Plating layer structure for plating pearl nickel on surface of zinc alloy

Abstract

The utility model discloses a plating layer structure for plating pearl nickel on a zinc alloy surface, which comprises a zinc alloy substrate, and an acidic zinc-nickel alloy plating layer, a citrate nickel plating layer, a bright nickel-copper alloy plating layer, a pearl nickel plating layer and a nano polymer protective film which are sequentially prepared on the zinc alloy substrate from inside to outside. According to the plating layer structure for plating the pearl nickel on the surface of the zinc alloy, the binding force of the plating layer is tested by a thermal shock method according to GB / T 5270-2005 Electrodeposition and Chemical Deposition Layer Adhesive Strength Test Method for Metal Cover Layer on Metal Matrix, the plating layer does not blister or fall off, and the binding force meets the standard requirement, so that the plating layer structure can be used for plating the pearl nickel on the surface of the zinc alloy. According to an acetate fog test for 76h according to GB / T 10125-2021 Artificial Atmosphere Corrosion Test Salt Spray Test, no corrosives are 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 pearl nickel plated on the surface of zinc alloy. Background Art

[0002] The pearl nickel coating is silver-white, has a soft and beautiful appearance, and has been widely used in the electroplating of hardware products, mainly for the decorative electroplating field.

[0003] The traditional process for electroplating pearl nickel on zinc alloy die-castings is usually to pre-plate copper cyanide, copper pyrophosphate plating, acid copper plating, bright nickel plating, pearl nickel plating, and post-treatment on the zinc alloy substrate in sequence. However, there is still a certain gap between the developed divalent copper cyanide-free copper plating process and cyanide copper plating over the years, and the problem of poor adhesion when using this process to plate copper on substrates such as zinc alloy has not been completely solved. [1] .

[0004] Nickel-copper alloy coatings have received increasing attention in the industry due to their good mechanical properties, high corrosion resistance, electrocatalytic properties, etc. [2] . The performance of nickel-copper alloy coatings is superior to that of nickel coatings, and replacing nickel coatings with them can increase the corrosion resistance and other properties of the coatings.

[0005] According to the traditional process, the pearl nickel coating needs to be treated by chromate electrolytic protection, but it is limited due to the high pollution problem of hexavalent chromium.

[0006] References: [1], Qin Zuzu, Li Jiansan, Xu Jinlai, Research progress of cyanide-free copper plating processes at home and abroad [J], Electroplating & Finishing, 2015, 34(3): 149-152. [2], Yang Ruisong, Li Mingtian, Wang Ying, etc., Influence of process parameters on the composition and phase structure of electroplated nickel-copper alloy coatings [J], Electroplating & Finishing, 2014, 33(15): 633-635. Content of the Utility Model

[0007] In order to solve the high pollution problem of cyanide pre-plating copper on zinc alloy die-castings, the utility model provides a coating structure of pearl nickel plated on the surface of zinc alloy. To achieve the above purpose, the utility model adopts the following technical solutions:

[0008] A coating structure of pearl nickel plated on the surface of zinc alloy, including a zinc alloy substrate, and an acidic zinc-nickel alloy coating, a citrate nickel coating, a bright nickel-copper alloy coating, a pearl nickel coating, and a nano-polymer protective film prepared on the zinc alloy substrate in sequence from inside to outside.

[0009] Preferably, the thickness of the acidic zinc-nickel alloy coating is 7-12 μm.

[0010] Preferably, the thickness of the citrate nickel coating is 1-3 μm.

[0011] Preferably, the thickness of the bright nickel - copper alloy coating is 5 - 13 μm.

[0012] Preferably, the thickness of the pearl nickel coating is 2 - 4 μm.

[0013] The acidic zinc - nickel alloy plating solution has a high throwing power. Electroplating the acidic zinc - nickel alloy on the matrix of zinc - alloy die - castings can effectively seal the pores on its surface and solve the problem of pitting corrosion that easily occurs in the coating. The acidic zinc - nickel alloy coating is bright. Replacing the traditional cyanide pre - copper plating and pyrophosphate copper plating with it can significantly increase the brightness of the coating, thus eliminating the copper - plating acid process in the traditional process and reducing the electroplating cost. Citrate nickel plating on the zinc - nickel alloy coating can form a nickel - plating layer with good adhesion. The pearl nickel coating is anodic relative to the nickel - copper alloy coating, and this coating structure can effectively prevent the erosion of corrosive media towards the zinc - alloy matrix.

