Potassium chloride cadmium-plated protective layer prepared on neodymium iron boron permanent magnet material

Abstract

The utility model provides a potassium chloride cadmium-plated protective layer prepared on a neodymium iron boron permanent magnet material. The potassium chloride cadmium-plated protective layer comprises a neodymium iron boron substrate, and a chemical nickel-plated layer, a potassium chloride cadmium-plated layer and a hexavalent chromium color passivation layer which are sequentially prepared on the neodymium iron boron substrate from inside to outside. According to the utility model, the potassium chloride cadmium-plated layer is prepared on the chemical nickel-plated layer, and the cadmium-plated layer has an electrochemical protection effect on the chemical nickel-plated layer; and the chemical nickel plating layer and the potassium chloride cadmium plating layer are prepared on the neodymium iron boron substrate, so that the corrosion resistance of the protective layer is remarkably improved.

Description

Technical Field

[0001] The utility model belongs to the field of metal electroplating, and in particular relates to a potassium chloride cadmium plating protective layer prepared on a neodymium iron boron permanent magnet material. Background Art

[0002] NdFeB material has high chemical activity, and there are many pores on the surface of sintered NdFeB matrix. During electroplating, the acidic or alkaline plating solution that penetrates into the pores on its surface will cause residual corrosion. [1] This is a difficulty faced by the electroplating of NdFeB materials. The traditional process uses the cyanide copper plating process to prepare a pre-copper layer on the surface of NdFeB, and then plate other coatings. The cyanide copper plating solution has excellent deep plating ability. The weakly alkaline cyanide copper plating solution is used for plating, which can better seal the pores on the surface of NdFeB. The plating solution remaining in the pores has weak corrosion on the NdFeB matrix, and the residual corrosion problem is very small, which will not damage the matrix and the coating. However, the high pollution problem of cyanide copper plating limits the use of this process. At present, citrate nickel plating is usually performed on the NdFeB matrix to prepare a pre-nickel layer, and then other coatings such as bright nickel are plated. However, the current coating structure does not have an electrochemical protective effect on the NdFeB matrix.

[0003] Aerospace companies have achieved good environmental and social benefits by using potassium chloride cadmium plating technology [2] There is no technical standard for cadmium plating on NdFeB in the electroplating industry, and there is no application case of cadmium plating on NdFeB. The potassium chloride cadmium plating layer has excellent corrosion resistance. Using potassium chloride cadmium plating process to prepare a protective layer on NdFeB workpieces is a new solution to effectively solve the problem of poor corrosion resistance of NdFeB plated parts.

[0004] References: [1] Li Hongying, Hao Zhuangzhi, Liu Yuhui, et al., Research progress on corrosion mechanism and surface protection technology of sintered NdFeB permanent magnet materials [J], Mining and Metallurgical Engineering, 2016, 36(6): 118-124. [2] Wang Daming, Guo Chongwu, Maintenance of potassium chloride cadmium plating process [J], Electroplating and Finishing, 2018, 37(23): 1099-1101. Utility Model Content

[0005] In order to solve the problem of poor corrosion resistance of the electroplated layer prepared on the NdFeB workpiece, the utility model provides a potassium chloride cadmium plating protective layer prepared on the NdFeB permanent magnet material. In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A potassium chloride cadmium plating protective layer prepared on a neodymium iron boron permanent magnet material comprises a neodymium iron boron substrate, and a chemical nickel plating layer, a potassium chloride cadmium plating layer, and a hexavalent chromium color passivation layer which are sequentially prepared from inside to outside on the neodymium iron boron substrate.

[0007] Preferably, the thickness of the chemical nickel plating layer is 3-5 μm.

[0008] Preferably, the thickness of the potassium chloride cadmium plating layer is 16 to 24 μm.

[0009] Preferably, the thickness of the hexavalent chromium color passivation layer is 0.3-0.6 μm.

[0010] There are many pores on the surface of NdFeB material, and a thicker cadmium plating layer is required to completely seal the pores.

[0011] Compared with the prior art, the utility model has the following beneficial effects:

[0012] 1. The potassium chloride cadmium plating protective layer prepared on the NdFeB permanent magnet material disclosed in the utility model prepares the potassium chloride cadmium plating layer on the chemical nickel plating layer, and the cadmium plating layer has an electrochemical protective effect on the chemical nickel plating layer;

[0013] 2. The utility model discloses a potassium chloride cadmium plating protective layer prepared on a NdFeB permanent magnet material, and a chemical nickel plating layer and a potassium chloride cadmium plating layer are prepared on a NdFeB substrate, which significantly improves the corrosion resistance of the protective layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of the present application, and do not constitute an improper limitation of the present invention. In the drawings:

[0015] Figure 1 It is a schematic diagram of the coating structure of Example 1 and Example 2 of the utility model. DETAILED DESCRIPTION

[0016] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The schematic embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0017] The technical solution includes sequentially performing pretreatment, chemical nickel plating, potassium chloride cadmium plating, and hexavalent chromium color passivation on a neodymium iron boron substrate.

