on the basis of the simple substance copper layer, a high-phosphorus nickel alloy plating layer is plated to be used as a surface layer.
A preparation method of an electroplated layer structure of a sintered neodymium-iron-boron magnet comprises the following steps;
sintering the neodymium iron boron magnet, wherein the size phi is 10 x 0.3 before electroplating, the performance Hcj12.6 and the Br12.8; after electroplating, the size phi 10 x 0.3, the performance Hcj12.95KOe and the intrinsic coercive force Hcj are increased by 350 Oe; Br12.65KGs, 150Gs reduction in residual Br.
Selecting 50 oil-free black pieces with phi 10 x 0.3 (performance Hcj12.6, Br12.8), and in the first step, sand blasting: putting 50 oil-free black pieces with phi 10 x 0.3 into an automatic sand blasting machine, putting 5000g of 60-mesh carborundum, setting parameters, starting sand blasting, detecting the roughness surface Ra8.5-10.5 mu m, wherein the sand blasting is carried out under the protection of nitrogen;
secondly, preparing a terbium copper alloy powder composite plating solution: weighing 500g of terbium copper alloy powder with the concentration of 45-50g/L, stirring and pouring into 10 liters of special copper electroplating bath solution, and adding nitrogen.
Thirdly, setting electroplating parameters: the temperature of the plating solution is 50-65 ℃; an electrolytic copper plate is used as an anode; the circulating pump is adopted to pull the plating solution with the flow of 90-100L/h, and the nitrogen is stirred at 0.02-0.05MPa to compound the plating solution;
fourthly, electroplating terbium copper alloy powder: preparing a roller of 0.5Kg and an eye diameter phi 2; 50 samples are loaded, the plating ball phi 3 x 0.2Kg and the current of a pre-regulated rectifier are added, the current of a barrel plating machine is carried by 10-20A to enter the plating solution, the plating is started at 6-10 r/min, and the alloy powder is stopped being plated when the film thickness reaches 12 mu m.
Fifthly, electroplating elemental copper: moving the barrel plating machine into a copper electroplating solution without terbium copper alloy powder for copper plating, supplying current to 15-20A, detecting the thickness of a bare copper film to be 1 mu m, and stopping copper plating;
proportioning of copper electroplating solution: 230g/L of hydroxyethylidene diphosphonic acid (HEDP), 15g/L of sodium potassium tartrate tetrahydrate, 25g/L of copper and potassium hydroxide for adjusting the pH of the plating solution to 9.2-10.0;
the proportion of the composite plating solution is as follows: 50-100g/L of terbium copper alloy powder;
the process conditions are as follows: the temperature is 60 ℃, Dk0.6-0.8A/dm 2 The electrolytic copper plate is used as an anode, a circulating pump is used for pulling, and the nitrogen is used for stirring the plating solution.
Sixthly, electrogalvanizing: the barrel plating machine is moved into zinc sulfate galvanizing plating solution for galvanizing, 15A current is supplied, and the galvanizing is stopped after the thickness of the zinc film is detected to be 6 mu m.
Seventhly, zinc color passivation: moving the barrel plating machine into a trivalent chromium passivation solution, passivating for 20-30 seconds at the temperature of 30-35 ℃ and the pH of 2.0-3, washing with water, and detecting the thickness of the passivation film to be 0.3 mu m.
Eighth step, drying: firstly, drying, and then continuously drying at 85 ℃ for 15 minutes in a drying box.
Further, preparing the terbium copper alloy particles;
selecting the raw materials in proportion: 80-95% of metal terbium and 5-20% of metal copper;
the preparation method of the terbium copper alloy powder particles comprises the following steps: weighing 9.5Kg of metal terbium, then weighing 0.5Kg of metal copper, putting the metal terbium and the metal copper into a crucible, and vacuumizing 1.5x10 -3 Smelting at the temperature of Pa and 1500 ℃, and cooling and throwing the slices by a water cooling roller;
then, carrying out HD hydrogen crushing to change the flaky terbium copper alloy into coarse particles with the length of about 0.5-3, the width of about 0.5-3 and the thickness of about 0.1-0.4 mm;
finally, JM is fed to prepare powder, namely granules with the diameter of about 0.1-3 mu m are prepared, and the granules are filled with argon gas to be packaged and stored for being used as raw materials of composite plating.
Further, the terbium copper alloy particles with the particle size of 0.1-3 mu m are dispersed and suspended in a copper electroplating solution system, the anode is an electrolytic copper plate, the cathode is a magnet product, the electroplating mode adopts a barrel plating or rack plating mode, after electrification, the suspended particles and the copper in the electroplating solution are co-deposited, the particles and the copper are deposited on the surface of the sintered neodymium iron boron magnet after sand blasting, and the particles and the copper are directly contacted with the magnet to be used as a bottom layer.
