Anode device for sulfite gold plating
By using a cation exchange film to isolate the plating solution and the anode in the sulfite gold plating anode device, and combining the titanium-coated anode, the problem of instability of the sulfite gold plating solution is solved, and the stability and corrosion resistance of the gold plating layer are improved. The goals of cost reduction and sustainable development have been achieved.
Patent Information
- Application Number
- CN202420436932.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-07
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2034-03-07
AI Technical Summary
The instability of the sulfite gold plating solution makes it difficult to completely replace cyanide gold plating in practical applications. The main reason is that the sulfite is oxidized on the anode and loses coordination ability, resulting in low stability and deposition current efficiency of the plating solution.
A sulfite gold-plated anode device is designed. By fixing a cation exchange membrane on the anode basket surface, the plating solution is separated from the anode, and anode liquid is installed in the anode chamber to control the pH value and prevent sulfite from entering the anode chamber. , and use titanium coating anode to reduce costs.
有效解决了亚硫酸根被氧化的问题,提高了镀液的稳定性和镀金层的平整性和耐蚀性,同时降低了成本,满足了可持续发展的需求。
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Figure CN222251090U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the field of metal electroplating, and in particular relates to an anode device for sulfite gold plating. Background Art
[0002] The gold-plated layer has excellent conductivity, corrosion resistance and a luxurious and elegant appearance. Its color is generally higher than 23K, and the color is stable at around 3N color. It is widely used in surface finishing of products such as finishing, electronics industry, and high-end decorations.
[0003] The traditional gold plating process widely uses the cyanide system, which has high bath stability and the deposited gold layer can meet the decorative and functional requirements. However, the free cyanide ion is highly toxic and poses a serious threat to the health of operators, the environment and social safety. In addition, the high coordination stability of the dicyanoaurous ion makes the reduction potential of gold more negative, and the hydrogen evolution reaction also proceeds at this potential, which reduces the deposition current efficiency. Therefore, the development of a new cyanide-free gold plating process is in line with the concept of sustainable development and is of great significance.
[0004] There are two types of electroplating gold systems: Au(Ⅰ) and Au(Ⅲ). The actual application of Au(Ⅲ) is far less than that of Au(Ⅰ). Since the invention of alkaline cyanide gold plating in 1838, almost all gold plating systems are Au(Ⅰ) systems, and cyanide ion is the most suitable ligand complexing agent for Au(Ⅰ).
[0005] Common cyanide-free Au(Ⅰ) gold plating systems include sulfite system, thiosulfate system and sulfite-thiosulfate composite system. The sulfite gold plating system has better bath dispersion ability than the cyanide gold plating system, and the gold coating obtained by electrodeposition is smooth, bright and has good ductility. However, in practical applications, the instability of sulfite has made it difficult to completely replace cyanide gold plating. [1] Generally, in order to improve the stability of the plating solution, the electrodeposition of gold in the sulfite system is carried out at a pH greater than 8.0, and a ligand containing an amine group is added to the plating solution to improve the stability of the plating solution.
[0006] Gold plating usually uses inert metal materials such as gold as the anode. During the electroplating process, sodium sulfite will be oxidized into sodium sulfate at the anode and lose its coordination ability. This is an important reason for the instability of sulfite gold plating solution.
[0007] References: [1] Yang Jiaqiang, Jin Lei, Yang Fangzu, et al., Overview of the progress of cyanide-free gold plating [J], Electroplating and Finishing, 2019, 41(12): 35-43. Summary of the invention
[0008] In order to solve the problem of low stability of sulfite gold plating solution, the utility model provides an anode device for sulfite gold plating. In order to achieve the above purpose, the utility model adopts the following technical solutions:
[0009] An anode device for sulfite gold plating comprises an anode basket, an anode basket upper cover, and an anode, forming an anode chamber in a sulfite gold plating tank to separate the plating solution from the anode;
[0010] The side of the anode basket facing the cathode is a porous plate surface, and the cation exchange membrane is fixed on the porous plate surface;
[0011] The anode chamber is filled with an anolyte.
[0012] Preferably, the anode basket and the anode basket upper cover are made of polyvinyl chloride plates.
[0013] Preferably, the anode is a titanium coated anode.
[0014] Preferably, the anode vertically passes through the upper cover of the anode basket, and the anode and the upper cover of the anode basket are welded together by plastic welding.
[0015] Preferably, the anode basket upper cover is provided with exhaust holes.
[0016] Preferably, the anode basket upper cover is fixed to the anode basket by bolts.
[0017] Preferably, the anolyte is a sodium sulfate solution with a mass concentration of 50 to 150 g / L.
[0018] The anode device is hung on the anode bar of the plating tank, and the plating tank is divided into two parts: the anode chamber and the plating solution area. During the electroplating process, the sulfite in the sulfite gold plating solution cannot pass through the cation exchange membrane to enter the anode chamber, which effectively solves the problem of sulfite being oxidized by the anode and losing its coordination ability in the traditional process. The water in the anode chamber is electrolyzed on the anode to produce oxygen and hydrogen ions, and the oxygen escapes from the anode chamber, and the excess hydrogen ions pass through the cation exchange membrane into the plating solution area. After the pH of the plating solution is reduced, sodium hydroxide solution is added to raise its pH to within the process range.
[0019] Compared with the prior art, the utility model has the following beneficial effects:
[0020] 1. The anode device for sulfite gold plating disclosed in the utility model uses a cation exchange membrane to separate the sulfite gold plating solution from the anode, thus overcoming the problem of sulfite being oxidized by the anode;
[0021] 2. The sulfite gold-plated anode device disclosed in the utility model uses titanium coating material as the anode, and its cost is significantly lower than that of a gold anode. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] 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:
[0023] Figure 1 It is a schematic diagram of the anode device of Example 1 and Example 2 of the utility model;
[0024] Figure 2 It is a schematic diagram of the coating structure of Example 1 and Example 2 of the utility model. DETAILED DESCRIPTION
[0025] 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.
