Method for manufacturing NdFeB rare earth permanent magnetic device with composite plating

Abstract

A method for manufacturing a NdFeB rare earth permanent magnetic device with composite plating includes steps of: firstly melting alloy, casting the alloy in a melted state onto a rotation copper roller with a water cooling function, so as to be cooled for forming alloy flakes; hydrogen decrepitating; mixing after hydrogen decrepitating; jet milling after mixing; mixing under nitrogen protection before molding in a nitrogen protection magnetic field pressing machine, and then packing in a protection tank before being moved out of the protection tank and isostatic pressing; sintering in a sintering device and aging for forming a NdFeB rare earth permanent magnet; machining for forming a NdFeB rare earth permanent magnetic device; and plating the NdFeB rare earth permanent magnetic device, wherein three layers of plated films are formed.

Claims

1. A method for manufacturing a NdFeB rare earth permanent magnetic device with composite plating, comprising steps of: firstly melting alloy, casting the alloy in a melted state onto a rotation copper roller with a water cooling function, so as to be cooled for forming alloy flakes; secondly hydrogen decrepitating the alloy flakes obtained in the step one; mixing hydrogen decrepitated flakes; jet milling mixed flakes; after jet milling, mixing milled flakes under nitrogen protection before molding in a nitrogen protection magnetic field pressing machine, and then packing in a protection tank before being moved out of the protection tank and isostatic pressing; after isostatic pressing, sintering and aging pressed flakes for forming a NdFeB rare earth permanent magnet; machining the NdFeB rare earth permanent magnet for forming a NdFeB rare earth permanent magnetic device; and processing the NdFeB rare earth permanent magnetic device in a vacuum chamber with a composite plating of magnetron sputtering coating and multi-arc ion plating, wherein three layers of plated films are formed; a first layer is a first magnetron sputtering coated film with a thickness of 0.02-5 m; a second layer is a composite plated film formed by magnetron sputtering coating and multi-arc ion plating, with a thickness of 1-10 m; and a third layer is a second magnetron sputtering coated film with a thickness of 0.1-5 m.

2. The method, as recited in claim 1, wherein a heater is arranged in the vacuum chamber, a heating temperature of the heater is 30-600 C.

3. The method, as recited in claim 1, further comprising a step of: after the composite plating, processing the NdFeB rare earth permanent magnetic device with heat treatment, wherein a heat treatment temperature is 60-900 C.

4. The method, as recited in claim 1, wherein an anode layer linear ion source is arranged in the vacuum chamber, a composite plating condition for processing the NdFeB rare earth permanent magnetic device is: a temperature of 30-600 C., a deposition pressure of 0.1-1 Pa under an argon condition; a power density of 1-20 w/cm.sup.2, a linear ion source working condition is, a discharge voltage of 100-3000V, an ion energy of 100-2000 eV, and a working pressure of 0.01-1 Pa under the argon condition, wherein during the composite plating, the magnetron sputtering coating and the multi-arc ion plating are utilized separately, alternatively or simultaneously.

5. The method, as recited in claim 1, wherein during the composite plating, argon and oxygen gas is inputted into the vacuum chamber, and an oxygen volume is 0.1-5% of an argon volume.

6. The method, as recited in claim 1, wherein the composite plating is physical vapor deposition; a magnetron sputtering coated film material is a material selected from a group consisting of Al, DyAl, TbAl, DyFe, TbFe, Ti, Mo, Si, stainless steel, Al.sub.2O.sub.3, ZrO.sub.2 and AZO; a material of the composite plated film formed by magnetron sputtering coating and multi-arc ion plating is selected from a group consisting of Al, Ti, Mo, Si, stainless steel, Al.sub.2O.sub.3, ZrO.sub.2, ITO and AZO.

7. The method, as recited in claim 1, further comprising steps of: blasting the NdFeB rare earth permanent magnetic device before composite plating, wherein a blasting material is selected from a group consisting of quartz, glass bead, aluminum oxide, cerium oxide, lanthanum oxide, a mixture of cerium oxide and lanthanum oxide, and zirconium oxide; and spraying the NdFeB rare earth permanent magnetic device before composite plating, wherein a spraying material is aluminum, an aluminum compound, or an electrophoresis paint.

