Method for preparing aluminum oxide coating on neodymium iron boron surface for new energy automobile motor

Abstract

The invention discloses a method for preparing an aluminum oxide coating on the surface of neodymium iron boron for a new energy automobile motor, which comprises the following steps: (1) pretreating the surface of a base material: firstly, carrying out corner passivation, degreasing, sand blasting and other pretreatments on a neodymium iron boron magnet, cleaning the surface of the neodymium iron boron magnet by using compressed air after the sand blasting pretreatment is completed, and drying the surface of the neodymium iron boron magnet; removing loose neodymium-iron-boron particles or sand grains on the surface of the neodymium-iron-boron magnet; (2) preheating treatment: respectively preheating the neodymium iron boron magnet and the powder; (3) plasma spraying: coating the surface of the neodymium-iron-boron magnet with the powder by adopting a plasma spraying technology; and (4) hole sealing is conducted, specifically, the sprayed neodymium-iron-boron magnet is soaked with hole sealing agent epoxy resin, redundant glue is wiped away with propyl alcohol, and the neodymium-iron-boron magnet is placed in a vacuum drying box to be dried. The aluminum oxide ceramic coating and the yttrium oxide ceramic coating prepared by the method have good coating uniformity, corrosion resistance, adhesive force and lower porosity.

Description

Technical Field

[0001] The present invention relates to the technical field of neodymium iron boron for new energy vehicle motors, and specifically relates to a method for preparing an alumina coating on the surface of neodymium iron boron for new energy vehicle motors. Background Technique

[0002] Neodymium iron boron is a tetragonal crystal formed by neodymium, iron, and boron (Nd2Fe14B); due to its own unique advantages, such as small volume, low mass, high coercivity, high magnetic energy product, high remanence density, etc., neodymium iron boron materials are favored in fields such as transportation, healthcare, electronic communication, geological exploration, metallurgical manufacturing, and aerospace.

[0003] Currently, there are mainly two ways to improve the corrosion resistance of neodymium iron boron materials: 1. Adding alloy elements; 2. Surface protection. However, the method of adding alloy elements has an insignificant improvement effect on the corrosion resistance of neodymium iron boron materials and will damage the original magnetism of the materials to a certain extent. The surface protection method mainly includes electroless plating, electroplating, physical vapor deposition, etc. The coatings formed by electroless plating and electroplating have unsatisfactory corrosion resistance, and the coating preparation process will cause environmental pollution. And physical vapor deposition technology has the defect of low film formation rate. Summary of the Invention

[0004] In order to solve the problem that the methods for improving the corrosion resistance of neodymium iron boron materials in the prior art have unsatisfactory effects, the present application provides a method for preparing an alumina coating on the surface of neodymium iron boron for new energy vehicle motors.

[0005] The present invention achieves the above object through the following technical solutions:

[0006] A method for preparing an alumina coating on the surface of neodymium iron boron for new energy vehicle motors, the steps include

[0007] (1) Substrate surface pretreatment: First, perform corner passivation, degreasing, sandblasting and other pretreatment on the neodymium iron boron magnet. After the sandblasting pretreatment is completed, use compressed air to clean the surface of the neodymium iron boron magnet to remove loose neodymium iron boron particles or sand grains on the surface of the neodymium iron boron magnet;

[0008] (2) Preheating treatment: Perform preheating treatment on the neodymium iron boron magnet and the powder respectively;

[0009] (3) Plasma spraying: Use plasma spraying technology to coat the powder on the surface of the neodymium iron boron magnet;

[0010] (4) Sealing: Immerse the sprayed neodymium iron boron magnet in the sealing agent epoxy resin, then wipe off the excess glue with propanol, and place it in a vacuum drying oven for drying;

[0011] (5) Grinding: Grind the surface coating of the sealed neodymium iron boron magnet;

[0012] (6) Secondary sealing: Immerse the NdFeB magnet after grinding treatment in the epoxy resin sealing agent, then wipe off the excess glue with propanol, and place it in a vacuum drying oven for drying.

[0013] A further improvement lies in that the powder is any one of alumina powder and yttrium oxide powder.

[0014] A further improvement lies in that the specific process of degreasing pretreatment of the NdFeB magnet is as follows: First, degrease the NdFeB magnet with a degreasing agent, wipe it dry, then immerse the NdFeB magnet in an acetone solution for ultrasonic cleaning, and use compressed air to blow dry the particles and liquid on the surface of the NdFeB magnet, and then put it into a vacuum drying oven at 60 °C for 24 h.

