Pearl palladium plating layer structure for pre-plating copper with polythiocyanate

Abstract

The utility model discloses a pearl palladium plating layer structure for pre-plating copper with polythiocyanate, which comprises a zinc alloy substrate, and a polythiocyanate pre-plating copper layer, a pyrophosphate copper plating layer, an acid copper plating layer, a high-corrosion-resistance nickel-phosphorus alloy plating layer, a pearl nickel plating layer and a pearl palladium plating layer which are sequentially prepared on the zinc alloy substrate from inside to outside. The utility model discloses a pearl palladium plating layer structure for pre-plating copper by polythiocyanate, which is characterized in that the binding force of a plating layer is measured by a thermal shock test method according to GB / T 5270-2005 Electrodeposition and Chemical Deposition Layer Adhesive Strength Test Method for Metal Cover Layer on Metal Matrix, and the binding force meets the standard requirement; a neutral salt spray test is carried out for 120 h 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 the prepared plating layer structure has good corrosion resistance.

Description

Technical Field

[0001] The utility model belongs to the field of metal electroplating, and particularly relates to a pearl palladium plating layer structure with pre-plated copper by polymerized thiocyanate. Background Art

[0002] Pure palladium plating can prepare a uniform, bright, silver-white palladium plating layer, which is suitable for surface plating of decorative products such as jewelry, watches and glasses.

[0003] According to the traditional process, the zinc alloy die-casting parts are prepared with a pre-plated copper layer by cyanide copper plating process, and then copper pyrophosphate plating, acid copper plating, bright nickel plating, etc. are carried out. Cyanide has problems of high pollution and high risk, and the use of cyanide has been more and more strictly controlled. It is imperative to develop a cyanide-free copper plating process that can replace cyanide copper plating. However, when directly plating copper on the surface of zinc alloy by the current divalent copper cyanide-free copper plating process, the problems of low coating adhesion and poor bath stability still need to be further studied. [1] .

[0004] The polymerized thiocyanate copper plating process is a newly developed cyanide-free copper plating process, which uses cuprous thiocyanate polymer as the main salt and sodium thiocyanate polymer as the complexing agent, and its process characteristics and performance are close to those of cyanide copper plating.

[0005] The high-corrosion-resistant nickel-phosphorus alloy coating has high corrosion resistance and is an ideal intermediate layer for gold plating, palladium plating, chromium replacement, trivalent chromium chromium plating, etc.

[0006] The pearl palladium plating layer is a more elegant decorative plating layer than the pure palladium plating layer, and has not been developed and applied yet.

[0007] 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. Content of the Utility Model

[0008] In order to solve the problem of high pollution of the cyanide pre-plated copper layer prepared by the traditional method for zinc alloy die-casting parts, the utility model provides a pearl palladium plating layer structure with pre-plated copper by polymerized thiocyanate. In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0009] A pearl palladium plating layer structure with pre-plated copper by polymerized thiocyanate, comprising a zinc alloy substrate, and a polymerized thiocyanate pre-plated copper layer, a copper pyrophosphate plating layer, an acid copper plating layer, a high-corrosion-resistant nickel-phosphorus alloy plating layer, a pearl nickel plating layer, and a pearl palladium plating layer sequentially prepared on the zinc alloy substrate from inside to outside;

[0010] The thickness of the pearl palladium plating layer is 0.05-0.1 μm;

[0011] The thickness of the pre-plated copper layer of polymeric thiocyanate is 2-6 μm.

[0012] Preferably, the thickness of the copper pyrophosphate plating is 6-11 μm.

[0013] Preferably, the thickness of the acid copper plating layer is 10-18 μm.

[0014] Preferably, the thickness of the high anti-corrosion nickel-phosphorus alloy plating layer is 5-10 μm.

[0015] Preferably, the thickness of the pearl nickel plating layer is 1.5-2.8 μm.

[0016] There are many pores on the surface of zinc alloy die-castings. After pre-plating copper with polymeric thiocyanate, it is usually necessary to add copper pyrophosphate plating to completely seal the pores. Plating a high anti-corrosion nickel-phosphorus alloy on the copper plating layer, the electrode potential of the nickel-phosphorus alloy plating layer is relatively negative, which is anodic plating layer for the copper plating layer. This kind of plating layer structure can better block the erosion of corrosive media towards the substrate direction. The corrosion resistance of the high anti-corrosion nickel-phosphorus alloy plating layer is higher than that of the bright nickel plating layer. Replacing the traditional bright nickel plating layer with the high anti-corrosion nickel-phosphorus alloy plating layer can further increase the corrosion resistance of the plating layer.

