Method for improving surface tension of side surface of saturated magnetized neodymium iron boron magnetic steel

Abstract

The invention discloses a method for improving the surface tension of the side surface of saturated magnetized neodymium-iron-boron magnetic steel, which comprises the following steps of: firstly, carrying out plasma cleaning treatment on the side surface of the saturated magnetized neodymium-iron-boron magnetic steel of which the side surface tension value is detected to be lower than 30mN / m after being stored for a period of time; then splicing the saturated magnetized neodymium iron boron magnetic steel subjected to plasma cleaning treatment into blocks according to a preset number to form a saturated magnetized neodymium iron boron magnetic steel group, then wrapping the saturated magnetized neodymium iron boron magnetic steel group by adopting snow pear paper, and then performing vacuum packaging by adopting a vacuum packaging bag, oxygen is adopted as a plasma generator in plasma cleaning treatment; the method has the advantages that after the surface tension value of the saturated magnetized neodymium-iron-boron magnetic steel is obviously reduced due to long-time storage, the surface tension value of the saturated magnetized neodymium-iron-boron magnetic steel can be effectively increased, and the situations of scrapping and returning caused by unqualified surface tension value of the saturated magnetized neodymium-iron-boron magnetic steel are reduced.

Description

Technical Field

[0001] The invention relates to a method for increasing surface tension, in particular to a method for increasing the side surface tension of saturation magnetized NdFeB magnetic steel. Background Art

[0002] As we all know, NdFeB magnets have become an indispensable high-end accessory in the field of 3C consumer electronics due to their superior magnetic properties. Consumer electronics such as mobile phones, tablets, laptops, watches, headphones and wireless charging devices all require the use of NdFeB magnets in their internal acoustic modules, motor modules, magnetic modules, etc. Figure 1 As shown, the NdFeB magnet with a rectangular structure has four sides, two of which are the sides where the long sides are located, called long side sides, and two are the sides where the wide sides are located, called short side sides. Each side is an adhesive surface, and glue is needed to bond its sides and the bonding surface of the loading workpiece during the assembly process. If the glue has poor wettability, it will lead to weak adhesion and low mechanical properties, thereby causing the risk of poor reliability and reduced life of the assembly consisting of the NdFeB magnet and the loading workpiece.

[0003] Improving the adhesion performance between NdFeB magnets and glue is generally achieved by increasing the roughness and surface tension of the side of the NdFeB magnet. Improving the roughness mainly increases the adhesive area and adhesive depth to widen the distribution of the glue, thereby improving the adhesion between the NdFeB magnet and the loaded workpiece. Due to the inherent material properties of NdFeB magnets and the characteristics of the coating that needs to be attached, it is difficult for conventional electroplated nickel coatings to achieve a roughness of Ra0.5μm or more. Even if chemical or physical roughening methods are used to achieve a roughness of Ra0.8μm or more, the appearance will be poor due to severe etching on the surface of the NdFeB magnet, which will cause complaints from downstream customers. According to the curing principle of glue, to achieve good adhesion, the first thing is to have good wetting between the glue and the NdFeB magnet, and at the same time, the glue and the NdFeB magnet interact to form sufficient adhesion. Both are indispensable. The infiltration of liquid is mainly caused by surface tension. When the surface tension of the liquid is less than the critical surface tension of the solid, it will infiltrate. Therefore, the higher the surface tension of the solid, the more conducive it is to infiltration. When the glue cannot infiltrate the surface of the NdFeB magnet well, air bubbles will remain in the gap to form a weak area, or when there are foreign matter and impurities on the surface that are insoluble in the cured glue, another phase will be formed in the solidified adhesive layer, thereby generating a weak interface layer between the NdFeB magnet and the glue, which in turn affects the bonding strength.

[0004] For NdFeB magnet suppliers, there are two types of supply: non-magnetic supply and magnetic supply. Non-magnetic supply refers to delivering non-magnetic magnets (unmagnetized NdFeB magnets) to downstream customers, who then magnetize the NdFeB magnets and assemble them. Magnetic supply refers to magnetizing the NdFeB magnets by the supplier and then handing them over to downstream customers for assembly. Since non-magnetic magnets have not undergone magnetization and post-magnetization inspection processes, they can be stored for a period of time without a significant decrease in surface tension. Even if the surface tension has been significantly reduced after being stored for a long time, their surface tension can still be increased again through electroplating rework and cleaning.