[0014] Compared with the prior art, the present utility model has the following beneficial effects:

[0015] 1. For the coating structure of pearl nickel plating on the surface of zinc alloy disclosed by the present utility model, the nano - polymer protective film is used to replace the traditional chromate electrolytic protective film, overcoming the high - pollution problem of chromate electrolytic protection.

[0016] 2. For the coating structure of pearl nickel plating on the surface of zinc alloy disclosed by the present utility model, electroplating zinc - nickel alloy to seal the pores on the surface of zinc - alloy die - castings and using citrate nickel plating to prepare a transitional coating overcome the high - pollution problem of using cyanide pre - copper plating plus pyrophosphate copper plating for hole - sealing by the traditional method. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present utility model, form a part of this application, and do not constitute an improper limitation to the present utility model. In the drawings:

[0018] Figure 1 It is a schematic diagram of the coating structure of Embodiment 1 and Embodiment 2 of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The present utility model will be described in detail below in conjunction with the drawings and specific embodiments. Here, the illustrative embodiments and descriptions of the present utility model are used to explain the present utility model, but do not limit the present utility model.

[0020] A coating structure of pearl nickel plating on the surface of zinc alloy, the process of which includes sequentially electroplating acidic zinc - nickel alloy, citrate nickel plating, bright nickel - copper alloy plating, pearl nickel plating, and nano - polymer electrolytic protection on the zinc - alloy matrix from the inside to the outside.

[0021] The current pretreatment process is used to remove wax, oil, and activate the matrix of zinc alloy die-castings.

[0022] The current acidic zinc-nickel alloy electroplating process is used to prepare an acidic zinc-nickel alloy coating.

[0023] Preferably, the thickness of the acidic zinc-nickel alloy coating is 7 - 12 μm.

[0024] Preferably, the acidic zinc-nickel alloy coating is prepared by using the DETRONZIN 1377 acidic zinc-nickel alloy electroplating process of Superbond Chemical Industry:

[0025] Zinc 22 - 30 g / L, nickel 22 - 30 g / L, potassium chloride 160 - 190 g / L, ammonium chloride 45 - 75 g / L, DETRONZIN1377A auxiliary agent 10 - 20 mL / L, DETRONZIN 1377B main brightener 0.5 - 1.5 mL / L, DETRONZIN 1377C complexing agent 10 - 20 mL / L, DETRONZIN 1377D additive 8 - 12 mL / L, bath temperature 27°C - 31°C, bath pH value 4.6 - 5.2, cathode current density 0.5 - 3.5 A / dm 2 , cathode movement 3 - 5 m / min.

[0026] The current citrate nickel plating process is used to prepare a citrate nickel coating.

[0027] Preferably, the thickness of the citrate nickel coating is 1 - 3 μm.

[0028] Preferably, the citrate nickel plating process is as follows:

[0029] 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, bath pH value 7.0 - 7.2, bath temperature 50°C - 60°C, cathode current density 1 - 1.5 A / dm 2 , cathode movement 4 - 6 m / min.

[0030] The current bright nickel-copper alloy electroplating process is used to prepare a bright nickel-copper alloy coating.

[0031] Preferably, the thickness of the bright nickel-copper alloy coating is 5 - 13 μm.

[0032] Preferably, the bright nickel-copper alloy coating is prepared by using the Nistar 6070 bright nickel-copper alloy electroplating process of Superbond Chemical Industry:

[0033] Nickel sulfate hexahydrate 180 - 220 g / L, copper sulfate pentahydrate 8 - 12 g / L, trisodium citrate 50 - 70 g / L, sodium dihydrogen hydroxyethanediphosphonate 20 - 30 g / L, boric acid 28 - 35 g / L, sodium chloride 5 - 8 g / L, NISTAR 6070 brightener 0.3 - 0.7 mL / L, NISTAR 6071 auxiliary agent 6 - 10 mL / L, NI-35 wetting agent 0.3 - 1.0 mL / L, pH value of plating solution 4.3 - 4.8, plating bath temperature 50°C - 55°C, cathode current density 2.6 - 3.2 A / dm 2 , cathode moving speed 3 - 5 m / min.

[0034] The pearl nickel coating is prepared by the current pearl nickel plating process.