Further, the proportioning raw materials are selected as follows: 90-95% of gold terbium and 2-5% of copper.
Compared with the prior art, the invention has the beneficial effects that: the invention adopts copper, zinc or high-phosphorus nickel as the intermediate layer and the surface layer, and the plating layers have no negative magnetic shielding effect;
according to the invention, the intrinsic coercive force Hcj of the magnet is improved by using an electroplating method, the thermal demagnetization rate is reduced, the remanence Br presents weak attenuation, and meanwhile, the corrosion prevention problem is solved, so that the method is a multi-purpose new method and new creation;
the invention provides the structure of the plating layer and the variety of various surface plating layers so as to avoid the negative effect of magnetic shielding, and the surface plating layer provided by the invention has corrosion resistance;
the invention provides a surface treatment method without acid treatment, namely, a limited rough surface is manufactured by adopting an automatic sand blasting method under the protection of nitrogen, so that the problem of environmental pollution is greatly reduced;
the invention improves the intrinsic coercive force Hcj of the sintered neodymium iron boron ultrathin small magnet, reduces the thermal demagnetization rate of the magnet and basically maintains the inherent remanence Br of the magnet through a new electroplating method and an electroplated layer structure; by changing the surface property of the plating layer, the plating layer with special functions of good binding force, corrosion resistance, adhesive property, weldability, laser etching property and the like can be obtained while good magnetic characteristics are obtained;
the electroplated layer structure of the invention is key to improving the intrinsic coercive force Hcj of the magnet, obtains various coatings with corrosion resistance while obtaining the characteristic of higher intrinsic coercive force Hcj, and simultaneously cancels the grain boundary diffusion process aiming at improving the intrinsic coercive force, thereby greatly reducing the cost.
The corrosion resistance problem of the magnet is solved by an electroplating method, and the intrinsic coercive force Hcj of the magnet is improved, so that the thermal demagnetization rate is reduced; the attenuation of the remanence Br is smaller than that of grain boundary diffusion. In the aspect of thin small magnets, the process can replace a grain boundary diffusion process, two key problems of high intrinsic coercive force Hcj and high remanence Br of the magnets are realized, and the efficiency is high and the cost is low. In addition, the sand blasting method replaces the traditional method for pretreating the surface of the magnet by nitric acid, sulfuric acid and hydrochloric acid, thereby greatly reducing the environmental pollution.
Drawings
FIG. 1 is a schematic diagram of the electroplated layer structure of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by a person of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.
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; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in a specific case to those of ordinary skill in the art.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.
As shown in fig. 1, an electroplated layer structure of a sintered nd-fe-b magnet comprises a sintered nd-fe-b magnet 1, wherein the sintered nd-fe-b magnet 1 sequentially comprises a terbium-copper alloy particle composite layer 2, a copper layer 3, a zinc layer 4 and a trivalent chromium passivation layer of 0.1-0.5 μm from inside to outside, and the zinc layer 4 can be replaced by a high-phosphorus nickel chemical plating layer;
the copper alloy particle composite layer (5-10 μm), the copper layer (1-5 μm), the zinc layer (5-10 μm) and the trivalent chromium passivation layer are 0.1-0.5 μm.
The copper layer 3 is positioned on the codeposition layer and is used as an intermediate layer;
the zinc layer 4 is positioned on the copper layer 3;
and performing trivalent chromium passivation treatment on the zinc layer 4 to generate a trivalent chromium passivation film layer as a surface layer.
According to a further preferable technical scheme, the magnet base body of the sintered neodymium-iron-boron magnet 1 is provided with a surface with the roughness of Ra6.3-12.5 mu m by adopting an automatic sand blasting method;
the terbium copper alloy particle composite layer 2 is terbium copper alloy fine powder particles, the fine powder particles and copper are co-deposited, and the terbium copper alloy particle composite layer 2 is in direct contact with the sintered neodymium iron boron magnet 1.
According to a further preferable technical scheme, the thickness of the terbium copper alloy fine powder particles and copper codeposition is about 10-20 mu m, and the sand-blasted rough surface is filled.
According to a further preferable technical scheme, a simple substance copper layer 3 is additionally plated on the basis of the composite plating layer of the terbium-copper alloy particle composite layer 2, the thickness of the simple substance copper layer is 1-5 mu m, and the simple substance copper layer is used as an intermediate layer.
According to a further preferable technical scheme, on the basis of the simple substance copper layer 3, a simple substance zinc + passivation film layer coating is electroplated, the thickness of the simple substance zinc + passivation film layer coating is 5-10 mu m, and the surface layer is made.
According to a further preferable technical scheme of the invention, a high-phosphorus nickel alloy plating layer is plated on the basis of the simple substance copper layer 3 to form a surface layer.
