Neodymium-iron-boron magnet with composite coating as well as preparation method and application of neodymium-iron-boron magnet

Abstract

The invention provides a neodymium-iron-boron magnet with a composite coating and a preparation method and application of the neodymium-iron-boron magnet with the composite coating, and the preparation method comprises the following steps: carrying out pretreatment on a neodymium-iron-boron substrate to obtain a pretreated neodymium-iron-boron substrate; sand blasting is not carried out in the pretreatment step; the pretreated neodymium iron boron substrate is subjected to first multi-arc ion plating treatment to prepare a first plating layer, and a first neodymium iron boron magnet is obtained; the first neodymium-iron-boron magnet is subjected to co-sputtering deposition coating treatment to prepare a second coating, the neodymium-iron-boron magnet with a composite coating is obtained, and co-sputtering deposition coating comprises co-deposition through second multi-arc ion plating treatment and magnetron sputtering treatment; according to the co-sputtering deposition coating, a multi-arc target material and a magnetron sputtering target material are specially arranged, so that the distribution uniformity and compactness of a second coating layer in the co-deposition process are improved, and the overall corrosion resistance requirement of the neodymium-iron-boron magnet is met.

Description

Technical Field

[0001] The invention relates to the technical field of NdFeB magnet coatings, and in particular to a NdFeB magnet with a composite coating, a preparation method and an application thereof. Background Art

[0002] NdFeB magnets are widely used in wind power, transportation, smart consumer electronics and other industries due to their excellent comprehensive magnetic properties. However, NdFeB magnets have poor chemical stability and are prone to oxidation during daily use. They are prone to severe electrochemical corrosion in a hot and humid environment, so surface treatment is required before application to improve the corrosion resistance of the magnets.

[0003] At present, conventional surface anti-corrosion treatment methods can be divided into: electroplating, chemical plating, chemical conversion film, electrophoresis and vacuum plating, etc., to obtain metal or alloy film layers, polymer coatings, chemical conversion film layers and composite coatings. Among them, vacuum plating technology is more environmentally friendly than other surface treatment methods and is widely used in NdFeB surface protection.

[0004] Commonly used vacuum plating methods include vacuum evaporation, magnetron sputtering and multi-arc ion plating, but the film layer formed by evaporation coating has poor bonding with the substrate, which is insufficient to improve the corrosion resistance of the magnet; magnetron sputtering coating has low production efficiency and is not suitable for low-cost mass production; multi-arc ion plating cannot meet the corrosion resistance requirements of NdFeB because the particles formed by multi-arc ion plating are relatively large.

[0005] Therefore, it is necessary to explore a simpler and more efficient film preparation technology that can meet the corrosion resistance requirements of NdFeB magnets. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a NdFeB magnet with a composite coating and a preparation method and application thereof. By combining the first multi-arc ion plating treatment with the co-sputtering deposition coating, the production efficiency of the coating can be significantly improved while ensuring the anti-corrosion performance of the composite coating, and the application prospect is broad.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a NdFeB magnet with a composite coating, wherein the composite coating is a first coating and a second coating sequentially arranged on the surface of the NdFeB magnet, and the preparation method comprises the following steps: a NdFeB substrate is pre-treated to obtain a pre-treated NdFeB substrate; no sandblasting is performed in the pre-treatment step; the pre-treated NdFeB substrate is subjected to a first multi-arc ion plating treatment to prepare a first coating to obtain a first NdFeB magnet; the first NdFeB magnet is subjected to a co-sputtering deposition coating treatment to prepare a second Co-sputtering deposition coating includes co-deposition by a second multi-arc ion plating process and a magnetron sputtering process; the co-sputtering deposition coating includes at least two groups of magnetron sputtering targets and at least one group of multi-arc targets; each group of multi-arc targets contains two multi-arc targets arranged opposite to each other, and each group of magnetron sputtering targets contains two magnetron sputtering targets arranged opposite to each other; wherein at least two groups of magnetron sputtering targets are arranged on both sides of the multi-arc target and are evenly distributed in an axisymmetric manner with the multi-arc target as the central axis.

[0009] As mentioned above, the film layer prepared by magnetron sputtering in the prior art has high density and excellent corrosion resistance, but the production efficiency is low and it is not suitable for low-cost mass production; the film layer prepared by multi-arc ion plating process has high production efficiency, but there are large particles in the prepared film layer, which cannot meet the corrosion resistance requirements of NdFeB magnets. In order to improve production efficiency, magnetron sputtering is first performed and then multi-arc ion plating, or multi-arc ion plating is first performed and then magnetron sputtering. There will be defects in the porous structure of the multi-arc ion plating layer, and if the sputtering speed needs to be increased, the thickness of the multi-arc ion plating needs to be increased, and the thickness of the magnetron sputtering is thinner, which will also lead to poor corrosion resistance of the composite coating.

[0010] In order to overcome the above-mentioned defects, the present invention creatively combines magnetron sputtering and multi-arc ion plating for co-sputtering deposition coating. By reasonably setting the position layout of the multi-arc target and the magnetron sputtering target, the alternating coordinated coating of large particles produced by multi-arc ion plating and small and medium particles of magnetron sputtering is achieved. This not only ensures the density of the coating, but also greatly reduces the coating time. Compared with the use of magnetron sputtering and co-sputtering deposition alone, the coating rate is increased by 60% to 70%, and the production efficiency is significantly improved.