[0015] A further improvement lies in that the parameters of sandblasting pretreatment of the NdFeB magnet are as follows: The sand grains are #100 white corundum, the pressure of compressed dry air is 0.3 MPa, the gun distance is 300 mm, the speed of the robotic arm is 1000 mm / s, the sand output is 1600 g / s, and the sandblasting angle is 90 degrees.

[0016] A further improvement lies in that the specific process of preheating treatment of the yttrium oxide powder is as follows: Place the yttrium oxide powder in a vacuum drying oven at 60 °C for preheating for 12 hours.

[0017] A further improvement lies in that the specific process of preheating treatment of the NdFeB magnet is as follows: First, place the pretreated NdFeB magnet in a vacuum drying oven at 135 °C for preheating for 2 h, and then preheat it with a plasma flame for 3 times.

[0018] A further improvement lies in that in step (3), the yttrium oxide powder (content ≥ 99.9%) is used to spray the NdFeB magnet, the coating thickness is 120 - 150 um, and the spraying parameters are as follows: The flow rate of argon is 1.10 - 2.76 m3 / h, the flow rate of hydrogen is 0.24 - 0.60 m3 / h, the current is 800 A, the powder output is 10 - 15 g / min, and the gun distance is 100 - 200 mm.

[0019] A further improvement lies in that in step (4), the sprayed NdFeB magnet is immersed in the epoxy resin sealing agent at 30 °C for 8 h, the temperature of vacuum drying is 140 °C, and the drying time is 8 h.

[0020] A further improvement lies in that in step (5), the surface coating of the sealed NdFeB magnet needs to be ground to Ra less than 2 um, the coating thickness is ground to 120 um, the temperature of vacuum drying is 140 °C, and the drying time is 1 h.

[0021] A further improvement lies in that in step (6), the ground NdFeB magnet is immersed in a sealing agent epoxy resin at 30 °C for 8 hours, and the temperature for vacuum drying is 140 °C with a drying time of 8 hours.

[0022] The present invention also provides a graphene flexible heating material prepared by the above preparation method.

[0023] The beneficial effects of the present invention are as follows:

[0024] (1) The alumina ceramic coating and yttrium oxide ceramic coating prepared on the surface of NdFeB for new energy vehicle motors both have good coating uniformity, corrosion resistance, adhesion, and low porosity.

[0025] (2) The method for preparing a ceramic coating on the surface of NdFeB for new energy vehicle motors uses plasma spraying technology to prepare a ceramic coating on the surface of the NdFeB substrate, which can achieve rapid preparation of the coating on the surface of the NdFeB substrate without generating by-products and without polluting the environment. Specific embodiments

[0026] The following further describes the present application in detail with reference to embodiments. It is necessary to point out here that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0027] Example 1

[0028] A method for preparing an alumina coating on the surface of NdFeB for new energy vehicle motors, the steps include:

[0029] (1) Substrate surface pretreatment: First, perform corner passivation, degreasing, sandblasting, etc. on the NdFeB magnet. First, degrease the NdFeB magnet with a degreasing agent, dry it, then immerse the NdFeB magnet in an acetone solution for ultrasonic cleaning, use compressed air to blow dry the particles and liquid on the surface of the NdFeB magnet, and then put it into a vacuum drying oven at 60 °C for 24 hours. The abrasive grains used in the sandblasting process are #100 white corundum, the pressure of the compressed drying air is 0.3 MPa, the gun distance is 300 mm, the speed of the robotic arm is 1000 mm / s, the sand output is 1600 g / s, and the sandblasting angle is 90 degrees. After the sandblasting pretreatment is completed, use compressed air to clean the surface of the NdFeB magnet to remove the loose NdFeB particles or abrasive grains on the substrate surface.

[0030] (2) Preheating treatment: The alumina powder and the NdFeB substrate are respectively subjected to preheating treatment. The preheating treatment process of the alumina powder is as follows: Place the alumina powder in a vacuum drying oven at 60°C and preheat for 12 hours. The preheating treatment process of the NdFeB substrate is as follows: First, place the pretreated NdFeB substrate in a vacuum drying oven at 135°C and preheat for 2 hours, and then preheat it with a plasma flame three times.

[0031] (3) Plasma spraying: Use the plasma spraying technology to coat the alumina powder (content ≥ 99.9%) on the surface of the NdFeB magnet. The coating thickness is 120 μm. When spraying, the flow rate of argon is 2.76 m³ / h, the flow rate of hydrogen is 0.60 m³ / h, the spraying current is 800 A, the powder output is 10 g / min, and the gun distance is 100 mm.

