Cyanide-free gold-imitating plating layer structure of aluminum alloy part

Abstract

The utility model discloses a cyanide-free imitation gold plating layer structure of an aluminum alloy part, which comprises an aluminum alloy substrate, and a chemical zinc deposition layer, a citrate pre-nickel plating layer, a nickel-copper alloy plating layer, a bright nickel plating layer, a cyanide-free imitation gold plating layer and an electrophoretic varnish coating which are sequentially prepared on the aluminum alloy substrate from inside to outside. According to the cyanide-free gold-imitating plating layer structure of the aluminum alloy part disclosed by the utility model, the binding force of the plating layer is tested by a thermal shock method according to the GB / T 5270-2005'metal covering layer electro-deposition and chemical deposition layer adhesion strength test method on a metal matrix ', the binding force meets the standard requirement, an acetate fog test is carried out for 168 hours according to the GB / T 10125-2021'artificial atmosphere corrosion test and salt spray test', and the binding force meets the standard requirement. And no red corrosives are generated on the surface of a plated part, and the plating layer structure has good corrosion resistance.

Description

TECHNICAL FIELD

[0001] The utility model belongs to metal surface treatment technical field, concretely relates to a kind of gold-like cyanide-free plating of aluminium alloy piece. BACKGROUND

[0002] Gold-like plating layer is bright in color, and is a decorative plating layer used to replace gold plating layer, mainly applied to the surface plating layer of metal accessories such as watches, glasses, and shoulder bags. The traditional method usually uses cyanide plating gold-like process to prepare gold-like plating layer. Since the use of cyanide is strictly controlled in China, it is imperative to develop cyanide-free plating gold-like process.

[0003] Nickel-copper alloy plating layer has good mechanical properties, corrosion resistance, and electrical and catalytic properties. Electroplated nickel-copper alloy has received increasing attention from domestic peers [1] . Nickel-copper alloy plating layer has better performance than nickel plating layer and copper plating layer.

[0004] According to the traditional process method, after chemical zinc deposition of the aluminum alloy piece, a pre-copper plating layer is prepared by cyanide copper plating process, and then a bottom copper plating layer is prepared by pyrophosphate copper plating and acid copper plating. The bivalent copper cyanide-free copper plating process developed for many years still has some gaps compared with cyanide copper plating, and there are still some problems to be solved in replacing cyanide copper plating [2] .

[0005] According to the traditional process, gold-like plating layer needs to be treated by chromate electrolysis protection or sprayed with organic varnish for protection, and both methods have pollution problems to be solved.

[0006] Reference: [1]. Yang Ruikong, Li Mingtian, Wang Ying, et al. Influence of process parameters on composition and phase structure of electroplated nickel-copper alloy plating layer [J]. Electroplating and Finishing, 2014, 33(15): 633-635. [2]. Qin Zuozu, Li Jian San, Xu Jinlai. Research progress of cyanide-free copper plating process at home and abroad [J]. Electroplating and Finishing, 2015, 34(3): 149-152. SUMMARY

[0007] In order to solve the high pollution problem of cyanide plating gold-like, the utility model provides a kind of gold-like cyanide-free plating of aluminium alloy piece plating layer structure. In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0008] A kind of gold-like cyanide-free plating of aluminium alloy piece plating layer structure, including aluminium alloy base body, and chemical zinc deposition layer, citrate pre-plating nickel layer, nickel-copper alloy plating layer, bright nickel plating layer, cyanide-free gold-like plating layer and electrophoretic varnish coating layer prepared in order from inside to outside on the aluminium alloy base body;

[0009] The cyan-free imitation gold plating layer is prepared by adopting the polymeric thiocyanate copper-zinc alloy plating process, and the plating layer thickness is 0.1-0.2 microns.

[0010] Preferably, the thickness of the citrate pre-nickel plating layer is 1-4 microns.

[0011] Preferably, the thickness of the nickel-copper alloy plating layer is 6-12 microns.

[0012] Preferably, the thickness of the bright nickel plating layer is 3-8 microns.

[0013] Preferably, the thickness of the electrophoretic varnish coating layer is 10-18 microns.