[0011] However, the inventors found in the process of research that co-sputtering deposition coating by magnetron sputtering and multi-arc ion plating needs to be carried out on a surface with low roughness. Therefore, before co-sputtering deposition coating, the surface of the loose and porous NdFeB substrate is first primed and leveled by multi-arc ion plating to ensure the density of the underlying film layer; the layout of the target materials of multi-arc ion plating and magnetron sputtering is subsequently controlled, and preferably the film deposition rate of the two processes is adjusted to adjust the synchronous deposition of large particles and small particles. When the low-energy atoms of magnetron sputtering collide with the high-energy atoms of multi-arc ion sputtering, the energy of the two eventually tends to be unified, and the film formation rate and film density are the best. This process ensures the uniformity and density of the co-deposited film layer to meet the overall corrosion resistance requirements of the NdFeB magnet.

[0012] Moreover, although the co-sputtering deposition coating of the present invention has high requirements on the roughness of the substrate, since multi-arc ion plating is carried out before the co-sputtering deposition coating, and since the multi-arc ion plating has the characteristic of preferentially growing along the grooves, the inventors found that even if sandblasting is not performed in the pre-treatment step, a high-density coating can be obtained subsequently, and one step can be omitted in the production process, further improving production efficiency.

[0013] Preferably, the pre-treatment includes grinding, chamfering and pickling performed in sequence.

[0014] Preferably, the abrasive for grinding and chamfering includes any one of triangular abrasive, trapezoidal abrasive or circular abrasive, or a combination of at least two of them, wherein a typical but non-limiting combination is a combination of triangular abrasive and trapezoidal abrasive, a combination of circular abrasive and trapezoidal abrasive, and a combination of triangular abrasive and circular abrasive.

[0015] Preferably, the chamfering grinding time is 4 to 10 hours, for example, 4 hours, 4.7 hours, 5.4 hours, 6 hours, 6.7 hours, 7.4 hours, 8 hours, 8.7 hours, 9.4 hours or 10 hours, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0016] Preferably, the pickling acid comprises any one of hydrochloric acid, nitric acid or sulfuric acid or a combination of at least two thereof, wherein typical but non-limiting combinations are a combination of hydrochloric acid and nitric acid, a combination of sulfuric acid and nitric acid, and a combination of hydrochloric acid and sulfuric acid.

[0017] Preferably, the pickling time is 10 to 120 s, for example, 10 s, 23 s, 35 s, 47 s, 59 s, 72 s, 84 s, 96 s, 108 s or 120 s, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0018] Preferably, before the first multi-arc ion plating treatment, the preparation method further comprises: the NdFeB substrate is first subjected to baking degassing and ion bombardment cleaning after the pre-treatment.

[0019] Preferably, the baking degassing temperature is 180-270°C, for example, it can be 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C or 270°C, but is not limited to the listed values, and other values ​​not listed in the range are equally applicable. The time is 30-50 min, for example, it can be 30 min, 33 min, 35 min, 37 min, 39 min, 42 min, 44 min, 46 min, 48 min or 50 min, but is not limited to the listed values, and other values ​​not listed in the range are equally applicable.

[0020] Preferably, the ion bombardment cleaning uses an inert gas.

[0021] Preferably, the inert gas in the ion bombardment cleaning is argon.

[0022] Preferably, the negative bias voltage of the ion bombardment cleaning is 1000-1500V, for example, it can be 1000V, 1056V, 1112V, 1167V, 1223V, 1278V, 1334V, 1389V, 1445V or 1500V, but is not limited to the listed values, and other values ​​not listed in the range are equally applicable. The cleaning time is 5-10min, for example, it can be 5min, 5.6min, 6.2min, 6.7min, 7.3min, 7.8min, 8.4min, 8.9min, 9.5min or 10min, but is not limited to the listed values, and other values ​​not listed in the range are equally applicable.

[0023] Preferably, the vacuum degree of the first multi-arc ion plating process is 6.5×10 -3 Pa~3×10 -3 Pa, for example, can be 6.5×10 -3 Pa, 6.0×10 -3 Pa, 5.5×10 -3 Pa, 5.0×10 -3 Pa, 4.5×10 -3 Pa, 4.0×10 -3 Pa, 3.5×10 -3 Pa or 3.0×10 -3 Pa, etc., but not limited to the listed values, other values ​​not listed in the range are also applicable.

[0024] Preferably, the target current in the first multi-arc ion plating process is 100-150A, for example, it can be 100A, 106A, 110A, 115A, 120A, 128A, 130A, 135A, 145A or 150A, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0025] Preferably, the number of groups of multi-arc targets in the first multi-arc ion plating process is 2 to 10 groups, for example, 2, 3, 4, 5, 6, 8 or 10 groups, etc., each group is 2 multi-arc targets arranged relatively.

