Nickel-free gold-substituted plating layer structure for pre-plating copper with polythiocyanate

Abstract

The utility model discloses a nickel-free gold-substituted plating layer structure with polythiocyanate pre-plated copper, which comprises a steel substrate, and a polythiocyanate pre-plated copper layer, an acid copper plating layer, a cupronickel tin plating layer, a gold-substituted plating layer and a nano polymer protective film which are sequentially prepared on the steel substrate from inside to outside. According to the nickel-free gold-substituted plating layer structure for pre-plating copper with polythiocyanate, 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, the binding force meets the standard requirement, and the plating layer can be used as a plating layer for plating copper with polythiocyanate, so that the nickel-free gold-substituted plating layer structure for pre-plating copper with polythiocyanate can be used as a plating layer for plating copper. According to an acetate fog test carried out for 72 hours 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 in particular relates to a nickel-free gold-substituting plating structure using polymerized thiocyanate as the pre-copper plating. Background Art

[0002] Copper-tin-zinc alloy plating with a tin content of 13% to 15% has a golden color similar to 18K to 24K gold. It is often used as a gold substitute and is highly favored by customers. Copper-tin-zinc alloy gold substitute has the characteristics of low porosity, realistic color, excellent corrosion resistance, and appropriate hardness. It can prevent the diffusion of the underlying metal to the surface layer and prevent the metal plating from discoloring. It is now widely used in lighting, furniture, luggage, clocks, jewelry, daily hardware, construction and other industries. [1] .

[0003] The traditional process of gold plating on steel parts is usually to perform cyanide copper plating, pyrophosphate copper plating, acid copper plating, bright nickel plating, gold plating, chromate electrolytic protection or painting on the steel substrate in sequence.

[0004] Gold plating on bright nickel layer provides perfect appearance.

[0005] References: [1] Huang Lingfei, Zeng Zhenou, Xie Jinping et al., Research on additives for cyanide-free copper-tin alloy imitation gold electroplating[J], Surface Technology, 2015, 34(11): 589-594. Utility Model Content

[0006] In order to solve the problem of skin allergies caused by nickel plating, the utility model provides a nickel-free gold plating structure with pre-copper plating using polythiocyanate. In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A nickel-free gold-substitute coating structure using polymerized thiocyanate pre-plated copper comprises a steel substrate, and a polymerized thiocyanate pre-plated copper layer, an acid copper coating layer, a white copper-tin coating layer, a gold-substitute coating layer, and a nano-polymer protective film, which are sequentially prepared on the steel substrate from the inside out.

[0008] The gold-substitute coating is a coating prepared by a copper-tin-zinc ternary alloy plating process, and the coating thickness is 0.1 to 0.5 μm;

[0009] The thickness of the polymerized thiocyanate pre-plated copper layer is 1 to 6 μm.

[0010] Preferably, the thickness of the acid copper plating layer is 8 to 24 μm.

[0011] Preferably, the thickness of the white copper tin plating layer is 2 to 8 μm.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. The nickel-free gold-plating structure of the polythiocyanate pre-copper plating disclosed in the utility model adopts a white copper tin plating layer instead of a bright nickel plating layer, thereby overcoming the skin allergy problem caused by the nickel plating layer;

[0014] 2. The nickel-free gold-substitute coating structure disclosed in the utility model is pre-plated with copper using polymeric thiocyanate, and a nano-polymer protective film is prepared on the gold-substitute coating, which overcomes the pollution problem of traditional chromate electrolytic protection or spray painting. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of this application, and do not constitute an improper limitation of the present invention. In the drawings:

[0016] Figure 1 It is a schematic diagram of the coating structure of Example 1 and Example 2 of the present utility model. DETAILED DESCRIPTION

[0017] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The schematic embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0018] A nickel-free gold-substitute coating structure using polymerized thiocyanate pre-copper plating comprises the following steps: preparing a polymerized thiocyanate pre-copper coating, an acid copper coating, a white copper-tin coating, a gold-substitute coating, and a nano-polymer protective film on a steel substrate in sequence from the inside out.

[0019] The steel substrate is degreased, derusted, and activated using the current pre-treatment process.

[0020] The polythiocyanate pre-copper plating layer is prepared by adopting the current polythiocyanate copper plating process.

[0021] Preferably, the thickness of the polythiocyanate pre-copper plating layer is 1 to 6 μm.

