Nickel-chromium alloy plating layer structure with polythiocyanate plated copper as bottom plating layer

Abstract

The utility model discloses a nickel-chromium alloy plating layer structure taking polythiocyanate plated copper as a bottom plating layer. Comprising a zinc alloy matrix, and a polythiocyanate copper pre-plating layer, a pyrophosphate copper plating layer, an acid copper plating layer, a bright nickel plating layer, a nickel-chromium alloy plating layer and a nano polymer protective film which are sequentially prepared on the zinc alloy matrix from inside to outside. According to GB / T 5270-2005 Metal Covering Layer Electro-Deposition and Chemical Deposition Layer Adhesion Strength Test Method on Metal Matrix, the binding force of a plating layer is tested by a thermal shock method, the binding force meets the standard requirement, an acetate fog test is carried out for 60 hours according to GB / T 10125-2021 Artificial Atmosphere Corrosion Test Salt Spray Test, no corrosives are generated on the surface of a plating piece, and the plating piece has good corrosion resistance. And the prepared plating 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-chromium alloy plating structure using polymerized thiocyanate copper plating as a base plating layer. Background Art

[0002] The hexavalent chromium plating is bright and white, and has the characteristics of high hardness, good wear resistance, corrosion resistance and high temperature resistance. In decorative electroplating, the traditional method uses hexavalent chromium plating as the surface plating. Due to the high pollution problem of hexavalent chromium plating, the industry has developed a new solution to replace the hexavalent chromium plating with a nickel-chromium alloy plating. The nickel-chromium alloy plating can be evenly plated on bright nickel and other platings. The plating has high hardness, excellent wear resistance and corrosion resistance, can resist high-temperature oxidation, and is bright and beautiful. However, since nickel-chromium co-deposition is difficult to achieve, its process is not yet mature enough. [1] .

[0003] Trivalent chromium plating is also an environmentally friendly electroplating process that replaces hexavalent chromium plating to prepare surface coatings. However, the trivalent chromium plating layer is not thick, and its hardness and corrosion resistance are lower than those of the hexavalent chromium plating layer. [2] Practice has shown that some zinc alloy die castings use trivalent chromium plating to prepare the surface coating. After a period of use, the chrome plating layer will be completely worn away, losing the decorative and protective effects of the chrome plating layer.

[0004] According to the traditional process, zinc alloy die castings use cyanide copper plating process to prepare the pre-copper layer, and then pyrophosphate copper plating, acid copper plating, bright nickel plating, etc. Cyanide has a high pollution problem, and my country has implemented increasingly strict control on its use. For this reason, the industry is actively developing a new cyanide-free copper plating process that can replace cyanide copper plating. [3] Polythiocyanate copper plating is a newly developed cyanide-free copper plating process in the industry and is currently in the development and trial stage.

[0005] References: [1] Zhu Ming, Wang Mingjing, Wang Zhihua, Effect of pulse frequency on the performance of electroplated nickel-chromium alloy [J], Electroplating and Finishing, 2013, 32(12): 14-16. [2] Tu Zhenmi, Zheng Jian, Li Ning, et al., Current status and development trend of trivalent chromium electroplating [J], Surface Technology, 2007, 36(5): 59-63+87. [3] Qin Zuzu, Li Jiansan, Xu Jinlai, Research progress of cyanide-free copper plating process at home and abroad [J], Electroplating and Finishing, 2015, 34(3): 149-152. Utility Model Content

[0006] In order to solve the high pollution problem of traditional hexavalent chromium plating and cyanide pre-copper plating, the utility model provides a nickel-chromium alloy plating structure with polythiocyanate copper plating as the base plating layer. In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A nickel-chromium alloy plating structure with polythiocyanate copper plating as a base plating layer, comprising a zinc alloy substrate, and a polythiocyanate pre-copper plating layer, a pyrophosphate copper plating layer, an acid copper plating layer, a bright nickel plating layer, a nickel-chromium alloy plating layer, and a nano polymer protective film sequentially prepared from the inside to the outside on the zinc alloy substrate;

[0008] The thickness of the nickel-chromium alloy plating layer is 0.8-1.4 μm.

[0009] Preferably, the thickness of the polymerized thiocyanate pre-copper plating layer is 2-5 μm.

[0010] Preferably, the thickness of the pyrophosphate copper plating layer is 5 to 10 μm.

[0011] Preferably, the thickness of the acid copper plating layer is 8 to 16 μm.

[0012] Preferably, the thickness of the bright nickel plating layer is 6 to 12 μm.

