Plating structure for plating zinc on cyanide-free copper-zinc alloy plating bottom coating

Abstract

The utility model discloses a plating layer structure for plating zinc on a cyanide-free copper-zinc alloy plating layer, which comprises an aluminum alloy substrate, and a chemical zinc deposition layer, a cyanide-free copper-zinc alloy plating layer, a potassium chloride zinc plating layer, a trivalent chromium olive green passivation film and a high-corrosion-resistance sealing layer which are sequentially prepared on the aluminum alloy substrate from inside to outside. According to GB / T 5270-2005 < GB / T 5270-2005 < GB / T > 5270-2005 < GB / T > 5270-2005 < GB / T > 5270-2005 < GB / T > < GB / T > 5270-2005 > < GB / T > 5270-2005 > < GB / T > A neutral salt spray test is carried out for 300 h according to GB / T 10125-2021 Artificial Atmosphere Corrosion Test Salt Spray Test, no corrosives are generated on the surface of the plating layer, and the corrosion resistance of the plating layer is far higher than the market requirement.

Description

TECHNICAL FIELD

[0001] The utility model belongs to metal electroplating field, concretely relates to a kind of zinc plating on the cyanide-free copper zinc alloy bottom plating layer plating layer structure. BACKGROUND

[0002] Potassium chloride zinc plating is widely used for its bright plating, high current efficiency, simple plating solution composition and easy maintenance. The third generation of potassium chloride zinc plating has reached or even surpassed the performance of cyanide-free alkaline zinc plating [1] , and its market share is increasing year by year.

[0003] The potassium chloride zinc plating layer has a better appearance after trivalent chromium olive green passivation, but the gloss of this plating layer is easy to darken.

[0004] The trivalent chromium passivation film is thin and does not have self-repairing property [2] , and it is easy to wear and scratch. When the passivation film is damaged, the zinc plating layer will be corroded by corrosive media.

[0005] The traditional process flow of aluminum alloy part zinc plating usually includes sequentially preparing a chemical zinc deposition layer, an acidic zinc plating layer and a trivalent chromium passivation film on the aluminum alloy substrate. The electrode potential of metallic zinc is positive to that of metallic aluminum, and the potential difference is large. The zinc plating layer on the aluminum alloy part is a cathodic plating layer, which does not have electrochemical protection effect on the substrate. This plating layer structure has low corrosion resistance.

[0006] The sealing layer prepared by the latest developed hydroxyl graphene modified sealing agent has self-repairing property [3] , and the sealing of the zinc plating layer passivated by trivalent chromium solves the problem of the trivalent chromium passivation film not having self-repairing property.

[0007] Reference: [1]. Xia Liang, Lin An, Guo Chongwu, Potassium Chloride Zinc Plating Process Suitable for Aviation and Aerospace Parts [J], Electroplating and Finishing, 2021, 40(17): 1328-1331. [2]. Wu Yinan, Trivalent Chromium Passivation of Zinc Plating Layer [J], Electroplating and Environmental Protection, 2003, 32(2): 30-32. [3]. Guo Chongwu, Lai Huanwen, Xia Liang, Performance Research of Graphene Oxide in Plating Sealing Agent [J], Electroplating and Finishing, 2021, 40(9): 696-670. SUMMARY

[0008] In order to solve the problem of trivalent chromium passivation film of zinc plating layer being easily damaged and not having self-repairing property, the utility model provides a plating layer structure for zinc plating on a cyanide-free copper zinc alloy bottom plating layer. In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0009] A plating layer structure for plating zinc on a cyanide-free copper-zinc alloy undercoat plating layer, comprising an aluminum alloy base body, and a chemical zinc deposition layer, a cyanide-free copper-zinc alloy plating layer, a potassium chloride zinc plating layer, a trivalent chromium olive green passivation film, and a high-corrosion-resistance sealing layer prepared in sequence from inside to outside on the aluminum alloy base body.