A preparation method of an electroplated layer structure of a sintered neodymium-iron-boron magnet comprises the following steps; sintering the neodymium iron boron magnet, wherein the size phi is 10 x 0.3 before electroplating, and the performance Hcj12.6 and Br12.8 are obtained; after electroplating, the size phi 10 x 0.3, the performance Hcj12.95KOe and the intrinsic coercive force Hcj are increased by 350 Oe; Br12.65KGs, the residual magnetism Br is reduced by 150 Gs;
selecting 50 oil-free black pieces with phi 10 x 0.3, performance Hcj12.6 and Br12.8;
step one, sand blasting: putting 50 oil-free black pieces with phi 10 x 0.3 into an automatic sand blasting machine, putting 5000g of 60-mesh carborundum, setting parameters, starting sand blasting, detecting the roughness surface Ra8.5-10.5 mu m, wherein the sand blasting is carried out under the protection of nitrogen;
secondly, preparing a terbium copper alloy powder composite plating solution: weighing 500g of terbium copper alloy powder with the concentration of 45-50g/L, stirring and pouring into 10 liters of special copper electroplating bath solution, and adding nitrogen.
Thirdly, setting electroplating parameters: the temperature of the plating solution is 50-65 ℃; an electrolytic copper plate is used as an anode; the circulating pump is adopted to pull the plating solution with the flow of 90-100L/h, and the nitrogen is stirred at 0.02-0.05MPa to compound the plating solution;
fourthly, electroplating terbium copper alloy powder: preparing a 0.5Kg roller and an eye diameter phi 2; 50 samples are loaded, the plating ball phi 3 x 0.2Kg and the current of a pre-regulated rectifier are added, the current of a barrel plating machine is carried by 10-20A to enter the plating solution, the plating is started at 6-10 r/min, and the alloy powder is stopped being plated when the film thickness reaches 12 mu m.
Fifthly, electroplating elemental copper: moving the barrel plating machine into a copper electroplating solution without terbium copper alloy powder for copper plating, supplying current to 15-20A, detecting the thickness of a bare copper film to be 1 mu m, and stopping copper plating;
copper electroplating solution proportioning: 230g/L of hydroxyethylidene diphosphate (HEDP), 15g/L of sodium potassium tartrate tetrahydrate and 25g/L of copper, and adding potassium hydroxide to adjust the pH of the plating solution to 9.2-10.0;
the proportion of the composite plating solution is as follows: 50-100g/L of terbium copper alloy powder;
the process conditions are as follows: the temperature is 60 ℃, Dk0.6-0.8A/dm 2 The electrolytic copper plate is used as an anode, a circulating pump is used for pulling, and the nitrogen is used for stirring the plating solution.
Sixthly, electrogalvanizing: the barrel plating machine is moved into zinc sulfate galvanizing plating solution for galvanizing, 15A current is supplied, and the galvanizing is stopped after the thickness of the zinc film is detected to be 6 mu m.
Seventhly, zinc color passivation: and moving the barrel plating machine into a trivalent chromium passivation solution, passivating for 20-30 seconds at the temperature of 30-35 ℃ and the pH value of 2.0-3, washing with water, and detecting the thickness of the passivation film to be 0.3 mu m.
And eighth step, drying: firstly, drying, and then continuously drying at 85 ℃ for 15 minutes in a drying box.
According to a further preferable technical scheme, the terbium copper alloy particles are prepared;
selecting the raw materials in proportion: 80-95% of metal terbium and 5-20% of metal copper;
the preparation method of the terbium copper alloy powder particles comprises the following steps: weighing 9.5Kg of metal terbium, then weighing 0.5Kg of metal copper, putting the metal terbium and the metal copper into a crucible, and vacuumizing 1.5x10 -3 Smelting at the temperature of Pa and 1500 ℃, and cooling and throwing the slices by a water cooling roller;
then, carrying out HD hydrogen crushing to change the flaky terbium copper alloy into coarse particles with the length of about 0.5-3, the width of about 0.5-3 and the thickness of about 0.1-0.4 mm;
finally, JM is fed to prepare powder, namely granules with the diameter of about 0.1-3 mu m are prepared, and the granules are filled with argon gas to be packaged and stored for being used as raw materials of composite plating.
According to a further preferable technical scheme, the terbium copper alloy particles with the particle size of 0.1-3 mu m are dispersed and suspended in a copper electroplating solution system, the anode is an electrolytic copper plate, the cathode is a magnet product, the electroplating mode adopts a barrel plating or rack plating mode, after electrification, the suspended particles and copper in the electroplating solution are co-deposited, and the particles and the copper are deposited on the surface of the sintered neodymium iron boron magnet after sand blasting and are in direct contact with the magnet to form a bottom layer.