[0013] The pre-copper layer is prepared on the surface of zinc alloy die castings by using the polythiocyanate copper plating process, and the coating has good bonding force with the substrate. Nickel is plated on the copper layer, and the electrode potential of the nickel layer is relatively negative, and the potential difference between the two is large. This coating structure can better block the corrosion of the corrosive medium toward the substrate. The nickel-chromium alloy coating has high corrosion resistance. The surface coating is prepared by plating nickel-chromium alloy on the bright nickel coating. When the coating is corroded, the corrosion occurs laterally on the bright nickel coating, but the corrosion rate is slow.

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

[0015] 1. The nickel-chromium alloy plating structure with polymerized thiocyanate copper plating as the bottom plating layer disclosed in the utility model adopts the nickel-chromium alloy plating process to replace the hexavalent chromium plating process to prepare the surface plating layer, thus overcoming the high pollution problem of using hexavalent chromium;

[0016] 2. The nickel-chromium alloy plating structure with polythiocyanate copper plating as the base plating layer disclosed in the utility model adopts the polythiocyanate copper plating process to prepare a cyanide-free pre-copper plating layer on the surface of the zinc alloy, thus overcoming the high pollution problem of using the cyanide copper plating process to prepare the pre-copper plating layer. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] Figure 1 It is a schematic diagram of the coating structure of Example 1 and Example 2 of the utility model. DETAILED DESCRIPTION

[0019] The present invention will be described in detail below in conjunction with 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.

[0020] A nickel-chromium alloy plating structure with polymerized thiocyanate copper plating as a base plating layer comprises a zinc alloy substrate, and a polymerized thiocyanate pre-copper plating layer, a pyrophosphate copper plating layer, an acid copper plating layer, a bright nickel plating layer, a nickel-chromium alloy plating layer, and a nano polymer protective film which are sequentially prepared from the inside to the outside on the zinc alloy substrate.

[0021] According to the current pre-treatment process, the zinc alloy die casting substrate is dewaxed, degreased, and activated.

[0022] The polythiocyanate copper plating process is used to prepare the polythiocyanate pre-plated copper layer after pretreatment of the zinc alloy die casting.

[0023] Preferably, the thickness of the polymerized thiocyanate pre-copper plating layer is 2-5 μm.

[0024] Preferably, the polymerized thiocyanate pre-copper plating layer is prepared by using Zunyi Huitong's HT-810 polymerized thiocyanate copper plating process:

[0025] Polymeric cuprous thiocyanate 17-23 g / L, polymeric sodium thiocyanate 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.

[0026] The zinc alloy die casting is subjected to polythiocyanate copper plating and then the pyrophosphate copper plating layer is prepared by the current pyrophosphate copper plating process.

[0027] Preferably, the thickness of the pyrophosphate copper plating layer is 5 to 10 μm.

[0028] The zinc alloy die castings were plated with pyrophosphate copper and then the acid copper coating was prepared by the current acid copper plating process.

[0029] Preferably, the thickness of the acid copper plating layer is 8 to 16 μm.

[0030] The zinc alloy die castings are plated with acid copper and then the bright nickel coating is prepared by the current bright nickel plating process.

[0031] Preferably, the thickness of the bright nickel plating layer is 6 to 12 μm.

[0032] The zinc alloy die casting is plated with bright nickel and then the nickel-chromium alloy coating is prepared by the current nickel-chromium alloy plating process.

[0033] Preferably, the thickness of the nickel-chromium alloy plating layer is 0.8-1.4 μm.

[0034] Preferably, the nickel-chromium alloy coating is prepared by the nickel-chromium alloy plating process developed by Chaobang Chemical:

[0035] Chromium chloride hexahydrate 80-120g / L, nickel sulfate hexahydrate 8-12g / L, glycine 12-18g / L, ammonium chloride 80-120g / L, potassium bromide 15-20g / L, ammonium formate 45-50g / L, boric acid 50-60g / L, moving agent 8-12mL / L, wetting agent 1-2mL / L, plating solution pH 2.5-3.0, plating tank temperature 25℃-35℃, cathode current density 10-18A / dm 2 , medium air agitation.

[0036] The zinc alloy die castings were plated with nickel-chromium alloy and then the nano-polymer protective film was prepared by electrolytic protection process.

[0037] Preferably, the nano polymer protective film is prepared by using the PROTEZVY 1126 electrolytic protection process of Chaobang Chemical:

[0038] PROTEZVY 1126 MUP tank opener 30-40 mL / L, PROTEZVY 1126 ADDITIVE C additive 70-90 mL / L, sodium hydroxide 0.15-0.25 g / L, bath pH 3.4-4.0, operating temperature 55°C-65°C, cathode current density 0.05-0.1 A / dm 2 , electrolysis time is 3 to 10 minutes.