[0010] The cyanide-free copper-zinc alloy plating layer is prepared by using a polythiocyanate copper-zinc alloy plating process.

[0011] The high-corrosion-resistance sealing layer is prepared by using a hydroxyl graphene modified sealing agent.

[0012] Preferably, the thickness of the cyanide-free copper-zinc alloy plating layer is 3-8 microns.

[0013] Preferably, the thickness of the potassium chloride zinc plating layer is 8-15 microns.

[0014] Preferably, the thickness of the high-corrosion-resistance sealing layer is 0.8-1.5 microns.

[0015] Compared with the prior art, the plating layer structure has the following beneficial effects:

[0016] 1. The plating layer structure for plating zinc on a cyanide-free copper-zinc alloy undercoat plating layer disclosed in the utility model uses a copper-zinc alloy plating layer as an undercoat plating layer, and overcomes the defect that direct zinc plating on an aluminum alloy surface does not have an electrochemical protection effect.

[0017] 2. The plating layer structure for plating zinc on a cyanide-free copper-zinc alloy undercoat plating layer disclosed in the utility model uses a hydroxyl graphene modified sealing agent to prepare a sealing layer, and overcomes the defect that a trivalent chromium passivation film does not have self-repairing property. DETAILED DESCRIPTION

[0018] The accompanying drawings, which are included to provide a further understanding of the utility model, form a part of the application and do not constitute an inappropriate limitation to the utility model, and in the drawings:

[0019] Figure 1 is a plating layer structure schematic view of the utility model embodiment 1 and embodiment 2. DETAILED DESCRIPTION

[0020] The utility model will be described in detail below in combination with the drawings and specific embodiments, and the illustrative embodiments and the description of the utility model are used to explain the utility model, but do not serve as a limitation to the utility model.

[0021] The aluminum alloy part base body is sequentially subjected to pretreatment, chemical zinc deposition, cyanide-free copper-zinc alloy plating, potassium chloride zinc plating, trivalent chromium olive green passivation, and hydroxyl graphene modified sealing agent sealing.

[0022] The current pretreatment process is used to remove oil, film, light and weak corrosion from the aluminum alloy base.

[0023] The chemical zinc layer is prepared by using the current aluminum alloy chemical zinc plating agent:

[0024] Preferably, the chemical zinc layer is prepared by using ALBUME AS-699 cyanide-free zinc plating process on aluminum from Superbond Chemical Industry:

[0025] ALBUME AS-699 cyanide-free zinc plating agent on aluminum 150-170 mL / L, zinc ion content in working solution 6-9 g / L, copper ion content 0.16-0.20 g / L, operating temperature 20-30℃, zinc plating time 60-120 s.

[0026] Preferably, the chemical zinc layer is prepared by using AZIN-113 acidic zinc plating agent on aluminum from Superbond Chemical Industry:

[0027] AZIN-113 acidic zinc plating agent on aluminum 50-250 mL / L, working temperature 15-30℃, zinc plating solution pH value 3.4-4.2, zinc plating time 20-80 s.

[0028] The process flow of the chemical zinc plating is: first zinc plating → water washing → zinc removal → water washing → second zinc plating → water washing.

[0029] The cyanide-free copper-zinc alloy plating layer is prepared by using the current polymeric thiocyanate copper-zinc alloy plating process.

[0030] Preferably, the thickness of the cyanide-free copper-zinc alloy plating layer is 3-8 μm.

[0031] Preferably, the cyanide-free copper-zinc alloy plating layer is prepared by using the following polymeric thiocyanate copper-zinc alloy plating process:

[0032] Polymeric cuprous thiocyanate 18-25 g / L, polymeric zinc thiocyanate 8-12 g / L, polymeric sodium thiocyanate 125-175 g / L, ammonium chloride 3-5 g / L, plating solution pH value 9.5-11.5, plating bath temperature 35-45℃, cathode current density 0.5-1.5 A / dm 2 , cathode moving speed 3-5 m / min, and using brass plate as anode.

