Method for improving surface tension of neodymium-iron-boron after electroplating nickel-copper-nickel

Abstract

The application discloses a method for improving surface tension of a neodymium-iron-boron product after electroplating of nickel-copper-nickel, and relates to the technical field of sintered neodymium-iron-boron magnetic materials, aiming at solving the problem that the surface tension of the neodymium-iron-boron product after electroplating of nickel-copper-nickel cannot meet the requirements and the product consistency is poor. The method comprises the following steps: performing plasma cleaning on the neodymium-iron-boron product after electroplating of nickel-copper-nickel, so as to improve the surface tension of the product without damaging the salt mist resistance of the plating layer, and make the surface tension of the product consistent. More preferably, the neodymium-iron-boron blank is processed into a certain size, and then is subjected to surface treatment of pickling and ultrasonic cleaning or laser cleaning before electroplating of nickel-copper-nickel, so that the surface tension of the final product can be improved more easily. The method effectively improves the problem of low surface tension caused by traditional electroplating of nickel-copper-nickel, greatly improves the product consistency, and almost has no difference between products of the same batch, and has no obvious influence on the salt mist resistance of the nickel-copper-nickel layer of the product.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of sintered neodymium-iron-boron magnetic materials, in particular to a method for improving the surface tension of neodymium-iron-boron after electroplating nickel-copper-nickel. BACKGROUND

[0002] At present, a large number of neodymium-iron-boron permanent magnet devices are used in many consumer electronic products in people's life, and the loudspeaker, earphone, incoming call vibration, lens focusing + anti-shake and touch screen feedback in a smart phone all need to use neodymium-iron-boron permanent magnet materials. With the continuous expansion of the application of neodymium-iron-boron permanent magnet materials in electronic consumer products, new requirements for the production of rare earth permanent magnet materials are continuously put forward.

[0003] With the continuous expansion of the application of neodymium-iron-boron and the continuous expansion of the market, people's understanding of neodymium-iron-boron is continuously improved. In addition to the unique magnetic flux, residual magnetism, coercive force and magnetic energy product of neodymium-iron-boron, the surface tension of the neodymium-iron-boron product after electroplating gradually appears. After the surface treatment of the magnet by electroplating nickel-copper-nickel, the surface tension is difficult to stably reach the product requirement. In general, even if the same batch of materials and the same batch of products are electroplated in batches and barrels, the surface tension index of the electroplated products has a large fluctuation value. The fluctuation value is usually about 10% in dyne value. Therefore, a method for improving the surface tension of neodymium-iron-boron after electroplating nickel-copper-nickel is urgently needed to solve this problem. SUMMARY

[0004] The purpose of the present application is to provide a method for improving the surface tension of neodymium-iron-boron after electroplating nickel-copper-nickel to solve the problem that the surface tension of neodymium-iron-boron after electroplating nickel-copper-nickel cannot meet the requirements and the product consistency is poor.

[0005] To achieve the above purpose, the present application provides the following technical scheme: a method for improving the surface tension of neodymium-iron-boron after electroplating nickel-copper-nickel, which performs plasma cleaning on the product after electroplating nickel-copper-nickel on the neodymium-iron-boron, so as to improve the surface tension of the product without damaging the salt mist resistance of the plating layer and make the surface tension of the product consistent.

[0006] Preferably, the blank of neodymium-iron-boron is processed to a certain size, then is subjected to surface treatment and then is electroplated with nickel-copper-nickel.

[0007] Preferably, the surface treatment includes pickling, and also includes ultrasonic cleaning or laser cleaning.

[0008] Preferably, the surface treatment is pickling with 2% volume fraction of dilute nitric acid and laser cleaning.

[0009] Preferably, the plasma cleaning adopts compressed air, the vacuum degree is not more than 300 Pa, and the plasma spray gun uniformly sweeps the surface of the product at a speed of 1-10 s / dm.

[0010] Preferably, the process parameters of the plasma cleaning include that the vacuum degree is 100 Pa, and the plasma spray gun uniformly scans the product surface at a speed of 2 s / dm.

[0011] Preferably, the step of electroplating nickel-copper-nickel includes that a drum containing Nd-Fe-B to be plated and auxiliary plating balls is sequentially subjected to electroplating treatment in a bottom nickel tank, a copper tank, a semi-bright nickel tank and a bright nickel tank, and after the electroplating is completed, cleaning, discharging and water spot blowing are performed.

[0012] Preferably, the process parameters of the electroplating nickel-copper-nickel are as follows: the rotation speed of the bottom nickel tank is 6 r / min, the current is 20-40 A, and the time is 70 min; the rotation speed of the copper tank is 6 r / min, the current is 25 A, and the time is 70 min; the rotation speed of the semi-bright nickel tank is 6 r / min, the current is 25 A, and the time is 60 min; and the rotation speed of the bright nickel tank is 6 r / min, the current is 25 A, and the time is 10 min.