[0032] (4) Sealing holes: Immerse the sprayed NdFeB magnet in the sealing agent epoxy resin at 30°C for 8 hours, then wipe off the excess glue with propanol, and place it in a vacuum drying oven at 140°C and dry for 8 hours.

[0033] (5) Grinding: Grind the surface coating of the sealed NdFeB magnet until Ra is less than 2 μm, and grind the coating thickness to 80 μm, and place it in a vacuum drying oven at 140°C and dry for 1 hour.

[0034] (6) Sealing holes: Immerse the ground NdFeB magnet in the sealing agent epoxy resin at 30°C for 8 hours, then wipe off the excess glue with propanol, and place it in a vacuum drying oven at 140°C and dry for 8 hours.

[0035] Example 2

[0036] A method for preparing an alumina coating on the surface of NdFeB for a new energy vehicle motor, the steps include:

[0037] (1) Substrate surface pretreatment: First, perform corner passivation, degreasing, sandblasting and other pretreatment on the NdFeB magnet. First, use a degreasing agent to degrease the NdFeB magnet, wipe it dry, then immerse the NdFeB magnet in an acetone solution for ultrasonic cleaning, use compressed air to blow dry the particles and liquid on the surface of the NdFeB magnet, and then put it into a vacuum drying oven at 60°C and dry for 24 hours. The abrasive grains used in the sandblasting process are #100 white corundum, the pressure of compressed dry air is 0.3 MPa, the gun distance is 300 mm, the speed of the robotic arm is 1000 mm / s, the abrasive output is 1600 g / s, and the sandblasting angle is 90 degrees. After the sandblasting pretreatment is completed, use compressed air to clean the surface of the NdFeB magnet to remove the loose NdFeB particles or abrasive grains on the substrate surface.

[0038] (2)Preheating treatment: The yttrium oxide powder and the NdFeB substrate are respectively subjected to preheating treatment. The preheating treatment process of the yttrium oxide powder is as follows: Place the yttrium oxide powder in a vacuum drying oven at 60°C and preheat for 12 hours. The preheating treatment process of the NdFeB substrate is as follows: First, place the pretreated NdFeB substrate in a vacuum drying oven at 135°C and preheat for 2 hours, and then preheat it with a plasma flame flow for 3 times.

[0039] (3)Plasma spraying: Use the plasma spraying technology to coat the yttrium oxide powder (content ≥ 99.9%) on the surface of the NdFeB magnet. The coating thickness is 150 μm. When spraying, the flow rate of argon is 1.10 m3 / h, the flow rate of hydrogen is 0.24 m3 / h, the spraying current is 800 A, the powder output is 15 g / min, and the gun distance is 200 mm.

[0040] (4)Sealing holes: Immerse the sprayed NdFeB magnet in the epoxy resin sealing agent at 30°C for 8 hours, then wipe off the excess glue with propanol, and place it in a vacuum drying oven at 140°C to dry for 8 hours.

[0041] (5)Grinding: Grind the surface coating of the sealed NdFeB magnet until Ra is less than 2 μm, and grind the coating thickness to 80 μm, and place it in a vacuum drying oven at 140°C to dry for 1 hour.

[0042] (6)Sealing holes: Immerse the ground NdFeB magnet in the epoxy resin sealing agent at 30°C for 8 hours, then wipe off the excess glue with propanol, and place it in a vacuum drying oven at 140°C to dry for 8 hours.

[0043] Prepare ceramic coating samples on the surface of NdFeB used in new energy vehicle motors respectively according to the methods of the above-mentioned Examples 1-2. The specifications of the NdFeB magnet used are 17.2 * 12.4 * 5.6 mm. Test the adhesion of the coating according to ASTM C633. The conditions of the neutral salt spray test are as follows: The temperature of the salt spray test chamber is 35 ± 2°C, the concentration of the sodium chloride solution is 50 ± 5 g / L, the pH is 6.5 - 7.2, and the continuous spraying method is adopted. The conditions of the PCT test are: 120 ± 2°C, 100% RH, and the absolute pressure is 0.1985 MPa. The performance test results are as follows in the table:

[0044] Group Coating Adhesion (MPa) Salt Spray Resistance Time (h) PCT Test Duration (h) Porosity (%) Coating Appearance Example 1 44.86 511 324 2.3 Smooth and Uniform Example 2 20.38 685 341 1.8 Smooth and Uniform

[0045] As can be seen from the above table, through the preparation methods in Examples 1-2 of the present invention, the alumina ceramic coating and the yttrium oxide ceramic coating prepared on the surface of NdFeB used in new energy vehicle motors both have good coating uniformity, corrosion resistance, adhesion and low porosity.