[0018] The NdFeB workpiece is degreased, derusted, and activated according to the current pre-treatment process.

[0019] After pretreatment of the NdFeB workpiece, a chemical nickel plating layer is prepared using the current chemical nickel plating process.

[0020] Preferably, the thickness of the chemical nickel plating layer is 3-5 μm.

[0021] Preferably, the chemical pre-plated nickel layer is prepared by using the GG-158 alkaline chemical nickel plating process of Chaobang Chemical:

[0022] GG-158 A opening agent 140~160mL / L, GG-158 B supplement 90~110mL / L, GG-158 C supplement 90~110mL / L, operating temperature 40℃~45℃, plating solution pH 7.5~8.5.

[0023] After chemical nickel plating on the NdFeB workpiece, the potassium chloride cadmium plating layer is prepared using the PULIZIER NCC-617 potassium chloride cadmium plating process developed by Chaobang Chemical.

[0024] Preferably, the thickness of the potassium chloride cadmium plating layer is 16-24 μm.

[0025] Cadmium chloride 25-35g / L, potassium chloride 100-140g / L, PULIZIER NCC-617 AC complexing agent 100-140g / L, PULIZIER NCC-617 Base auxiliary agent 25-30mL / L, PULIZIER NCC-617 Bri brightener 1.5-2.5mL / L, PULIZIER NCC-617 HCD high zone brightener 8-12mL / L, plating tank temperature 20℃-35℃, plating solution pH 7-9, cathode current density 0.5-1.5A / dm 2 , the cathode moves 2 to 4 m / min.

[0026] The NdFeB workpiece was plated with cadmium in potassium chloride and then the hexavalent chromium colored passivation film was prepared by the current hexavalent chromium passivation process.

[0027] Preferably, the thickness of the hexavalent chromium color passivation layer is 0.3-0.6 μm.

[0028] Preferably, the hexavalent chromium color passivation layer is prepared using HC-5 high protection low chromium color passivation agent produced by Chaobang Chemical:

[0029] The volume concentration of HC-5 high protection low chrome color passivator is 2% to 4%, the passivation temperature is 20℃ to 35℃, the pH value of the passivation solution is 1.3 to 2.0, the passivation time is 5 to 20s, and weak air stirring or workpiece swing is used.

[0030] After passivation, the NdFeB workpiece is dried at 60℃~65℃ for 10~15min. Example 1

[0031] like Figure 1 As shown, a potassium chloride cadmium plating protective layer prepared on a NdFeB permanent magnet material comprises a NdFeB substrate 1, and a chemical nickel plating layer 2, a potassium chloride cadmium plating layer 3, and a hexavalent chromium color passivation layer 4 sequentially prepared on the NdFeB substrate 1 from the inside to the outside.

[0032] 1. Pre-treatment:

[0033] The NdFeB substrate 1 is subjected to the current pre-treatment process of "chemical degreasing → water washing → sulfuric acid pickling → water washing → ultrasonic degreasing → water washing → lactic acid activation → water washing".

[0034] 2. Chemical nickel plating:

[0035] After pretreatment of the NdFeB workpiece, a chemical nickel plating layer 2 is prepared by using the GG-178 alkaline chemical nickel plating process of Chaobang Chemical, and the coating thickness is 4 μm.

[0036] GG-178 A additive 42mL / L, GG-178 B reducing agent 32mL / L, GG-178 C stabilizer 45mL / L, operating temperature 45℃, plating solution pH 7.6.

[0037] 3. Potassium chloride cadmium plating:

[0038] After the NdFeB workpiece is electrolessly nickel-plated, the potassium chloride cadmium plating layer 3 is prepared using the PULIZIER NCC-617 potassium chloride cadmium plating process developed by Chaobang Chemical, and the coating thickness is 20 μm.

[0039] Cadmium chloride 27g / L, potassium chloride 110g / L, PULIZIER NCC-617 AC complexing agent 110g / L, PULIZIERNCC-617 Base auxiliary agent 28mL / L, PULIZIER NCC-617 Bri brightener 2.0mL / L, PULIZIER NCC-617HCD high zone brightener 10mL / L, plating tank temperature 30℃, plating solution pH 8, cathode current density 1.0A / dm 2 , cathode moves 3m / min.

[0040] 4. Passivation:

[0041] After the NdFeB workpiece was plated with potassium chloride and cadmium, the hexavalent chromium color passivation layer 4 was prepared using the HC-5 high-protection low-chromium color passivator produced by Chaobang Chemical. The thickness of the passivation layer was 0.5 μm.

[0042] The volume concentration of HC-5 high protection low chrome color passivator is 3.5%, the passivation temperature is 25℃, the pH of the passivation solution is 1.5, the passivation time is 10s, and the workpiece is swinging.