[0005] like Figure 2 As shown in the figure, after magnetization, multiple pieces of NdFeB magnets will be adsorbed together and supplied in vacuum bags. The conventional packaging method is that the short side of the NdFeB magnet is in direct contact with the vacuum bag, and the flat surfaces are adsorbed together. Figure 2 It can be seen that after magnetization, the planes of the NdFeB magnets are adsorbed to each other, and the sides are exposed outside; during assembly, the four sides of the NdFeB magnets are in contact with the inner wall of the loaded workpiece and bonded together with glue, that is, the four sides of the NdFeB magnets are adhesive surfaces, so it is only necessary to increase the surface tension of the sides.

[0006] The tension changes of the flat surface (non-adhesive surface, i.e. the surface where the long side and wide side are located), the long side side (adhesive surface) and the short side side (adhesive surface) of the NdFeB magnet when it is placed after magnetization are shown in the figure below: Figure 3 As shown. Figure 3 It can be seen that after the initial magnetization, the tension values ​​of the plane, long side and short side of the NdFeB magnet are basically the same, but as the placement time increases, the tension value gradually shows the situation of plane>long side>short side. The reason is that in addition to the inherent property of poor timeliness of surface tension value (the decomposition and volatilization of organic additives in the coating and the influence of dust and foreign matter), it is also because the surface of the NdFeB magnet is in contact with the vacuum bag for a long time, and the vacuum bag is generally composed of high molecular polymers. The chemical components such as plasticizers and lubricants contained in it will precipitate and migrate to the surface of the coating over time. These types of substances will definitely cause the surface free energy of the NdFeB magnet to decrease, thereby reducing the hydrophilicity of the NdFeB magnet, weakening the wetting and bonding with the glue, and resulting in reduced mechanical properties. Before the dispensing assembly of NdFeB magnets, the surface tension value of the side surface must meet 34mN / m to achieve good infiltration. However, after the NdFeB magnets are packed in vacuum bags and placed for a long time, the surface tension value decays seriously. After several months of storage, the dyne is only about 28-30mN / m, which is far lower than the surface tension standard of NdFeB magnets during assembly. After the surface tension value of the side surface of NdFeB magnets is significantly reduced, it is no longer possible to perform post-plating treatment or cleaning operations, which is a difficulty in the industry. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a method for improving the side surface tension of saturated magnetized NdFeB magnets, which can effectively improve the surface tension value of the saturated magnetized NdFeB magnets after the surface tension value of the saturated magnetized NdFeB magnets has dropped significantly due to long-term storage, and reduce the scrapping and return of the saturated magnetized NdFeB magnets due to unqualified surface tension values.

[0008] The technical solution adopted by the present invention to solve the above technical problems is: a method for increasing the side surface tension of saturated magnetized NdFeB magnets, firstly performing plasma cleaning treatment on the side surfaces of saturated magnetized NdFeB magnets whose side surface tension values ​​are detected to be lower than 30mN / m after being stored for a period of time, and then assembling the saturated magnetized NdFeB magnets after the plasma cleaning treatment according to a preset number of blocks to form a saturated magnetized NdFeB magnet group, and then first wrapping the saturated magnetized NdFeB magnet group with snow pear paper and then vacuum packaging it with a vacuum packaging bag, wherein the plasma cleaning treatment uses oxygen as a plasma generator.

[0009] Compared with the prior art, the present invention has the advantage that by performing plasma cleaning on the side of the saturated magnetized NdFeB magnet with a side surface tension value lower than 30mN / m, under the action of a high-frequency electric field, oxygen molecules in the oxygen as a plasma generator are ionized into oxygen ions and free electrons to form plasma. After the plasma contacts the side of the saturated magnetized NdFeB magnet, it will react with the organic matter attached to the side surface to destroy the molecular structure of the organic matter, thereby eliminating the surface organic matter and improving the The purpose is to improve the side surface tension of the saturated magnetized NdFeB magnet, and first use snow pear paper to wrap the saturated magnetized NdFeB magnet group, which can avoid the saturated magnetized NdFeB magnet from directly contacting the vacuum packaging bag, and delay the subsequent attenuation rate of the side surface tension of the saturated magnetized NdFeB magnet. Therefore, after the surface tension value of the saturated magnetized NdFeB magnet decreases significantly due to long-term storage, the present invention can effectively improve its surface tension value, and reduce the scrapping and return of the saturated magnetized NdFeB magnet due to unqualified surface tension value.