[0026] Preferably, the coating time in the first multi-arc ion plating process is 5 to 10 minutes, for example, it can be 5 minutes, 5.6 minutes, 6.2 minutes, 6.7 minutes, 7.3 minutes, 7.8 minutes, 8.4 minutes, 8.9 minutes, 9.5 minutes or 10 minutes, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0027] Preferably, the coating rate in the first multi-arc ion plating process is 0.2-0.6 μm / min, for example, it can be 0.2 μm / min, 0.25 μm / min, 0.29 μm / min, 0.34 μm / min, 0.38 μm / min, 0.43 μm / min, 0.47 μm / min, 0.52 μm / min, 0.56 μm / min or 0.6 μm / min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0028] Preferably, the negative bias voltage of the first multi-arc ion plating is 50-200V, for example, it can be 50V, 67V, 84V, 100V, 117V, 134V, 150V, 167V, 184V or 200V, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0029] Preferably, the thickness of the first coating layer is 2 to 3 μm, for example, it can be 2 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm or 3 μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0030] Preferably, the surface roughness Ra of the first coating is 0.5-1.6 μm, for example, it can be 0.5 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm or 1.6 μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0031] Preferably, the material of the first coating layer includes titanium or aluminum alloy.

[0032] Preferably, the working atmosphere of the co-sputtering deposition coating process is argon.

[0033] Preferably, the working gas pressure of the co-sputtering deposition coating process is 0.1-0.5Pa, for example, it can be 0.1Pa, 0.12Pa, 0.13Pa, 0.14Pa, 0.15Pa, 0.2Pa, 0.22Pa, 0.25Pa, 0.3Pa, 0.35Pa, 0.4Pa, 0.45Pa or 0.5Pa, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0034] Preferably, the co-sputtering time of the co-sputtering deposition coating process is 1 to 2 hours, for example, it can be 1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0035] Preferably, the coating rate of the co-sputtering deposition coating process is 3 to 10 μm / h, for example, it can be 3 μm / h, 3.8 μm / h, 4.6 μm / h, 5.4 μm / h, 6.2 μm / h, 6.9 μm / h, 7.7 μm / h, 8.5 μm / h, 9.3 μm / h or 10 μm / h, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0036] Preferably, the number of multi-arc target groups for the co-sputtering deposition coating process is 2 to 10 groups, for example, it can be 2 groups, 3 groups, 4 groups, 5 groups, 6 groups, 8 groups or 10 groups.

[0037] Preferably, the number of magnetron sputtering target groups for the co-sputtering deposition coating process is 3 to 8 groups, for example, 3 groups, 4 groups, 5 groups, 6 groups, 7 groups or 8 groups.

[0038] Preferably, in the co-sputtering deposition coating process, each group of multi-arc targets are distributed on both sides of the vacuum chamber, the vacuum chamber is cylindrical, with the central axis of the cylinder as the axis of symmetry, the multi-arc targets are symmetrically distributed on the same circle, and the line connecting the multi-arc targets on both sides is the diameter of the cross-sectional circular surface of the cylinder.

[0039] Preferably, each group of multi-arc targets is arranged along the axial direction of the cylinder.

[0040] Preferably, the magnetron sputtering target is disposed inside the multi-arc target, and the magnetron sputtering target is arranged along a cylindrical circumference.

[0041] Preferably, in the cylinder, the magnetron sputtering targets are arranged in two circles, with the number of targets in each circle being 3 to 8, for example, 3, 4, 5, 6, 7 or 8.

[0042] Preferably, the distance between the magnetron sputtering target and the NdFeB substrate is 50 to 200 mm, for example, it can be 50 mm, 67 mm, 84 mm, 100 mm, 117 mm, 134 mm, 150 mm, 167 mm, 184 mm or 200 mm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0043] Preferably, the ratio of the distance L1 between the multi-arc target and the NdFeB substrate to the distance L2 between the magnetron sputtering target and the NdFeB substrate in the co-sputtering deposition coating process is 1 to 4:1, for example, it can be 1:1, 1.4:1, 1.7:1, 2:1, 2.4:1, 2.7:1, 3:1, 3.4:1, 3.7:1 or 4:1, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0044] Preferably, in the first multi-arc ion plating process, the distance between the multi-arc target and the NdFeB substrate is 150-320 mm, for example, it can be 150 mm, 169 mm, 188 mm, 207 mm, 226 mm, 245 mm, 264 mm, 283 mm, 302 mm or 320 mm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0045] Preferably, the targets of the first multi-arc ion plating process and the second multi-arc ion plating process are each independently a titanium target or an aluminum alloy target.

[0046] Preferably, the target purity of the titanium target is ≥99%, for example, it can be 99%, 99.2%, 99.3%, 99.4%, 99.5%, 99.8%, 99.9%, 99.992%, 99.995% or 99.999%, etc.

[0047] Preferably, the mass content of aluminum element in the aluminum alloy target is 70-90%, for example, it can be 70%, 73%, 75%, 77%, 79%, 82%, 84%, 86%, 88% or 90%, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0048] Preferably, the aluminum alloy target also includes doping elements.

[0049] Preferably, the doping elements in the aluminum alloy target include any one of Ti, Cr, Si or Mg or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of Ti and Cr, a combination of Si and Cr, a combination of Ti and Mg, and a combination of Mg and Cr.

[0050] Preferably, the material of the magnetron sputtering target in the co-sputtering deposition coating process is aluminum.