[0017] Compared with the prior art, the present utility model has the following beneficial effects:

[0018] 1. A pearl palladium plating layer structure pre-plated with polymeric thiocyanate disclosed by the present utility model uses the copper plating process of polymeric thiocyanate to replace cyanide copper plating to prepare the pre-plated copper layer, overcoming the problems of high pollution and high risk brought by the use of cyanide;

[0019] 2. The pearl palladium plating layer structure pre-plated with polymeric thiocyanate disclosed by the present utility model fills the blank of pearl palladium plating in the domestic market. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present utility model, constitute a part of this application, and do not constitute an improper limitation to the present utility model. In the drawings:

[0021] Figure 1 It is a schematic diagram of the plating layer structure of Embodiment 1 and Embodiment 2 of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] 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.

[0023] This technical solution includes successively preparing a polymeric thiocyanate pre - copper plating layer, a pyrophosphate copper plating layer, an acid copper plating layer, a highly corrosion - resistant nickel - phosphorus alloy plating layer, a pearl nickel plating layer, and a pearl palladium plating layer on the matrix of a zinc - alloy die - casting from the inside to the outside.

[0024] The existing pretreatment process is used to dewax, degrease, and activate the matrix of the zinc - alloy die - casting.

[0025] After the pretreatment of the zinc - alloy die - casting, a polymeric thiocyanate pre - copper plating layer is prepared by using the polymeric thiocyanate copper - plating process.

[0026] Preferably, the thickness of the polymeric thiocyanate pre - copper plating layer is 2 - 6μm.

[0027] Preferably, the polymeric thiocyanate pre - copper plating layer is prepared by using the HT - 810 polymeric thiocyanate copper - plating process of Zunyi Huitong:

[0028] Copper(I) polymeric thiocyanate 17 - 23g / L, sodium polymeric thiocyanate 100 - 160g / L, potassium sodium tartrate 8 - 12g / L, HT - 810 brightener 1 - 2mL / L, HT - 810 leveling agent 2 - 4mL / L, bath temperature 45°C - 55°C, bath pH value 12 - 13, cathode current density 0.5 - 1.0A / dm 2 , cathode movement 4 - 6m / min, anode current density ≤0.5A / dm 2 , and an oxygen - free electrolytic copper angle (or copper grains) is used as the anode.

[0029] After the polymeric thiocyanate pre - copper plating of the zinc - alloy die - casting, a pyrophosphate copper plating layer is prepared by using the existing pyrophosphate copper - plating process.

[0030] Preferably, the thickness of the pyrophosphate copper plating layer is 5 - 11μm.

[0031] After the pyrophosphate copper plating of the zinc - alloy die - casting, an acid copper plating layer is prepared by using the existing acid copper - plating process.

[0032] Preferably, the thickness of the acid copper plating layer is 10 - 18μm.

[0033] After the acid copper plating of the zinc - alloy die - casting, a highly corrosion - resistant nickel - phosphorus alloy plating layer is prepared by using the existing highly corrosion - resistant nickel - phosphorus alloy plating process.

[0034] Preferably, the thickness of the highly corrosion - resistant nickel - phosphorus alloy plating layer is 6 - 10μm.

[0035] Preferably, the highly corrosion - resistant nickel - phosphorus alloy plating layer is prepared by using the PROTEXYER 8713 highly corrosion - resistant nickel - phosphorus alloy plating process of Superbond Chemical Industry:

[0036] PROTEXYER 8713 Hull Cell conditioner 580 - 620 mL / L, nickel sulfate hexahydrate 280 - 340 g / L, bath pH 2.6 - 2.7, bath temperature 60°C - 65°C, cathode current density 3 - 6 A / dm 2 , cathode movement 3 - 5 m / min.

[0037] After zinc alloy die-castings are plated with high anti-corrosion nickel-phosphorus alloy, the pearl nickel coating is prepared by the current pearl nickel plating process.

[0038] Preferably, the thickness of the pearl nickel coating is 1.5 - 2.8 μm.

[0039] After zinc alloy die-castings are plated with pearl nickel, the pearl palladium coating is prepared by the current decorative palladium plating process.

[0040] Preferably, the thickness of the pearl palladium coating is 0.05 - 0.1 μm.

[0041] Preferably, the pearl palladium coating is prepared by the Pallatec PD-300 pure palladium plating process of Superbond Chemical Industry:

[0042] Pallatec PD-300 Hull Cell conditioner 750 mL / L, palladium chloride ammonium 8 g / L, bath pH 8.5 - 9.5, bath temperature 28°C - 30°C, cathode current density 0.5 - 1 A / dm 2 , cathode movement 4 - 6 m / min, using a platinum metal plate as the anode.

