Cyanide-free cadmium plating coating structure of neodymium iron boron workpiece
By preparing chemical pre-nickel plating, chemical nickel plating, cyanide-free cadmium plating, trivalent chromium passivation and graphene encapsulation layers on neodymium iron boron workpieces, the problems of poor corrosion resistance and high pollution of the electroplating layer of neodymium iron boron workpieces are solved, and high corrosion resistance and self-repairability are achieved, which is suitable for aerospace accessories.
Patent Information
- Application Number
- CN202421597334.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-08
- Publication Date
- 2025-07-22
- Estimated Expiration
- 2034-07-08
AI Technical Summary
The electroplating layer of neodymium iron boron workpieces has poor corrosion resistance, and the traditional cyanide copper plating process is seriously polluted. The existing cyanide cadmium plating process has not been used in neodymium iron boron. In addition, traditional passivation films have problems of high pollution and insufficient self-repairability.
The chemically pre-nickel layer, electroless nickel layer, cyano-free cadmium-plating layer, trivalent chromium black passivation film and graphene sealing layer were prepared in turn on the neodymium-ferrous boron matrix. The cyano-free cadmium-plating process and trivalent chromium passivation were used to replace hexavalent chromium passivation, and the cyano-free cadmium-plating layer was sealed with graphene modification sealing agent.
It prevents corrosive media from eroding the substrate, overcomes the problem of high pollution, improves the corrosion resistance and self-repairability of the coating, has good binding force and excellent corrosion resistance.
Smart Images
Figure CN223134593U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the field of metal electroplating, and particularly relates to a coating structure of cyanide-free cadmium plating on a neodymium iron boron workpiece. Background Art
[0002] The surface of the neodymium iron boron substrate has many pores, and the material itself has high chemical activity. There are residual corrosion problems with the acidic or alkaline plating solutions that penetrate into the pores on the surface of the neodymium iron boron material during electroplating [1] , resulting in easy appearance of rust spots on the surface of the plated parts. The traditional process uses a cyanide copper plating process to prepare a pre-plated copper layer on the surface of neodymium iron boron, and then other coatings are plated, such as copper + nickel or copper + nickel + chromium coatings. The cyanide copper plating solution has excellent throwing power. When plating with a weakly alkaline cyanide copper plating solution, it can better seal the pores on the surface of neodymium iron boron, and the plating solution remaining in the pores has very weak corrosiveness and will not damage the neodymium iron boron substrate and the coating. However, cyanide copper plating has high pollution problems, which limits the use of this process. At present, usually a citrate nickel plating is carried out on the neodymium iron boron substrate to prepare a pre-plated nickel layer, and then other coatings such as bright nickel are plated. However, the current such coating structure does not have an electrochemical protection effect on the neodymium iron boron substrate.
[0003] Aerospace enterprises have adopted a potassium chloride cyanide-free cadmium plating process to replace the highly toxic cyanide cadmium plating, achieving good environmental and social benefits [2] . In the electroplating industry, there are currently no application cases of cadmium plating on neodymium iron boron. The potassium chloride cyanide-free cadmium plating layer has excellent corrosion resistance. Preparing a potassium chloride cyanide-free cadmium plating layer on a neodymium iron boron workpiece can effectively solve the problem of poor corrosion resistance of neodymium iron boron plated parts.
[0004] References: [1], Li Hongying, Hao Zhuangzhi, Liu Yuhui, etc., Research progress on the 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 cyanide-free cadmium plating process [J], Electroplating & Finishing, 2018, 37(23): 1099-1101. Content of the Utility Model
[0005] In order to solve the problem of poor corrosion resistance of the electroplated layer prepared on aerospace neodymium iron boron workpieces, the utility model provides a coating structure of cyanide-free cadmium plating on neodymium iron boron workpieces. To achieve the above purpose, the utility model adopts the following technical solutions:
[0006] A coating structure of cyanide-free cadmium plating on a neodymium iron boron workpiece, including a neodymium iron boron substrate, and a chemical pre-plated nickel layer, an electroless nickel plating layer, a cyanide-free cadmium plating layer, a trivalent chromium black passivation film, and a graphene sealing layer sequentially prepared on the neodymium iron boron substrate from the inside to the outside.
