阅读说明：本技术 提高烧结钕铁硼薄片磁体压断力的电镀层结构及制备方法 (Electroplated layer structure for improving fracture force of sintered neodymium-iron-boron sheet magnet and preparation method ) 是由 郝志平 黄书林 王佳兴 张旭辉 张信 于 2021-02-23 设计创作，主要内容包括：本发明公开了一种提高磁体压断力的电镀层结构,属于磁体电镀层领域。提高磁体压断力的电镀层结构,所述电镀层结构包括镍钴合金镀层,所述电镀层以镍钴合金镀层作为外表层；所述镍钴合金镀层厚度为8～9um,所述电镀层结构还包括与所述的磁体直接接触的锌层,所述锌层作为底层；位于所述锌层上的镍磷合金层,所述镍磷合金层做中间转换层；位于所述镍磷合金层上的铜层,所述铜层作为中间层；所述镍钴合金镀层位于所述的铜层上；本发明采用镍钴合金镀层,用较薄的镍钴合金镀层就可以顶替较厚的镍镀层所贡献的压断力力值,也就是采用相对较薄的镍钴合金镀层,既保证了产品压断力力值的需求,又保持了原有的热减磁率、磁通量和耐腐蚀性水平。(The invention discloses an electroplated layer structure for improving the press breaking force of a magnet, and belongs to the field of magnet electroplated layers. The electroplated layer structure is used for improving the magnetic fracture force and comprises a nickel-cobalt alloy plated layer, and the nickel-cobalt alloy plated layer is used as an outer surface layer of the electroplated layer; the thickness of the nickel-cobalt alloy coating is 8-9 um, the electroplated layer structure further comprises a zinc layer in direct contact with the magnet, and the zinc layer serves as a bottom layer; the nickel-phosphorus alloy layer is positioned on the zinc layer and serves as an intermediate conversion layer; a copper layer on the nickel-phosphorus alloy layer, the copper layer serving as an intermediate layer; the nickel-cobalt alloy plating layer is positioned on the copper layer; the invention adopts the nickel-cobalt alloy plating layer, and the thinner nickel-cobalt alloy plating layer can replace the press breaking force value contributed by the thicker nickel plating layer, namely, the thinner nickel-cobalt alloy plating layer is adopted, thereby not only ensuring the requirement of the press breaking force value of the product, but also keeping the original heat demagnetization rate, magnetic flux and corrosion resistance level.)

1. Improve plating layer structure of magnetic compression break force, its characterized in that, the plating layer structure includes nickel cobalt alloy cladding material (5), the plating layer uses nickel cobalt alloy cladding material (5) as the extexine, nickel cobalt alloy cladding material (5) thickness is 8 ~ 9 um.

2. A magnet press-break force plating layer structure as claimed in claim 1, wherein said nickel-cobalt alloy plating layer (5) has a thickness of 8.5 um.

3. A magnet press-break force plated layer structure as claimed in claim 1, further comprising

A zinc layer (2) in direct contact with the magnet (1), the zinc layer (2) serving as a bottom layer;

the nickel-phosphorus alloy layer (3) is positioned on the zinc layer (2), and the nickel-phosphorus alloy layer (3) is used as an intermediate conversion layer;

a copper layer (4) on the nickel-phosphorus alloy layer (3), the copper layer (4) serving as an intermediate layer;

the nickel-cobalt alloy plating layer (5) is located on the copper layer (4).

4. A magnet fracture force electroplated layer structure according to claim 3, characterized in that the thickness of the zinc layer (2) is 1-3 um, the thickness of the nickel-phosphorus alloy layer (3) is 2-4 um, and the thickness of the copper layer (4) is 3-5 um.

5. A magnet press-break force plated layer structure as claimed in claim 1, further comprising

A zinc layer (2) in direct contact with the magnet (1), the zinc layer (2) serving as a bottom layer;

a zinc-nickel alloy layer (6) positioned on the zinc layer (2), wherein the zinc-nickel alloy layer (6) is used as an intermediate conversion layer;

a copper layer (4) on the zinc-nickel alloy layer (6), the copper layer (4) acting as an intermediate layer;

the nickel-cobalt alloy plating layer (5) is located on the copper layer (4).

6. A magnet fracture force electroplated coating structure as claimed in claim 5, wherein the thickness of the zinc layer (2) is 1-3 um, the thickness of the zinc-nickel alloy layer (6) is 2-4 um, and the thickness of the copper layer (4) is 3-5 um.

7. A plating layer structure for improving the fracture force of a sintered neodymium iron boron sheet magnet, which is characterized in that the plating layer structure adopts the plating layer structure as claimed in claim 1.