[0013] Preferably, after the Nd-Fe-B electroplated nickel-copper-nickel product is subjected to the plasma cleaning, the thickness of the bottom nickel is 3-8 um.

[0014] Compared with the prior art, the method has the following beneficial effects:

[0015] The method for improving the surface tension of the Nd-Fe-B electroplated nickel-copper-nickel product includes that the product electroplated nickel-copper-nickel is subjected to the plasma cleaning, preferably, compressed air is used for the plasma cleaning, the vacuum degree is selected to be not more than 300 Pa, and the plasma spray gun uniformly scans the product surface at a speed of 1-10 s / dm; in a preferred embodiment, the vacuum degree is controlled to be about 100 Pa, and the plasma spray gun uniformly scans the product surface at a speed of 2 s / dm; in addition, in order to ensure the product quality, preferably, after the Nd-Fe-B electroplated nickel-copper-nickel product is subjected to the plasma cleaning, the thickness of the bottom nickel is 3-8 um. DETAILED DESCRIPTION

[0016] The method for improving the surface tension of the Nd-Fe-B electroplated nickel-copper-nickel product includes that the product electroplated nickel-copper-nickel is subjected to the plasma cleaning, preferably, compressed air is used for the plasma cleaning, the vacuum degree is selected to be not more than 300 Pa, and the plasma spray gun uniformly scans the product surface at a speed of 1-10 s / dm; in a preferred embodiment, the vacuum degree is controlled to be about 100 Pa, and the plasma spray gun uniformly scans the product surface at a speed of 2 s / dm; in addition, in order to ensure the product quality, preferably, after the Nd-Fe-B electroplated nickel-copper-nickel product is subjected to the plasma cleaning, the thickness of the bottom nickel is 3-8 um.

[0017] In order to further improve the surface tension of the product, the neodymium iron boron blank is processed into a certain size, and then is subjected to surface treatment and then nickel-copper-nickel electroplating; specifically, the surface treatment can include pickling, and can also include ultrasonic cleaning or laser cleaning; wherein the pickling can use 2% by volume fraction of dilute nitric acid pickling.

[0018] Comparative Example:

[0019] The 35H grade neodymium iron boron blank is selected, and is cut into a product with a size of 62mmx8.6mmx2.2mm. The vibration chamfer is R0.2±0.1mm. The product after vibration chamfering is subjected to 2% by volume fraction of dilute nitric acid pickling, and then nickel-copper-nickel electroplating is started. 0.5kg of the product after pickling is weighed into a roller, and then 1.5kg of 6mm diameter auxiliary plating balls are added, and then the product is sequentially subjected to bottom nickel tank, copper tank, semi-bright nickel tank and bright nickel tank electroplating treatment. The process parameters are respectively: bottom nickel tank (speed 6r / min, current 20-40A, time 70min); copper tank (speed 6r / min, current 25A, time 70min); semi-bright nickel tank (speed 6r / min, current 25A, time 60min); and bright nickel tank (speed 6r / min, current 25A, time 10min); after electroplating, cleaning, discharging and water spot blowing are performed, wherein the center bottom nickel thickness of the tested product is 5.6um, 4 pieces of the product are subjected to 35℃ neutral salt spray test for 48h without corrosion; the surface tension dyne pen experimental data are as follows:

[0020]

[0021]

[0022] Example 1:

[0023] The 35H grade neodymium iron boron blank is selected, and is cut into a product with a size of 62mmx8.6mmx2.2mm. The vibration chamfer is R0.2±0.1mm. The product after vibration chamfering is subjected to 2% by volume fraction of dilute nitric acid pickling, and then nickel-copper-nickel electroplating is started. 0.5kg of the product after pickling is weighed into a roller, and then 1.5kg of 6mm diameter auxiliary plating balls are added, and then the product is sequentially subjected to bottom nickel tank, copper tank, semi-bright nickel tank and bright nickel tank electroplating treatment. The process parameters are respectively: bottom nickel tank (speed 6r / min, current 20-40A, time 70min); copper tank (speed 6r / min, current 25A, time 70min); semi-bright nickel tank (speed 6r / min, current 25A, time 60min); and bright nickel tank (speed 6r / min, current 25A, time 10min); after electroplating, cleaning, discharging and water spot blowing are performed, wherein the center bottom nickel thickness of the tested product is 5.6um, 4 pieces of the product are subjected to 35℃ neutral salt spray test for 48h without corrosion; the surface tension dyne pen experimental data are as follows:

