CN1752283A - Method of Nd-Fe-B permanent magnet material surface coating - Google Patents
Method of Nd-Fe-B permanent magnet material surface coating Download PDFInfo
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- CN1752283A CN1752283A CN 200510030733 CN200510030733A CN1752283A CN 1752283 A CN1752283 A CN 1752283A CN 200510030733 CN200510030733 CN 200510030733 CN 200510030733 A CN200510030733 A CN 200510030733A CN 1752283 A CN1752283 A CN 1752283A
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Abstract
A process for chemically plating a copper film on the surface of permanent-magnet Nd-Fe-B material to improve its antioxidizing power includes such steps as preparing the chemically Cu-plating liquid from copper sulfate, EDTA Na2.2H2O and formaldehyde HCHO, washing magnetic Nd-Fe-B powder with HCl solution, putting it in said Cu-plating liquid, reaction, washing with distilled water and drying by hot air.
Description
Technical Field
The invention relates to a method for coating a surface of an Nd-Fe-B permanent magnet material, belonging to the technical field of chemical coating processes.
Background
The nano composite permanent magnetic material Nd-Fe-B is a novel permanent magnetic material. The composite material composed of soft and hard magnetic phases utilizes the advantages of high magnetocrystalline anisotropy of hard magnetic phases and high saturation magnetization of soft magnetic phases, and obtains excellent magnetic performance through ferromagnetic exchange effect between nanoscale two-phase crystal grains. Theoretical calculation shows that the maximum magnetic energy product (BH) of the nanometer exchange coupling magnet is metmaxTheoretical value of 1MJ.m-3However, the maximum magnetic energy product reported by related documents at home and abroad is far from the same, and especially the preparation of the anisotropic Nd-Fe-B bonded magnet is still a weak item in China.
A high-temp hot-pressing and hot-deforming method for preparing anisotropic Nd-Fe-B permanent-magnet material includes such steps as pressing the magnetic powderon press at room temp to obtain the magnetic powder with density of 5.0-6.1g.cm-3Then hot pressing and hot deforming at high temperature (300-800 ℃). According to the latest report, Nd-Fe-B permanent magnetic material with high anisotropy and high magnetic property can be prepared, and the maximum energy product of the Nd-Fe-B permanent magnetic material is 440kJ.m-3. Because Nd-Fe-B permanent magnetic material contains high rare earth elements, is easy to oxidize, especially at high temperature, and thus, the method involves harsh process conditions of vacuum or protective atmosphere, which is not easy in practical production. Therefore, a method for coating Nd-Fe-B permanent magnet material is proposed to improve the surface oxidation resistance.
Disclosure of Invention
The invention aims to coat the surface of an Nd-Fe-B permanent magnetic material, namely a layer of copper film is coated on the surface of Nd-Fe-B permanent magnetic powder by a chemical plating method so as to improve the oxidation resistance of the surface of the Nd-Fe-B permanent magnetic powder. It is based on Cu2+And Nd-Fe-B magnetic powderThe charge transfer process is carried out, the reaction is only limited on the surface of the magnetic powder, and the coating of irregular particles with uneven surfaces is very effective.
The invention relates to a method for coating the surface of Nd-Fe-B permanent magnet material, which adopts a chemical plating method and is characterized by comprising the following steps:
a. firstly, preparing an electroless copper plating solution, wherein the formula is as follows:
copper sulfate CuSO4·5H2O 0.1-0.4mol/L
Complexing agent EDTA Na2·2H2O 0.1-0.4mol/L
Formaldehyde HCHO 0.1-0.4mol/L
Cleaning Nd-Fe-B magnetic powder with 0.10-0.25N HCl solution before electroless copper plating, cleaning the surface of the magnetic powder, and then pouring the magnetic powder into the electroless copper plating solution prepared in advance while stirring, wherein the proportion of the magnetic powder to the plating solution is that 40-50g of magnetic powder is added into each liter of plating solution, namely 40-50g/L, the temperature of electroless copper plating reaction is 50-70 ℃, and the reaction time is 50-90 min.
c. After the electroless copper plating reaction is finished, washing with distilled water to remove Cl-And (3) ionizing, and drying for 20 minutes by using hot air at 65-85 ℃ to obtain the copper-plated magnetic powder with the coating amount of 3-8%.