[0043] After zinc alloy die-castings are plated with pearl palladium and washed clean, they are dried at 70°C - 80°C for 15 - 25 min. Example 1

[0044] As Figure 1 shown, a pearl palladium coating structure pre-plated with polymeric thiocyanate copper includes a zinc alloy substrate 1, and a polymeric thiocyanate pre-plated copper layer 2, a pyrophosphate copper plating layer 3, an acid copper plating layer 4, a high anti-corrosion nickel-phosphorus alloy coating 5, a pearl nickel coating 6, and a pearl palladium coating 7 sequentially prepared on the zinc alloy substrate 1 from the inside to the outside.

[0045] 1. Pretreatment:

[0046] 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".

[0047] 2. Polymeric thiocyanate pre-plated copper:

[0048] After the pretreatment of the zinc alloy die-casting, the polymeric thiocyanate pre-plated copper layer 2 is prepared by the HT-810 polymeric thiocyanate copper plating process of Zunyi Huitong, and the coating thickness is 3 μm.

[0049] Copper thiocyanate 18 g / L, sodium thiocyanate 120 g / L, potassium sodium tartrate 10 g / L, HT-810 brightener 1.5 mL / L, HT-810 leveling agent 3 mL / L, bath temperature 53 °C, bath pH 12.8, cathode current density 0.7 A / dm 2 , cathode movement 5 m / min, anode current density 0.4 A / dm 2 , using oxygen-free electrolytic copper angle as anode.

[0050] 3. Copper pyrophosphate plating:

[0051] After pre-plating copper with thiocyanate on zinc alloy die-castings, the current copper pyrophosphate plating process is used to prepare a copper pyrophosphate plating layer 3 with a thickness of 8 μm.

[0052] 4. Acid copper plating:

[0053] After copper pyrophosphate plating on zinc alloy die-castings, the current acid copper plating process is used to prepare an acid copper plating layer 4 with a thickness of 12 μm.

[0054] 5. High corrosion-resistant nickel-phosphorus alloy plating:

[0055] After acid copper plating on zinc alloy die-castings, the EMFASI 8812 high corrosion-resistant nickel-phosphorus alloy plating process of Superbond Chemical is used to prepare a high corrosion-resistant nickel-phosphorus alloy plating layer 5 with a thickness of 8 μm.

[0056] EMFASI 8812 MU bath conditioner 480 mL / L, nickel sulfate hexahydrate 300 g / L, bath pH 2.6, operating temperature 62 °C, cathode current density 4 A / dm 2 , cathode movement 4 m / min.

[0057] 6. Pearl nickel plating:

[0058] After high corrosion-resistant nickel-phosphorus alloy plating on zinc alloy die-castings, the current pearl nickel plating process is used to prepare a pearl nickel plating layer 6 with a thickness of 2 μm.

[0059] 7. Pearl palladium plating:

[0060] After pearl nickel plating on zinc alloy die-castings, the Pallatec PD-300 pure palladium plating process of Superbond Chemical is used to prepare a pearl palladium plating layer 7 with a thickness of 0.08 μm.

[0061] Pallatec PD-300 bath solution 750 mL / L, palladium chloride ammonium 8 g / L, bath pH 9.3, bath temperature 28 °C, cathode current density 0.8 A / dm 2 , cathode movement 5 m / min, using platinum metal plate as anode.

[0062] 8. Drying:

[0063] The zinc alloy die-casting parts are plated with pearl palladium and washed clean with water, and then dried at 80 °C for 15 minutes. Example 2

[0064] As Figure 1 shown, a pearl palladium plating layer structure with pre-plated copper by polymerized thiocyanate includes a zinc alloy substrate 1, and a polymerized thiocyanate pre-plated copper layer 2, a pyrophosphate copper plating layer 3, an acid copper plating layer 4, a high-corrosion-resistant nickel-phosphorus alloy plating layer 5, a pearl nickel plating layer 6, and a pearl palladium plating layer 7 sequentially prepared on the zinc alloy substrate 1 from the inside to the outside.

[0065] 1. Pretreatment:

[0066] The zinc alloy die-casting part substrate 1 is subjected to "chemical dewaxing → water washing → ultrasonic dewaxing → water washing → ultrasonic degreasing → water washing → activation → water washing".

[0067] 2. Polymerized thiocyanate pre-plated copper:

[0068] After the pretreatment of the zinc alloy die-casting parts, the polymerized thiocyanate pre-plated copper layer 2 is prepared by using the HT-810 polymerized thiocyanate copper plating process of Zunyi Huitong, and the coating thickness is 5 μm.

[0069] Copper thiocyanate polymer 22 g / L, sodium thiocyanate polymer 150 g / L, potassium sodium tartrate 10 g / L, HT-810 brightener 1.5 mL / L, HT-810 leveling agent 3 mL / L, bath temperature 52 °C, bath pH 12.5, cathode current density 0.8 A / dm 2 , cathode movement 5 m / min, anode current density 0.3 A / dm 2 , and an oxygen-free electrolytic copper granule is used as the anode.