According to a further preferable technical scheme, the raw materials in the ratio are selected as follows: 90-95% of gold terbium and 2-5% of copper.
The electroplated layer structure of the invention consists of the following parts;
the magnet base body is provided with a certain roughness surface Ra6.3-12.5 mu m by an automatic sand blasting method, and the sand blasting is carried out under the protection of nitrogen.
The composite coating comprises: fine terbium copper alloy powder particles, wherein the particles and copper are co-deposited, and the composite coating is in direct contact with the substrate;
on the basis of the composite coating, a layer of simple substance copper is additionally plated to form an intermediate coating;
electroplating a simple substance zinc + passivation film layer coating on the basis of the simple substance copper coating, wherein the simple substance zinc + passivation film layer coating is used as a surface layer;
on the basis of simple substance copper or plating a high phosphorus nickel alloy plating layer, the layer can also be used as a surface layer.
Terbium copper alloy particles and copper are codeposited and directly contacted with the sintered neodymium iron boron magnet to be used as a bottom layer;
the copper layer is positioned on the codeposition layer and is used as an intermediate layer;
a zinc layer on the copper layer,
and a zinc passivation layer, wherein trivalent chromium passivation treatment is carried out on the zinc layer to generate a passivation film layer as a surface layer.
Firstly, chamfering and automatic sand blasting under the protection of nitrogen can be carried out on the sintered neodymium-iron-boron magnet 1; then, a special composite copper electroplating solution is adopted to electroplate a terbium copper alloy layer 2 on the sintered neodymium iron boron magnet 1. A copper layer 3 is electroplated on the terbium copper alloy layer 2 using a copper electroplating solution. And finally, electroplating a zinc layer 4 on the copper layer 3 by adopting a zinc electroplating solution, and treating the zinc electroplated layer 4 by using a trivalent chromium passivation solution to obtain a color zinc passivation layer as a surface layer.
The magnet base body is provided with a certain roughness surface Ra6.3-12.5 mu m by an automatic sand blasting method, terbium copper alloy particles (0.1-3 mu m) are dispersed and suspended in a special copper electroplating solution system, the anode is an electrolytic copper plate, the cathode is a magnet product, and the electroplating mode can be barrel plating or rack plating. After electrification, the suspended particles and copper in the electroplating solution are co-deposited, the particles and the copper are deposited on the surface of the sintered neodymium iron boron magnet after sand blasting, and the particles and the copper are directly contacted with the magnet to form a bottom layer;
the composite coating comprises: the thickness of the terbium copper alloy fine powder particles and copper codeposition is about 10-20 mu m, and the coarse surface after sand blasting is filled;
on the basis of the composite coating, a layer of elementary copper with the thickness of 1-5 mu m is additionally plated to form an intermediate layer;
on the basis of elemental copper, or electroplating elemental zinc and a passivation film layer coating of 5-10 mu m to form a surface layer;
the Hcj of the magnet coated by the structure of the composite coating is improved by 200-2000 Oe; the thermal demagnetization rate ranges from 1% to 5%; the decay of the remanence Br is about 50-150 Gs; the salt spray (NSS) test levels of the coatings of different surface layers are as follows: the salt spray test of the color zinc coating as the surface layer is 96-120Hr, or the salt spray test of the color zinc coating as the surface layer by replacing the zinc layer with the high-phosphorus nickel coating is 96-144 Hr; the coating has no magnetic shielding effect, and ensures the maximum initial magnetic flux of the matrix.
The first embodiment is as follows:
sintering the neodymium iron boron magnet, wherein the size phi is 10 x 0.3 before electroplating, and the performance Hcj12.6 and Br12.8 are obtained; after electroplating, the size phi 10 x 0.3, the performance Hcj12.95KOe and the intrinsic coercive force Hcj are increased by 350 Oe; Br12.65KGs, the residual magnetism Br is reduced by 150 Gs;
selecting 50 oil-free black pieces with phi 10 x 0.3 (performance Hcj12.6, Br12.8), and performing first-step sand blasting: 50 oil-free black pieces with phi 10 x 0.3 are put into an automatic sand blasting machine, 5000g of 60-mesh carborundum is put into the machine, parameters are set, sand blasting is started, and the roughness surface Ra8.5 mu m is detected, wherein the sand blasting is carried out under the protection of nitrogen.
Preparing a terbium copper alloy powder composite plating solution in the second step: weighing 500g of terbium copper alloy powder with the concentration of 50g/L, stirring and pouring into 10 liters of special copper electroplating bath solution, and adding nitrogen.