The reaction formula of electroless copper plating is as follows:
in order to prevent the copper powder in the plating solution from being folded and forming a rough plating layer, the concentration of copper ions is preferably 0.1 to 0.4 mol/L.
Formaldehyde is a reducing agent, and if the concentration of the reducing agent is too high, a disproportionation reaction is promoted to form a large amount of copper powder, and if the concentration is too low, the reduction reaction is insufficient, and it is difficult to secure the thickness of the copper plating layer.
The complexing agent in the chemical copper plating solution is EDTA Na2·2H2O，EDTA Na2·2H2O is English abbreviation of ethylenediamine tetraacetic acid. In theory in the bathEDTA Na2·2H2The concentration of Ois 0.6 to 0.9 times of that of the complex copper ions; if the complexing agent is too low, copper ions in the plating solution cannot be sufficiently complexed to precipitate copper powder, and if the complexing agent is too high, reduction of copper ions is inhibited.
After the surface of the Nd-Fe-B permanent magnetic powder is covered with a layer of copper film, the oxidation resistance of the surface of the Nd-Fe-B permanent magnetic powder can be improved, the high-temperature pressing density of the Nd-Fe-B permanent magnetic powder can be improved in the subsequent process, and the internal gaps of the magnet are reduced. Hot pressing and thermal deformation are carried out on the permanent magnetic powder coated with the copper film on the surface to obtain the permanent magnetic powder with the density of 6.5-7.5 g-cm-3The Nd-Fe-B permanent magnet has high anisotropy and high magnetic performance.
The invention has the advantages of simple process and low cost. For Nd-Fe-B permanent magnetic material which contains high rare earth elements and is easy to oxidize, in the subsequent processing process of high-temperature hot pressing and thermal deformation, the high-temperature oxidation resistance of the material can be greatly improved due to the adoption of a chemical copper plating process in advance. According to the test, the high temperature oxidation resistance can be improved by 20-100% at the high temperature of 600-800 ℃.
Detailed description of the invention
Embodiments of the invention will now be described in the following:
example 1
The specific process and steps of this example are as follows:
(1) firstly, preparing chemical copper plating solution, wherein the formula is as follows:
copper sulfate CuSO4·5H2O 0.3mol/L
Complexing agent EDTA Na2·2H2O 0.3mol/L
Formaldehyde HCHO 0.3mol/L
Wherein EDTA Na2·2H2O is ethylenediamine tetraacetic acid
(2) Before electroless copper plating, 50g of Nd-Fe-B magnetic powder is washed by 0.2N HCl solution to clean the surface of the magnetic powder, then the magnetic powder is slowly added into the prepared 1L of electroless copper plating solution under stirring, and the reaction time is kept for 20 minutes when the heating temperature reaches 65 ℃.
(3) After the reaction is finished, washing the mixture for 20 minutes by using distilled water, and then drying the mixture for 20 minutes by using hot air at the temperature of 80 ℃ to obtain the copper-plated magnetic powder with the coating amount of 5 percent.
The Nd-Fe-B permanent magnetic powder coated with the copper-plated surface can be prepared into the Nd-Fe-B permanent magnetic powder with the density of 6.5-7.5g.cm in the high-temperature hot pressing and thermal deformation processing process of the next procedure-3Nd-Fe-B permanent magnets; the density of the permanent magnet prepared by Nd-Fe-B permanent magnet powder without plating the copper surface in the high-temperature hot pressing and thermal deformation processing process of the next procedure is 6.3-7.2g.cm-3。
According to the test, at the high temperature of 750 ℃, the oxidation resistance of the material is improved by 30 percent due to the chemical copper plating.