[0035] Preferably, the thickness of the pearl nickel coating is 2 - 4 μm.

[0036] Preferably, the pearl nickel coating is prepared by the PN-918 long-lasting pearl nickel electroplating process of Superbond Chemical Industry:

[0037] Nickel sulfate hexahydrate 380 - 480 g / L, nickel chloride hexahydrate 35 - 45 g / L, boric acid 40 - 50 g / L, PN-918A long-lasting pearl nickel auxiliary agent 10 - 15 mL / L, PN-918B long-lasting pearl nickel wetting agent 2 - 4 mL / L, PN-918C long-lasting pearl nickel leveling agent 2 - 4 mL / L, PN-918F long-lasting pearl nickel fine sand agent 0.2 - 0.7 mL / L, PN-918T long-lasting pearl nickel coarse sand agent 0.2 - 0.7 mL / L, pH value of plating solution 4.0 - 4.8, plating bath temperature 55°C - 60°C, cathode current density 3 - 8 A / dm 2 , cathode moving speed 2 - 3 m / min.

[0038] The nano-polymer electrolytic protection film is prepared by the current nano-polymer electrolytic protection process.

[0039] Preferably, the nano-polymer electrolytic protection film is prepared by the PROTEZVY 1126 electrolytic protection process of Superbond Chemical Industry:

[0040] PROTEZVY 1126 MUP bath conditioner 30 - 40 mL / L, PROTEZVY 1126 ADDITIVE C additive 70 - 90 mL / L, sodium hydroxide 0.15 - 0.25 g / L, pH value of bath solution 3.4 - 4.0, operating temperature 55°C - 65°C, cathode current density 0.05 - 0.1 A / dm 2 , electrolysis time 3 - 10 min.

[0041] After the zinc alloy die-casting is electroplated, it is dried by the conventional process. Example 1

[0042] As Figure 1 shown, a coating structure of pearl nickel plating on the surface of a zinc alloy includes a zinc alloy substrate 1, and an acidic zinc-nickel alloy coating 2, a citrate nickel plating layer 3, a bright nickel-copper alloy coating 4, a pearl nickel coating 5, and a nano-polymer protective film 6 prepared on the zinc alloy substrate 1 in sequence from the inside to the outside.

[0043] 1. Pretreatment:

[0044] The zinc alloy die-casting substrate 1 is subjected to "chemical dewaxing → water washing → ultrasonic dewaxing → water washing → ultrasonic degreasing → water washing → activation → water washing" using the current pretreatment process.

[0045] 2. Zinc-nickel alloy plating:

[0046] After the pretreatment of the zinc alloy die-casting, the acidic zinc-nickel alloy coating 2 is prepared by using the DETRONZIN 1377 acidic zinc-nickel alloy electroplating process of Superbond Chemical Industry, and the coating thickness is 8μm.

[0047] Zinc 26g / L, nickel 26g / L, potassium chloride 175g / L, ammonium chloride 60g / L, DETRONZIN 1377A auxiliary agent 15mL / L, DETRONZIN 1377B main brightener 1.2mL / L, DETRONZIN 1377C complexing agent 15mL / L, DETRONZIN 1377D additive 10mL / L, plating bath temperature 28°C, plating solution pH 4.8, cathode current density 2.6A / dm 2 , cathode movement 4m / min.

[0048] 3. Citrate nickel plating:

[0049] After the zinc alloy die-casting is plated with zinc-nickel alloy, the citrate nickel plating layer 3 is prepared by using the following citrate nickel plating process, and the coating thickness is 2μm.

[0050] Nickel sulfate hexahydrate 220g / L, sodium chloride 11g / L, boric acid 33g / L, magnesium sulfate 35g / L, plating solution pH 71, plating bath temperature 55°C, cathode current density 1.2A / dm 2 , cathode movement 5m / min.

[0051] 4. Nickel-copper alloy plating:

[0052] After the zinc alloy die-casting is plated with citrate nickel, the bright nickel-copper alloy coating 4 is prepared by using the Nistar 6070 bright nickel-copper alloy plating process of Superbond Chemical Industry, and the coating thickness is 8μm.

[0053] Nickel sulfate hexahydrate 200 g / L, copper sulfate pentahydrate 10 g / L, trisodium citrate 60 g / L, sodium dihydrogen ethylenediamine tetraacetate 23 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 4.6, plating bath temperature is 53 °C, cathode current density is 2.8 A / dm 2 , and the cathode moves at 4 m / min.