[0014] The corrosion resistance of the nickel-copper alloy plating layer is far higher than that of the copper plating layer, and the traditional bottom copper plating layer is replaced by the nickel-copper alloy plating layer, so that the corrosion resistance and other performances of the plating layer can be significantly improved. The electrode potential of the bright nickel plating layer is obviously lower than that of the nickel-copper alloy plating layer, and the nickel-copper alloy plating layer has the electrochemical protection effect, so that the corrosion of the corrosion medium to the aluminum alloy substrate can be effectively prevented.

[0015] Compared with the prior art, the utility model has the following beneficial effects:

[0016] 1. The plating layer structure of the aluminum alloy part cyan-free imitation gold plating adopts the polymeric thiocyanate imitation gold plating process to prepare the imitation gold plating layer, and the high pollution problem of the cyanide imitation gold plating is overcome.

[0017] 2. The plating layer structure of the aluminum alloy part cyan-free imitation gold plating adopts the citrate nickel plating process to preplate nickel, and the high pollution problem of the cyanide pre-copper plating process is overcome.

[0018] 3. The plating layer structure of the aluminum alloy part cyan-free imitation gold plating prepares the electrophoretic varnish coating layer on the cyan-free imitation gold plating layer, can significantly increase the protective decorative effect of the imitation gold plating layer, and the pollution problem of the traditional chromate electrolytic protection method and the organic spraying method is overcome. BRIEF DESCRIPTION OF DRAWINGS

[0019] The drawings described herein are used to provide further understanding of the utility model and form part of the present application, and do not constitute undue limitation on the utility model, and in the drawings:

[0020] Figure 1 It is the plating layer structure schematic view of the embodiment 1 and the embodiment 2 of the utility model. DETAILED DESCRIPTION

[0021] 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 constitute the limitation on the utility model.

[0022] A cyanide-free gold-imitating plated layer structure of an aluminum alloy part, which comprises the following steps: pretreatment of an aluminum alloy substrate, and sequentially preparing a chemical zinc deposition layer, a citrate pre-nickel plating layer, a nickel-copper alloy plating layer, a bright nickel plating layer, a cyanide-free gold-imitating plating layer, and an electrophoretic varnish coating layer on the aluminum alloy substrate from inside to outside.

[0023] The current pretreatment process is used to remove oil, alkali corrosion, lightening, and micro-corrosion from the aluminum alloy part substrate.

[0024] The current aluminum alloy chemical zinc deposition agent is used to prepare a chemical zinc deposition layer.

[0025] Preferably, the chemical zinc deposition layer is prepared using the ALBUME AS-699 cyanide-free zinc deposition agent of Superbond Chemicals:

[0026] The ALBUME AS-699 cyanide-free zinc deposition agent is 150-170 mL / L, the working solution contains 6-9 g / L of zinc ions and 0.16-0.20 g / L of copper ions, the operating temperature is 20-30°C, and the zinc deposition time is 60-120 s.

[0027] The process flow is: first zinc deposition → water washing → zinc removal → water washing → second zinc deposition → water washing.

[0028] The current citrate nickel plating process is used to prepare a citrate pre-nickel plating layer.

[0029] Preferably, the thickness of the citrate pre-nickel plating layer is 1-4 μm.

[0030] Preferably, the citrate pre-nickel plating layer is prepared using the following citrate nickel plating process:

[0031] 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, plating solution pH value 7.0-7.2, plating bath temperature 50-60°C, cathode current density 1-1.5 A / dm 2 , and cathode moving speed 4-6 m / min.

[0032] The current nickel-copper alloy plating process is used to prepare a nickel-copper alloy plating layer.

[0033] Preferably, the thickness of the nickel-copper alloy plating layer is 6-12 μm.

[0034] Preferably, the nickel-copper alloy plating layer is prepared using the Nistar 6070 bright nickel-copper alloy plating process of Superbond Chemicals:

[0035] Nickel sulfate hexahydrate 180-220 g / L, copper sulfate pentahydrate 8-12 g / L, trisodium citrate 50-70 g / L, disodium hydroxyethylidene diphosphonate 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, temperature of plating bath 50-55 °C, cathode current density 2.6-3.2 A / dm 2 Cathode moving speed 3-5 m / min.