8. The method, as recited in claim 1, wherein there are three layers of the plated films; the first layer is the first magnetron sputtering coated film, and a film material thereof is a material selected from a group consisting of Al, DyAl, TbAl, DyFe, and TbFe; the second layer is the composite plated film formed by magnetron sputtering coating and multi-arc ion plating, and a film material thereof is selected from a group consisting of Al, NiCr, Ti, Mo, Si, Al.sub.2O.sub.3, ZrO.sub.2, and AZO; and the third layer is the second magnetron sputtering coated film, and a film material thereof is selected from a group consisting of Al, NiCr, Ti, Mo, Si, Al.sub.2O.sub.3, ZrO.sub.2, and AZO.

9. The method, as recited in claim 1, wherein there are three layers of the plated films; the first layer is the first magnetron sputtering coated film, and a film material thereof is DyAl or TbAl; the second layer is the composite plated film formed by magnetron sputtering coating and multi-arc ion plating, and a film material thereof is selected from a group consisting of Al and NiCr; and the third layer is the second magnetron sputtering coated film, and a film material thereof is Al.

10. The method, as recited in claim 1, wherein in a range of 0-0.5 mm extending inwardly from an external surface of the NdFeB rare earth permanent magnetic device with the composite plating, a heavy rare earth content in a main phase grain within the range is higher than a heavy rare earth content in a main phase grain inside the NdFeB rare earth permanent magnetic device; heavy rare earth with a high content is distributed outside a main phase R.sub.2T.sub.14B, and forms a structure of RH.sub.2T.sub.14B surrounding R.sub.2T.sub.14B; a RH.sub.2T.sub.14B phase and a R.sub.2T.sub.14B phase have no grain boundary phase; wherein R refers to rare earth in a main phase of a metallographic structure of a NdFeB rare earth permanent magnet, T refers to Fe and Co, and RH refers to rare earth in the main phase comprising the heavy rare earth with a content higher than an average value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Referring to drawings, the present invention is further illustrated.

(2) FIG. 1 is a sketch view of vacuum plating according to a prior art.

(3) FIG. 2 is a sketch view of vacuum plating according to the present invention.

(4) Element reference: 1-vacuum chamber, 2-heating boat, 3-supporting platform, 4-heating boat supporter, 5-cylinder, 6-shaft, 7-supporting part, 8-axle, 9-aluminum wire, 10-feeding roller, 11-heat-resistance protection tube, 12-concave opening, 13-gear, 14-magnetic part, 15-horizontal vacuum shell, 16-anode layer linear ion source, 17-multi-arc ion source, 18-vacuum pump, 19-flat cathode magnetron target, 20-heating device, 21-first driving gear, 22-first driven gear, 23-second driving gear, 24-second driven gear, 25-rotation frame, 26-material tank, 27-permanent magnetic device, 28-cylinder cathode magnetron target, 29-first shaft, 30-second shaft, 31-evacuating pipeline.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(5) Referring to FIG. 2, the present invention provides a composite plating equipment combining magnetron sputtering coating and multi-arc ion plating, wherein a cylinder cathode magnetron target 28 is arranged at an axis of a horizontal vacuum shell 15 connected to a vacuum pump 18; a plurality of (eight as shown in FIG. 2) material tanks 26 formed by stainless steel nets are arranged on a periphery of a rotation frame 25; and a plurality of permanent magnetic devices 27 are arranged in every material tank 26. A motor (not shown) outside a vacuum chamber 1 is connected to a first driving gear 21 through a movable sealing transmitting shaft for driving a first driven gear 22 mounted on the rotation frame 25, in such a manner that the rotation frame 25 revolves around a first shaft 29. A second driving gear 23 mounted on the horizontal vacuum shell 15 drives a second driven gear 24 to rotate around a second shaft 30 through revolving to the rotation frame 25. Shafts are arranged at two ends of the material tank 26 for being connected to the second shaft 30, in such a manner that the material tank revolves while rotates for stirring the permanent magnetic devices 27 in the material tanks 26, so as to evenly deposit a target material thereon. An anode layer linear ion source 16, a plurality of multi-arc ion sources 17, an evacuating pipeline 31 connected to the vacuum pump 18, a plurality of flat cathode magnetron targets 19 and a heating device 20 are arranged outside the horizontal vacuum shell 15.