[0010] Furthermore, the specific process of plasma cleaning the side of the saturated magnetized NdFeB magnet with a side surface tension value of less than 30mN / m detected after being stored for a period of time is as follows:

[0011] Step S1, using multiple pieces of saturated magnetized NdFeB magnets to sequentially adsorb and splice to form magnetic steel strips, the side of each piece of saturated magnetized NdFeB magnet is exposed, the height direction of each magnetic steel strip is along the splicing direction of the saturated magnetized NdFeB magnet, the multiple magnetic steel strips are spaced and adsorbed on an iron plate, wherein the thickness of the iron plate is 2 to 5 mm, the height direction of each magnetic steel strip is perpendicular to the iron plate and less than 100 mm, and the interval between any two adjacent magnetic steel strips is 20 to 30 mm;

[0012] Step S2, placing the iron plate and the magnetic steel strip adsorbed thereon as a whole on a preset bracket in a reaction chamber of the plasma cleaning machine, and closing the reaction chamber door of the plasma cleaning machine;

[0013] Step S3, starting the vacuum pump to evacuate the reaction chamber of the plasma cleaning machine until the vacuum degree of the reaction chamber of the plasma cleaning machine is evacuated to below 0.2 MPa;

[0014] Step S4, introducing oxygen (O2) as a plasma generator into the reaction chamber of the plasma cleaning machine, the oxygen flow rate is 1 to 10 liters / minute, the introduction time is 1 to 3 minutes, the gas excitation power of the plasma cleaning machine is set to 150 to 200W, and the plasma cleaning machine is turned on to perform plasma cleaning operation on the side of the saturated magnetized NdFeB magnet, and the plasma cleaning operation time is 2 to 5 minutes;

[0015] Step S5, after the plasma cleaning operation is completed, turn off the plasma cleaning machine, fill nitrogen into the reaction chamber of the plasma cleaning machine until the pressure in the reaction chamber of the plasma cleaning machine is equal to atmospheric pressure, then wait for the reaction chamber of the plasma cleaning machine to cool to room temperature, open the reaction chamber door of the plasma cleaning machine, and take out the iron plate and the magnetic steel strip adsorbed thereon.

[0016] Furthermore, each magnetic steel bar is formed by splicing 30 to 50 pieces of saturated magnetized NdFeB magnetic steel.

[0017] Furthermore, the vacuum packaging bag is a PE bag.

[0018] Furthermore, the saturated magnetized NdFeB magnet is a square nickel-plated magnet with an adhesive surface as the side surface and not a polar adsorption surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the assembly of NdFeB magnet and loaded workpiece;

[0020] Figure 2 This is a schematic diagram of multiple NdFeB magnets adsorbing each other after magnetization;

[0021] Figure 3 It is a diagram showing the tension variation of the flat surface (non-adhesive surface), long side surface (adhesive surface) and short side surface (adhesive surface) of the NdFeB magnet when it is placed after magnetization;

[0022] Figure 4 It is a schematic diagram of a plurality of magnetic steel strips adsorbed on an iron plate in the method for increasing the surface tension of the side surface of a saturated magnetized NdFeB magnetic steel of the present invention;

[0023] Figure 5A schematic diagram of a method for improving the side surface tension of a saturated magnetized NdFeB magnet of the present invention, wherein the saturated magnetized NdFeB magnets after plasma cleaning are assembled into blocks according to a preset number to form a saturated magnetized NdFeB magnet group;

[0024] Figure 6 A tension variation trend diagram of saturated magnetized NdFeB magnets treated by the method for increasing the side surface tension of saturated magnetized NdFeB magnets according to the present invention as a function of placement time;

[0025] Figure 7 This is a trend diagram of the tension variation of the saturated magnetized NdFeB magnet after argon plasma treatment in Comparative Example 3 of the present invention over the placement time. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below with reference to the accompanying drawings.