[0036] The bright nickel plating layer is prepared by using the current bright nickel plating process.

[0037] Preferably, the thickness of the bright nickel plating layer is 3-8 μm.

[0038] The cyanide-free imitation gold plating layer is prepared by using the following polymeric thiocyanate imitation gold plating process.

[0039] Preferably, the thickness of the imitation gold plating layer is 0.1-0.2 μm.

[0040] Polymeric cuprous thiocyanate 18-25 g / L, polymeric zinc thiocyanate 8-10.5 g / L, polymeric sodium thiocyanate 125-175 g / L, ammonium chloride 3-5 g / L, pH value of plating solution 9.5-11.5, temperature of plating bath 35-45 °C, cathode current density 0.5-1.5 A / dm 2 Cathode moving speed 3-5 m / min, and using brass plate as anode.

[0041] The electrophoretic clear coating is prepared by using the current electrophoretic coating process.

[0042] Preferably, the thickness of the electrophoretic clear coating is 10-18 μm.

[0043] Preferably, the electrophoretic clear coating is prepared by using the AKINI 120 electrophoretic coating process of Super Bond Chemicals:

[0044] AKINI 120 electrophoretic paint 300-350 g / L, pH value of tank solution 4-5, operating temperature 25-30 °C, tank voltage 30-50 V, using plated part as cathode and titanium plate as anode, and coating is dried and cured at 120-140 °C for 20-30 min. Example 1

[0045] As Figure 1As shown, a cyanide-free gold-like plated coating structure of an aluminum alloy part comprises an aluminum alloy base 1, and a chemical zinc deposition layer 2, a citrate pre-plated nickel layer 3, a nickel-copper alloy plating layer 4, a bright nickel plating layer 5, a cyanide-free gold-like plating layer 6, and an electrophoretic varnish coating 7 prepared on the aluminum alloy base 1 from inside to outside.

[0046] 1. Pretreatment:

[0047] The current pretreatment process is used to pretreat 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".

[0048] 2. Chemical zinc deposition:

[0049] The ALBUME AS-699 cyanide-free zinc deposition agent of Superbond Chemical Industry is used to prepare the chemical zinc deposition layer 2 after the pretreatment of the aluminum alloy part.

[0050] 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.

[0051] The process flow is: first zinc deposition → water washing → zinc removal → water washing → second zinc deposition → water washing.

[0052] 3. Citrate nickel plating:

[0053] The following citrate nickel plating process is used to prepare the citrate pre-plated nickel layer 3 after the pretreatment of the aluminum alloy part, and the plating layer thickness is 2 μm.

[0054] Nickel sulfate hexahydrate 180 g / L, sodium chloride 10 g / L, boric acid 30 g / L, magnesium sulfate 30 g / L, plating solution pH 7.1, plating bath temperature 53℃, cathode current density 1.2 A / dm 2 , cathode moving speed 5 m / min.

[0055] 4. Nickel-copper alloy plating:

[0056] The Nistar 6070 bright nickel-copper alloy plating process of Superbond Chemical Industry is used to prepare the nickel-copper alloy plating layer 4 after the citrate nickel plating of the aluminum alloy part, and the plating layer thickness is 8 μm.

[0057] Nickel sulfate hexahydrate 200 g / L, copper sulfate pentahydrate 10 g / L, trisodium citrate 60 g / L, disodium hydroxyethylidene diphosphonate 25 g / L, boric acid 32 g / L, sodium chloride 7 g / L, NISTAR 6070 brightener 0.4 mL / L, NISTAR 6071 auxiliary agent 8 mL / L, NI-35 wetting agent 0.7 mL / L, plating solution pH 4.6, plating bath temperature 53℃, cathode current density 3 A / dm 2Cathode moving speed: 4 m / min.

[0058] 5. Bright nickel plating:

[0059] After the aluminum alloy part is plated with nickel-copper alloy, a bright nickel plating layer 5 is prepared by using the current bright nickel plating process, and the thickness of the plating layer is 6 μm.