[0022] Preferably, the polythiocyanate pre-copper plating layer is prepared using Zunyi Huitong's HT-810 polythiocyanate copper plating process:

[0023] Polycuprous thiocyanate 17-23 g / L, sodium polythiocyanate 100-160 g / L, potassium sodium tartrate 8-12 g / L, HT-810 brightener 1-2 mL / L, HT-810 moving agent 2-4 mL / L, plating tank temperature 45°C-55°C, plating solution pH 12-13, cathode current density 0.5-1.0 A / dm 2 , cathode movement 4~6m / min, anode current density ≤0.5A / dm 2, use oxygen-free electrolytic copper corners (or copper particles) as anodes.

[0024] The acid copper plating layer is prepared by adopting the current acid copper plating process.

[0025] Preferably, the thickness of the acid copper plating layer is 8 to 24 μm.

[0026] The white copper tin plating layer is prepared by adopting the current white copper tin plating process.

[0027] Preferably, the thickness of the white copper tin plating layer is 2 to 8 μm.

[0028] Preferably, the white copper tin coating is prepared using the ASELY CTA-535 white copper tin coating process of Chaobang Chemical:

[0029] Potassium cyanide 60-95g / L, cuprous cyanide 12-20g / L, potassium hydroxide 5-20g / L, ASELY CTA-604 cupro-tin salt 50-65g / L, ASELY CTA-602 zinc supplement 12-25mL / L, ASELY CTA-535Initial cupro-tin starter 20-50mL / L, ASELY CTA-535Bri cupro-tin brightener 2-6mL / L, ASELY CTA-535WA cupro-tin wetting agent 0.5-5mL / L, plating solution pH 12.5-13.5, plating tank temperature 45℃-55℃, cathode current density 1.5-2.5A / dm 2 , the cathode moves 4 to 6 m / min.

[0030] The gold-substitute plating layer is prepared by adopting the current gold-substitute plating process.

[0031] Preferably, the thickness of the gold-substitute plating layer is 0.1 to 0.5 μm.

[0032] Preferably, the gold-substitute coating is prepared using Chaobang Chemical's YB-223 bright copper-tin-zinc gold-substitute coating process:

[0033] Potassium cyanide 50-80g / L, cuprous cyanide 18-25g / L, zinc cyanide 6-10g / L, potassium hydroxide 1-4g / L, CTA-604 tin salt 1-4g / L, CTA-606 Initial opener 80-120mL / L, CTA-606 Bri brightener 10-25mL / L, CTA-606 Carrier auxiliary 3-10mL / L, plating solution pH 12-13, plating tank temperature 48℃-60℃, cathode current density 0.6-1.8A / dm 2 , the cathode moves 4 to 6 m / min.

[0034] The nano polymer protective film is prepared by adopting the current nano polymer electrolytic protection process.

[0035] Preferably, the nano-polymer protective film is prepared using the PROTEZVY 1126 electrolytic protection process of Chaobang Chemical:

[0036] PROTEZVY 1126MUP opener 30-40 mL / L, PROTEZVY 1126ADDITIVE C 70-90 mL / L, sodium hydroxide 0.15-0.25 g / L, bath pH 3.4-4.0, operating temperature 55-65°C, cathode current density 0.05-0.1 A / dm 2 , electrolysis time 3 to 10 minutes.

[0037] After electroplating, the steel parts are dried according to conventional processes.

[0038] Example 1:

[0039] like Figure 1 As shown, a nickel-free gold-substitute coating structure with polythiocyanate pre-copper plating includes a steel substrate 1, and a polythiocyanate pre-copper plating layer 2, an acid copper plating layer 3, a white copper tin plating layer 4, a gold-substitute coating 5, and a nano-polymer protective film 6 prepared on the steel substrate 1 from the inside to the outside.

[0040] 1. Pre-treatment:

[0041] According to the current pre-treatment process, the steel substrate 1 is subjected to "alkaline chemical degreasing → water washing → acid washing → water washing → alkaline cathodic electrolytic degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → activation → water washing".

[0042] 2. Polythiocyanate copper plating:

[0043] The polythiocyanate pre-plated copper layer 2 was prepared on the pre-treated steel parts using the HT-810 polythiocyanate copper plating process of Zunyi Huitong, with a coating thickness of 3 μm.