[0033] The potassium chloride zinc plating layer is prepared by using the current third-generation potassium chloride zinc plating process.

[0034] Preferably, the thickness of the potassium chloride zinc plating layer is 8-16 μm.

[0035] Preferably, the potassium chloride zinc plating layer is prepared by using DETRONZIN 401 potassium chloride zinc plating process from Superbond Chemical Industry:

[0036] Zinc chloride 60-70 g / L, potassium chloride 180-220 g / L, boric acid 25-35 g / L, DETRONZIN 401 brightener 0.8-1.5 mL / L, DETRONZIN 401 softener 25-35 mL / L, plating bath temperature 15-30℃, plating bath pH value 4.8-5.6, cathode current density 2.0-4.0 A / dm 2 .

[0037] Preferably, the potassium chloride zinc plating layer is prepared by using DETRONZIN 406 low-foaming potassium chloride zinc plating process of Superbond Chemical Industry Co., Ltd.:

[0038] Zinc chloride 60-70 g / L, potassium chloride 180-220 g / L, boric acid 27-33 g / L, DETRONZIN 406 brightener 0.5-1.5 mL / L, DETRONZIN 406 softener 25-35 mL / L, plating bath temperature 15-30℃, plating bath pH value 5.0-5.5, cathode current density 2.0-4.0 A / dm 2 .

[0039] The trivalent chromium olive green passivation film is prepared by using the existing trivalent chromium olive green passivation process.

[0040] Preferably, the trivalent chromium olive green passivation film is prepared by using TRIROS 723 trivalent chromium olive green passivation process of Superbond Chemical Industry Co., Ltd.:

[0041] TRIROS 723 A agent 80-120 mL / L, TRIROS 723 B agent 100-140 mL / L, passivation bath pH value 1.3-2.3, operation temperature 20-30℃, air agitation or swing plating, passivation time 30-60 s.

[0042] The high corrosion-resistant sealing layer is prepared by using PRODICO 480 graphene sealing agent of Superbond Chemical Industry Co., Ltd.:

[0043] The PRODICO 480 graphene sealing agent is diluted with water to 2.5-3.2 times to prepare a sealing solution;

[0044] The plated workpiece is immersed in the sealing solution for 5-15 s, drained after taking out of the tank, and the residual sealing solution on the surface of the plated workpiece is blown off by high-pressure air;

[0045] The plated workpiece is dried and cured at 70-90℃ for 20-35 min. Examples

[0046] As Figure 1As shown, a plating structure of zinc plating on cyanide-free copper-zinc alloy undercoat plating layer includes an aluminum alloy base 1, and a chemical zinc deposition layer 2, a cyanide-free copper-zinc alloy plating layer 3, a potassium chloride zinc plating layer 4, a trivalent chromium olive green passivation film 5, and a high corrosion-resistant sealing layer 6 prepared on the aluminum alloy base 1 from inside to outside.

[0047] 1. Pretreatment:

[0048] The current pretreatment process is used for the aluminum alloy base 1, i.e. "chemical oil removal → water washing → ultrasonic oil removal → water washing → alkali corrosion → water washing → lightening → water washing → micro corrosion → water washing".

[0049] 2. Chemical zinc deposition:

[0050] The ALBUME AS-699 cyanide-free zinc deposition agent of Superbond Chemical Industry is used to prepare the chemical zinc deposition layer 2 on the pretreated aluminum alloy.

[0051] The ALBUME AS-699 cyanide-free zinc deposition agent is 155 mL / L, the working solution contains 7 g / L of zinc ions and 0.18 g / L of copper ions, the operation temperature is 28℃, and the zinc deposition time is 100 s.

[0052] The process flow is: first zinc deposition → water washing → zinc removal → water washing → second zinc deposition → water washing.