[0046] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention.

Claims

1. A method for preparing an aluminum oxide coating on the surface of NdFeB for new energy vehicle motors, characterized in that: Steps include (1) Substrate surface pretreatment: First, the NdFeB magnets are pretreated by edge passivation, degreasing, sandblasting, etc. After the sandblasting pretreatment is completed, the surface of the NdFeB magnets is cleaned with compressed air to remove the loose NdFeB particles or sand on the surface of the NdFeB magnets; (2) Preheating treatment: preheating the NdFeB magnet and powder respectively; (3) Plasma spraying: Plasma spraying technology is used to coat the powder on the surface of NdFeB magnets; (4) Sealing: Soak the sprayed NdFeB magnet with epoxy resin as a sealing agent, then wipe off the excess glue with propanol and place it in a vacuum drying oven for drying; (5) Grinding: Grinding the surface coating of the NdFeB magnet after sealing; (6) Secondary sealing: Soak the ground NdFeB magnet in epoxy resin, then wipe off the excess glue with propanol and place it in a vacuum drying oven for drying.

2. The method for preparing an aluminum oxide coating on the surface of NdFeB for new energy vehicle motors according to claim 1, characterized in that: The powder is any one of aluminum oxide powder and yttrium oxide powder.

3. The method for preparing an aluminum oxide coating on the surface of NdFeB for new energy vehicle motors according to claim 1, characterized in that: The specific process of degreasing pretreatment of the NdFeB magnet is as follows: first, the NdFeB magnet is degreased using a degreasing agent, and then the NdFeB magnet is immersed in an acetone solution for ultrasonic cleaning after being wiped dry, and the particles and liquid on the surface of the NdFeB magnet are blown dry with compressed air, and then placed in a vacuum drying oven at 60°C for 24 hours.

4. The method for preparing an aluminum oxide coating on the surface of NdFeB for new energy vehicle motors according to claim 1, characterized in that: The parameters for sandblasting pretreatment of the NdFeB magnet are: the sand is #100 white corundum, the compressed dry air pressure is 0.3 MPa, the gun distance is 300 mm, the robot arm speed is 1000 mm / s, the sand output is 1600 g / s, and the sandblasting angle is 90 degrees.

5. The method for preparing an aluminum oxide coating on the surface of NdFeB for new energy vehicle motors according to claim 1, characterized in that: The specific process of the yttrium oxide powder preheating treatment is: placing the yttrium oxide powder in a 60° C. vacuum drying oven for preheating for 12 hours.

6. The method for preparing an aluminum oxide coating on the surface of NdFeB for new energy vehicle motors according to claim 1, characterized in that: The specific process of the preheating treatment of the NdFeB magnet is: firstly, the pretreated NdFeB magnet is placed in a 135° C. vacuum drying oven for preheating for 2 hours, and then preheated by plasma flame flow for 3 times.

7. The method for preparing an aluminum oxide coating on the surface of NdFeB for new energy vehicle motors according to claim 1, characterized in that: The yttrium oxide powder (content ≥ 99.9%) used in step (3) is sprayed on the NdFeB magnet, and the coating thickness is 120-150um. The spraying parameters are: argon flow rate is 1.10-2.76m3 / h, hydrogen flow rate is 0.24-0.60m3 / h, current is 800A, powder output is 10-15g / min, and gun distance is 100-200mm.

8. The method for preparing an aluminum oxide coating on the surface of NdFeB for new energy vehicle motors according to claim 1, characterized in that: In step (4), the sprayed NdFeB magnet is immersed in a 30°C sealing agent epoxy resin for 8 hours, and the vacuum drying temperature is 140°C for 8 hours.

9. The method for preparing an aluminum oxide coating on the surface of NdFeB for new energy vehicle motors according to claim 1, characterized in that: In step (5), the surface coating of the sealed NdFeB magnet needs to be ground to Ra less than 2um, the coating thickness is ground to 120um, the vacuum drying temperature is 140°C, and the drying time is 1h.

10. The method for preparing an aluminum oxide coating on the surface of NdFeB for new energy vehicle motors according to claim 1, characterized in that: In step (6), the ground NdFeB magnet is immersed in a 30°C sealing agent epoxy resin for 8 hours, and the vacuum drying temperature is 140°C for 8 hours.