[0007] Preferably, the thickness of the chemical pre-nickel plating layer is 1-2 μm.
[0008] Preferably, the thickness of the electroless nickel plating layer is 6-12 μm.
[0009] Preferably, the thickness of the cyanide-free cadmium plating layer is 8-16 μm.
[0010] Preferably, the thickness of the graphene sealing layer is 0.8-2.0 μm.
[0011] Compared with the prior art, the utility model has the following beneficial effects:
[0012] 1. The cyanide-free cadmium plating layer structure of the neodymium iron boron workpiece disclosed by the utility model prepares a cadmium plating layer on the electroless nickel plating layer. The cadmium plating layer is an anodic plating layer, and this plating layer structure can effectively prevent the erosion of corrosive media towards the substrate direction;
[0013] 2. The cyanide-free cadmium plating layer structure of the neodymium iron boron workpiece disclosed by the utility model uses trivalent chromium passivation to replace the traditional hexavalent chromium passivation, overcoming the high pollution problem of using hexavalent chromium;
[0014] 3. The cyanide-free cadmium plating layer structure of the neodymium iron boron workpiece disclosed by the utility model uses a hydroxyl graphene-modified plating layer sealant to seal the cyanide-free cadmium plating layer passivated by trivalent chromium black, overcoming the defect that the trivalent chromium passivation film does not have self-repairability. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The drawings described herein are used to provide a further understanding of the utility model, constitute a part of this application, and do not constitute an improper limitation of the utility model. In the drawings:
[0016] Figure 1 is a schematic diagram of the plating layer structure of Embodiment 1 and Embodiment 2 of the utility model. DETAILED DESCRIPTION OF THE INVENTION
[0017] The following will detail the utility model in conjunction with the drawings and specific embodiments. Here, the schematic embodiments and descriptions of the utility model are used to explain the utility model, but not to limit the utility model.
[0018] The plating layer structure of the cyanide-free cadmium plating of the neodymium iron boron workpiece prepared by the utility model has a preparation process flow including pre-treatment, chemical pre-nickel plating, electroless nickel plating, cyanide-free cadmium plating, trivalent chromium black passivation, and graphene-modified sealant sealing on the neodymium iron boron substrate in sequence.
[0019] The neodymium iron boron workpiece is ground, degreased, and activated according to the current pre-treatment process.
[0020] After the pre-treatment of the neodymium iron boron workpiece, a chemical pre-nickel plating layer is prepared by using the current low-temperature electroless nickel plating process.
[0021] Preferably, the thickness of the chemical pre-nickel plating layer is 1-2 μm.
[0022] Preferably, the chemical pre-nickel plating layer is prepared by using the GG-158 alkaline electroless nickel plating process of Superb Chemical:
[0023] GG-158 A starter 140-160 mL / L, GG-158 B replenisher 90-110 mL / L, GG-158 C replenisher 90-110 mL / L, operating temperature 30°C-45°C, bath pH value 7.5-8.5.
[0024] After chemical pre-nickel plating of the neodymium iron boron workpiece, an electroless nickel plating layer is prepared by using the current high-temperature electroless nickel plating process.
[0025] Preferably, the thickness of the electroless nickel plating layer is 6-12 μm.
[0026] Preferably, the electroless nickel plating layer is prepared by using the GG-166 high-phosphorus electroless nickel plating process of Superb Chemical:
[0027] GG-166 A additive 55-65 mL / L, GG-178 B reducing agent GG-166 B 170-190 mL / L, operating temperature 85°C-92°C, bath pH value 4.6-5.2.
[0028] After electroless nickel plating of the neodymium iron boron workpiece, a non-cyanide cadmium plating layer is prepared by using the current non-cyanide cadmium plating process.