[0051] Preferably, the ratio of the working current of the multi-arc target to the working current of the magnetron sputtering target in the co-sputtering deposition coating process is (2-5):1, for example, it can be 2:1, 2.4:1, 2.7:1, 3:1, 3.4:1, 3.7:1, 4:1, 4.4:1, 4.7:1 or 5:1, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0052] After research, it was found that the present invention ensures that the deposition rates of multi-arc ion plating and magnetron sputtering coating are matched by controlling the matching of the working current intensity of the multi-arc target and the magnetron sputtering target, as well as the layout of the two target materials, thereby ensuring the overall density and uniformity of the film layer and meeting the corrosion resistance requirements of the film layer.

[0053] Preferably, the operating voltage of the second multi-arc ion plating process in the co-sputtering deposition coating process is 80-120V, for example, it can be 80V, 85V, 89V, 94V, 98V, 103V, 107V, 112V, 116V or 120V, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0054] Preferably, the thickness of the second coating is 5 to 10 μm, for example, 5 μm, 5.6 μm, 6.2 μm, 6.7 μm, 7.3 μm, 7.8 μm, 8.4 μm, 8.9 μm, 9.5 μm or 10 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0055] Preferably, the material of the second coating layer includes aluminum alloy, titanium aluminum alloy or aluminum.

[0056] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0057] The NdFeB substrate is ground and chamfered by abrasives for 4 to 10 hours and pickled by acid solution for 10 to 120 seconds to obtain a pre-treated NdFeB substrate; no sandblasting is performed in the pre-treatment step.

[0058] After pretreatment, the NdFeB substrate was first baked at 180-270℃ for 30-50min for degassing, and then placed in a vacuum coating chamber with argon gas introduced. The negative bias voltage was 1000-1500V and the vacuum degree was 6.5×10 -3 Pa~3×10 -3 Pa conditions for ion bombardment cleaning for 5 to 10 minutes to obtain a cleaned NdFeB substrate.

[0059] The cleaned NdFeB substrate is placed in a vacuum coating chamber, and 2 to 10 groups of multi-arc targets made of titanium or aluminum alloy targets are provided, each group of two multi-arc targets are arranged opposite to each other, and the distance between the multi-arc targets and the NdFeB substrate is 150 to 320 mm. -3 Pa~3×10 -3 The first multi-arc ion plating process is carried out for 5 to 10 minutes under the conditions of 0.2 to 0.6 μm / min, a target current of 100 to 150 A, a coating rate of 0.2 to 0.6 μm / min, and a negative bias of 50 to 200 V to prepare a first coating layer and obtain a first NdFeB magnet.

[0060] The first NdFeB magnet is subjected to a co-sputtering deposition coating treatment to prepare a second coating to obtain a NdFeB magnet with a composite coating, wherein the co-sputtering deposition coating includes co-deposition using a second multi-arc ion plating treatment and a magnetron sputtering treatment; wherein the ratio of the multi-arc target working current to the magnetron sputtering target working current is (2 to 5):1, and the negative voltage of the second multi-arc ion plating treatment in the co-sputtering deposition coating treatment is 80 to 120V.

[0061] The co-sputtering deposition coating includes at least two groups of magnetron sputtering targets and at least one group of multi-arc targets; each group of multi-arc targets contains two multi-arc targets arranged opposite to each other, and each group of magnetron sputtering targets contains two magnetron sputtering targets arranged opposite to each other; wherein at least two groups of magnetron sputtering targets are arranged on both sides of the multi-arc targets and are evenly distributed in an axisymmetric manner with the multi-arc targets as the central axis. The number of multi-arc target groups processed by the co-sputtering deposition coating is 2 to 10; the number of magnetron sputtering target groups processed by the co-sputtering deposition coating is 3 to 8.

[0062] In the co-sputtering deposition coating process, each group of multi-arc targets are distributed on both sides of the vacuum chamber. The vacuum chamber is cylindrical, with the central axis of the cylinder as the axis of symmetry. The multi-arc targets are symmetrically distributed on the same circumference, and the line connecting the multi-arc targets on both sides is the diameter of the cross-sectional circular surface of the cylinder.

[0063] Each group of multi-arc targets is arranged along the axial direction of the cylinder; the magnetron sputtering targets are arranged inside the multi-arc targets, and the magnetron sputtering targets are arranged along the circumference of the cylinder; inside the cylinder, the magnetron sputtering targets are arranged in two circles, with 3 to 8 targets in each circle.

[0064] The distance between the magnetron sputtering target and the NdFeB matrix is ​​50 to 200 mm; the ratio between the distance L1 between the multi-arc target and the NdFeB matrix in the co-sputtering deposition coating process and the distance L2 between the magnetron sputtering target and the NdFeB matrix is ​​1 to 4:1; the distance between the multi-arc target and the NdFeB matrix in the first multi-arc ion plating process is 150 to 320 mm.

[0065] In a second aspect, the present invention provides a NdFeB magnet with a composite coating, wherein the NdFeB magnet with a composite coating is prepared by the method for preparing a NdFeB magnet with a composite coating described in the first aspect.

[0066] The NdFeB magnet with a composite coating provided in the second aspect of the present invention has excellent corrosion resistance and broad application prospects.

