Plating layer structure plated with white gun color tin-nickel alloy

Abstract

The utility model discloses a plating layer structure for plating white gun color tin-nickel alloy, which comprises a neodymium iron boron base body, and a citrate nickel-plated layer, a nickel-copper alloy plating layer, a bright nickel-plated layer and a white gun color tin-nickel alloy plating layer which are sequentially prepared on the neodymium iron boron base body from inside to outside. According to the coating structure plated with the white gun color tin-nickel alloy disclosed by the utility model, the binding force of the coating is tested by a thermal shock method according to GB / T 5270-2005 < GB / T 5270-2005 < GB / T > 5270-2005 < GB / T > 5270-2005 < GB / T > 5270-2005 > < GB / T > 5270-2005 > < GB / T > 5270-2005 A neutral salt spray test is carried out according to GB / T 10125-2021 Artificial Atmosphere Corrosion Test Salt Spray Test for 150h, no corrosive substance is generated on the surface of a plated part, and a plated layer has good corrosion resistance.

Description

Technical Field

[0001] The utility model belongs to the technical field of metal surface treatment, and particularly relates to a coating structure of a white gun color tin-nickel alloy plating. Background Art

[0002] The corrosion resistance and anti-discoloration performance of tin-nickel alloy are significantly better than those of single-metal tin or nickel coatings. Its coating has characteristics such as no cracks, small internal stress, and good solderability, and has been widely used as a protective and decorative coating for parts in electronics, electrical appliances, precision machinery, optical instruments, photographic equipment, chemical utensils, etc. [1] The white gun color tin-nickel alloy coating is shiny white, with uniform alloy content and extremely high corrosion resistance. It is an ideal anti-corrosion coating and functional coating, and is usually used to replace the hexavalent chromium electroplated coating.

[0003] The surface of the neodymium iron boron substrate has many pores, and the material itself has relatively high chemical activity. During the electroplating process of neodymium iron boron workpieces, there are residual corrosion problems with the acidic or alkaline electroplating solutions immersed in the pores on the surface of neodymium iron boron. [2] This affects the protective performance of the coating. In the past, the copper-nickel-chromium electroplating process was usually used to prepare a protective layer on the surface of neodymium iron boron, but cyanide electroplated copper and hexavalent chromium electroplated chromium have high pollution problems, which limit the use of this process.

[0004] The industry has conducted a lot of research on cyanide-free copper electroplating processes that can replace cyanide electroplated copper, but there are still certain gaps in performance between the developed divalent copper cyanide-free copper electroplating process and cyanide electroplated copper. [3] Therefore, the current process usually prepares a pre-nickel plating layer by citrate nickel electroplating on the neodymium iron boron substrate, and then electroplates bright nickel and other coatings. However, the electrode potential of the nickel plating layer is significantly more positive than that of the neodymium iron boron substrate, and the nickel plating layer prepared by directly electroplating nickel on the neodymium iron boron substrate is a cathodic coating. When the coating is damaged or has pores, the corrosive medium destroys the neodymium iron boron substrate through galvanic corrosion. Therefore, this coating structure has poor corrosion resistance.

[0005] References: [1], Chu Kejing, Wang Wei, Sun Bin, etc., Research and Development of Tin-Nickel Alloy Electromagnetic Shielding Fabric and Study on Coating Performance [J], Electrochemistry, 2009, 15(1): 92-95. [2], Li Hongying, Hao Zhuangzhi, Liu Yuhui, etc., 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. [3], Qin Zuzu, Li Jiansan, Xu Jinlai, Research Progress on Cyanide-Free Copper Electroplating Processes at Home and Abroad [J], Electroplating & Finishing, 2015, 34(3): 149-152. Content of the Utility Model

[0006] In order to overcome the technical defect that direct nickel plating on the surface of neodymium iron boron does not have the function of electrochemical protection, the utility model provides a coating structure of white gun color tin-nickel alloy. In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0007] A coating structure of white gun color tin-nickel alloy, comprising a neodymium iron boron substrate, and a citrate nickel plating layer, a nickel-copper alloy plating layer, a bright nickel plating layer, and a white gun color tin-nickel alloy plating layer sequentially prepared on the neodymium iron boron substrate from the inside to the outside;

[0008] The thickness of the nickel-copper alloy plating layer is 5-12 μm.