[0053] 3. Cyanide-free copper-zinc alloy plating:

[0054] The cyanide-free copper-zinc alloy plating layer 3 with a thickness of 5 μm is prepared on the pretreated aluminum alloy by using the following polythiocyanate copper-zinc alloy plating process.

[0055] The polythiocyanate copper 20 g / L, polythiocyanate zinc 9 g / L, polythiocyanate sodium 140 g / L, and ammonium chloride 4 g / L, the plating solution pH is 10.5, the plating bath temperature is 40℃, the cathode current density is 1.0 A / dm 2 , the cathode moves at a speed of 4 m / min, and a brass plate is used as the anode.

[0056] 4. Potassium chloride zinc plating:

[0057] The DETRONZIN 401 potassium chloride zinc plating process of Superbond Chemical Industry is used to prepare the potassium chloride zinc plating layer 4 with a thickness of 12 μm on the cyanide-free copper-zinc alloy plated aluminum alloy.

[0058] Zinc chloride 65 g / L, potassium chloride 200 g / L, boric acid 30 g / L, DETRONZIN 401 brightener 1 mL / L, and DETRONZIN 401 softener 30 mL / L, the plating bath temperature is 25℃, the plating solution pH is 5.2, and the cathode current density is 3 A / dm 2 .

[0059] 5. Passivation:

[0060] The trivalent chromium olive green passivation film 5 was prepared on the potassium chloride zinc plated aluminum alloy part by using the RIROS 723 trivalent chromium olive green passivation process of Superbond Chemical Industry.

[0061] The TRIROS 723 A agent was 100 mL / L, the TRIROS 723 B agent was 120 mL / L, the passivation liquid pH was 2.0, the operation temperature was 25°C, the plated part was swung, and the passivation time was 45 s.

[0062] 6. Sealing:

[0063] The high corrosion-resistant sealing layer 6 was prepared on the trivalent chromium olive green passivated aluminum alloy part by using the PRODICO 480 graphene sealing agent of Superbond Chemical Industry, and the sealing layer thickness was 1.2 μm.

[0064] The PRODICO 480 graphene sealing agent was diluted with water to 2.8 times to prepare a sealing liquid;

[0065] The plated part was immersed in the sealing liquid for 8 s, drained after being taken out of the tank, and the residual sealing liquid on the surface of the plated part was blown away by high-pressure air;

[0066] The plated part was dried and cured at 80°C for 30 min. Example

[0067] As shown in Figure 1 A plated layer structure of zinc plating on a cyanide-free copper-zinc alloy undercoat layer, comprising an aluminum alloy base 1, and a chemical zinc deposition layer 2, a cyanide-free copper-zinc alloy plating layer 3, a potassium chloride zinc plating layer 4, a trivalent chromium olive green passivation film 5, and a high corrosion-resistant sealing layer 6 prepared in sequence from inside to outside on the aluminum alloy base 1.

[0068] 1. Pretreatment:

[0069] The current pretreatment process was used to perform “chemical oil removal → water washing → ultrasonic oil removal → water washing → alkali corrosion → water washing → lightening → water washing → micro corrosion → water washing” on the aluminum alloy part base 1.

[0070] 2. Chemical zinc deposition:

[0071] The chemical zinc deposition layer 2 was prepared on the pretreated aluminum alloy part by using the AZIN-113 acidic aluminum zinc deposition agent of Superbond Chemical Industry.

[0072] The AZIN-113 acidic aluminum zinc deposition agent was 150 mL / L, the working temperature was 25°C, the zinc deposition liquid pH was 3.8, and the zinc deposition time was 50 s.

[0073] The process flow was: first zinc deposition → water washing → zinc removal → water washing → second zinc deposition → water washing.

[0074] 3. Cyanide-free copper-zinc alloy plating:

[0075] A cyanide-free copper-zinc alloy plating layer 3 with a thickness of 5 μm is prepared on the pretreated aluminum alloy part by using the following polythiocyanate copper-zinc alloy plating process.