[0054] 5. Pearl nickel plating:

[0055] After zinc alloy die-castings are plated with nickel-copper alloy, a pearl nickel coating 5 is prepared by using the PN-918 long-lasting pearl nickel electroplating process of Chaobang Chemical Industry, and the coating thickness is 3 μm.

[0056] Nickel sulfate hexahydrate 480 g / L, nickel chloride hexahydrate 45 g / L, boric acid 50 g / L, PN-918A long-lasting pearl nickel auxiliary agent 15 mL / L, PN-918B long-lasting pearl nickel wetting agent 4 mL / L, PN-918C long-lasting pearl nickel leveling agent 4 mL / L, PN-918F long-lasting pearl nickel fine sand agent 0.7 mL / L, PN-918T long-lasting pearl nickel coarse sand agent 0.5 mL / L, pH of the plating solution is 4.6, plating bath temperature is 58 °C, cathode current density is 5 A / dm 2 , and the cathode moving speed is 3 m / min.

[0057] 6. Nano-polymer electrolytic protection:

[0058] After zinc alloy die-castings are plated with pearl nickel, a nano-polymer protective film 6 is prepared by using the PROTEZVY 1126 electrolytic protection process of Chaobang Chemical Industry.

[0059] PROTEZVY 1126 MUP starter 32 mL / L, PROTEZVY 1126 ADDITIVE C additive 75 mL / L, sodium hydroxide 0.17 g / L, pH of the bath solution is 3.6, operating temperature is 60 °C, cathode current density is 0.08 A / dm 2 , and the electrolysis time is 8 min.

[0060] 7. Drying:

[0061] After the nano-polymer electrolytic protection of zinc alloy die-castings, "water washing → pure water washing → drying at 80 °C for 20 min" is carried out. Example 2

[0062] As Figure 1As shown in the figure, a plating structure of pearl nickel plating on the surface of zinc alloy includes a zinc alloy substrate 1, and an acidic zinc-nickel alloy plating layer 2, a citrate nickel plating layer 3, a bright nickel-copper alloy plating layer 4, a pearl nickel plating layer 5, and a nano-polymer protective film 6 prepared on the zinc alloy substrate 1 from the inside to the outside in sequence.

[0063] 1. Pretreatment:

[0064] The substrate 1 of the zinc alloy die-casting parts is subjected to "chemical dewaxing → water washing → ultrasonic dewaxing → water washing → ultrasonic degreasing → water washing → activation → water washing" by using the current pretreatment process.

[0065] 2. Zinc-nickel alloy plating:

[0066] After the pretreatment of the zinc alloy die-casting parts, the acidic zinc-nickel alloy plating layer 2 is prepared by using the DETRONZIN 1377 acidic zinc-nickel alloy electroplating process of Superbond Chemical Industry, and the plating layer thickness is 8μm.

[0067] Zinc 30g / L, nickel 30g / L, potassium chloride 190g / L, ammonium chloride 75g / L, DETRONZIN 1377A auxiliary agent 15mL / L, DETRONZIN 1377B main brightener 1.2mL / L, DETRONZIN 1377C complexing agent 20mL / L, DETRONZIN 1377D additive 10mL / L, plating bath temperature 28°C, plating solution pH 4.8, cathode current density 3.2A / dm 2 , cathode movement 4m / min.

[0068] 3. Citrate nickel plating:

[0069] After the zinc alloy die-casting parts are plated with zinc-nickel alloy, the citrate nickel plating layer 3 is prepared by using the following citrate nickel plating process, and the plating layer thickness is 2μm.

[0070] Nickel sulfate hexahydrate 180g / L, sodium chloride 10g / L, boric acid 30g / L, magnesium sulfate 30g / L, plating solution pH 7.0, plating bath temperature 60°C, cathode current density 1.2A / dm 2 , cathode movement 5m / min.

[0071] 4. Nickel-copper alloy plating:

[0072] After the zinc alloy die-casting parts are plated with citrate nickel, the bright 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 plating layer thickness is 8μm.