(6) Before plating, the vacuum chamber 1 is evacuated to an order of 10.sup.4 Pa, and is inputted with argon gas; a working pressure is 0.01-1 Pa. The material tank 26 revolves while rotates. The anode layer linear ion source 16 is started, a discharging voltage thereof is 100-3000V. Ions hit the permanent magnetic devices 27 for 5-10 min Every material tank 26 is insulated, or is powered with a voltage of 50-200V. Pre-cleaning with ion hitting is for cleaning oxide and carbon hydride on a surface of the permanent magnetic device 27, in such a manner that the surface is roughened, so as to improve effects of surface energy and ion assisted deposition. The heating device 20 heats the material tanks 26 and the permanent magnetic devices 27 to a temperature of 120-600 C., for removing moisture and improving film adhesion. During plating, a temperature is raised to 200 C., every material tank 26 revolves while rotates and is cleaned by high-pressure ions; the vacuum chamber 1 is evacuated again to the order of 10.sup.4 Pa, and is inputted with the argon gas; the working pressure is 0.1-1 Pa; the flat cathode magnetron targets 19, the cylinder cathode magnetron target 28 and the multi-arc ion sources 17 are started separately, alternatively or simultaneously, for depositing the target material on the permanent magnetic devices 27, so as to form layers of a elemental film and a dielectric film.

(7) The present invention is further illustrated with the following preferred embodiments.

Preferred Embodiment 1

(8) A method comprises steps of:

(9) 1) melting 600 Kg alloy selected from A1, A2, A3 and A4 in Table 1, casting the alloy in a melted state onto a rotation copper roller with a water cooling function, so as to be cooled for forming alloy flakes; hydrogen decrepitating; mixing after hydrogen decrepitating; jet milling after mixing; mixing under nitrogen protection before molding in a nitrogen protection magnetic field pressing machine, wherein an oxygen content in a protection tank is 150 ppm, an orientation magnetic field strength is 1.8 T, an in-chamber temperature is 2 C., a size of the magnet is 625242 mm, and an orientation direction is a 42 size direction; and then packing in the protection tank before being moved out of the protection tank and isostatic pressing with a pressure of 200 MPa, sintering in a sintering device and aging; and

(10) 2) after sintering, machining for forming a sheet with a size of 302010 mm; selectively processing the sheet with chamfer, blasting, aluminum spraying, electrophoresis and spraying; then providing vacuum plating, wherein a first layer is a first magnetron sputtering coated film, a second layer is a composite plated film formed by magnetron sputtering coating and multi-arc ion plating, and a third layer is a second magnetron sputtering coated film, wherein thicknesses thereof are respectively 0.02-5 m, 0.1-15 m and 1-5 m; wherein in some experiments, a fourth layer is formed, the fourth layer is a fourth magnetron sputtering coated film with a thickness of 0.1-5 m; if there are only three layers, then no elemental symbol is marked on the fourth layer; results of materials, magnetic performances and anti-corrosion ability of each layer are shown in Table 2.

(11) TABLE-US-00001 TABLE 1 components of rare earth permanent alloys in preferred embodiments and contrast example No. Component A1 Nd.sub.30Dy.sub.1Fe.sub.67.9B.sub.0.9A.sub.10.2 A2 Nd.sub.30Dy.sub.1Fe.sub.67.5Co.sub.1.2Cu.sub.0.1B.sub.0.9Al.sub.0.1 A3 (Pr.sub.0.2Nd.sub.0.8).sub.25Dy.sub.5Fe.sub.67.4Co.sub.1.2Cu.sub.0.3B.sub.0.9Al.sub.0.2 A4 (Pr.sub.0.2Nd.sub.0.8).sub.25Dy.sub.5Tb.sub.1Fe.sub.65Co.sub.2.4Cu.sub.0.3B.sub.0.9Al.sub.0.2Ga.sub.0.1Zr.sub.0.1