[0067] Preferably, the NdFeB magnet with a composite coating has a tolerance time of ≥800 h in a neutral salt spray test, for example, 800 h, 805 h, 810 h, 815 h, 820 h, 825 h, 830 h, 835 h, 840 h, 845 h, 850 h, 860 h, 900 h, 920 h or 950 h.

[0068] Preferably, the bonding strength between the composite coating and the substrate in the NdFeB magnet with a composite coating is ≥23 MPa, for example, it can be 23 MPa, 23.5 MPa, 24 MPa, 24.5 MPa, 25 MPa, 26 MPa, 27 MPa, 28 MPa, 29 MPa, 30 MPa, 32 MPa or 35 MPa.

[0069] Preferably, the total thickness of the composite coating in the NdFeB magnet with a composite coating is 7 to 13 μm, for example, it can be 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm or 13 μm, etc.

[0070] In a third aspect, the present invention provides an application of the NdFeB magnet with a composite coating as described in the second aspect in wind power, transportation or smart consumer electronic products.

[0071] The NdFeB magnet with a composite coating provided in the second aspect of the present invention has excellent corrosion resistance, and the composite coating has excellent bonding strength with the substrate, and has excellent application prospects.

[0072] Compared with the prior art, the present invention has at least the following beneficial effects:

[0073] (1) The method for preparing a NdFeB magnet with a composite coating provided by the present invention forms a corrosion-resistant alloy film layer on the surface of the NdFeB magnet by vacuum plating. The process needs to ensure the bonding strength between the film layer and the substrate. The bonding strength between the composite coating and the substrate is ≥23MPa. The film layer has good corrosion resistance and can improve production efficiency. Compared with the time of depositing the aluminum alloy film layer by magnetron sputtering, the time is shortened by 60-70%;

[0074] (2) The preparation method of the NdFeB magnet with a composite coating provided by the present invention rationally arranges the multi-arc target and the magnetron sputtering target to ensure that large and small particles are evenly distributed during the coating process, the coating has high uniformity, and can improve the corrosion resistance of the entire film layer, wherein the weathering time of the neutral salt spray test is ≥500H;

[0075] (3) The method for preparing the NdFeB magnet with a composite coating provided by the present invention preferably matches the rate of aluminum alloy deposition in the process of preparing the aluminum alloy film layer by multi-arc ion plating and magnetron sputtering co-deposition through the adjustment of process parameters, thereby ensuring that the formed film layer is obtained by co-deposition of the two processes, thereby improving the overall uniformity and density of the film layer while ensuring the generation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 It is a front view of the layout of the multi-arc target and the magnetron sputtering target in step (4) of the method for preparing a NdFeB magnet with a composite coating provided in Example 1 of the present invention.

[0077] Figure 2 It is a top view of the layout of the multi-arc target and the magnetron sputtering target in step (4) of the method for preparing a NdFeB magnet with a composite coating provided in Example 1 of the present invention.

[0078] In the figure: 1-magnetron sputtering target; 2-hanger; 3-vacuum chamber; 4-multi-arc target. DETAILED DESCRIPTION

[0079] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0080] It should be understood that the terms "first", "second", etc. are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly indicate the number of technical features indicated. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0081] Example 1

[0082] This embodiment provides a method for preparing a NdFeB magnet with a composite coating, the method comprising the following steps:

[0083] (1) A NdFeB substrate (size: 18*15.6*10 mm) was ground and chamfered for 6 h and pickled for 60 s with 5 wt % dilute nitric acid to remove oil and rust, thereby obtaining a pre-treated NdFeB substrate; no sandblasting was performed in the pre-treatment step.

[0084] (2) After pretreatment, the NdFeB substrate is clamped on a hanger and placed in a vacuum chamber, and is baked and degassed at 210°C for 40 minutes. Then, argon gas is introduced and ion bombardment cleaning is performed for 5 minutes under a negative bias voltage of 1200 V to obtain a cleaned NdFeB substrate.

[0085] (3) The cleaned NdFeB substrate is placed in a vacuum coating chamber, and 5 groups of multi-arc targets made of aluminum alloy targets (aluminum content 85at%, titanium content 15at%) are set, each group of two multi-arc targets are set opposite to each other, and the distance between the multi-arc targets and the NdFeB substrate is 100mm. The background vacuum is 5×10 -3 The first multi-arc ion plating treatment was carried out for 10 min under the conditions of 140 Pa, 120 A target current, 0.3 μm / min coating rate and 80 V negative bias to prepare the first coating layer and obtain the first NdFeB magnet.

[0086] (4) The first NdFeB magnet is subjected to a co-sputtering deposition coating treatment to prepare a second coating, thereby obtaining a NdFeB magnet having a composite coating, wherein the co-sputtering deposition coating includes co-deposition for 1.5 hours using a second multi-arc ion plating treatment and a magnetron sputtering treatment; wherein the working atmosphere is argon, the working pressure is 0.3 Pa, the ratio of the working current of the multi-arc target to the working current of the magnetron sputtering target is 3.5:1, the working voltage of the second multi-arc ion plating treatment in the co-sputtering deposition coating treatment is 100 V, and the coating rate of the co-sputtering deposition coating treatment is 8 μm / h.