[0029] Preferably, the thickness of the non-cyanide cadmium plating layer is 8-16 μm.
[0030] Preferably, the non-cyanide cadmium plating process is prepared by using the PULIZIER NCC-617 potassium chloride non-cyanide cadmium plating process developed by Superb Chemical:
[0031] Cadmium chloride 25-35 g / L, potassium chloride 100-140 g / L, PULIZIER NCC-617 AC complexing agent 100-140 g / L, PULIZIER NCC-617 Base auxiliary agent 25-30 mL / L, PULIZIER NCC-617 Bri brightener 1.5-2.5 mL / L, PULIZIER NCC-617 HCD high zone brightener 8-12 mL / L, bath temperature 20°C-35°C, bath pH value 7-9, cathode current density 0.5-1.5 A / dm 2 , cathode movement 2-4 m / min.
[0032] After non-cyanide cadmium plating of the neodymium iron boron workpiece, a trivalent chromium black passivation film is prepared by using the current trivalent chromium black passivation process.
[0033] Preferably, the trivalent chromium black passivation film is prepared by using TRIROS BP-886 trivalent chromium black passivating agent of Superbond Chemical Industry:
[0034] 40 - 80 mL / L of TRIROS BP-886 A agent, 30 - 70 mL / L of TRIROS BP-886 B agent, passivation temperature 20°C - 30°C, pH value of the passivation solution 2.3 - 2.7, passivation time 40 - 120 s.
[0035] After trivalent chromium black passivation of the neodymium iron boron workpiece, a graphene sealing layer is prepared by using the hydroxyl graphene modified sealing agent developed by Superbond Chemical Industry.
[0036] Preferably, the thickness of the graphene sealing layer is 0.8 - 2.2 μm.
[0037] Preferably, the graphene sealing layer is prepared by using PRODICO 480 graphene modified sealing agent developed by Superbond Chemical Industry:
[0038] The PRODICO 480 graphene modified sealing agent is diluted with water by 2.5 - 3.2 times to prepare a sealing solution. The workpiece is immersed in the sealing solution for 8 - 15 s, drained after leaving the tank, and the residual sealing solution on the surface of the workpiece is blown off with high-pressure air. After sealing, it is dried and cured at 70°C - 85°C for 20 - 30 min. Example 1
[0039] As Figure 1 shown, a coating structure of cyanide-free cadmium plating for neodymium iron boron workpiece includes a neodymium iron boron substrate 1, and a chemical pre-plated nickel layer 2, a chemical nickel plating layer 3, a cyanide-free cadmium plating layer 4, a trivalent chromium black passivation film 5, and a graphene sealing layer 6 prepared on the neodymium iron boron substrate 1 from inside to outside in sequence.
[0040] 1. Pretreatment:
[0041] The neodymium iron boron workpiece substrate 1 is subjected to "grinding and chamfering → water washing → chemical degreasing → water washing → ultrasonic degreasing → water washing → lactic acid activation → water washing" by using the current pretreatment process.
[0042] 2. Chemical pre-plated nickel:
[0043] After pretreatment of the neodymium iron boron workpiece, the chemical pre-plated nickel layer 2 is prepared by using the GG-158 alkaline electroless nickel plating process of Superbond Chemical Industry, and the coating thickness is 1.5 μm.
[0044] 160 mL / L of GG-158 A starter, 110 mL / L of GG-158 B replenisher, 110 mL / L of GG-158 C replenisher, operating temperature 32°C, pH value of the plating solution 7.8.
[0045] 3. Electroless nickel plating:
[0046] After the neodymium iron boron workpiece is chemically pre-plated with nickel, the electroless nickel plating layer 3 is prepared by using the GG-166 high-phosphorus electroless nickel plating process of Chaobang Chemical Industry, and the coating thickness is 9 μm.
[0047] GG-166 A additive: 60 mL / L, GG-166 B additive: 180 mL / L, operating temperature: 87 °C, pH of plating solution: 4.8.