(12) TABLE-US-00002 TABLE 2 results of layer materials, magnetic performance and anti-corrosion abilities according to the present invention Neutral Magnetic salt Pre- First Second Third product Coercivity spray PCT No. No. treatment layer layer layer (MGOe) (KOe) (h) (h) 1 A1 chamfer Al Al + Al Al 47.9 17.7 210 85 2 A1 blasting Al Si + Al Al 48.3 18.9 220 90 3 A1 blasting ZrO.sub.2 Al + Ti Al 48.5 18.8 225 93 4 A1 blasting TbAl Al + Al Al 48.7 18.7 215 92 5 A2 blasting DyFe NiCr + NiCr 49.6 20.3 205 98 Al 6 A2 chamfer TbFe AZO + AZO 49.2 20.5 220 105 Al 7 A2 blasting DyAl Mo + Ti Mo 49.3 20.4 228 123 8 A2 chamfer DyAl AZO + AZO 49.1 20.6 217 112 Al 9 A3 blasting DyFe Mo + NiCr 41.7 25.8 224 135 NiCr 10 A3 chamfer DyFe NiCr + NiCr 41.4 25.4 216 120 NiCr 11 A3 chamfer Ti Ti + Al Ti 41.6 25.1 235 130 12 A3 chamfer NiCr NiCr + NiCr 41.3 25.2 222 102 Al 13 A4 blasting Mo Mo + Al Mo 42.6 26.9 234 103 14 A4 blasting Si Si + Al Si 43.1 27.5 196 86 15 A4 blasting AZO AZO + AZO 43.4 27.3 198 76 Al 16 A4 aluminum Al.sub.2O.sub.3 Al.sub.2O.sub.3 + Al.sub.2O.sub.3 42.8 26.8 213 83 spraying Al 17 A4 blasting ZrO.sub.2 ZrO.sub.2 + ZrO.sub.2 43.3 27.1 205 78 Al

Contrast Example 1

(13) Melting 600 Kg alloy selected from A1, A2, A3 and A4 in Table 1, casting the alloy in a melted state onto a rotation copper roller with a water cooling function, so as to be cooled for forming alloy flakes; coarsely decrepitating with a vacuum hydrogen decrepitating furnace; jet milling after decrepitating; mixing under nitrogen protection before molding in a nitrogen protection magnetic field pressing machine, wherein an orientation magnetic field strength is 1.8 T, a size of the magnet is 625242 mm, and an orientation direction is a 42 size direction; and then packing in the protection tank before being moved out of the protection tank and isostatic pressing with a pressure of 200 MPa; then sintering in a vacuum sintering device and aging; and machining for forming a sheet with a size of 302010 mm; selectively processing the sheet with chamfer and blasting; then providing NiCuNi electroplating, wherein results of magnetic performance and anti-corrosion ability are shown in Table 3.

(14) TABLE-US-00003 TABLE 3 results of magnetic performance and anti-corrosion ability in contrast example Neutral Magnetic salt Pre- First Second Third product Coercivity spray PCT No. No. treatment layer layer layer (MGOe) (KOe) (h) (h) 18 B1 blasting Ni Cu Ni 47.3 17.1 50 24 19 B2 blasting Ni Cu Ni 48.7 18.9 55 30 20 B3 chamfer Ni Cu Ni 40.1 23.6 60 35 21 B4 chamfer Ni Cu Ni 39.3 26.2 70 40

Preferred Embodiment 2

(15) The components in the preferred embodiment 1 are selected for manufacturing a NdFeB rare earth permanent magnetic device, wherein a first layer is made of a DyAl alloy, a second layer is made of A1+A1, and a third layer is made of A1. Results thereof are shown in Table 4. No. 1 is a contrast example without heating and heat treatment. Referring to Table 4, a plating temperature and a heat treatment temperature after plating have effects on the magnetic performance of the materials and significantly improve coercivity, which means that by increasing a working temperature of the magnets, heavy rare earth is less used at the same using temperature, which saves rare resources.