[0087] See also Figures 1-2 The co-sputtering deposition coating includes 8 groups of magnetron sputtering targets 1 (aluminum targets) and 6 groups of multi-arc targets 4 (aluminum-silicon targets, with an aluminum content of 90at% and a silicon content of 10at%); each group of multi-arc targets 4 contains 2 relatively arranged multi-arc targets 4, and each group of magnetron sputtering targets 1 contains 2 relatively arranged magnetron sputtering targets 1; at least two groups of magnetron sputtering targets 1 are arranged on both sides of the multi-arc target 4 and are evenly distributed in an axisymmetric manner with the multi-arc target 4 as the center axis.

[0088] In the co-sputtering deposition coating process, each group of multi-arc targets 4 are distributed on both sides of the vacuum chamber 3. The vacuum chamber 3 is cylindrical, with the central axis of the cylinder as the axis of symmetry. The multi-arc targets 4 are symmetrically distributed on the same circumference, and the connecting line of the multi-arc targets 4 on both sides is the diameter of the cross-sectional circular surface of the cylinder.

[0089] Each group of multi-arc target materials 4 is arranged along the axial direction of the cylinder; the magnetron sputtering target material 1 is arranged inside the multi-arc target material 4, and the magnetron sputtering target material 1 is arranged along the circumference of the cylinder; in the cylinder, the magnetron sputtering target material 1 is arranged in two circles, and the number of each circle is 8, that is, 4 groups.

[0090] The distance between the magnetron sputtering target 1 and the NdFeB matrix is ​​80 mm (inner circle) and 120 mm (outer circle), and is divided into inner circle and outer circle by the hanger 2; the ratio between the distance L1 between the multi-arc target 4 and the NdFeB matrix in the co-sputtering deposition coating process and the distance L2 between the magnetron sputtering target 1 and the NdFeB matrix is ​​1.875:1 and 1.25:1; the distance between the multi-arc target 4 and the NdFeB matrix in the first multi-arc ion plating process is 150 mm.

[0091] Example 2

[0092] This embodiment provides a method for preparing a NdFeB magnet with a composite coating, the method comprising the following steps:

[0093] (1) A NdFeB substrate (size: 18*15.6*10 mm) was ground and chamfered for 4 h with abrasive (trapezoidal abrasive) and pickled for 10 s with 5 wt % dilute nitric acid to remove oil and rust, thereby obtaining a pre-treated NdFeB substrate; no sandblasting was performed in the pre-treatment step.

[0094] (2) After pretreatment, the NdFeB substrate was first baked at 270°C for degassing for 30 minutes, then placed in a vacuum coating chamber, introduced with argon gas, and ion bombarded and cleaned for 10 minutes under a negative bias voltage of 1000 V to obtain a cleaned NdFeB substrate.

[0095] (3) The cleaned NdFeB substrate is placed in a vacuum coating chamber, and 6 groups of multi-arc targets made of aluminum alloy targets (aluminum content 80at%, titanium content 20at%) are set, each group of two multi-arc targets are set opposite to each other, and the distance between the multi-arc targets and the NdFeB substrate is 120 mm, and the background vacuum degree is 6.5×10 -3 The first multi-arc ion plating treatment was carried out for 10 minutes under the conditions of 0.2 μm / min, target current of 100 A, coating rate of 0.2 μm / min and working voltage of 120 V to prepare the first coating layer and obtain the first NdFeB magnet.

[0096] (4) The first NdFeB magnet is subjected to a co-sputtering deposition coating treatment to prepare a second coating, thereby obtaining a NdFeB magnet having a composite coating, wherein the co-sputtering deposition coating includes co-deposition for 1 hour using a second multi-arc ion plating treatment and a magnetron sputtering treatment; wherein the working atmosphere is argon, the working gas pressure is 0.1 Pa, the ratio of the working current of the multi-arc target to the working current of the magnetron sputtering target is 2:1, the working voltage of the second multi-arc ion plating treatment in the co-sputtering deposition coating treatment is 100 V, and the coating rate of the co-sputtering deposition coating treatment is 5 μm / h.

[0097] The co-sputtering deposition coating includes 8 groups of magnetron sputtering targets (aluminum targets) and 4 groups of multi-arc targets (aluminum-silicon targets, with an aluminum content of 80at% and a silicon content of 20at%); in the cylinder, the magnetron sputtering targets are arranged in two circles, with 12 targets in each circle, i.e., 6 groups.

[0098] The distance between the magnetron sputtering target and the NdFeB substrate is 50 mm (inner circle) and 100 mm (outer circle); the ratio between the distance L1 between the multi-arc target and the NdFeB substrate and the distance L2 between the magnetron sputtering target and the NdFeB substrate in the co-sputtering deposition coating process is 4:1 and 2:1; the distance between the multi-arc target and the NdFeB substrate in the first multi-arc ion plating process is 200 mm. The rest of the arrangement is the same as in Example 1.

[0099] Example 3

[0100] This embodiment provides a method for preparing a NdFeB magnet with a composite coating. The preparation method is the same as that of Embodiment 1 except that the ratio of the working current of the multi-arc target to the working current of the magnetron sputtering target is 5.5:1, and will not be described again.