[0070] 3. Pyrophosphate copper plating:

[0071] After the zinc alloy die-casting parts are pre-plated with polymerized thiocyanate copper, the pyrophosphate copper plating layer 3 is prepared by using the current pyrophosphate copper plating process, and the coating thickness is 6 μm.

[0072] 4. Acid copper plating:

[0073] After the zinc alloy die-casting parts are plated with pyrophosphate copper, the acid copper plating layer 4 is prepared by using the current acid copper plating process, and the coating thickness is 15 μm.

[0074] 5. High-corrosion-resistant nickel-phosphorus alloy plating:

[0075] After the zinc alloy die-casting parts are plated with acid copper, the high-corrosion-resistant nickel-phosphorus alloy plating layer 5 is prepared by using the EMFASI 8812 high-corrosion-resistant nickel-phosphorus alloy plating process of Chaobang Chemical Industry, and the coating thickness is 6 μm.

[0076] EMFASI 8812 Hull Cell conditioner 530 mL / L, nickel sulfate hexahydrate 330 g / L, bath pH 2.6, operating temperature 62 °C, cathode current density 4 A / dm 2 , cathode movement 4 m / min.

[0077] 6. After zinc alloy die-castings are plated with high-corrosion-resistant nickel-phosphorus alloy, a pearl nickel coating 5 is prepared using the current pearl nickel plating process, and the coating thickness is 2 μm.

[0078] 7. Plating pearl palladium:

[0079] After zinc alloy die-castings are plated with pearl nickel, a pearl palladium coating 7 is prepared using the Pallatec PD-300 pure palladium plating process of Superbond Chemical Industry Co., Ltd., and the coating thickness is 0.08 μm.

[0080] Pallatec PD-300 Hull Cell conditioner 750 mL / L, palladium chloride ammonium 8 g / L, bath pH 8.7, bath temperature 30 °C, cathode current density 0.8 A / dm 2 , cathode movement 5 m / min, using a platinum metal plate as the anode.

[0081] 8. Drying:

[0082] After zinc alloy die-castings are plated with pearl palladium and washed clean, they are dried at 70 °C for 25 min.

[0083] Test Example 1:

[0084] For the pearl palladium-coated samples prepared in Example 1 and Example 2 of this embodiment, according to GB / T 5270–2005 "Review of Test Methods for Adhesion of Metallic Coatings on Metallic Substrates - Electrodeposited and Chemically Deposited Coatings", the adhesion of the coating was determined by the thermal shock test method. The samples were placed in a heating furnace and heated to 150 °C for 30 min, then taken out and suddenly cooled in water at room temperature. No blistering or peeling occurred on the coating, and its adhesion was good.

[0085] Test Example 2:

[0086] For the pearl palladium-coated samples prepared in Example 1 and Example 2 of this embodiment, a neutral salt spray test was carried out for 120 h according to GB / T 10125–2021 "Artificial Atmosphere Corrosion Tests - Salt Spray Tests". No corrosion products were formed on the surface of the samples, and the prepared coatings had good corrosion resistance.

[0087] The above has introduced in detail the technical solutions provided by the embodiments of the present utility model. Specific examples are used herein to elaborate on the principles and implementation manners of the embodiments of the present utility model. The description of the above embodiments is only applicable to helping 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 pearl palladium coating structure pre-plated with copper using polymerized thiocyanate, characterized in that: It comprises a zinc alloy substrate, and a polymerized thiocyanate pre-copper plating layer, a pyrophosphate copper plating layer, an acid copper plating layer, a high corrosion resistance nickel-phosphorus alloy plating layer, a pearl nickel plating layer, and a pearl palladium plating layer, which are sequentially prepared from the inside to the outside on the zinc alloy substrate; The thickness of the pearl palladium coating is 0.05 to 0.1 μm; The thickness of the polymerized thiocyanate pre-plated copper layer is 2-6 μm.

2. The pearl palladium plating structure with pre-copper plating using polythiocyanate as claimed in claim 1, characterized in that: The thickness of the pyrophosphate copper plating is 5 to 11 μm.

3. The pearl palladium plating structure with pre-copper plating with polythiocyanate as claimed in claim 1, characterized in that: The thickness of the acid copper plating layer is 10-18 μm.

4. The pearl palladium plating structure with pre-copper plating with polythiocyanate as claimed in claim 1, characterized in that: The thickness of the high corrosion resistance nickel-phosphorus alloy coating is 6-10 μm.

5. The structure of pearl palladium plating with pre-copper plating by polythiocyanate as claimed in claim 1, characterized in that: The thickness of the pearl nickel plating layer is 1.5-2.8 μm.

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