[0009] Preferably, the thickness of the citrate nickel plating layer is 4-7 μm.

[0010] Preferably, the thickness of the bright nickel plating layer is 5-12 μm.

[0011] Preferably, the thickness of the white gun color tin-nickel alloy plating layer is 1-5 μm.

[0012] The nickel plating layer is prepared on the surface of neodymium iron boron by using a neutral citrate nickel plating process. The residual corrosion problem of the plating solution remaining in the pores on the surface of neodymium iron boron is very small, and it has basically no destructive effect on the substrate. Bright nickel is plated on the nickel-copper alloy plating layer. The electrode potential of the bright nickel plating layer is significantly more negative than that of the nickel-copper alloy plating layer. The bright nickel plating layer has an electrochemical protection effect on the nickel-copper alloy plating layer. This coating structure can effectively prevent the corrosion medium from eroding the neodymium iron boron substrate. White gun color tin-nickel alloy is plated on the bright nickel plating layer. Since the electrode potential of the white gun color tin-nickel alloy plating layer is more positive than that of the bright nickel plating layer, when the coating is corroded, the corrosion medium first corrodes the bright nickel plating layer in the transverse direction. However, the corrosion resistance of the white gun color tin-nickel alloy is extremely high, and it has a good protection effect on the nickel plating layer. The corrosion rate of the nickel plating layer is very slow.

[0013] Compared with the prior art, the utility model has the following beneficial effects:

[0014] 1. The coating structure of white gun color tin-nickel alloy disclosed by the utility model prepares a bright nickel plating layer and a white gun color tin-nickel alloy plating layer on the nickel-copper alloy plating layer, overcoming the technical defect that direct nickel plating on the neodymium iron boron substrate in the current process does not have the function of electrochemical protection;

[0015] 2. The coating structure of white gun color tin-nickel alloy disclosed by the utility model has a salt spray resistance performance far higher than the requirements of the standard of GB / T34491–2017 "Surface Coatings on Sintered Neodymium Iron Boron". Description of the Drawings

[0016] The drawings described herein are used to provide a further understanding of the utility model, form a part of this application, and do not constitute an improper limitation of the utility model. In the drawings:

[0017] Figure 1 It is a schematic diagram of the coating structure of Embodiment 1 and Embodiment 2 of the present utility model. Specific embodiments

[0018] The present utility model will be described in detail below in conjunction with the drawings and specific embodiments. Here, the schematic embodiments and descriptions of the present utility model are used to explain the present utility model, but do not limit the present utility model.

[0019] A coating structure of white gun-color tin-nickel alloy plating includes a neodymium iron boron substrate, and a citrate nickel plating layer, a nickel-copper alloy plating layer, a bright nickel plating layer, and a white gun-color tin-nickel alloy plating layer sequentially prepared on the neodymium iron boron substrate from the inside to the outside.

[0020] Grind and chamfer, degrease, and activate the neodymium iron boron workpiece substrate according to the current pretreatment process.

[0021] After the pretreatment of the neodymium iron boron workpiece, a citrate nickel plating layer is prepared by using the current citrate nickel plating process.

[0022] Preferably, the thickness of the citrate nickel plating layer is 4-7 μm.

[0023] Preferably, the citrate nickel plating process is as follows:

[0024] Nickel sulfate hexahydrate 180-250 g / L, sodium chloride 10-12 g / L, boric acid 30-35 g / L, magnesium sulfate 30-40 g / L, pH value of the plating solution 7.0-7.2, plating bath temperature 50 °C - 60 °C, cathode current density 1-1.5 A / dm 2 , cathode movement 4-6 m / min.

[0025] After the citrate nickel plating of the neodymium iron boron workpiece, a nickel-copper alloy plating layer is prepared by using the current nickel-copper alloy plating process.