[0101] Example 4

[0102] This embodiment provides a method for preparing a NdFeB magnet with a composite coating. The preparation method is the same as that of Embodiment 1 except that the ratio of the working current of the multi-arc target to the working current of the magnetron sputtering target is 1.5:1, and will not be described again.

[0103] Example 5

[0104] The present embodiment provides a method for preparing a NdFeB magnet with a composite coating. The preparation method is the same as Example 1 except that the distance L1 between the multi-arc target and the NdFeB substrate in the co-sputtering deposition coating process is 400 mm, that is, the ratios of L1 to the distance L2 between the magnetron sputtering target and the NdFeB substrate are 5:1 and 3.33:1, that is, 5:1 is higher. The rest is not repeated here.

[0105] Example 6

[0106] The present embodiment provides a method for preparing a NdFeB magnet with a composite coating. The preparation method is the same as that in Example 1, except that the distance L1 between the multi-arc target and the NdFeB substrate in the co-sputtering deposition coating process is 100 mm, that is, the ratios of L1 to the distance L2 between the magnetron sputtering target and the NdFeB substrate are 0.83:1 and 1.25:1, that is, 0.83:1 is on the low side. No further details are given here.

[0107] Example 7

[0108] The present embodiment provides a method for preparing a NdFeB magnet with a composite coating. The preparation method is the same as that in Example 1, except that the center angle between the two magnetron sputtering targets located on one side of the multi-arc target is different, that is, the center angle between the magnetron sputtering target close to the multi-arc target and the multi-arc target is recorded as A1, and the center angle between two adjacent magnetron sputtering targets is recorded as A2, wherein A1 is 15° and A2 is 25°. The details are not repeated here.

[0109] Comparative Example 1

[0110] This comparative example provides a method for preparing a NdFeB magnet with a composite coating. The method is the same as Example 1 except that step (3) is skipped and step (4) is performed directly. The details are not described here.

[0111] Comparative Example 2

[0112] This comparative example provides a method for preparing a NdFeB magnet with a composite coating. The preparation method is the same as Example 1 except that the multi-arc target is arranged on one side of the magnetron sputtering target in step (4), and will not be described again.

[0113] Test method:

[0114] 1) Salt spray test conditions: temperature 35±2℃, 50±5g / LNaCl, splash speed 1.5ml / 80cm 2 h, PH:7.0.

[0115] 2) Bonding strength test conditions: in accordance with GB / T8642-2002 Determination of tensile bonding strength of thermal spraying.

[0116] 3) Calculation of total average coating rate: The total average coating rate is the thickness of the final composite coating divided by the total coating time.

[0117] 4) Film thickness test: Use the mirror grinding method to test the film thickness. Observe the coating under a microscope and randomly select 6 points on the coating for testing. The average value of the 6-point coating thickness is the coating thickness value of the surface. The other surfaces are tested using this method. The final coating thickness value is the average value of the 6-surface coating thickness.

[0118] 5) Roughness test of the first coating: Use a roughness measuring instrument to measure the roughness of multiple groups (such as ten groups) at different sampling areas of the first coating to be tested and then calculate the average value.

[0119] The test results of the above embodiments and comparative examples are shown in Table 1.

[0120] Table 1

[0121]

[0122]

[0123] In Table 1, “ / ” indicates that there is no relevant data.

[0124] From Table 1, we can see the following points:

[0125] (1) It can be seen from Examples 1 to 2 that the method for preparing a NdFeB magnet with a composite coating provided by the present invention has the advantage of a fast total coating rate of more than 6.96 μm / H, and can achieve a technical effect of a salt spray resistance test of more than 576 H and a bonding strength of more than 31.86 MPa at such a high coating rate.

[0126] (2) It can be seen from Example 1 and Examples 3 to 4 that when the ratio of the working current of the multi-arc target to the working current of the magnetron sputtering target in Example 3 is too high, the salt spray resistance test capability is significantly reduced; when the ratio of the working current of the multi-arc target to the working current of the magnetron sputtering target in Example 4 is too low, the coating rate of the second coating layer is low, resulting in a significant decrease in the thickness of the second coating layer in the same time, and ultimately resulting in a significant decrease in the salt spray resistance test and the bonding strength. This shows that the present invention preferably controls the ratio of the working current of the multi-arc target to the working current of the magnetron sputtering target within a reasonable range, and can achieve excellent coating performance on the basis of a higher coating rate.

[0127] (3) It can be seen from Example 1 and Examples 5 to 7 that the present invention preferably arranges the positions of the multi-arc target and the magnetron sputtering target in a reasonable manner, which can better ensure the performance of the coating while improving the plating speed.

[0128] (4) In comparative example 1, step (3) is not performed, resulting in the bonding strength between the coating and the substrate being reduced to 23.67, and the salt spray resistance being significantly reduced. In comparative example 2, since the multi-arc target in step (4) is arranged on one side of the magnetron sputtering target, the coating thickness on the substrate surface is uneven. This indicates that the present invention, by combining magnetron sputtering with multi-arc target sputtering and preparing the first coating before co-sputtering deposition, can improve the coating rate while ensuring the salt spray resistance of the NdFeB substrate and the bonding strength between the substrate and the coating.