Thirdly, setting electroplating parameters: the temperature of the plating solution is 60 ℃; an electrolytic copper plate is used as an anode; the flow of the plating solution is pulled by a circulating pump at 100 liters/hour, and simultaneously the nitrogen is stirred at 0.05MPa to compound the plating solution. Fourthly, electroplating terbium copper alloy powder: preparing a 0.5Kg roller and an eye diameter phi 2; 50 samples were loaded and 0.2Kg of the plating bead phi 3 was added. Pre-adjusting the current 20A of a current transformer, introducing the current 20A of the barrel plating machine into the plating solution, starting electroplating at 6 r/min, and stopping electroplating the alloy powder when the film thickness reaches 12 mu m. Step five, electroplating elemental copper: the barrel plating machine is moved into a copper plating solution without terbium copper alloy powder for copper plating, the current is supplied for 20A, and the thickness of the bare copper film is detected to be 1 mu m, and the copper plating is stopped.
And sixthly, electrogalvanizing: the barrel plating machine is moved into zinc sulfate galvanizing electroplating solution for galvanizing, 15A current is supplied, and galvanizing is stopped by detecting the thickness of the zinc film to be 6 mu m.
Seventhly, zinc color passivation: and (3) moving the barrel plating machine into a trivalent chromium passivation solution, passivating for 30 seconds at 35 ℃ under the pH value of 2.0, washing with water, and detecting the thickness of the passivation film to be 0.3 mu m.
And eighth step, drying: drying the mixture firstly, and then continuously drying the mixture in a drying box at 85 ℃ for 15 minutes. And (3) detection:
preparing terbium copper alloy particles;
selecting the raw materials in proportion: 95% of metal terbium and 5% of metal copper;
the preparation method of the terbium copper alloy powder particles comprises the following steps: weighing 9.5Kg of metal terbium, then weighing 0.5Kg of metal copper, putting the metal terbium and the metal copper into a crucible, and vacuumizing 1.5x10 -3 Smelting at the temperature of Pa and 1500 ℃, and cooling and throwing the slices by a water cooling roller;
then, carrying out HD hydrogen crushing to change the flaky terbium copper alloy into coarse particles with the length of about 3mm and the width of about 2; about 0.1mm thick;
and finally, preparing powder by JM, namely preparing particles with the diameter of about 0.1-3 mu m, filling argon, packaging and storing, and using as a raw material for composite plating.
The second embodiment is as follows:
sintering the neodymium iron boron magnet, wherein the size phi is 10 x 0.3 before electroplating, the performance Hcj12.6 and the Br12.8; after electroplating, the size phi 10 x 0.3, the performance Hcj12.95KOe and the intrinsic coercive force Hcj are increased by 350 Oe; Br12.65KGs, the residual magnetism Br is reduced by 150 Gs;
selecting 50 oil-free black pieces with phi 10 x 0.3, performance Hcj12.6 and Br12.8; step one, sand blasting: putting 50 oil-free black pieces with phi 10 x 0.3 into an automatic sand blasting machine, putting 5000g of 60-mesh carborundum, setting parameters, starting sand blasting, and detecting a roughness surface Ra10.5 mu m, wherein the sand blasting is carried out under the protection of nitrogen;
secondly, preparing a terbium copper alloy powder composite plating solution: weighing 500g of terbium copper alloy powder with the concentration of 45g/L, stirring and pouring into 10 liters of special copper electroplating bath solution, and adding nitrogen.
Thirdly, setting electroplating parameters: the temperature of the plating solution is 65 ℃; an electrolytic copper plate is used as an anode; a circulating pump is adopted to pull the plating solution with the flow of 95 liters/hour, and simultaneously nitrogen is stirred at 0.02MPa to compound the plating solution; fourthly, electroplating terbium copper alloy powder: preparing a 0.5Kg roller and an eye diameter phi 2; 50 samples are loaded, the plating ball phi 3 x 0.2Kg and the current of a pre-regulated rectifier 15A are added, the barrel plating machine is provided with a current of 20A and enters the plating solution, the plating is started at 10 r/min, and the alloy powder is stopped being plated when the film thickness reaches 12 mu m.
Fifthly, electroplating elemental copper: moving the barrel plating machine into a copper electroplating solution without terbium copper alloy powder for copper plating, supplying current of 20A, detecting the thickness of a bare copper film to be 1 mu m, and stopping copper plating;
copper electroplating solution proportioning: 230g/L of hydroxyethylidene diphosphate (HEDP), 15g/L of sodium potassium tartrate tetrahydrate and 25g/L of copper, and adding potassium hydroxide to adjust the pH of the plating solution to 9.2;
the proportion of the composite plating solution is as follows: 100g/L of terbium copper alloy powder;
the process conditions are as follows: the temperature is 60 ℃, and the Dk0.8A/dm 2 The electrolytic copper plate is used as an anode, a circulating pump is used for pulling, and the nitrogen is used for stirring the plating solution.