[0026] Preferably, the thickness of the nickel-copper alloy plating layer is 5-12 μm.

[0027] Preferably, the nickel-copper alloy plating layer is prepared by using the Nistar 6070 bright nickel-copper alloy plating process of Superbond Chemical Industry:

[0028] Nickel sulfate hexahydrate 180 - 220 g / L, copper sulfate pentahydrate 8 - 12 g / L, trisodium citrate 50 - 60 g / L, disodium hydroxyethylethylenediphosphonate 20 - 30 g / L, sodium chloride 5 - 8 g / L, NISTAR 6070 brightener 0.3 - 0.7 mL / L, NISTAR6071 auxiliary agent 6 - 10 mL / L, NI-35 wetting agent 0.3 - 1.0 mL / L, pH value of the plating solution 4.3 - 4.8, plating bath temperature 50 °C - 55 °C, cathode current density 2.6 - 3.2 A / dm 2 , cathode movement 3 - 5 m / min.

[0029] After the neodymium iron boron workpiece is plated with nickel - copper alloy, the bright nickel plating layer is prepared by the current bright nickel plating process.

[0030] Preferably, the thickness of the bright nickel plating layer is 5 - 12 μm.

[0031] After the neodymium iron boron workpiece is plated with bright nickel, the white gunmetal tin - nickel alloy plating layer is prepared by the current white gunmetal tin - nickel alloy plating process.

[0032] Preferably, the thickness of the white gunmetal tin - nickel alloy plating layer is 1 - 5 μm.

[0033] Preferably, the white gunmetal pearl tin - nickel alloy plating layer is prepared by the PGA - 215 white gunmetal tin - nickel alloy plating process of Superbond Chemical Industry:

[0034] Nickel chloride hexahydrate 135 - 175 g / L, PGA - 215A additive 450 - 500 mL / L, PGA - 215B additive 30 - 60 mL / L, PGA - 215C additive 10 - 30 mL / L, pH value of the plating solution 3.5 - 4.5, plating bath temperature 63 °C - 73 °C, cathode current density 0.5 - 1.5 A / dm 2 , cathode movement 4 - 6 m / min.

[0035] After the neodymium iron boron workpiece is plated with white gunmetal tin - nickel alloy, oxidation protection is carried out.

[0036] Preferably, hydrogen peroxide oxidation protection method is used for oxidation protection.

[0037] Hydrogen peroxide with a mass fraction of 30% 10 - 30 mL / L, sodium dihydrogen phosphate 10 - 30 g / L, pH value of the bath solution 4.0 - 4.8, operation at room temperature, oxidation time 10 - 30 s.

[0038] After the neodymium iron boron workpiece is oxidized and protected, it is washed with water and dried. Example 1

[0039] As Figure 1As shown in the figure, a coating structure of white gun-color tin-nickel alloy includes a neodymium iron boron substrate 1, and a citrate nickel plating layer 2, a nickel-copper alloy plating layer 3, a bright nickel plating layer 4, and a white gun-color tin-nickel alloy plating layer 5 sequentially prepared on the neodymium iron boron substrate 1 from the inside to the outside.

[0040] 1. Pretreatment:

[0041] The neodymium iron boron substrate 1 is subjected to "grinding chamfering → water washing → chemical degreasing → water washing → ultrasonic degreasing → water washing → lactic acid activation → water washing" using the current pretreatment process.

[0042] 2. Citrate nickel plating:

[0043] After the pretreatment of the neodymium iron boron workpiece, the citrate nickel plating layer 2 is prepared by the following citrate nickel plating process, and the coating thickness is 5μm.

[0044] Nickel sulfate hexahydrate 230g / L, sodium chloride 12g / L, boric acid 33g / L, magnesium sulfate 33g / L, the pH of the plating solution is 7.2, the plating bath temperature is 55°C, the cathode current density is 1.2A / dm 2 , and the cathode moves at 5m / min.