8. The preparation method of the electroplated layer structure for improving the fracture force of the sintered NdFeB sheet magnet is characterized by mainly comprising the following steps of:

s1, firstly, preprocessing the sintered NdFeB sheet magnet (7);

s2, electroplating a zinc layer (2) on the sintered NdFeB sheet magnet (7);

s3, plating a nickel-phosphorus alloy layer (3) on the zinc layer (2) by adopting chemical nickel plating solution;

s4, electroplating a copper layer (4) on the nickel-phosphorus alloy layer (3);

s5, plating a nickel-cobalt alloy layer (5) on the copper layer (4).

9. The method for preparing a plating layer structure for improving the fracture force of the sintered nd-fe-b sheet magnet according to claim 8, wherein the pretreatment in the step S1 includes chamfering, degreasing, acid washing and ultrasonic water washing.

10. The method for preparing a plating layer structure for improving fracture force of sintered nd-fe-b sheet magnet according to claim 8, wherein the plating method in step S2 is to perform plating with zinc sulfate system plating solution, and the plating method in step S4 is to perform plating with copper pyrophosphate system plating solution; the electroplating method of the step S5 is electroplating by using a nickel sulfate electroplating solution system containing cobalt sulfate.

Technical Field

The invention relates to the technical field of magnet electroplated layers, in particular to an electroplated layer structure for improving the fracture force of a sintered neodymium-iron-boron sheet magnet and a preparation method thereof.

Background

In the sintered NdFeB industry, NdFe/EP.Zn2/Ap.NiP3/EP.Cu4Ni8 or NdFe/EP.Zn2ZnNi3Cu4Ni8 or NdFe/EP.Ni5Cu4Ni8 electroplated layer structures are generally adopted, namely, electroplated nickel coatings are used as surface layers, the fracture force of the magnet adopting the nickel electroplated layers is obviously low, and the consequence of low fracture force is that after the magnetic sheets are assembled into a device, the fracture rate of the magnetic sheets is higher in a drop test, the failure complaint rate of electronic devices in the market is higher, for example, acoustic devices of mobile phones lose the sound production function due to the fracture of the magnetic sheets, and no sound is produced. The mobile phone without sound is almost a scrapped mobile phone.

In order to improve the breaking force of the thin magnetic sheet, over the years, material engineers add metal cobalt into the magnet material to improve the strength of the magnet, the effect is not obvious and the material alloy cost is increased; the electroplating engineer adopts a method of simply increasing the thickness of the coating to improve the pressure breaking force, and the pressure breaking force is improved; however, when the thickness of the plating layer is increased, in order to ensure that the size of the magnet is within the specified tolerance, the size of the magnet base body must be reduced, that is, the volume of the magnet must be reduced, and the reduction of the volume of the magnet before plating inevitably reduces the magnetic flux of the magnet, which is fatal, so that it is not good to simply increase the thickness of the surface nickel or increase the thickness of the total plating layer.

Disclosure of Invention

The invention aims to solve the problems in the prior art, and provides an electroplated layer structure for improving the fracture force of a sintered neodymium-iron-boron sheet magnet and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

improve the plating layer structure of magnetic compression break force, the plating layer structure includes the nickel cobalt alloy cladding material, the plating layer uses the nickel cobalt alloy cladding material as the extexine, nickel cobalt alloy cladding material (5) thickness is 8 ~ 9 um.

Preferably, the thickness of the nickel-cobalt alloy plating layer is 8.5 um.

Preferably, the plating layer structure further comprises

A zinc layer in direct contact with said magnet, said zinc layer serving as a bottom layer;

the nickel-phosphorus alloy layer is positioned on the zinc layer and serves as an intermediate conversion layer;

a copper layer on the nickel-phosphorus alloy layer, the copper layer serving as an intermediate layer;

the nickel-cobalt alloy plating layer is located on the copper layer.

Preferably, the thickness of zinc layer is 1 ~ 3um, the thickness of nickel-phosphorus alloy layer is 2 ~ 4um, the thickness of copper layer is 3 ~ 5 um.

Preferably, the plating layer structure further comprises

A zinc layer in direct contact with said magnet, said zinc layer serving as a bottom layer;

the zinc-nickel alloy layer is positioned on the zinc layer and is used as an intermediate conversion layer;

a copper layer on the zinc-nickel alloy layer, the copper layer serving as an intermediate layer;

the nickel-cobalt alloy plating layer is located on the copper layer.

Preferably, the thickness of zinc layer is 1 ~ 3um, the thickness of zinc-nickel alloy layer is 2 ~ 4um, the thickness of copper layer is 3 ~ 5 um.

A plated layer structure for improving the fracture force of a sintered nd-fe-b sheet magnet, the plated layer structure adopting the plated layer structure of claim 1.