[0024] Product No. 1 2 3 4 5 34# Does the pen retract? No No Yes No No 36# Does the pen retract? Yes Yes Yes Yes Yes

[0025] Example 2

[0026] Select 35H grade Nd-Fe-B blank, cut into size 62mm x 8.6mm x 2.2mm product. Vibration chamfer R0.2±0.1mm. The product after vibration chamfering is pickled with 2% volume fraction of dilute nitric acid, laser cleaned, and then starts nickel-copper-nickel electroplating. Weigh 0.5kg of the product after laser cleaning into the drum, then add 1.5kg of 6mm diameter co-deposition balls, and then sequentially pass through the bottom nickel tank, copper tank, semi-bright nickel tank and bright nickel tank for electroplating treatment. The process parameters are respectively: bottom nickel tank (speed 6r / min, current 20-40A, time 70min); copper tank (speed 6r / min, current 25A, time 70min); semi-bright nickel tank (speed 6r / min, current 25A, time 60min); and bright nickel tank (speed 6r / min, current 25A, time 10min); after electroplating, clean, discharge, and dry water spots, among which the center bottom nickel thickness of the test product is 4.8um, and 4 pieces of product are tested for 48h neutral salt spray test at 35℃ without corrosion; the surface tension dyne pen experimental data are as follows:

[0027] Product No. 1 2 3 4 5 34# Does the pen retract? No No No No No 36# Does the pen retract? No No No No No 38# Does the pen retract? No No No No No 40# Does the pen retract? Yes Yes Yes Yes Yes

[0028] Example 3

[0029] Select 35H grade Nd-Fe-B blank, cut into size 62mm x 8.6mm x 2.2mm product. Vibration chamfer R0.2±0.1mm. The product after vibration chamfering is pickled with 2% volume fraction of dilute nitric acid, and then starts nickel-copper-nickel electroplating. Weigh 0.5kg of the product after pickling into the drum, then add 1.5kg of 6mm diameter co-deposition balls, and then sequentially pass through the bottom nickel tank, copper tank, semi-bright nickel tank and bright nickel tank for electroplating treatment. The process parameters are respectively: bottom nickel tank (speed 6r / min, current 20-40A, time 70min); copper tank (speed 6r / min, current 25A, time 70min); semi-bright nickel tank (speed 6r / min, current 25A, time 60min); and bright nickel tank (speed 6r / min, current 25A, time 10min); after electroplating, clean, discharge, and dry water spots, and finally perform plasma cleaning treatment. Among which the center bottom nickel thickness of the test product is 4.8um, and 4 pieces of product are tested for 48h neutral salt spray test at 35℃ without corrosion; the surface tension dyne pen experimental data are as follows:

[0030] Product No. 1 2 3 4 5 34# Does the pen retract? No No No No No 36# Does the pen retract? No No No No No 38# Does the pen retract? No No No No No 40# Does the pen retract? No No No No No 60# Does the pen retract? No No No No No 64# Does the pen retract? Yes Yes Yes Yes Yes

[0031] Example 4

[0032] Select 35H grade Nd-Fe-B blank, cut into size 62mm x 8.6mm x 2.2mm product. Vibration chamfer R0.2±0.1mm. The product after vibration chamfer is pickled with 2% volume fraction dilute nitric acid, laser cleaned, and then starts nickel-copper-nickel electroplating. The product after laser cleaning is weighed 0.5kg and poured into a roller, then 1.5kg of 6mm diameter auxiliary plating ball is added, and then the product is sequentially electroplated in a bottom nickel tank, a copper tank, a semi-bright nickel tank and a bright nickel tank. The process parameters are respectively: bottom nickel tank (speed 6r / min, current 20-40A, time 70min); copper tank (speed 6r / min, current 25A, time 70min); semi-bright nickel tank (speed 6r / min, current 25A, time 60min); and bright nickel tank (speed 6r / min, current 25A, time 10min); after electroplating, the product is cleaned, discharged, and water spots are blown dry, and finally plasma cleaning is performed. The center bottom nickel thickness of the tested product is 4.8um, and 4 pieces of product are tested for 48h neutral salt spray test at 35℃ without corrosion; the surface tension of the product is as follows:

[0033] Product No. 1 2 3 4 5 34# Does the pen retract? No No No No No 36# Does the pen retract? No No No No No 38# Does the pen retract? No No No No No 40# Does the pen retract? No No No No No 60# Does the pen retract? No No No No No 64# Does the pen retract? No No No No No 68# Does the pen retract? No No No No No 70# Does the pen retract? Yes Yes Yes Yes Yes

[0034] The above comparative examples are the existing conventional processing methods. From the experimental results, 34#dynes pen is retracted, 1 out of 10 pieces of product 32#dynes pen is retracted, 3 pieces of 28#dynes pen are retracted, the surface tension of the same batch of products fluctuates greatly, examples 1 and 2 have more surface treatment before electroplating based on the comparative examples, the surface tension is slightly improved, but the product inconsistency problem is not solved, example 3 has plasma cleaning treatment on the product at the end based on the comparative examples, the surface tension is significantly improved, and the consistency is good, example 4 has laser cleaning before electroplating and plasma cleaning after electroplating, the surface tension is improved from 32#dynes pen not retracted to 68#dynes pen not retracted, there is no difference in the same batch of products, and the salt spray resistance is not affected.