[0048] 4. Non-cyanide cadmium plating:
[0049] After the neodymium iron boron workpiece is electroless nickel plated, the non-cyanide cadmium plating layer 4 is prepared by using the PULIZIER NCC-617 potassium chloride non-cyanide cadmium plating process of Chaobang Chemical Industry, and the coating thickness is 12 μm.
[0050] Cadmium chloride: 27 g / L, potassium chloride: 110 g / L, PULIZIER NCC-617 AC complexing agent: 110 g / L, PULIZIER NCC-617 Base auxiliary agent: 28 mL / L, PULIZIER NCC-617 Bri brightener: 2.0 mL / L, PULIZIER NCC-617HCD high zone brightener: 10 mL / L, bath temperature: 30 °C, pH of plating solution: 8, cathode current density: 1.0 A / dm 2 , cathode movement: 3 m / min.
[0051] 5. Trivalent chromium black passivation:
[0052] After the neodymium iron boron workpiece is non-cyanide cadmium plated, the trivalent chromium black passivation film 5 is prepared by using the TRIROS BP-886 trivalent chromium black passivating agent of Chaobang Chemical Industry.
[0053] TRIROS BP-886A agent: 50 mL / L, TRIROS BP-886B agent: 40 mL / L, passivation temperature: 25 °C, pH of passivation solution: 2.6, passivation time: 100 s.
[0054] 6. Sealing:
[0055] After the neodymium iron boron workpiece is passivated, the graphene sealing layer 6 is prepared by using the PRODICO 480 graphene modified sealing agent developed by Chaobang Chemical Industry, and the thickness of the sealing layer is 1.2 μm.
[0056] Dilute the PRODICO 480 graphene modified sealing agent with water to 2.8 times to prepare the sealing solution. Immerse the workpiece in the sealing solution for 10 s, drain it after taking it out of the tank, and blow off the residual sealing solution on the surface of the workpiece with high-pressure air. After sealing, dry and cure it at 75 °C for 30 min. Example 2
[0057] As Figure 1As shown in the figure, a coating structure for cyanide-free cadmium plating of NdFeB workpieces includes an NdFeB substrate 1, and a chemical pre-nickel plating layer 2, a nickel plating layer 3, a cyanide-free cadmium plating layer 4, a trivalent chromium black passivation film 5, and a graphene sealing layer 6 sequentially prepared on the NdFeB substrate 1 from the inside to the outside.
[0058] 1. Pretreatment:
[0059] The NdFeB substrate 1 is subjected to "grinding and chamfering → water washing → chemical degreasing → water washing → ultrasonic degreasing → water washing → lactic acid activation → water washing" using the current pretreatment process.
[0060] 2. Chemical pre-nickel plating:
[0061] After the pretreatment of the NdFeB workpiece, the chemical pre-nickel plating layer 2 is prepared by using the GG-158 alkaline electroless nickel plating process of Chaobang Chemical Industry, and the coating thickness is 1.5 μm.
[0062] GG-158 A starter 150 mL / L, GG-158 B replenisher 100 mL / L, GG-158 C replenisher 100 mL / L, operating temperature 32 °C, pH of the plating solution 8.0.
[0063] 3. Electroless nickel plating:
[0064] After the chemical pre-nickel plating of the NdFeB workpiece, the electroless nickel plating layer 3 is prepared by using the GG-166 high-phosphorus electroless nickel plating process of Chaobang Chemical Industry, and the coating thickness is 9 μm.
[0065] GG-166 A additive 63 mL / L, GG-166 B additive 175 mL / L, operating temperature 90 °C, pH of the plating solution 5.0.
[0066] 4. Cyanide-free cadmium plating:
[0067] After the electroless nickel plating of the NdFeB workpiece, the cyanide-free cadmium plating layer 4 is prepared by using the PULIZIER NCC-617 potassium chloride cyanide-free cadmium plating process of Chaobang Chemical Industry, and the coating thickness is 12 μm.