[0129] The present invention illustrates the detailed features of the present invention through the above embodiments, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvement to the present invention, equivalent replacement of the technical features selected by the present invention, addition of auxiliary technical features, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a NdFeB magnet with a composite coating, characterized in that: The composite coating is a first coating and a second coating sequentially disposed on the surface of the NdFeB magnet, and the preparation method comprises the following steps: The NdFeB matrix is ​​pre-treated to obtain a pre-treated NdFeB matrix; no sandblasting is performed in the pre-treatment step; The pre-treated NdFeB substrate is subjected to a first multi-arc ion plating treatment to prepare a first coating layer, thereby obtaining a first NdFeB magnet; The first NdFeB magnet is subjected to a co-sputtering deposition coating process to prepare a second coating layer, thereby obtaining a NdFeB magnet having a composite coating layer, wherein the co-sputtering deposition coating process includes co-sputtering deposition by a second multi-arc ion plating process and a magnetron sputtering process; The co-sputtering deposition coating includes at least two groups of magnetron sputtering targets and at least one group of multi-arc targets; Each group of multi-arc targets contains two multi-arc targets arranged opposite to each other, and each group of magnetron sputtering targets contains two magnetron sputtering targets arranged opposite to each other; at least two groups of magnetron sputtering targets are arranged on both sides of the multi-arc target and are evenly distributed in an axisymmetric manner with the multi-arc target as the central axis.

2. The preparation method according to claim 1, characterized in that: The pre-treatment includes grinding, chamfering and pickling performed in sequence; Preferably, the pickling acid comprises any one of hydrochloric acid, nitric acid or sulfuric acid, or a combination of at least two thereof; Preferably, the pickling time is 10 to 120 seconds.

3. The preparation method according to claim 1 or 2, characterized in that: Before the first multi-arc ion plating treatment, the preparation method further comprises: after the pre-treatment, the NdFeB substrate is first subjected to baking degassing and ion bombardment cleaning.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The vacuum degree of the first multi-arc ion plating process is 6.5×10 -3 Pa~3×10 -3 Pa; Preferably, the target current in the first multi-arc ion plating process is 100-150A; Preferably, the number of groups of multi-arc targets in the first multi-arc ion plating process is 2 to 10 groups, and each group is 2 multi-arc targets arranged opposite to each other; Preferably, the coating time in the first multi-arc ion plating process is 5 to 10 minutes; Preferably, the coating rate in the first multi-arc ion plating process is 0.2-0.6 μm / min; Preferably, the negative bias voltage of the substrate during the first multi-arc ion plating treatment is 50-200V; Preferably, the thickness of the first coating layer is 2-3 μm.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The working atmosphere of the co-sputtering deposition coating process is argon; Preferably, the working gas pressure of the co-sputtering deposition coating process is 0.1-0.5 Pa; Preferably, the co-sputtering time of the co-sputtering deposition coating process is 1 to 2 hours; Preferably, the coating rate of the co-sputtering deposition coating process is 3-10 μm / h.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The number of groups of multi-arc target materials for the co-sputtering deposition coating process is 2 to 10 groups; Preferably, the number of magnetron sputtering target groups for the co-sputtering deposition coating process is 3 to 8 groups; Preferably, in the co-sputtering deposition coating process, each group of multi-arc targets are distributed on both sides of the vacuum chamber, the vacuum chamber is cylindrical, the central axis of the cylinder is used as the symmetry axis, the multi-arc targets are symmetrically distributed on the same circumference, and the line connecting the multi-arc targets on both sides is the diameter of the cross-sectional circular surface of the cylinder; Preferably, each group of multi-arc targets is arranged along the axial direction of the cylinder; Preferably, the magnetron sputtering target is arranged inside the multi-arc target, and the magnetron sputtering target is arranged along the circumference of a cylinder; Preferably, in the cylindrical shape, the magnetron sputtering targets are arranged in two circles, with 3 to 8 targets in each circle; Preferably, the distance between the magnetron sputtering target and the NdFeB substrate is 50 to 200 mm; Preferably, in the co-sputtering deposition coating process, the ratio between the distance L1 between the multi-arc target and the NdFeB substrate and the distance L2 between the magnetron sputtering target and the NdFeB substrate is 1 to 4:1; Preferably, in the first multi-arc ion plating process, the distance between the multi-arc target and the NdFeB substrate is 150-320 mm.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The targets of the first multi-arc ion plating process and the second multi-arc ion plating process are each independently a titanium target or an aluminum alloy target; Preferably, the material of the magnetron sputtering target in the co-sputtering deposition coating process is aluminum.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The ratio of the working current of the multi-arc target material to the working current of the magnetron sputtering target material in the co-sputtering deposition coating process is (2-5):1; Preferably, the negative bias voltage of the second multi-arc ion plating in the co-sputtering deposition coating process is 80-120V; Preferably, the second coating layer has a thickness of 5-10 μm.

9. A NdFeB magnet with a composite coating, characterized in that: The NdFeB magnet with a composite coating is prepared by the method for preparing a NdFeB magnet with a composite coating as claimed in any one of claims 1 to 8.

10. Use of the NdFeB magnet with a composite coating as claimed in claim 9 in wind power, transportation or smart consumer electronic products.

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