[0035] The present application finds that, in the process of electroplating nickel copper nickel, the pretreatment of electroplating, plating bath solution ratio, and post-treatment of electroplating are the main factors affecting the surface tension of the magnet by experimental testing, after studying the mechanism and theory of the influence of electroplating nickel copper nickel on the surface tension of neodymium iron boron. The reason may be that before electroplating, the cleaner the surface of neodymium iron boron is washed, after the material enters the electroplating tank, the tank solution and the surface of the neodymium iron boron magnet react chemically, the plating layer formed on the surface of the product is more bright, after electroplating, the surface of the product is treated by plasma cleaning, the material surface matter usually has solid, liquid and gas three states under certain temperature and pressure conditions, if a certain means (such as heating, discharge, etc.) is taken to make the gas molecules dissociate and ionize, when the density of charged particles produced by ionization reaches a certain value, a new state of matter aggregation is formed. Overall, the total number of positive and negative charges is equal in value, and is electrically neutral. We call such a completely or partially ionized but overall electrically neutral gas as plasma. In short, plasma refers to ionized gas, which is a collection of electrons, ions, atoms, molecules or free radicals.

[0036] After the neodymium iron boron of the present application is treated by electroplating nickel copper nickel, the wettability of the material surface layer is improved, so that various materials can carry out coating, surface plating and other actual operations, the adhesion and bonding ability are improved, in addition, organic chemical pollutants, oil stains and grease can also be removed. The surface modification of the material by plasma can produce chemical bonds in the middle of the grafted layer and the surface molecular structure, so that the material has excellent use performance.

[0037] The above is only a preferred embodiment of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical range disclosed by the present application can be easily thought by those skilled in the art, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be limited by the protection scope defined by the claims.

[0038] The details not described in the present application are the known technology of those skilled in the art.

Claims

1. A method of increasing the surface tension of electroplated nickel-copper-nickel on neodymium-iron-boron, characterized in that: The blank of Nd-Fe-B is processed into a certain size, then is surface treated and electroplated with nickel-copper-nickel, the surface treatment includes pickling, and also includes ultrasonic cleaning or laser cleaning; the product of Nd-Fe-B after electroplating with nickel-copper-nickel is plasma cleaned, for improving the surface tension of the product without destroying the salt spray resistance of the plating layer, and making the surface tension of the product consistent; The step of electroplating with nickel-copper-nickel includes: the roller containing the Nd-Fe-B to be plated and the accompanying plated ball is sequentially electroplated with bottom nickel tank, copper tank, semi-bright nickel tank and bright nickel tank, and after electroplating, cleaning, discharging and blowing dry water spots are carried out; The plasma cleaning uses compressed air, the vacuum degree is not more than 300 Pa, and the plasma spray gun uniformly sweeps the surface of the product at a speed of 1-10 s / dm; After the Nd-Fe-B electroplated with nickel-copper-nickel is plasma cleaned, the thickness of the bottom nickel is 3-8 um.

2. The method for improving the surface tension of the electroplated nickel-copper-nickel on neodymium-iron-boron according to claim 1, characterized in that: The surface treatment is 2% volume fraction of dilute nitric acid pickling and laser cleaning.

3. The method for improving the surface tension of the electroplated nickel-copper-nickel on neodymium-iron-boron according to claim 1, characterized in that, The process parameters of the plasma cleaning include: the vacuum degree is 100 Pa, and the plasma spray gun uniformly sweeps the surface of the product at a speed of 2 s / dm.

4. The method for improving the surface tension of the electroplated nickel-copper-nickel on neodymium-iron-boron according to claim 1, characterized in that, The process parameters of the electroplating with nickel-copper-nickel are: the rotation speed of the bottom nickel tank is 6 r / min, the current is 20-40 A, and the time is 70 min; the rotation speed of the copper tank is 6 r / min, the current is 25 A, and the time is 70 min; the rotation speed of the semi-bright nickel tank is 6 r / min, the current is 25 A, and the time is 60 min; the rotation speed of the bright nickel tank is 6 r / min, the current is 25 A, and the time is 10 min.

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