Sixthly, electrogalvanizing: the barrel plating machine is moved into zinc sulfate galvanizing electroplating solution for galvanizing, 15A current is supplied, and galvanizing is stopped by detecting the thickness of the zinc film to be 6 mu m.
Seventhly, zinc color passivation: and moving the barrel plating machine into a trivalent chromium passivation solution, carrying out passivation for 30 seconds at the temperature of 35 ℃ and the pH3, washing with water, and detecting the thickness of the passivation film to be 0.3 mu m.
Eighth step, drying: firstly, drying, and then continuously drying at 85 ℃ for 15 minutes in a drying box.
Preparing terbium copper alloy particles;
selecting the raw materials in proportion: 85% of metal terbium and 10% of metal copper;
the preparation method of the terbium copper alloy powder particles comprises the following steps: weighing 9.5Kg of metal terbium, then weighing 0.5Kg of metal copper, putting the metal terbium and the metal copper into a crucible, and vacuumizing 1.5x10 -3 Smelting at the temperature of Pa and 1500 ℃, and cooling and throwing the slices by a water cooling roller;
then, carrying out HD hydrogen crushing to change the flaky terbium copper alloy into coarse particles with the length of about 2mm, the width of about 3mm and the thickness of about 0.4 mm;
and finally, preparing powder by JM, namely preparing particles, filling argon gas into the particles with the diameter of about 3 mu m, packaging and storing the particles, and using the particles as a raw material for composite plating.
The third concrete embodiment:
a preparation method of an electroplated layer structure of a sintered neodymium-iron-boron magnet comprises the following steps;
sintering the neodymium iron boron magnet, wherein the size phi is 10 x 0.3 before electroplating, the performance Hcj12.6 and the Br12.8; after electroplating, the size phi 10 x 0.3, the performance Hcj12.95KOe and the intrinsic coercive force Hcj are increased by 350 Oe; Br12.65KGs, the residual magnetism Br is reduced by 150 Gs;
selecting 50 oil-free black pieces with phi 10 x 0.3, performance Hcj12.6 and Br12.8; step one, sand blasting: putting 50 oil-free black pieces with phi 10 x 0.3 into an automatic sand blasting machine, putting 5000g of 60-mesh carborundum, setting parameters, starting sand blasting, and detecting the roughness surface Ra10 mu m, wherein the sand blasting is carried out under the protection of nitrogen;
secondly, preparing a terbium copper alloy powder composite plating solution: weighing 500g of terbium copper alloy powder with the concentration of 50g/L, stirring and pouring into 10 liters of special copper electroplating bath solution, and adding nitrogen.
Thirdly, setting electroplating parameters: the temperature of the plating solution is 60 ℃; an electrolytic copper plate is used as an anode; a circulating pump is adopted to pull the flow of the plating solution at 100 liters/hour, and simultaneously nitrogen is stirred to compound the plating solution at 0.05 MPa; fourthly, electroplating terbium copper alloy powder: preparing a 0.5Kg roller and an eye diameter phi 2; 50 samples are loaded, the plating ball phi 3 x 0.2Kg and the current of a pre-regulated rectifier 20A are added, the current of a barrel plating machine is carried by 15A to enter the plating solution, the plating is started at 6 r/min, and the alloy powder is stopped being plated when the film thickness reaches 12 mu m.
Fifthly, electroplating elemental copper: moving the barrel plating machine into a copper electroplating solution without terbium copper alloy powder for copper plating, supplying current to 15-20A, detecting the thickness of a bare copper film to be 1 mu m, and stopping copper plating;
proportioning of copper electroplating solution: 230g/L of hydroxyethylidene diphosphonic acid (HEDP), 15g/L of potassium sodium tartrate tetrahydrate, 25g/L of copper and potassium hydroxide for regulating the pH value of the plating solution to 10.0;
the proportion of the composite plating solution is as follows: 100g/L of terbium copper alloy powder;
the process conditions are as follows: the temperature is 60 ℃, and the Dk0.8A/dm 2 The electrolytic copper plate is used as an anode, a circulating pump is used for pulling, and the nitrogen is used for stirring the plating solution.
Sixthly, electrogalvanizing: the barrel plating machine is moved into zinc sulfate galvanizing electroplating solution for galvanizing, 15A current is supplied, and galvanizing is stopped by detecting the thickness of the zinc film to be 6 mu m.
Seventhly, zinc color passivation: and moving the barrel plating machine into a trivalent chromium passivation solution, passivating for 30 seconds at the temperature of 35 ℃ and the pH value of 2.0, washing with water, and detecting the thickness of the passivation film to be 0.3 mu m.
Eighth step, drying: firstly, drying, and then continuously drying at 85 ℃ for 15 minutes in a drying box.