[0044] Polythiocyanate cuprous acid 19g / L, polythiocyanate sodium 120g / L, potassium sodium tartrate 10g / L, HT-810 brightener 1.5mL / L, HT-810 moving agent 3mL / L, plating tank temperature 50℃, plating solution pH 12.8, cathode current density 0.8A / dm 2 , cathode movement 5m / min, anode current density 0.4A / dm 2 , use oxygen-free electrolytic copper corner as the anode.

[0045] 3. Acid copper plating:

[0046] An acid copper coating 3 was prepared on a steel part that had been copper-plated with polythiocyanate using a current acid copper plating process. The coating thickness was 16 μm.

[0047] 4. White copper tin plating:

[0048] A cupronickel-tin coating 4 was prepared on a steel part that had been plated with acid copper using the ASELY CTA-535 cupronickel-tin coating process of Chaobang Chemical. The coating thickness was 6 μm.

[0049] Potassium cyanide 80g / L, cuprous cyanide 17g / L, potassium hydroxide 15g / L, ASELY CTA-604 cupro-tin salt 60g / L, ASELY CTA-602 zinc supplement 19mL / L, ASELY CTA-535Initial cupro-tin opener 35mL / L, ASELY CTA-535Bri cupro-tin brightener 4mL / L, ASELY CTA-535WA cupro-tin wetting agent 3mL / L, plating solution pH 13.2, plating tank temperature 50℃, cathode current density 2.2A / dm 2 , cathode moves 5m / min.

[0050] 5. Gold plating:

[0051] On the steel parts plated with white copper and tin, a gold-plated layer 5 was prepared by using Chaobang Chemical's YB-223 bright copper-tin-zinc gold-plating process, with a coating thickness of 0.3 μm.

[0052] Potassium cyanide 55g / L, cuprous cyanide 19g / L, zinc cyanide 7g / L, potassium hydroxide 2g / L, CTA-604 tin salt 2g / L, CTA-606 Initial opener 90mL / L, CTA-606 Bri brightener 18mL / L, CTA-606 Carrier auxiliary 6mL / L, plating solution pH 12.4, plating tank temperature 55℃, cathode current density 1.0A / dm 2 , cathode moves 5m / min.

[0053] 6. Polymer electrolytic protection:

[0054] A nano-polymer protective film 6 was prepared on a gold-plated steel part using Chaobang Chemical's PROTEZVY 1126 electrolytic protection process.

[0055] PROTEZVY 1126MUP opener 32 mL / L, PROTEZVY 1126ADDITIVE C additive 75 mL / L, sodium hydroxide 0.17 g / L, bath pH 3.6, operating temperature 60°C, cathode current density 0.08 A / dm 2 , electrolysis time 8min.

[0056] 7. Drying:

[0057] After polymer electrolytic protection, the steel parts are subjected to "water washing → pure water washing → drying at 80℃ for 20 minutes".

[0058] Example 2:

[0059] like Figure 1 As shown, a nickel-free gold-substitute coating structure with polythiocyanate pre-copper plating includes a steel substrate 1, and a polythiocyanate pre-copper plating layer 2, an acid copper plating layer 3, a white copper tin plating layer 4, a gold-substitute coating 5, and a nano-polymer protective film 6 prepared on the steel substrate 1 from the inside to the outside.

[0060] 1. Pre-treatment:

[0061] According to the current pre-treatment process, the steel substrate 1 is subjected to "alkaline chemical degreasing → water washing → acid washing → water washing → alkaline cathodic electrolytic degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → activation → water washing".

[0062] 2. Polythiocyanate copper plating:

[0063] The polythiocyanate pre-plated copper layer 2 was prepared on the pre-treated steel parts using the HT-810 polythiocyanate copper plating process of Zunyi Huitong, with a coating thickness of 2 μm.

[0064] Polythiocyanate cuprous 22g / L, polythiocyanate sodium 150g / L, potassium sodium tartrate 10g / L, HT-810 brightener 1.5mL / L, HT-810 moving agent 3mL / L, plating tank temperature 53℃, plating solution pH 12.5, cathode current density 0.8A / dm 2 , cathode movement 5m / min, anode current density 0.3A / dm 2 , using oxygen-free electrolytic copper particles as anode.

[0065] 3. Acid copper plating:

[0066] An acid copper coating 3 was prepared on a steel part that had been copper-plated with polythiocyanate using a current acid copper plating process. The coating thickness was 16 μm.

[0067] 4. White copper tin plating:

[0068] A cupronickel-tin coating 4 was prepared on a steel part that had been plated with acid copper using the ASELY CTA-535 cupronickel-tin coating process of Chaobang Chemical. The coating thickness was 6 μm.