[0060] 6. Cyanide-free imitation gold plating:

[0061] After the aluminum alloy part is plated with bright nickel, a cyanide-free imitation gold plating layer 6 is prepared by using the following polythiocyanate imitation gold plating process, and the thickness of the plating layer is 0.15 μm.

[0062] Polythiocyanate copper 24 g / L, polythiocyanate zinc 10 g / L, polythiocyanate sodium 160 g / L, ammonium chloride 4.2 g / L, pH of the plating solution 9.7, temperature of the plating bath 38 ℃, cathode current density 1.0 A / dm 2 , cathode moving speed 4 m / min, and a brass plate is used as the anode.

[0063] 7. Electrophoretic painting:

[0064] After the aluminum alloy part is plated with cyanide-free imitation gold, an electrophoretic clear paint coating 7 is prepared by using the AKINI 120 electrophoretic coating process of Superbang Chemicals, and the thickness of the coating is 15 μm.

[0065] AKINI 120 electrophoretic paint 340 g / L, pH of the bath 4.3, operating temperature 26 ℃, bath voltage 40 V, the plated part is used as the cathode, and a titanium plate is used as the anode.

[0066] 8. Drying and curing:

[0067] After the aluminum alloy part is electrophoretically painted, it is dried and cured at 135 ℃ for 20 min. Example 2

[0068] As shown in Figure 1 FIG. 1, a plating layer structure of an aluminum alloy part plated with cyanide-free imitation gold includes an aluminum alloy base 1, and a chemical zinc deposition layer 2, a citrate pre-nickel plating layer 3, a nickel-copper alloy plating layer 4, a bright nickel plating layer 5, a cyanide-free imitation gold plating layer 6, and an electrophoretic clear paint coating 7 prepared in sequence from inside to outside on the aluminum alloy base 1.

[0069] 1. Pretreatment:

[0070] The current pretreatment process is 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.

[0071] 2. Chemical zinc deposition:

[0072] The chemical zinc coating 2 was prepared by using the ALBUME AS-699 cyanide-free zinc plating agent of Superbond Chemical Industry Co., Ltd. on the pretreated aluminum alloy part.

[0073] The ALBUME AS-699 cyanide-free zinc plating agent 165 mL / L, the working solution containing 8 g / L of zinc ions and 0.19 g / L of copper ions, the operation temperature 25 ℃, and the zinc plating time 100 s.

[0074] The process flow is: first zinc plating → water washing → zinc stripping → water washing → second zinc plating → water washing.

[0075] 3. Citrate nickel plating:

[0076] The citrate pre-nickel coating 3 with a thickness of 2 μm was prepared by using the following citrate nickel plating process on the aluminum alloy part after the chemical zinc plating.

[0077] Nickel sulfate hexahydrate 250 g / L, sodium chloride 12 g / L, boric acid 35 g / L, magnesium sulfate 40 g / L, the plating solution pH 7.1, the plating bath temperature 55 ℃, cathode current density 1.2 A / dm 2 , cathode moving speed 5 m / min.

[0078] 4. Nickel-copper alloy plating:

[0079] The nickel-copper alloy coating 4 with a thickness of 8 μm was prepared by using the Nistar 6070 bright nickel-copper alloy plating process of Superbond Chemical Industry Co., Ltd. on the aluminum alloy part after the citrate nickel plating.

[0080] Nickel sulfate hexahydrate 190 g / L, copper sulfate pentahydrate 9 g / L, trisodium citrate 55 g / L, disodium hydroxyethylidene diphosphonate 25 g / L, boric acid 30 g / L, sodium chloride 6 g / L, NISTAR 6070 brightener 0.5 mL / L, NISTAR 6071 auxiliary agent 8 mL / L, NI-35 wetting agent 0.6 mL / L, the plating solution pH 4.5, the plating bath temperature 52 ℃, cathode current density 2.7 A / dm 2 , cathode moving speed 5 m / min.

[0081] 5. Bright nickel plating:

[0082] The bright nickel coating 5 with a thickness of 6 μm was prepared by using the existing bright nickel plating process on the aluminum alloy part after the nickel-copper alloy plating.