Preparing terbium copper alloy particles;
selecting the raw materials in proportion: 95% of metal terbium and 8% of metal copper;
the preparation method of the terbium copper alloy powder particles comprises the following steps: weighing 9.5Kg of metal terbium, then weighing 0.5Kg of metal copper, putting the metal terbium and the metal copper into a crucible, and vacuumizing 1.5x10 -3 Smelting at the temperature of Pa and 1500 ℃, and cooling and throwing the slices by a water cooling roller;
then, carrying out HD hydrogen crushing to change the flaky terbium copper alloy into coarse particles with the length of about 0.5, the width of about 0.5 and the thickness of about 0.1 mm;
and finally, preparing powder by adding JM, namely preparing particles with the diameter of about 0.8 mu m, and filling argon for packaging and storing the particles for the raw materials of the composite plating.
And (3) magnetic property detection:
after plating, every 20 pieces were stacked together, three sets of Hcj12.95, 13.00, 13.1(KOe) were measured, and the measurement of residual magnetism Br was found to have a large error.
Before plating, every 20 pieces are stacked together, and the performance Hcj12.6 and Br12.8 are measured;
detecting the thermal demagnetization rate after plating: 100 ℃ for 30 minutes, 4.5%, 4.8%, 5.2%, 5.5%, 4.0%.
Comparative example thermal demagnetization before plating: 30 minutes at 100 ℃, 7.6%, 8.2%, 7.5%, 9.1%, 8.3%.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (10)

1. The utility model provides an electroplating layer structure of sintered neodymium iron boron magnet which characterized in that: the electroplated layer structure comprises a sintered neodymium iron boron magnet (1), wherein the sintered neodymium iron boron magnet (1) sequentially comprises a terbium copper alloy particle composite layer (2), a copper layer (3), a zinc layer (4) and a trivalent chromium passivation layer of 0.1-0.5 mu m from inside to outside, and the zinc layer (4) can be replaced by a high-phosphorus nickel chemical plating layer;
the copper layer (3) is positioned on the codeposition layer and is used as an intermediate layer;
the zinc layer (4) is positioned on the copper layer (3);
and performing trivalent chromium passivation treatment on the zinc layer (4) to generate a trivalent chromium passivation film layer as a surface layer.
2. The electroplated layer structure of sintered nd-fe-b magnet as claimed in claim 1, wherein: the magnet substrate of the sintered neodymium-iron-boron magnet (1) is provided with a surface with the roughness of Ra6.3-12.5 mu m by adopting an automatic sand blasting method;
the terbium copper alloy particle composite layer (2) is terbium copper alloy fine powder particles, the fine powder particles and copper are co-deposited, and the terbium copper alloy particle composite layer (2) is in direct contact with the sintered neodymium iron boron magnet (1) substrate.
3. The electroplated layer structure of the sintered NdFeB magnet as claimed in claim 2, wherein: the fine terbium copper alloy powder particles and copper are co-deposited to a thickness of about 10-20 μm, filling the sandblasted rough surface.
4. The electroplated layer structure of sintered nd-fe-b magnet as claimed in claim 3, wherein: and on the basis of the composite coating of the terbium copper alloy particle composite layer (2), a simple substance copper layer (3) is additionally coated, the thickness of the simple substance copper layer is 1-5 mu m, and the middle layer is made.
5. The electroplated layer structure of sintered NdFeB magnet as claimed in claim 4, wherein: electroplating a simple substance zinc + passivation film layer coating with the thickness of 5-10 mu m on the basis of the simple substance copper layer (3) to form a surface layer.
6. The electroplated layer structure of sintered NdFeB magnet as claimed in claim 4, wherein: and plating a high-phosphorus nickel alloy plating layer on the basis of the simple substance copper layer (3) to form a surface layer.