[0045] 3. Nickel-copper alloy plating:

[0046] After the citrate nickel plating of the neodymium iron boron workpiece, the nickel-copper alloy plating layer 3 is prepared by the Nistar 6070 bright nickel-copper alloy plating process of Superbond Chemical Industry, and the coating thickness is 10μm.

[0047] Nickel sulfate hexahydrate 190g / L, copper sulfate pentahydrate 9g / L, trisodium citrate 55g / L, sodium dihydrogen ethylenediamine tetraacetate 25g / L, boric acid 30g / L, sodium chloride 6g / L, NISTAR 6070 brightener 0.5mL / L, NISTAR 6071 auxiliary agent 8mL / L, NI-35 wetting agent 0.6mL / L, the pH of the plating solution is 4.6, the plating bath temperature is 53°C, the cathode current density is 2.8A / dm 2 , and the cathode moves at 4m / min.

[0048] 4. Bright nickel plating:

[0049] After the nickel-copper alloy plating of the neodymium iron boron workpiece, the bright nickel plating layer 4 is prepared by the current bright nickel plating process, and the coating thickness is 8μm.

[0050] 5. White gun-color tin-nickel alloy plating:

[0051] After the bright nickel plating of the neodymium iron boron workpiece, the white gun-color tin-nickel alloy plating layer 5 is prepared by the PGA-215 white gun-color tin-nickel alloy plating process of Superbond Chemical Industry, and the coating thickness is 3μm.

[0052] Nickel chloride hexahydrate 170 g / L, PGA-215A additive 490 mL / L, PGA-215B additive 50 mL / L, PGA-215C additive 25 mL / L, pH of the plating solution is 3.8, plating bath temperature is 68 °C, cathode current density is 1.2 A / dm 2 , cathode movement is 5 m / min.

[0053] 6. Oxidation protection:

[0054] After the neodymium iron boron workpiece is plated with white gunmetal tin-nickel alloy, hydrogen peroxide oxidation method is used for oxidation protection.

[0055] Hydrogen peroxide with a mass fraction of 30% is 20 mL / L, sodium dihydrogen phosphate is 20 g / L, pH of the bath solution is 4.4, operating at room temperature, oxidation time is 20 s.

[0056] 7. Drying:

[0057] After the oxidation protection of the neodymium iron boron workpiece, it is subjected to "water washing → pure water washing → drying". Example 2

[0058] As Figure 1 shown, a coating structure of white gunmetal tin-nickel alloy plating includes a neodymium iron boron substrate 1, and a citrate nickel plating layer 2, a nickel-copper alloy plating layer 3, a bright nickel plating layer 4, and a white gunmetal tin-nickel alloy plating layer 5 sequentially prepared on the neodymium iron boron substrate 1 from inside to outside.

[0059] 1. Pretreatment:

[0060] The neodymium iron boron 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.

[0061] 2. Citrate nickel plating:

[0062] After the pretreatment of the neodymium iron boron workpiece, the citrate nickel plating layer 2 is prepared by the following citrate nickel plating process, and the coating thickness is 4 μm.

[0063] Nickel sulfate hexahydrate 210 g / L, sodium chloride 12 g / L, boric acid 30 g / L, magnesium sulfate 40 g / L, pH of the plating solution is 7.1, plating bath temperature is 50 °C, cathode current density is 1.2 A / dm 2 , cathode movement is 5 m / min.

[0064] 3. Nickel-copper alloy plating:

[0065] After the citrate nickel plating of the neodymium iron boron workpiece, the nickel-copper alloy plating layer 4 is prepared by using the Nistar 6070 bright nickel-copper alloy plating process of Superbond Chemical Industry, and the coating thickness is 8 μm.

[0066] Nickel sulfate hexahydrate 210 g / L, copper sulfate pentahydrate 11 g / L, trisodium citrate 65 g / L, sodium dihydrogen ethylenediamine tetraacetate 28 g / L, boric acid 32 g / L, sodium chloride 7 g / L, NISTAR 6070 brightener 0.5 mL / L, NISTAR 6071 auxiliary agent 8 mL / L, NI-35 wetting agent 0.6 mL / L, pH of the plating solution is 4.5, plating bath temperature is 52 °C, cathode current density is 3.0 A / dm 2 , cathode moving speed is 4 m / min.