[0043] 5. Drying:

[0044] After passivation, the NdFeB workpiece was dried at 60°C for 15 minutes. Example 2

[0045] like Figure 1As shown, a potassium chloride cadmium plating protective layer prepared on a NdFeB permanent magnet material comprises a NdFeB substrate 1, and a chemical nickel plating layer 2, a potassium chloride cadmium plating layer 3, and a hexavalent chromium color passivation layer 4 sequentially prepared on the NdFeB substrate 1 from the inside to the outside.

[0046] 1. Pre-treatment:

[0047] The NdFeB substrate 1 is subjected to the current pre-treatment process of "chemical degreasing → water washing → sulfuric acid pickling → water washing → ultrasonic degreasing → water washing → lactic acid activation → water washing".

[0048] 2. Chemical nickel plating:

[0049] After pretreatment of the NdFeB workpiece, a chemical nickel plating layer 2 is prepared by using the GG-158 alkaline chemical nickel plating process of Chaobang Chemical, and the coating thickness is 4 μm.

[0050] GG-158 A opener 150mL / L, GG-158 B supplement 100mL / L, GG-158 C supplement 100mL / L, operating temperature 45℃, plating solution pH 7.8.

[0051] 3. Potassium chloride cadmium plating:

[0052] After the NdFeB workpiece is electrolessly nickel-plated, the potassium chloride cadmium plating layer 3 is prepared using the PULIZIER NCC-617 potassium chloride cadmium plating process developed by Chaobang Chemical, and the coating thickness is 20 μm.

[0053] Cadmium chloride 33g / L, potassium chloride 130g / L, PULIZIER NCC-617 AC complexing agent 130g / L, PULIZIERNCC-617 Base auxiliary agent 28mL / L, PULIZIER NCC-617 Bri brightener 2.0mL / L, PULIZIER NCC-617HCD high zone brightener 8mL / L, plating tank temperature 28℃, plating solution pH 7.5, cathode current density 1.2A / dm 2 , cathode moves 3m / min.

[0054] 4. Passivation:

[0055] After the NdFeB workpiece was plated with potassium chloride and cadmium, the hexavalent chromium color passivation layer 4 was prepared using the HC-5 high-protection low-chromium color passivator produced by Chaobang Chemical. The thickness of the passivation layer was 0.5 μm.

[0056] The volume concentration of HC-5 high protection low chrome color passivator is 2.5%, the passivation temperature is 25℃, the pH of the passivation solution is 1.8, the passivation time is 7s, and the workpiece swings.

[0057] 5. Drying:

[0058] After passivation, the NdFeB workpiece was dried at 60°C for 15 minutes.

[0059] Test Example 1:

[0060] NdFeB KCl cadmium-plated samples were prepared according to the process of Example 1 and Example 2. According to GB / T 5270-2005 "Review of test methods for adhesion strength of electrodeposited and chemically deposited metal coatings on metal substrates", the samples were placed in a heating furnace and heated to 250°C for 30 minutes. They were taken out and suddenly cooled in water at room temperature. No bubbling or shedding occurred in the coating, and the prepared coating had good bonding strength.

[0061] Test Example 2:

[0062] According to the process of Example 1 and Example 2, NdFeB potassium chloride cadmium-plated samples were prepared, and the corrosion resistance was tested according to GB / T10125-2021 "Artificial atmosphere corrosion test salt spray test". The sample was subjected to a neutral salt spray test for 2000 hours and no white corrosion products were generated on its surface. The time for the prepared coating to not rust is more than 41 times the time for the nickel plating layer to rust after a neutral salt spray test of 48 hours as specified in GB / T 34491-2017 "Sintered NdFeB surface coating".

[0063] The technical solutions provided by the embodiments of the present utility model are described in detail above. The principles and implementation methods of the embodiments of the present utility model are described in detail in this article using specific examples. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present utility model. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present utility model, which all belong to the protection scope of the present utility model.

Claims

1. A potassium chloride cadmium plating protective layer prepared on a neodymium iron boron permanent magnet material, characterized in that: The invention comprises a neodymium iron boron substrate, and a chemical nickel plating layer, a potassium chloride cadmium plating layer, and a hexavalent chromium color passivation layer which are sequentially prepared from the inside to the outside on the neodymium iron boron substrate.

2. The potassium chloride cadmium plating protective layer prepared on the NdFeB permanent magnet material according to claim 1, characterized in that: The thickness of the chemical nickel plating layer is 3-5 μm.

3. The potassium chloride cadmium plating protective layer prepared on the NdFeB permanent magnet material according to claim 1, characterized in that: The thickness of the potassium chloride cadmium plating layer is 16-24 μm.

4. The potassium chloride cadmium plating protective layer prepared on the NdFeB permanent magnet material according to claim 1, characterized in that: The thickness of the hexavalent chromium color passivation layer is 0.3-0.6 μm.

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