(16) TABLE-US-00004 TABLE 4 effects caused by plating temperature and heat treatment temperature on magnetic performance and anti-corrosion ability Heat Neutral Plating treatment Magnetic salt Pre- temperature temperature product Coercivity spray PCT No. No. treatment ( C.) ( C.) (MGOe) (KOe) (h) (h) 1 A1 chamfer 47.4 17.5 220 85 2 A1 blasting 100 810 48.5 19.9 230 95 3 A1 blasting 150 710 48.7 19.8 235 99 4 A1 blasting 200 610 48.9 19.7 225 94 5 A2 blasting 250 490 49.3 21.3 215 97 6 A2 chamfer 300 410 49.6 21.5 230 115 7 A2 blasting 350 360 49.5 21.4 229 133 8 A2 chamfer 400 310 49.7 21.6 227 122 9 A3 blasting 450 280 41.6 26.8 236 145 10 A3 chamfer 500 260 41.5 25.9 224 135 11 A3 chamfer 550 200 41.9 25.7 239 148 12 A3 chamfer 600 110 41.7 25.6 227 108 Note: 1) anti-corrosion ability (PCT experiment) Condition: sample10 10 10 mm, 2 atm, 120 C., 100% moisture, 48 h, weight loss less than 5 mg/cm.sup.2. 2) salt spray experiment: Condition: 5% NaCl solution, 25 C., no less than 48 h, no surface change.

(17) In the preferred embodiment 2, blasting is provided before vacuum plating, because: during manufacturing of the rare earth permanent magnetic device, oil and dirt are on a surface, which will greatly decrease stability of vacuum plating and the anti-corrosion ability of plated products. Therefore, reasonable cleaning device and technique are basic assurance of quality and performance of rare earth permanent device vacuum plating. Sufficient adhesion is only able to be guaranteed by the reasonable cleaning device. A blasting material is selected from a group consisting of quartz, glass bead, aluminum oxide, cerium oxide, lanthanum oxide, a mixture of cerium oxide and lanthanum oxide, and zirconium oxide; and spraying is provided before the composite plating, wherein a spraying material is aluminum, an aluminum compound, or an electrophoresis paint.

(18) In the preferred embodiment 2, high-pressure ion cleaning is provided during plating: wherein the vacuum chamber is evacuated to an order of 10.sup.4 Pa, and is inputted with argon gas; a working pressure is 0.01-1 Pa. The material tank revolves while rotates. The anode layer linear ion source is started, a discharging voltage thereof is 100-3000V. Ions hit the permanent magnetic devices for 5-10 min. The material tank is insulated, or is powered with a voltage of 50-200V.

(19) In the preferred embodiment 2, a plating configuration is as follows. A reasonable configuration comprises: a single and a double magnetron configuration (comprising flat and cylinder rotation magnetron cathode configurations), a multi-arc cathode configuration, an anode layer linear ion source, a heating device and a vacuum pump. Different plating configurations will lead to different production rates, ion energy, etc., and have a significant effect on plated product performance. The vacuum chamber is evacuated to an order more than 10.sup.4 Pa, and is inputted with the argon gas; a working pressure is 310.sup.1 Pa. The material tank revolves while rotates. Magnetron sputtering deposition and are evaporation deposition work separately, alternatively or simultaneously; magnetron sputtering deposition as well as arc evaporation deposition, and ion hitting work separately or alternatively.

(20) In the preferred embodiment 2, material feeding during the plating is as follows. A structure of the material tank has a great effect on appearance of the plated production and quality of the layers. Therefore, surface scratching and other physical damage should be avoided. The material tank is a cylinder or polygonal column made of stainless steel net. A plurality of isolated spaces are formed by isolating boards in the material tank, and no less than one permanent magnetic device is arranged in each space.

(21) In the preferred embodiment 2, after the composite plating, the heat treatment is provided, wherein a heat treatment temperature is 100-900 C.

(22) It is further illustrated by the preferred embodiments and the contrast example that significantly improving magnetic performance and anti-corrosion ability with the present invention has a brilliant future.

(23) One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting.

(24) It will thus be seen that the objects of the present invention have been fully and effectively accomplished. Its embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.