[0027] Embodiment 1: A method for increasing the side surface tension of saturated magnetized NdFeB magnets, firstly performing plasma cleaning treatment on the side surfaces of saturated magnetized NdFeB magnets whose side surface tension values ​​are detected to be lower than 30mN / m after being stored for a period of time, then assembling the saturated magnetized NdFeB magnets after the plasma cleaning treatment according to a preset number of blocks to form a saturated magnetized NdFeB magnet group, then firstly wrapping the saturated magnetized NdFeB magnet group with snow pear paper and then vacuum packaging it with a vacuum packaging bag, wherein the plasma cleaning treatment uses oxygen as a plasma generator.

[0028] In this embodiment, plasma cleaning treatment is performed on the side surface of saturated magnetized NdFeB magnets with a side surface tension value lower than 30mN / m. Under the action of a high-frequency electric field, oxygen molecules in oxygen as a plasma generator are ionized into oxygen ions and free electrons to form plasma. After the plasma contacts the side surface of the saturated magnetized NdFeB magnet, it will undergo an oxidation reaction with organic matter attached to the side surface to destroy the molecular structure of the organic matter, thereby achieving the purpose of eliminating the surface organic matter and increasing the side surface tension of the saturated magnetized NdFeB magnet. By first wrapping the saturated magnetized NdFeB magnet group with snow pear paper, it is possible to avoid direct contact between the saturated magnetized NdFeB magnet and the vacuum packaging bag, thereby delaying the subsequent attenuation rate of the side surface tension of the saturated magnetized NdFeB magnet.

[0029] Embodiment 2: This embodiment is basically the same as Embodiment 1, except that: in this embodiment, the specific process of plasma cleaning the side surface of the saturated magnetized NdFeB magnet whose side surface tension value is detected to be lower than 30mN / m after being stored for a period of time is as follows:

[0030] Step S1: Figure 4As shown, 40 pieces of saturated magnetized NdFeB magnets are sequentially adsorbed and spliced ​​to form a magnetic steel bar 2, the side of each saturated magnetized NdFeB magnet is exposed, the height direction of the magnetic steel bar 2 is along the splicing direction of the saturated magnetized NdFeB magnet, and multiple magnetic steel bars 2 are arranged at intervals and adsorbed on an iron plate 1, wherein the thickness of the iron plate 1 is 2mm, the height direction of each magnetic steel bar 2 is perpendicular to the iron plate 1, the height of the magnetic steel bar is 80mm, and any two adjacent magnetic steel bars are perpendicular to each other. The steel bars 2 are spaced 25mm apart to prevent them from being attracted together due to being too close; the saturated magnetized NdFeB magnet is a rectangular magnet, and the four edges in the height direction are chamfered, and the length×width×height specifications are: 9.5mm×6.5mm×2mm, and the chamfer radius R is 0.8mm. The plating of the saturated magnetized NdFeB magnet is nickel-copper-nickel+chemical nickel; the adhesive surface of the saturated magnetized NdFeB magnet is the side surface and is not a polar adsorption surface;

[0031] Step S2, placing the iron plate 1 and the magnetic steel strip 2 adsorbed thereon as a whole on a bracket preset in a reaction chamber of the plasma cleaning machine, and closing the reaction chamber door of the plasma cleaning machine;

[0032] Step S3, starting the vacuum pump to evacuate the reaction chamber of the plasma cleaning machine until the vacuum degree of the reaction chamber of the plasma cleaning machine is evacuated to below 0.2 MPa;

[0033] Step S4, introducing oxygen (O2) as a plasma generator into the reaction chamber of the plasma cleaning machine, the oxygen flow rate is 3 liters / minute, the introduction time is 2 minutes, the gas excitation power of the plasma cleaning machine is set to 150W, and the plasma cleaning machine is turned on to perform plasma cleaning operation on the side of the saturated magnetized NdFeB magnet, and the plasma cleaning operation time is 2 minutes;

[0034] Step S5, after the plasma cleaning operation is completed, turn off the plasma cleaning machine, fill nitrogen into the reaction chamber of the plasma cleaning machine until the pressure in the reaction chamber of the plasma cleaning machine is equal to atmospheric pressure, then wait for the reaction chamber of the plasma cleaning machine to cool to room temperature, open the reaction chamber door of the plasma cleaning machine, and take out the iron plate 1 and the magnetic steel strip 2 adsorbed thereon.