The preparation method of the electroplated layer structure for improving the fracture force of the sintered NdFeB sheet magnet mainly comprises the following steps of:

s1, firstly, preprocessing the sintered NdFeB sheet magnet;

s2, plating a zinc layer on the sintered NdFeB sheet magnet;

s3, plating a nickel-phosphorus alloy layer on the zinc layer by adopting chemical nickel plating solution;

s4, electroplating a copper layer on the nickel-phosphorus alloy layer;

and S5, plating a nickel-cobalt alloy layer on the copper layer.

Preferably, the pretreatment in step S1 includes chamfering, degreasing, pickling, and ultrasonic water washing.

Preferably, the plating method in step S2 is plating using a zinc sulfate-based plating solution, and the plating method in step S4 is plating using a copper pyrophosphate-based plating solution; the electroplating method of the step S5 is electroplating by using a nickel sulfate electroplating solution system containing cobalt sulfate.

Compared with the prior art, the invention provides the electroplated layer structure for improving the fracture force of the sintered neodymium-iron-boron sheet magnet and the preparation method thereof, and the electroplated layer structure has the following beneficial effects:

1. by changing the property of the surface plating layer and adopting the nickel-cobalt alloy plating layer, the breaking force value contributed by the thicker nickel plating layer can be replaced by the thinner nickel-cobalt alloy plating layer, namely, the thinner nickel-cobalt alloy plating layer is adopted, so that the requirement of the breaking force value of the product is ensured, and the original thermal demagnetization rate, magnetic flux and corrosion resistance level are maintained.

2. The coating structure and the preparation method thereof can properly find an optimal fit point according to the incidence relation among the coating thickness, the breaking force, the magnetic flux, the thermal demagnetization rate and the corrosion resistance, and the coating structure and the preparation method thereof are optimally matched with the magnetic property, the mechanical property and the corrosion resistance.

Drawings

FIG. 1 is a schematic structural diagram of embodiment 1 of the present invention;

FIG. 2 is a schematic structural diagram of embodiment 2 of the present invention;

fig. 3 is a schematic structural diagram of embodiment 3 of the present invention.

In the figure: 1. a magnet; 2. a zinc layer; 3. a nickel-phosphorus alloy layer; 4. a copper layer; 5. nickel-cobalt alloy plating; 6. a zinc-nickel alloy layer; 7. and sintering the neodymium iron boron sheet magnet.

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 of the embodiments.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

Example 1:

referring to fig. 1: the electroplated layer structure for improving the magnetic fracture force is characterized by comprising a nickel-cobalt alloy plated layer 5, wherein the electroplated layer takes the nickel-cobalt alloy plated layer 5 as an outer surface layer;

the thickness of the nickel-cobalt alloy plating layer 5 is 8-9 um, and the thickness of the nickel-cobalt alloy plating layer 5 is 8.5 um;

the electroplated layer structure also comprises

A zinc layer 2 in direct contact with the magnet 1, the zinc layer 2 serving as a bottom layer;

the nickel-phosphorus alloy layer 3 is positioned on the zinc layer 2, and the nickel-phosphorus alloy layer 3 is used as an intermediate conversion layer;

a copper layer 4 positioned on the nickel-phosphorus alloy layer 3, wherein the copper layer 4 is used as an intermediate layer;

the nickel-cobalt alloy plating layer 5 is positioned on the copper layer 4;

the thickness of zinc layer 2 is 1 ~ 3um, and the thickness of nickel phosphorus alloy-layer 3 is 2 ~ 4um, and the thickness of copper layer 4 is 3 ~ 5 um.

Example 2:

referring to fig. 2, the electroplated layer structure for improving the magnetic fracture force comprises a nickel-cobalt alloy plated layer 5, and the electroplated layer takes the nickel-cobalt alloy plated layer 5 as an outer surface layer;

the thickness of the nickel-cobalt alloy plating layer 5 is 8-9 um; the thickness of the nickel-cobalt alloy plating layer 5 is 8.5um

The electroplated layer structure also comprises

A zinc layer 2 in direct contact with the magnet 1, the zinc layer 2 serving as a bottom layer;

a zinc-nickel alloy layer 6 positioned on the zinc layer 2, wherein the zinc-nickel alloy layer 6 is used as an intermediate conversion layer;

a copper layer 4 on the zinc-nickel alloy layer 6, the copper layer 4 serving as an intermediate layer;

the nickel-cobalt alloy plating layer 5 is positioned on the copper layer 4;

the thickness of zinc layer 2 is 1 ~ 3um, and the thickness of zinc-nickel alloy layer 6 is 2 ~ 4um, and the thickness of copper layer 4 is 3 ~ 5 um.