[0083] 6. Cyanide-free imitation gold plating:

[0084] The cyanide-free imitation gold coating 6 with a thickness of 0.15 μm was prepared by using the following polythiocyanate imitation gold plating process on the aluminum alloy part after the bright nickel plating.

[0085] Polymeric cuprous thiocyanate 19 g / L, polymeric zinc thiocyanate 8.5 g / L, polymeric sodium thiocyanate 140 g / L, ammonium chloride 3.8 g / L, pH of plating solution 10.2, temperature of plating bath 42℃, cathode current density 1.0 A / dm 2 , cathode moving at 4 m / min, and using a brass plate as anode.

[0086] 7. Electrophoretic painting:

[0087] The cyanide-free gold-imitated plated aluminum alloy parts were prepared with the electrophoretic clear coating 7 of AKINI 120 of Superb Chemical Co., Ltd. in a thickness of 15 μm.

[0088] AKINI 120 electrophoretic paint 310 g / L, pH of bath 4.7, operating temperature 28℃, bath voltage 40 V, using plated parts as cathode and titanium plate as anode.

[0089] 8. Drying and curing:

[0090] The electrophoretically painted aluminum alloy parts were dried and cured at 125℃ for 30 min.

[0091] Test Example 1:

[0092] The cyanide-free gold-imitated plated aluminum alloy parts prepared in Example 1 and Example 2 were subjected to acetic acid salt spray test according to GB / T 10125–2021 “Artificial Atmosphere Corrosion Test Salt Spray Test” for 168 h, and no rust was observed on the surface of the plated parts, which was much higher than the requirement of GB / T 9797–2022 “Metallic Coating Layer Nickel + Chromium and Copper + Nickel + Chromium Electroplated Layer” for no rust for 48 h.

[0093] Test Example 2:

[0094] The cyanide-free gold-imitated plated aluminum alloy parts prepared in Example 1 and Example 2 were tested for coating adhesion by thermal shock method according to GB / T 5270–2005 “Metallic Coating Layer on Metal Substrate Electrodeposited and Chemically Deposited Layer Test Method for Adhesion Strength”, i.e. the plated parts were heated to 180℃ in a heating furnace for 30 min, and then were taken out and quenched in water at room temperature. No blistering and peeling of the coating was observed, and the prepared coating structure had good adhesion.

[0095] Test Example 3:

[0096] The cyanide-free gold-imitated plated aluminum alloy parts prepared in Example 1 and Example 2 were tested according to GB / T 2423.3-2016 “Basic Environmental Test Procedures for Electrical and Electronic Products Test Ca: Constant Temperature and Humidity Test Method” at a temperature of 40℃ and a relative humidity of 93% for 600 h, and no visible change in the appearance of the coating was observed, and the prepared coating structure had good discoloration resistance.

[0097] The technical solutions provided by the embodiments of the present application are described in detail above, 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 pointed out 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, and these all belong to the protection scope of the present application.

Claims

1. A cyanide-free gold-plating coating structure for aluminum alloy parts, characterized in that: It includes an aluminum alloy substrate, and chemical zinc plating, citrate pre-plated nickel plating, nickel-copper alloy plating, bright nickel plating, cyanide-free imitation gold plating, and electrophoretic varnish coating, which are sequentially prepared from the inside to the outside on the aluminum alloy substrate. The cyanide-free imitation gold plating is an imitation gold plating prepared by a polymeric thiocyanate copper-zinc alloy plating process, with a plating thickness of 0.1–0.2 μm.

2. The cyanide-free gold plating structure for aluminum alloy parts as described in claim 1, characterized in that: The thickness of the citrate pre-plated nickel layer is 1–4 μm.

3. The cyanide-free gold plating structure for aluminum alloy parts as described in claim 1, characterized in that: The thickness of the nickel-copper alloy coating is 6–12 μm.

4. The cyanide-free gold plating structure for aluminum alloy parts as described in claim 1, characterized in that: The thickness of the bright nickel plating is 3–8 μm.

5. The cyanide-free gold plating structure for aluminum alloy parts as described in claim 1, characterized in that: The thickness of the electrophoretic varnish coating is 10–18 μm.

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