[0067] 4. Bright nickel plating:

[0068] After the neodymium iron boron workpiece is plated with nickel-copper alloy, a bright nickel plating layer 4 is prepared by the current bright nickel plating process, and the coating thickness is 10 μm.

[0069] 5. Tin-nickel alloy plating in white gun color:

[0070] After the neodymium iron boron workpiece is plated with bright nickel, a white gun color tin-nickel alloy coating 5 is prepared by the PGA-215 tin-nickel alloy plating process of Chaobang Chemical Industry, and the coating thickness is 3 μm.

[0071] Nickel chloride hexahydrate 140 g / L, PGA-215A additive 460 mL / L, PGA-215B additive 40 mL / L, PGA-215C additive 15 mL / L, pH of the plating solution is 4.2, plating bath temperature is 65 °C, cathode current density is 0.5 A / dm 2 , cathode moving speed is 5 m / min.

[0072] 6. Oxidation protection:

[0073] After the neodymium iron boron workpiece is plated with white gun color tin-nickel alloy, hydrogen peroxide oxidation method is used for oxidation protection.

[0074] Hydrogen peroxide with a mass fraction of 30% 10 mL / L, sodium dihydrogen phosphate 10 g / L, pH value of the bath is 4.6, operating at room temperature, oxidation time is 25 s.

[0075] 7. Drying:

[0076] After the electro-oxidation protection of the neodymium iron boron workpiece, it is subjected to "water washing → pure water washing → drying".

[0077] Test example 1:

[0078] The neodymium iron boron samples plated with white gun-color tin-nickel alloy prepared in Example 1 and Example 2 were subjected to a neutral salt spray test for 150 h in accordance with GB / T 10125–2021 "Artificial Atmosphere Corrosion Tests - Salt Spray Tests", and no rust was found on the surface of the plated parts. For the coating structure prepared by the present utility model, the time without white rust in the neutral salt spray test is more than 3 times the time of rust appearance in the neutral salt spray test of 48 h for the nickel-copper-nickel coating on the surface of neodymium iron boron specified in GB / T 34491–2017 "Surface Coatings on Sintered Neodymium Iron Boron".

[0079] Test Example 2:

[0080] The neodymium iron boron samples plated with white gun-color tin-nickel alloy prepared in Example 1 and Example 2 were tested for the adhesion of the coating by the thermal shock method in accordance with GB / T 5270–2005 "Review of Test Methods for Adhesion of Metallic Coatings on Metallic Substrates - Electrodeposited and Chemically Deposited Coatings". The plated parts were heated in a heating furnace to 250 °C and held for 30 min, then taken out and suddenly cooled in water at room temperature. No blistering or peeling of the coating occurred. The test shows that the coating structure prepared by the present utility model has good adhesion.

[0081] The technical solutions provided by the embodiments of the present utility model have been introduced in detail above. Specific examples are used in this article 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. A coating structure of a white gunmetal tin-nickel alloy, characterized in that: It comprises a neodymium iron boron substrate, and a citrate nickel plating layer, a nickel-copper alloy plating layer, a bright nickel plating layer, and a white gun-colored tin-nickel alloy plating layer which are sequentially prepared from the inside to the outside on the neodymium iron boron substrate; The thickness of the nickel-copper alloy plating layer is 5 to 12 μm.

2. The coating structure of the white gunmetal tin-nickel alloy as claimed in claim 1, characterized in that: The thickness of the citrate nickel plating layer is 4-7 μm.

3. The coating structure of the white gunmetal tin-nickel alloy as claimed in claim 1, characterized in that: The thickness of the bright nickel plating layer is 5 to 12 μm.

4. The coating structure of the white gunmetal tin-nickel alloy as claimed in claim 1, characterized in that: The thickness of the white gunmetal tin-nickel alloy plating layer is 1-5 μm.

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