[0035] In this embodiment, after the plasma cleaning process is completed, Figure 5 As shown, the saturated magnetized NdFeB magnets after plasma cleaning are pieced together according to a preset number to form a saturated magnetized NdFeB magnet group, and then the saturated magnetized NdFeB magnet group is first wrapped with snow pear paper and then vacuum packaged with a vacuum packaging bag, wherein the vacuum packaging bag is a PE bag.

[0036] In order to verify the effect of the method for improving the side surface tension of saturated magnetized NdFeB magnets of the present invention, the saturated magnetized NdFeB magnets obtained by the method for improving the side surface tension of saturated magnetized NdFeB magnets of the second embodiment of the present invention were used as test samples, and comparative samples were set to test the change process of the tension value (dyne value). The test results are as follows: Figure 6 The difference between the control sample and the test sample is that the control sample is directly vacuum packed in a vacuum packaging bag after the plasma cleaning treatment, without being wrapped in Sydney paper first. Figure 6 In the test, the vacuum bag packaging corresponds to the comparison sample, and the Sydney paper + vacuum bag packaging corresponds to the test sample. Figure 6 It can be seen that after the plasma cleaning treatment, the dyne value of the saturated magnetized NdFeB magnet wrapped in snow pear paper reached 38mN / m after 17 days of placement, and the dyne value remained at 34-36mN / m even after 46 days of placement. Correspondingly, the dyne value of the saturated magnetized NdFeB magnet not wrapped in snow pear paper was 32-34mN / m after 46 days of placement. It can be seen that the oxygen plasma cleaning method is adopted, and then the snow pear paper is wrapped and then vacuum packaged. After the plasma treatment, the NdFeB magnet is first wrapped in snow pear paper and then vacuum packaged, so as to avoid the direct contact between the surface of the saturated magnetized NdFeB magnet and the vacuum bag, effectively isolate the penetration and migration of organic matter in the vacuum bag, and achieve the effect of increasing the surface tension of the saturated magnetized NdFeB magnet and delaying the tension attenuation rate.

[0037] Embodiment 3: This embodiment is basically the same as Embodiment 2, with the only difference being that in this embodiment, the plasma cleaning operation time is 3 minutes.

[0038] Embodiment 4: This embodiment is basically the same as Embodiment 2, with the only difference being that in this embodiment, the plasma cleaning operation time is 5 minutes.

[0039] In order to further verify the effect of the method for improving the side surface tension of saturation magnetized NdFeB magnets of the present invention, five comparative examples are set to compare with the second to fourth embodiments of the present invention.

[0040] Comparative Example 1: This comparative example is basically the same as Example 2, except that in this comparative example, the plasma cleaning operation time is 1 minute.

[0041] Comparative Example 2: This comparative example is basically the same as Example 2, with the only difference being that in this comparative example, inert gas argon (Ar) is introduced into the reaction chamber of the plasma cleaning machine as a plasma generator.

[0042] Comparative Example 3: This comparative example is basically the same as Comparative Example 1, except that in this comparative example, the plasma cleaning operation time is 3 minutes.

[0043] Comparative Example 4: This comparative example is basically the same as Comparative Example 1, except that in this comparative example, the plasma cleaning operation time is 5 minutes.

[0044] Comparative Example 5: This comparative example does not use the plasma cleaning method. The difference from the above comparative examples is that the side of the saturated magnetized NdFeB magnet with a side surface tension value of less than 30mN / m detected after being stored for a period of time is wiped with an alcohol cloth. The specific process is as follows:

[0045] Step S1, using 40 pieces of saturated magnetized NdFeB magnets to sequentially adsorb and splice to form a magnetic steel bar 2, with the side of each piece of saturated magnetized NdFeB magnet exposed to the outside;

[0046] Step S2, place the magnetic steel bar 2 sideways on an iron plate, wherein the thickness of the iron plate is 2 mm, and wipe the four sides of the magnetic steel bar with an alcohol cloth, wiping each side for 4 to 6 seconds;

[0047] Step S3, wait for about 15 to 20 seconds, and the alcohol evaporates naturally. Make a batch of saturation magnetized NdFeB magnets, and test their tension values ​​after magnetization, and they are all 38mN / m. Put the batch of saturation magnetized NdFeB magnets for 6 months and test them again, select the saturation magnetized NdFeB magnets with tension values ​​decayed to 28mN / m, divide them into multiple groups, and respectively use the methods of Examples 2 to 5 of the present invention and Comparative Examples 1 to 5 to process them, and after the processing is completed, test the tension value of each group of NdFeB magnets, where the specific test data are shown in Table 1:

[0048] Table 1 (Judgment standard: the test liquid covers 75% of the surface of the magnetic steel and does not shrink within 3 seconds, which is considered qualified)

[0049]

[0050] As shown in Table 1 above, Example 2 to Example 4 and Comparative Example 1 adopt oxygen plasma cleaning treatment, and the treatment time is 2min, 3min, 5min and 1min respectively; Comparative Examples 2 to Comparative Example 4 adopt argon (Ar) plasma cleaning treatment, and the treatment time is 2min, 3min and 5min respectively. Except for the different excitation gases, the other parameters are consistent with the oxygen plasma treatment method; Comparative Example 5 adopts alcohol wiping method. Because alcohol is a weak polar molecule, according to the principle of like dissolves like, it can dissolve the organic matter on the surface of NdFeB magnet to a certain extent, thereby improving the surface tension value of NdFeB magnet. The tension value on the right side of Table 1 is dyne result NG unqualified (the detection liquid does not cover more than 75% of the area), and the tension value on the left side is dyne value OK qualified, that is, the surface tension value that can be actually achieved in each experiment. It can be seen from the data in Table 1 that the dyne value of the side surface of the NdFeB magnet reaches 38mN / m after magnetization. After long-term storage in a vacuum bag (6 months), the dyne value drops to only 28mN / m. The dyne value is significantly improved after oxygen plasma treatment. The dyne value can be increased to 42mN / m after 2-3min oxygen plasma cleaning treatment; and the dyne value is increased to 36mN / m after 1min oxygen plasma cleaning treatment (Comparative Example 1). Obviously, this is because the oxygen plasma cleaning treatment time is short, and the reaction between oxygen plasma and organic matter on the surface of the NdFeB magnet is not sufficient; after 5min of treatment, the dyne value can meet 44mN / m, but the extended treatment time means slower efficiency, and the actual requirement can be met in 2-3min. Comparative Examples 2 to 4 simultaneously verify the use of rare gas argon as a plasma generator. Since argon (Ar) is a rare inert gas, its treatment essentially generates a high-energy particle flow to impact the surface of the magnetic steel that needs to be cleaned, which is a physical impact. Compared with the chemical reaction caused by oxygen plasma treatment, the ability of argon plasma to remove surface organic matter is weaker. Under the same excitation power, even after treatment for 5 minutes, the dyne value only reaches 36mN / m; Comparative Example 5 uses an alcohol cloth to wipe the side of the magnetic steel. Because the decontamination ability of alcohol is weak, the dyne value only recovers to 32mN / m.

[0051] In summary, the method for increasing the side surface tension of saturated magnetized NdFeB magnets of the present invention is aimed at NdFeB magnets that have been saturated magnetized and whose surface tension value has significantly decreased after long-term storage. The method adopts a plasma cleaning method, uses oxygen as a plasma generating gas, and excites an electric field with a power of 150 to 200 W, so that the oxygen is broken down and plasmaized and plasma is generated through glow discharge, so that the magnetic steel strips in the reaction chamber of the plasma cleaning machine are covered by oxygen plasma and cleaned. The oxygen plasma reacts chemically with the exposed surface (side, i.e., adhesive surface) of the NdFeB magnet to remove organic matter, pollutants and other impurities on the surface of the NdFeB magnet, thereby increasing the surface tension of the side of the NdFeB magnet, increasing its wettability to polar solvents, and improving adhesion and hydrophilicity.