[0069] Potassium cyanide 75g / L, cuprous cyanide 15g / L, potassium hydroxide 10g / L, ASELY CTA-604 Cupro-Sn Salt 55g / L, ASELY CTA-602 Zinc Supplement 16mL / L, ASELY CTA-535Initial Cupro-Sn Opener 35mL / L, ASELY CTA-535Bri Cupro-Sn Brightener 4mL / L, ASELY CTA-535WA Cupro-Sn Wetting Agent 3mL / L, plating solution pH 12.8, plating tank temperature 50°C, cathode current density 1.9A / dm 2 , cathode moves 5m / min.

[0070] 5. Gold plating:

[0071] On the steel parts plated with white copper and tin, a gold-plated layer 5 was prepared by using Chaobang Chemical's YB-223 bright copper-tin-zinc gold-plating process, with a coating thickness of 0.3 μm.

[0072] Potassium cyanide 75g / L, cuprous cyanide 24g / L, zinc cyanide 9g / L, potassium hydroxide 3g / L, CTA-604 tin salt 3g / L, CTA-606 Initial opener 110mL / L, CTA-606 Bri brightener 18mL / L, CTA-606 Carrier auxiliary 6mL / L, plating solution pH 12.6, plating tank temperature 55℃, cathode current density 1.2A / dm 2 , cathode moves 5m / min.

[0073] 6. Polymer electrolytic protection:

[0074] A nano-polymer protective film 6 was prepared on a gold-plated steel part using Chaobang Chemical's PROTEZVY 1126 electrolytic protection process.

[0075] PROTEZVY 1126MUP opener 38 mL / L, PROTEZVY 1126ADDITIVE C 85 mL / L, sodium hydroxide 0.23 g / L, bath pH 3.8, operating temperature 60°C, cathode current density 0.08 A / dm 2 , electrolysis time 6min.

[0076] 7. Drying:

[0077] After polymer electrolytic protection, the steel parts are subjected to "water washing → pure water washing → drying at 80℃ for 20 minutes".

[0078] Test Example 1:

[0079] The gold-plated steel samples prepared in Examples 1 and 2 were tested for adhesion using the thermal shock method in accordance with GB / T 5270–2005, "Review of Test Methods for Adhesion Strength of Electrodeposited and Chemically Deposited Metal Coatings on Metal Substrates." The plated parts were heated to 300°C in a furnace for 30 minutes, then removed and suddenly cooled in room temperature water. No blistering or peeling of the coating occurred, indicating that the coating structures prepared in these Examples had good adhesion.

[0080] Test Example 2:

[0081] The steel surface gold-plated samples prepared in Example 1 and Example 2 were subjected to acetic acid salt spray test for 72 hours in accordance with GB / T10125-2021 "Artificial atmosphere corrosion test salt spray test". There was no rust on the plated surface, and the corrosion resistance was good.

[0082] Test Example 3:

[0083] The gold-plated steel samples prepared in Examples 1 and 2 were tested for 1000 hours at a temperature of 40°C and a relative humidity of 93% in accordance with GB / T2423.3-2016 "Basic Environmental Testing Procedures for Electrical and Electronic Products Test Ca: Steady Humidity Test Method". There was no visible change in the appearance of the coating, and the coating structure had good anti-discoloration ability.

[0084] The technical solutions provided by the embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only intended to help understand the principles of the embodiments of the present invention. It should be noted that, for those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention.

Claims

1. A nickel-free gold-plating structure pre-plated with copper using polymeric thiocyanate, characterized in that: The invention comprises a steel substrate, and a polymer thiocyanate pre-plated copper layer, an acid copper plating layer, a white copper tin plating layer, a gold substitute plating layer, and a nano polymer protective film which are sequentially prepared on the steel substrate from the inside to the outside; The gold-substitute coating is a coating prepared by a copper-tin-zinc ternary alloy plating process, and the coating thickness is 0.1 to 0.5 μm; The thickness of the polymerized thiocyanate pre-plated copper layer is 1 to 6 μm.

2. The nickel-free gold-plating structure using polythiocyanate pre-copper plating as claimed in claim 1, characterized in that: The thickness of the acid copper plating layer is 8 to 24 μm.

3. The nickel-free gold-plating structure with pre-copper plating using polymeric thiocyanate as claimed in claim 1, characterized in that: The thickness of the white copper tin plating layer is 2 to 8 μm.

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