[0068] Cadmium chloride 33 g / L, potassium chloride 130 g / L, PULIZIER NCC-617 AC complexing agent 130 g / L, PULIZIER NCC-617 Base auxiliary agent 28 mL / L, PULIZIER NCC-617 Bri brightener 2.0 mL / L, PULIZIER NCC-617HCD high-zone brightener 8 mL / L, bath temperature 28 °C, pH of the plating solution 8, cathode current density 1.2 A / dm 2 , cathode movement 3 m / min.
[0069] 5. Trivalent chromium black passivation:
[0070] After the neodymium iron boron workpiece is cadmium-plated without cyanide, a trivalent chromium black passivation film 5 is prepared by using TRIROS BP-886 trivalent chromium black passivation agent of Superbond Chemical Industry Co., Ltd.
[0071] 70 mL / L of TRIROS BP-886A agent, 60 mL / L of TRIROS BP-886B agent, passivation temperature of 25 °C, pH of the passivation solution of 2.4, and passivation time of 80 s.
[0072] 6. Sealing:
[0073] After the neodymium iron boron workpiece is passivated, a graphene sealing layer 6 is prepared by using PRODICO 480 graphene modified sealing agent developed by Superbond Chemical Industry Co., Ltd., and the thickness of the sealing layer is 1.2 μm.
[0074] The PRODICO 480 graphene modified sealing agent is diluted with water to 2.8 times to prepare a sealing solution. The plated parts are immersed in the sealing solution for 10 s, drained after taking out of the tank, and the residual sealing solution on the surface of the plated parts is blown off with high-pressure air. After sealing, it is dried and cured at 80 °C for 25 min.
[0075] Test Example 1:
[0076] Neodymium iron boron cyanide-free cadmium-plated samples are prepared according to the process procedures of Example 1 and Example 2. According to GB / T 5270–2005 "Review of Test Methods for Adhesion of Metallic Coatings on Metallic Substrates - Electrodeposited and Chemically Deposited Coatings", the samples are heated in a heating furnace to 250 °C and kept warm for 30 min, then taken out and suddenly cooled in water at room temperature. No blistering or peeling occurs on the coatings, and the adhesion of the prepared coatings is good.
[0077] Test Example 2:
[0078] Neodymium iron boron cyanide-free cadmium-plated samples are prepared according to the process procedures of Example 1 and Example 2. The corrosion resistance is tested according to GB / T 10125–2021 "Artificial Atmosphere Corrosion Tests - Salt Spray Tests". No white corrosion products are generated on the surface of the samples after 1600 h of neutral salt spray test, and the prepared coatings have excellent corrosion resistance.
[0079] The technical solutions provided by the embodiments of the present utility model have been introduced in detail above. Specific examples are used herein to elaborate on the principles and implementation manners of the embodiments of the present utility model. The descriptions of the above embodiments are only applicable to help understand the principles of the embodiments of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several modifications and improvements can still be made, and these all belong to the protection scope of the present utility model.
Claims
1. The coating structure of cyanide-free cadmium plating for NdFeB workpieces is characterized in that: It includes a neodymium iron boron matrix, and a chemical pre-nickel plating layer, an electroless nickel plating layer, a cyanide-free cadmium plating layer, a trivalent chromium black passivation film, and a graphene sealing layer that are sequentially prepared on the neodymium iron boron matrix from the inside to the outside.
2. The coating structure of the non-cyanide cadmium plating for NdFeB workpieces according to claim 1, characterized in that: The thickness of the chemical pre-nickel plating layer is 1 - 2 μm.
3. The coating structure of the non-cyanide cadmium plating for Nd-Fe-B workpieces as described in claim 1, characterized in that: The thickness of the electroless nickel plating layer is 6 - 12 μm.
4. The cadmium-free plating layer structure of the neodymium iron boron workpiece according to claim 1, characterized in that: The thickness of the cyanide-free cadmium plating layer is 8 - 16 μm.
5. The coating structure of the non-cyanide cadmium plating for NdFeB workpieces according to claim 1, characterized in that: The thickness of the graphene sealing layer is 0.8 - 2.0 μm.