[0039] Zinc alloy die castings are electrolytically protected and then washed and dried. Example 1

[0040] like Figure 1 As shown, a nickel-chromium alloy coating structure with polymerized thiocyanate copper plating as a base coating comprises a zinc alloy substrate 1, and a polymerized thiocyanate pre-copper coating 2, a pyrophosphate copper coating 3, an acid copper coating 4, a bright nickel coating 5, a nickel-chromium alloy coating 6, and a nano-polymer protective film 7 sequentially prepared on the zinc alloy substrate 1 from the inside to the outside.

[0041] 1. Pre-treatment:

[0042] 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".

[0043] 2. Polythiocyanate copper plating:

[0044] After pretreatment of the zinc alloy die casting, the HT-810 polythiocyanate copper plating process of Zunyi Huitong was used to prepare a polythiocyanate pre-plated copper layer 2, and the coating thickness was 3 μm.

[0045] Polymerized cuprous thiocyanate 18g / L, polymerized sodium thiocyanate 120g / 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 12.3, cathode current density 0.7A / dm 2 , cathode movement 5m / min, anode current density 0.4A / dm 2 , use oxygen-free electrolytic copper corner as anode.

[0046] 3. Pyrophosphate copper plating:

[0047] After the zinc alloy die casting is plated with polythiocyanate copper, a pyrophosphate layer 3 is prepared by using the current pyrophosphate copper plating process, and the coating thickness is 7 μm.

[0048] 4. Acid copper plating:

[0049] After the zinc alloy die casting is pyrophosphate copper plated, the acid copper plating layer 4 is prepared by the current acid copper plating process, and the plating thickness is 12 μm.

[0050] 5. Bright nickel plating:

[0051] After the zinc alloy die casting is plated with acid copper, a bright nickel plating layer 5 is prepared by using the current bright nickel plating process, and the plating thickness is 8 μm.

[0052] 6. Nickel-chromium alloy plating:

[0053] After the zinc alloy die casting is plated with bright nickel, the nickel-chromium alloy plating process developed by Chaobang Chemical is used to prepare a nickel-chromium alloy coating 6, and the coating thickness is 1.2 μm.

[0054] Chromium chloride hexahydrate 90g / L, nickel sulfate hexahydrate 9g / L, glycine 14g / L, ammonium chloride 90g / L, potassium bromide 16g / L, ammonium formate 46g / L, boric acid 52g / L, moving agent 10mL / L, wetting agent 1.5mL / L, plating solution pH 2.8, plating tank temperature 30℃, cathode current density 14A / dm 2 , medium air agitation.

[0055] 7. Electrolytic protection:

[0056] The zinc alloy die castings were plated with nickel-chromium alloy and then the nano-polymer protective film was prepared using the PROTEZVY 1126 electrolytic protection process of Chaobang Chemical 7.

[0057] PROTEZVY 1126 MUP tank opener 32mL / L, PROTEZVY 1126 ADDITIVE C additive 75mL / L, sodium hydroxide 0.17g / L, bath pH 3.8, operating temperature 60℃, cathode current density 0.08A / dm 2 , electrolysis for 8 minutes.

[0058] 8. Drying:

[0059] After electrolytic protection, zinc alloy die castings are subjected to "water washing → pure water washing → drying". Example 2

[0060] like Figure 1 As shown, a nickel-chromium alloy coating structure with polymerized thiocyanate copper plating as a base coating comprises a zinc alloy substrate 1, and a polymerized thiocyanate pre-copper coating 2, a pyrophosphate copper coating 3, an acid copper coating 4, a bright nickel coating 5, a nickel-chromium alloy coating 6, and a nano-polymer protective film 7 sequentially prepared on the zinc alloy substrate 1 from the inside to the outside.

[0061] 1. Pre-treatment:

[0062] 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".

[0063] 2. Polythiocyanate copper plating:

[0064] After pretreatment of the zinc alloy die casting, the HT-810 polythiocyanate copper plating process of Zunyi Huitong was used to prepare a polythiocyanate pre-plated copper layer 2, and the coating thickness was 3 μm.

[0065] Polymerized cuprous thiocyanate 22g / L, polymerized sodium thiocyanate 150g / L, potassium sodium tartrate 10g / L, HT-810 brightener 1.5mL / L, HT-810 moving agent 3mL / L, plating tank temperature 52℃, plating solution pH 12.2, 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.