7. The method for preparing the electroplated layer structure of the sintered neodymium-iron-boron magnet as claimed in any one of claims 1 to 6, wherein: comprises the following steps;
sintering the neodymium iron boron magnet, wherein the size phi is 10 x 0.3 before electroplating, and the performance Hcj12.6 and Br12.8 are obtained; after electroplating, the size phi 10 x 0.3, the performance Hcj12.95KOe and the intrinsic coercive force Hcj are increased by 350 Oe; Br12.65KGs, the residual magnetism Br is reduced by 150 Gs;
selecting 50 oil-free black pieces with phi 10 x 0.3, performance Hcj12.6 and Br12.8;
step one, sand blasting: putting 50 oil-free black pieces with phi 10 x 0.3 into an automatic sand blasting machine, putting 5000g of 60-mesh carborundum, setting parameters, starting sand blasting, detecting the roughness surface Ra8.5-10.5 mu m, wherein the sand blasting is carried out under the protection of nitrogen;
secondly, preparing a terbium copper alloy powder composite plating solution: weighing 500g of terbium copper alloy powder with the concentration of 45-50g/L, stirring and pouring into 10 liters of special copper electroplating bath solution, and adding nitrogen;
thirdly, setting electroplating parameters: the temperature of the plating solution is 50-65 ℃; an electrolytic copper plate is used as an anode; the circulating pump is adopted to pull the plating solution with the flow of 90-100L/h, and the nitrogen is stirred at 0.02-0.05MPa to compound the plating solution;
fourthly, electroplating terbium copper alloy powder: preparing a 0.5Kg roller and an eye diameter phi 2; loading 50 samples, adding 0.2Kg of plating ball phi 3, pre-adjusting rectifier current 15-20A, putting the current of 10-20A carried by a barrel plating machine into the plating solution, starting electroplating after 6-10 r/min, and stopping electroplating alloy powder when the film thickness reaches 12 mu m;
fifthly, electroplating elemental copper: moving the barrel plating machine into a copper electroplating solution without terbium copper alloy powder for copper plating, supplying current to 15-20A, detecting the thickness of a bare copper film to be 1 mu m, and stopping copper plating;
copper electroplating solution proportioning: 230g/L of hydroxyethylidene diphosphate (HEDP), 15g/L of sodium potassium tartrate tetrahydrate and 25g/L of copper, and adding potassium hydroxide to adjust the pH of the plating solution to 9.2-10.0;
the proportion of the composite plating solution is as follows: 50-100g/L of terbium copper alloy powder;
the process conditions are as follows: the temperature is 60 ℃, Dk0.6-0.8A/dm 2 An electrolytic copper plate is used as an anode, a circulating pump is adopted for pulling, and nitrogen is used for stirring the plating solution;
sixthly, electrogalvanizing: moving the barrel plating machine into zinc sulfate galvanizing electroplating solution for galvanizing, supplying 15A current, detecting the thickness of the zinc film to be 6 mu m, and stopping galvanizing;
seventhly, zinc color passivation: moving the barrel plating machine into a trivalent chromium passivation solution, passivating for 20-30 seconds at the temperature of 30-35 ℃ and the pH of 2.0-3, washing with water, and detecting the thickness of the passivation film to be 0.3 mu m;
eighth step, drying: firstly, drying, and then continuously drying at 85 ℃ for 15 minutes in a drying box.
8. The method for preparing a electroplated layer structure of a sintered neodymium-iron-boron magnet according to any one of claim 7, characterized by preparing terbium copper alloy particles;
selecting the raw materials in proportion: 80-95% of metal terbium and 5-20% of metal copper;
the preparation method of the terbium copper alloy powder particles comprises the following steps: weighing 9.5Kg of metal terbium, then weighing 0.5Kg of metal copper, putting the metal terbium and the copper into a crucible, and vacuumizing 1.5x10 -3 Smelting at the temperature of Pa and 1500 ℃, and cooling and throwing the slices by a water cooling roller;
then, carrying out HD hydrogen crushing to change the flaky terbium copper alloy into coarse particles with the length of about 0.5-3, the width of about 0.5-3 and the thickness of about 0.1-0.4 mm;
finally, JM is fed to prepare powder, namely granules with the diameter of about 0.1-3 mu m are prepared, and the granules are filled with argon gas to be packaged and stored for being used as raw materials of composite plating.
9. The method for preparing a plating layer structure of a sintered nd-fe-b magnet according to any one of claim 7, wherein the terbium copper alloy particles with a particle size of 0.1-3 μm are dispersed and suspended in a copper plating solution system, the anode is an electrolytic copper plate, the cathode is a magnet product, the plating mode adopts a barrel plating or rack plating mode, after electrification, the suspended particles and copper in the plating solution are co-deposited, and the particles and copper are deposited on the surface of the sintered nd-fe-b magnet after sand blasting and are in direct contact with the magnet to form a bottom layer.
10. The method for preparing the electroplated layer structure of the sintered neodymium-iron-boron magnet according to any one of the claims 7, wherein the proportioning raw materials are selected from the following components: 90-95% of gold terbium and 2-5% of copper.
CN202210706503.5A 2022-06-21 2022-06-21 Electroplated layer structure of sintered neodymium-iron-boron magnet and preparation method Pending CN114990652A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117438207A (en) * 2023-12-20 2024-01-23 江西金力永磁科技股份有限公司 Method for improving binding force of surface coating of high-grade sintered NdFeB magnet

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117438207A (en) * 2023-12-20 2024-01-23 江西金力永磁科技股份有限公司 Method for improving binding force of surface coating of high-grade sintered NdFeB magnet
CN117438207B (en) * 2023-12-20 2024-04-12 江西金力永磁科技股份有限公司 Method for improving binding force of surface coating of high-grade sintered NdFeB magnet

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