Example 3:

referring to fig. 3, a plating layer structure for improving the fracture force of a sintered nd-fe-b sheet magnet, wherein the plating layer structure adopts the plating layer structure of claim 1;

the preparation method of the electroplated layer structure for improving the fracture force of the sintered NdFeB sheet magnet is characterized by mainly comprising the following steps of:

s1, firstly, preprocessing the sintered NdFeB sheet magnet 7; the pretreatment in step S1 includes chamfering, degreasing, pickling, and ultrasonic water washing;

s2, plating a zinc layer 2 on the sintered NdFeB sheet magnet 7; the electroplating method in step S2 adopts zinc sulfate-based electroplating solution for electroplating;

s3, plating a nickel-phosphorus alloy layer 3 on the zinc layer 2 by adopting chemical nickel plating solution;

s4, plating a copper layer 4 on the nickel-phosphorus alloy layer 3; the electroplating method of the step S4 is to use the copper pyrophosphate system electroplating solution to carry out electroplating,

s5, plating a nickel-cobalt alloy layer 5 on the copper layer 4; the electroplating method of step S5 is to use the nickel sulfate electroplating solution system containing cobalt sulfate to carry out electroplating

Embodiments of the invention will be further illustrated below in connection with tests and tests:

by adopting a coated thin magnet with intrinsic coercivity belonging to H grade, taking a magnetic sheet with the specification of 11.15 × 7.15 × 0.75T mm and the magnetic performance of 52H as an example, when the thickness of a coating is basically within the range of NdFe/EP.Zn1-3/Ap.NiP2-4/EP.Cu3-5 NiCo8.0-9.0, the thermal demagnetization rate of the coating is less than 5%; the initial magnetic flux attenuation rate is less than 5%; the salt spray test is carried out for 72 hours without change; the press breaking force of the sample is increased by about 50N compared with that of the sample before electroplating, and the press breaking force improvement rate is about 40-60%; the press-breaking force of the substrate is 73N, the press-breaking force when the common nickel plating layer is used as the surface layer is about 85N, and only about 12N is increased; the press-breaking force when the nickel-cobalt alloy plating layer is adopted as the surface layer is about 125N, and is increased by about 50N.

This is because the break stress at 7.5 μm for the ni-co alloy plating layer is higher than the inflection point, while the break stress at 12.5 μm for the ni-co alloy plating layer is higher than the inflection point, which means that the thinner ni-co alloy plating layer can replace the break stress value contributed by the thicker ni-co alloy plating layer; namely, a relatively thin nickel-cobalt alloy plating layer is adopted, so that the requirement of the pressure breaking force value of the product is met, and the original heat demagnetization rate, magnetic flux and corrosion resistance level are maintained;

the electroplated layer structure is the key for remarkably improving the pressure breaking force value of the thin magnetic sheet on the premise of keeping the characteristics of low heat demagnetization rate, low initial magnetic flux attenuation rate, higher plating bonding force, higher corrosion resistance grade level and the like of the magnet, and is the best plated layer structure in the electroplated layer structure found and applied in the current sintered neodymium iron boron permanent magnet material industry for the thin magnetic sheet and the ultrathin magnetic sheet.

As shown in fig. 3, the present invention provides a sintered nd-fe-b magnet 1 and a plating structure thereof. The coating structure of the sintered neodymium iron boron magnet 1 sequentially comprises a 1-3 mu m zinc layer 2, a 2-4 mu m nickel-phosphorus alloy layer 3, a 3-5 mu m copper layer 4 and an 8-9 mu m nickel-cobalt alloy layer 5 from inside to outside.

The following methods are used for testing various indexes such as the breaking force of the magnet: the specification (unit: mm) of the sintered neodymium iron boron magnet with the coating structure is 11.15 × 7.15 × 0.75T (T represents the magnetizing direction), and the magnetic performance of the magnet is as follows: the maximum magnetic energy product (BH) m is 52MGOe, and the intrinsic coercivity Hcj is 18 KOe; each test takes 30Pcs, only the sample for measuring the magnetic flux and the thermal demagnetization rate is saturated and magnetized, and the pressure break force and the salt spray test are not magnetized; the magnetic characteristic measurement condition is tested under the condition of 120 ℃ 1Hr open circuit, the corrosion resistance test adopts a neutral salt spray test (NSS), the pressure test adopts a manometer and a special tool, the plating thickness is tested by a metallographic method, and the obtained test results are shown in the following table:

the test data can prove that the breaking force of the sample of the nickel-cobalt electroplated layer of the magnet coated by the nickel-cobalt alloy coating is increased by about 40N (Newton) compared with that of the sample of the nickel-cobalt electroplated layer, and is increased by about 50N (Newton) compared with that of the sample before electroplating; the magnetic flux attenuation rate of the plating layer of the invention is about 4%, and the magnetic flux attenuation rate is about 8% when the thickness of the nickel plating layer is more than 12 μm, which shows that the increase of the thickness of the plating layer can increase the breaking force, but the magnetic flux attenuation is the cost.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.