[0073] Nickel sulfate hexahydrate 220 g / L, copper sulfate pentahydrate 12 g / L, trisodium citrate 70 g / L, sodium dihydrogen ethylenediamine tetraacetate 28 g / L, boric acid 35 g / L, sodium chloride 8 g / L, NISTAR 6070 brightener 0.6 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 2.8 A / dm 2 , and the cathode moves at 4 m / min.

[0074] 5. Plating pearl nickel:

[0075] After the zinc alloy die-casting is plated with nickel-copper alloy, a pearl nickel coating 5 is prepared by using the PN-918 long-lasting pearl nickel electroplating process of Superbond Chemical Industry, and the coating thickness is 3 μm.

[0076] Nickel sulfate hexahydrate 430 g / L, nickel chloride hexahydrate 40 g / L, boric acid 45 g / L, PN-918A long-lasting pearl nickel auxiliary agent 12 mL / L, PN-918B long-lasting pearl nickel wetting agent 3 mL / L, PN-918C long-lasting pearl nickel leveling agent 3 mL / L, PN-918F long-lasting pearl nickel fine sand agent 0.5 mL / L, PN-918T long-lasting pearl nickel coarse sand agent 0.4 mL / L, pH of the plating solution is 4.4, plating bath temperature is 57 °C, cathode current density is 4 A / dm 2 , and the cathode moving speed is 3 m / min.

[0077] 6. Nano-polymer electrolytic protection:

[0078] After the zinc alloy die-casting is plated with pearl nickel, a nano-polymer protective film 6 is prepared by using the PROTEZVY 1126 electrolytic protection process of Superbond Chemical Industry.

[0079] PROTEZVY 1126 MUP bath starter 38 mL / L, PROTEZVY 1126 ADDITIVE C additive 85 mL / L, sodium hydroxide 0.23 g / L, pH of the bath solution is 3.8, operating temperature is 60 °C, cathode current density is 0.08 A / dm 2 , and the electrolysis time is 6 min.

[0080] 7. Drying:

[0081] After the nano-polymer electrolytic protection of the zinc alloy die-casting, it is subjected to "water washing → pure water washing → drying at 80 °C for 20 min".

[0082] Test example 1:

[0083] The zinc alloy electroplated with pearl nickel samples prepared in Example 1 and Example 2 were tested for the adhesion of the coating by the thermal shock method according to 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 150 °C and held for 30 min, then taken out and suddenly cooled in water at room temperature. No blistering or peeling occurred on the coating, and the coating structure prepared in this example has good adhesion.

[0084] Test Example 2:

[0085] The zinc alloy electroplated with pearl nickel samples prepared in Example 1 and Example 2 were subjected to an acetic acid salt spray test for 76 h according to GB / T 10125–2021 "Corrosion Tests in Artificial Atmospheres - Salt Spray Tests". No rust appeared on the surface of the plated parts, and their corrosion resistance was good.

[0086] Test Example 3:

[0087] The zinc alloy electroplated with pearl nickel samples prepared in Example 1 and Example 2 were tested for 1000 h under the conditions of a temperature of 40 °C and a relative humidity of 93% according to GB / T 2423.3-2016 "Basic Environmental Test Procedures for Electric and Electronic Products - Test Ca: Damp Heat, Steady State". No visible change occurred in the appearance of the coating, and this coating structure has good anti-discoloration ability.

[0088] 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 deformations and improvements can still be made, and these all belong to the protection scope of the present utility model.

Claims

1. A plating structure of pearl nickel plated on the surface of a zinc alloy, characterized in that: It includes a zinc alloy substrate, and an acidic zinc-nickel alloy coating, a citrate nickel plating layer, a bright nickel-copper alloy coating, a pearl nickel coating, and a nano-polymer protective film which are sequentially prepared on the zinc alloy substrate from the inside to the outside.

2. The coating structure of pearl nickel plating on the zinc alloy surface according to claim 1, wherein: The thickness of the acidic zinc-nickel alloy coating is 7 to 12 μm.

3. The coating structure of pearl nickel plating on the zinc alloy surface according to claim 1, wherein: The thickness of the citrate nickel plating layer is 1 to 3 μm.

4. The coating structure of pearl nickel plating on the zinc alloy surface according to claim 1, characterized in that: The thickness of the bright nickel-copper alloy coating is 5 to 13 μm.

5. The coating structure of pearl nickel plating on the zinc alloy surface according to claim 1, characterized in that: The thickness of the pearl nickel coating is 2 to 4 μm.

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