[0066] 3. Pyrophosphate copper plating:

[0067] After the zinc alloy die casting is plated with polythiocyanate copper, a pyrophosphate layer 3 is prepared by using the current pyrophosphate copper plating process, and the coating thickness is 7 μm.

[0068] 4. Acid copper plating:

[0069] After the zinc alloy die casting is pyrophosphate copper plated, the acid copper plating layer 4 is prepared by the current acid copper plating process, and the plating thickness is 12 μm.

[0070] 5. Bright nickel plating:

[0071] After the zinc alloy die casting is plated with acid copper, a bright nickel plating layer 5 is prepared by using the current bright nickel plating process, and the plating thickness is 8 μm.

[0072] 6. Nickel-chromium alloy plating:

[0073] After the zinc alloy die casting is plated with bright nickel, the nickel-chromium alloy plating process developed by Chaobang Chemical is used to prepare a nickel-chromium alloy coating 6, and the coating thickness is 1.2 μm.

[0074] Chromium chloride hexahydrate 110g / L, nickel sulfate hexahydrate 11g / L, glycine 19g / L, ammonium chloride 110g / L, potassium bromide 19g / L, ammonium formate 49g / L, boric acid 58g / L, moving agent 10mL / L, wetting agent 1.5mL / L, plating solution pH 2.7, plating tank temperature 28℃, cathode current density 14A / dm 2 , medium air agitation.

[0075] 7. Electrolytic protection:

[0076] The zinc alloy die castings were plated with nickel-chromium alloy and then the nano-polymer protective film was prepared using the PROTEZVY 1126 electrolytic protection process of Chaobang Chemical 7.

[0077] PROTEZVY 1126 MUP tank opener 38mL / L, PROTEZVY 1126 ADDITIVE C additive 85mL / L, sodium hydroxide 0.23g / L, bath pH 3.8, operating temperature 60℃, cathode current density 0.08A / dm 2 , electrolysis for 6 minutes.

[0078] 8. Drying:

[0079] After electrolytic protection, zinc alloy die castings are subjected to "water washing → pure water washing → drying".

[0080] Test Example 1:

[0081] The zinc alloy die-casting nickel-chromium alloy-plated samples prepared in Example 1 and Example 2 were subjected to acetic acid salt spray test for 60 hours in accordance with GB / T 10125-2021 "Artificial atmosphere corrosion test salt spray test", and there was no rust on the surface of the plated parts, which exceeded the requirements of GB / T9797-2022 "Metal coating nickel + chromium and copper + nickel + chromium electroplating layer" standard.

[0082] Test Example 2:

[0083] The nickel-chromium alloy plated zinc alloy die castings prepared in Example 1 and Example 2 were tested for coating adhesion by thermal shock method according to 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 placed in a heating furnace and heated to 150°C for 30 minutes, then taken out and suddenly cooled in water at room temperature. No blistering or shedding occurred in the coating. The test showed that the coating structure prepared by the utility model had good adhesion.

[0084] The technical solutions provided by the embodiments of the present utility model are described in detail above. The principles and implementation methods of the embodiments of the present utility model are described in detail in this article using specific examples. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present utility model. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present utility model, which all belong to the protection scope of the present utility model.

Claims

1. A nickel-chromium alloy plating structure with polythiocyanate copper plating as the base plating layer, characterized in that: It comprises a zinc alloy substrate, and a polymerized thiocyanate pre-plated copper layer, a pyrophosphate copper plating layer, an acid copper plating layer, a bright nickel plating layer, a nickel-chromium alloy plating layer, and a nano polymer protective film which are sequentially prepared from the inside to the outside on the zinc alloy substrate; The thickness of the nickel-chromium alloy plating layer is 0.8-1.4 μm.

2. The nickel-chromium alloy plating structure with polythiocyanate copper plating as the base plating layer as claimed in claim 1, characterized in that: The thickness of the polymerized thiocyanate pre-plated copper layer is 2-5 μm.

3. The nickel-chromium alloy plating structure with polythiocyanate copper plating as the base plating layer as claimed in claim 1, characterized in that: The thickness of the pyrophosphate copper plating layer is 5 to 10 μm.

4. The nickel-chromium alloy plating structure with polythiocyanate copper plating as the bottom plating layer as claimed in claim 1, characterized in that: The thickness of the acid copper plating layer is 8 to 16 μm.

5. The nickel-chromium alloy plating structure with polythiocyanate copper plating as the bottom plating layer as claimed in claim 1, characterized in that: The thickness of the bright nickel plating layer is 6 to 12 μm.

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