Claims (1)
1. A method for coating a surface of an Nd-Fe-B permanent magnetic material adopts a chemical plating method, and a layer of copper film is coated on the surface of Nd-Fe-B permanent magnetic powder to improve the oxidation resistance of the Nd-Fe-B permanent magnetic powder, and the method is characterized by comprising the following technical processes and steps:
a. firstly, preparing chemical copper plating solution, wherein the formula is as follows:
copper sulfate CuSO4·5H2O 0.1-0.4mol/L
Complexing agent EDTA Na2·2H2O 0.1-0.4mol/L
Formaldehyde HCHO 0.1-0.4mol/L
b. Before electroless copper plating, Nd-Fe-B magnetic powder is cleaned by 0.1-0.25N HCl solution, the surface of the magnetic powder is cleaned, then the magnetic powder is poured into the prepared electroless copper plating solution while stirring, the proportion relationship of the magnetic powder and the plating solution is that 40-50g of magnetic powder is added into each liter of plating solution, namely 40-50g/L, the temperature of electroless copper plating reaction is 50-70 ℃, and the reaction time is 50-90 min.
c. After the electroless copper plating reaction is finished, washing with distilled water to remove Cl-And (3) ionizing, and drying for 20 minutes by using hot air at 65-85 ℃ to obtain the copper-plated magnetic powder with the coating amount of 3-8%.
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| CN 200510030733 CN1752283A (en) | 2005-10-27 | 2005-10-27 | Method of Nd-Fe-B permanent magnet material surface coating |
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| CN 200510030733 CN1752283A (en) | 2005-10-27 | 2005-10-27 | Method of Nd-Fe-B permanent magnet material surface coating |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100456395C (en) * | 2006-08-25 | 2009-01-28 | 浙江大学 | Preparation method of high corrosion resistance sintered neodymium iron boron |
| CN101372740B (en) * | 2007-08-23 | 2011-05-11 | 北京中科三环高技术股份有限公司 | Copper plating bath for coating copper and method for surface copper plating permanent magnetic material using the same |
| CN101724830B (en) * | 2008-10-16 | 2012-02-29 | 北京中科三环高技术股份有限公司 | Nickel plating bath for permanent magnet material and permanent magnet material surface treatment method thereof |
| CN103632833A (en) * | 2013-12-03 | 2014-03-12 | 江苏大学 | Preparation method of high-performance high-corrosion-resistance sintered Nd-Fe-B magnetic body |
| CN112259314A (en) * | 2020-09-25 | 2021-01-22 | 南京理工大学 | R (Fe, M)12Rare earth permanent magnetic material and preparation method thereof |
-
2005
- 2005-10-27 CN CN 200510030733 patent/CN1752283A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100456395C (en) * | 2006-08-25 | 2009-01-28 | 浙江大学 | Preparation method of high corrosion resistance sintered neodymium iron boron |
| CN101372740B (en) * | 2007-08-23 | 2011-05-11 | 北京中科三环高技术股份有限公司 | Copper plating bath for coating copper and method for surface copper plating permanent magnetic material using the same |
| CN101724830B (en) * | 2008-10-16 | 2012-02-29 | 北京中科三环高技术股份有限公司 | Nickel plating bath for permanent magnet material and permanent magnet material surface treatment method thereof |
| CN103632833A (en) * | 2013-12-03 | 2014-03-12 | 江苏大学 | Preparation method of high-performance high-corrosion-resistance sintered Nd-Fe-B magnetic body |
| CN103632833B (en) * | 2013-12-03 | 2015-12-09 | 江苏大学 | The preparation method of the high anti-corrosion Sintered NdFeB magnet of a kind of high-performance |
| CN112259314A (en) * | 2020-09-25 | 2021-01-22 | 南京理工大学 | R (Fe, M)12Rare earth permanent magnetic material and preparation method thereof |
| CN112259314B (en) * | 2020-09-25 | 2024-02-13 | 南京理工大学 | R (Fe, M) 12 Rare earth permanent magnet material and preparation method thereof |
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Open date: 20060329 |