[0052] Since the currently available methods for increasing the surface tension of NdFeB magnets, such as post-treatment agent cleaning and adjustment of plating solution brightener, are all for unmagnetized NdFeB magnets, they are not applicable to NdFeB magnets that have been saturated and magnetized and adsorbed into strips. The method for improving the side surface tension of saturated magnetized NdFeB magnets of the present invention is to improve the problem of decreased surface tension of saturated magnetized NdFeB magnets after long-term storage, thereby reducing the adhesive mechanics, and provides a new idea and a new improvement plan. It can be used as an effective treatment measure for NdFeB magnet suppliers or downstream customers who need to prepare in advance but dare not store for a long time. It is supplemented by wrapping with snow pear paper to avoid direct contact between the surface of the NdFeB magnet and the vacuum bag, effectively isolating the penetration and migration of organic matter in the vacuum bag, thereby delaying the attenuation of dyne. Even after 46 days of placement, the side dyne value is still maintained at 34-36mN / m. By using argon plasma treatment, the dyne value is only increased to 36mN / m after cleaning, and the dyne value drops to 34mN / m after 10 days of placement. After 17 days of placement, the dyne value is only 32mN / m. Figure 7 Therefore, the present invention adopts the method of oxygen plasma treatment, and the surface tension retention time of more than 30 days is enough to cover the time from product transportation to downstream customer assembly, thereby meeting the adhesive performance of NdFeB magnets, and has broad application prospects and significant effects.

Claims

1. A method for increasing the surface tension of the side of a saturated magnetized NdFeB magnet, characterized in that First, the side surfaces of saturated magnetized NdFeB magnets whose side surface tension values ​​are detected to be lower than 30mN / m after being stored for a period of time are subjected to plasma cleaning treatment. Then, the saturated magnetized NdFeB magnets after the plasma cleaning treatment are assembled into a saturated magnetized NdFeB magnet group according to a preset number. Then, the saturated magnetized NdFeB magnet group is first wrapped with snow pear paper and then vacuum-packed with a vacuum packaging bag. In the plasma cleaning treatment, oxygen is used as the plasma generator.

2. The method for increasing the surface tension of the side of a saturated magnetized NdFeB magnet according to claim 1, characterized in that The specific process of plasma cleaning the side of saturated magnetized NdFeB magnets with a side surface tension value of less than 30mN / m after being stored for a period of time is as follows: Step S1, using multiple pieces of saturated magnetized NdFeB magnets to sequentially adsorb and splice to form magnetic steel strips, the side of each piece of saturated magnetized NdFeB magnet is exposed, the height direction of each magnetic steel strip is along the splicing direction of the saturated magnetized NdFeB magnet, the multiple magnetic steel strips are spaced and adsorbed on an iron plate, wherein the thickness of the iron plate is 2 to 5 mm, the height direction of each magnetic steel strip is perpendicular to the iron plate and less than 100 mm, and the interval between any two adjacent magnetic steel strips is 20 to 30 mm; Step S2, placing the iron plate and the magnetic steel strip adsorbed thereon as a whole on a preset bracket in a reaction chamber of the plasma cleaning machine, and closing the reaction chamber door of the plasma cleaning machine; Step S3, starting the vacuum pump to evacuate the reaction chamber of the plasma cleaning machine until the vacuum degree of the reaction chamber of the plasma cleaning machine is evacuated to below 0.2 MPa; Step S4, introducing oxygen (O2) as a plasma generator into the reaction chamber of the plasma cleaning machine, the oxygen flow rate is 1 to 10 liters / minute, the introduction time is 1 to 3 minutes, the gas excitation power of the plasma cleaning machine is set to 150 to 200W, and the plasma cleaning machine is turned on to perform plasma cleaning operation on the side of the saturated magnetized NdFeB magnet, and the plasma cleaning operation time is 2 to 5 minutes; Step S5, after the plasma cleaning operation is completed, turn off the plasma cleaning machine, fill nitrogen into the reaction chamber of the plasma cleaning machine until the pressure in the reaction chamber of the plasma cleaning machine is equal to atmospheric pressure, then wait for the reaction chamber of the plasma cleaning machine to cool to room temperature, open the reaction chamber door of the plasma cleaning machine, and take out the iron plate and the magnetic steel strip adsorbed thereon.

3. The method for increasing the surface tension of the side of saturated magnetized NdFeB magnet according to claim 2, characterized in that Each magnetic steel bar is formed by splicing 30 to 50 pieces of saturated magnetized NdFeB magnets.

4. The method for increasing the surface tension of the side of a saturated magnetized NdFeB magnet according to claim 1, characterized in that The vacuum packaging bag is a PE bag.

5. The method for increasing the surface tension of the side of saturated magnetized NdFeB magnet according to claim 1, characterized in that The saturated magnetized NdFeB magnet is a square nickel-plated magnet with the adhesive surface as the side and not the polar adsorption surface.

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