[0076] Polythiocyanate copper 23 g / L, polythiocyanate zinc 11 g / L, polythiocyanate sodium 165 g / L, ammonium chloride 4 g / L, plating bath pH 10.5, plating bath temperature 40°C, cathode current density 1.0 A / dm 2 , cathode moving speed 4 m / min, and using brass plate as anode.

[0077] 4. Zinc plating:

[0078] A potassium chloride zinc plating layer 4 with a thickness of 12 μm is prepared on the cyanide-free copper-zinc alloy plated aluminum alloy part by using DETRONZIN 406 low-foam potassium chloride zinc plating process of Superbond Chemicals.

[0079] Zinc chloride 65 g / L, potassium chloride 210 g / L, boric acid 30 g / L, DETRONZIN 406 brightener 1 mL / L, DETRONZIN 406 softener 30 mL / L, plating bath temperature 25°C, plating bath pH 5.2, cathode current density 3 A / dm 2 .

[0080] 5. Passivation:

[0081] A trivalent chromium olive green passivation film 5 is prepared on the potassium chloride zinc plated aluminum alloy part by using RIROS 723 trivalent chromium olive green passivation process of Superbond Chemicals.

[0082] TRIROS 723 A agent 120 mL / L, TRIROS 723 B agent 140 mL / L, passivation bath pH 1.6, operating temperature 25°C, air agitation, and passivation time 38 s.

[0083] 6. Sealing:

[0084] A high corrosion-resistant sealing layer 6 with a thickness of 1.2 μm is prepared on the trivalent chromium olive green passivated aluminum alloy part by using PRODICO 480 graphene sealing agent of Superbond Chemicals.

[0085] The PRODICO 480 graphene sealing agent is diluted with water to 2.8 times to prepare a sealing solution;

[0086] The plated part is immersed in the sealing solution for 12 s, drained after taken out of the tank, and the residual sealing solution on the surface of the plated part is blown off with high-pressure air;

[0087] The plated part is dried and cured at 75°C for 35 min.

[0088] Test Example 1:

[0089] The galvanized sample of the aluminum alloy piece prepared in the embodiment 1 and the embodiment 2 is heated to 220 DEG C in a heating furnace for 30 min, and is taken out and rapidly cooled in water at room temperature, and the coating does not appear to bubble and fall off, and the bonding force is good.

[0090] Test example 2:

[0091] The galvanized sample of the aluminum alloy piece prepared in the embodiment 1 and the embodiment 2 is heated to 220 DEG C in a heating furnace for 30 min, and is taken out and rapidly cooled in water at room temperature, and the coating does not appear to bubble and fall off, and the bonding force is good.

[0092] The above describes the technical solutions provided by the embodiments of the present application in detail, and the principles and implementation manners of the embodiments of the present application are described by applying specific examples. The above description of the embodiments is only applicable to helping understand the principles of the embodiments of the present application. It should be noted that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application.

Claims

1. A plating structure for plating zinc on a cyanide-free copper-zinc alloy undercoat plating layer, characterized by: The zinc-alloy coating is prepared on the aluminum alloy substrate by a cyanide-free copper-zinc alloy plating process. The cyanide-free copper-zinc alloy plating layer is prepared by a polymeric thiocyanate copper-zinc alloy plating process. The high-corrosion-resistance sealing layer is prepared by a hydroxyl graphene modified sealing agent.

2. The plating structure for plating zinc on a cyanide-free copper-zinc alloy underlayer according to Claim 1, characterized by: The thickness of the cyanide-free copper-zinc alloy plating layer is 3-8 μm.

3. The plating structure for plating zinc on a cyanide-free copper-zinc alloy underlayer as recited in claim 1, wherein: The thickness of the potassium chloride zinc plating layer is 8-15 μm.

4. The plating structure for plating zinc on a cyanide-free copper-zinc alloy underlayer according to Claim 1, wherein: The thickness of the high-corrosion-resistance sealing layer is 0.8-1.5 μm.

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