[0026] The gold-plated layer is prepared by a sulfite gold-plating process, and an anode device is used instead of a traditional gold anode to improve the stability of the sulfite gold-plating solution.
[0027] The anode device comprises an anode basket, an anode basket upper cover, and an anode, forming an anode chamber to separate the plating solution from the anode.
[0028] Preferably, the side of the anode basket facing the cathode is a porous plate surface, and the cation exchange membrane is fixed on the porous plate surface to form a cation channel.
[0029] Preferably, the anode basket and the anode basket upper cover are made of polyvinyl chloride plates, and the anode is a titanium-coated anode.
[0030] Preferably, the anode vertically passes through the upper cover of the anode basket, and the anode and the upper cover of the anode basket are welded together by plastic welding.
[0031] Preferably, the anode basket upper cover is fixed to the anode basket by bolts to form the anode device.
[0032] Preferably, the upper cover of the anode basket is provided with exhaust holes for discharging oxygen generated on the anode during electroplating.
[0033] Preferably, the anolyte is a sodium sulfate solution with a mass concentration of 50 to 150 g / L, which is added into the anode chamber.
[0034] The anode device is hung on the anode bar of the plating tank, and the plating tank is divided into two parts: the anode chamber and the plating solution area.
[0035] Preferably, the anode is a titanium-coated anode used in trivalent chromium sulfate plating.
[0036] The process flow of preparing the gold-plated layer by using the sulfite gold-plating process is as follows:
[0037] A cyanide-free pre-plated copper layer, an acid copper plating layer, a bright nickel plating layer and a gold plating layer are sequentially prepared on a steel substrate.
[0038] The steel workpieces are degreased, derusted and activated according to the current pre-treatment process.
[0039] A cyanide-free pre-plated copper layer is prepared on a pre-treated steel part by using a polymerized thiocyanate copper plating process, and the plating thickness is 1 to 5 μm.
[0040] Preferably, the cyanide-free pre-copper plating layer is prepared by Zunyi Huitong's HT-810 polymerized thiocyanate copper plating process:
[0041] 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 ≤0.5 A / dm 2 , use oxygen-free electrolytic copper corners (or copper particles) as anodes.
[0042] After the steel parts are pre-plated with cyanide-free copper, the acid copper coating is prepared by the current acid copper plating process, and the coating thickness is 8 to 18 μm.
[0043] After the steel parts are plated with acid copper, the current bright nickel plating process is adopted to prepare a bright nickel plating layer, and the thickness of the plating layer is 8 to 15 μm.
[0044] After the steel parts are plated with bright nickel, the gold-plated layer is prepared by the current sulfite gold-plating process, and the thickness of the plating layer is 0.05 to 1.2 μm.
[0045] Preferably, the sulfite gold plating adopts the following process:
[0046] Gold 10-15g / L, sodium sulfite 140-180g / L, potassium citrate 80-100g / L, EDTA disodium salt 35-45g / L, cobalt sulfate heptahydrate 0.5-1.0g / L, potassium chloride 50-100g / L, plating solution pH 8-10, plating tank temperature 40℃-60℃, cathode current density 0.3-0.8A / dm 2 , the cathode moves 3 to 5 m / min, and the anode is the anode device described in the present technical solution.
[0047] After the steel parts are gold-plated and washed with water, they are dried at 70℃~80℃ for 15~25min. Example
[0048] The gold-plated layer is prepared by a sulfite gold-plating process, and an anode device is used to replace a traditional gold-plating anode to improve the stability of the sulfite gold-plating solution.
[0049] like Figure 1 As shown, the anode device includes an anode basket 1, an anode basket upper cover 2, and an anode 3, forming an anode chamber to separate the plating solution from the anode. The side of the anode basket facing the cathode is a porous plate surface, and a cation exchange membrane is fixed on the porous plate surface to form a cation channel. The anode basket and the anode basket upper cover are made of polyvinyl chloride plates, and the anode adopts a titanium coated anode used for sulfate trivalent chromium plating. The anode is vertically passed through the anode basket upper cover, and the anode and the anode basket upper cover are welded together by plastic welding. The anode basket upper cover and the anode basket are bolted together to form an anode device. The anode basket upper cover is provided with an exhaust hole for discharging the oxygen generated on the anode during electroplating. The anolyte is a sodium sulfate solution with a mass concentration of 100g / L, which is added to the anode chamber. The anode device is hung on the anode bar of the plating tank, and the plating tank is divided into two parts: the anode chamber and the plating solution area.
[0050] like Figure 2 As shown, a cyanide-free pre-plated copper layer 2, an acid copper plating layer 3, a bright nickel plating layer 4, and a gold plating layer 5 are sequentially prepared on a steel substrate 1.
[0051] 1. Pre-treatment:
[0052] According to the current pre-treatment process, the steel substrate 1 is subjected to "alkaline chemical degreasing → water washing → acid washing → water washing → alkaline cathode electrolytic degreasing → water washing → alkaline anode electrolytic degreasing → water washing → activation → water washing".
[0053] 2. Cyanide-free copper plating:
[0054] After pretreatment, the steel parts are subjected to Zunyi Huitong's HT-810 polymerized thiocyanate copper plating process to prepare a pre-plated copper layer 2, and the coating thickness is 2 μm.
[0055] 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 12.6, cathode current density 0.8A / dm 2 , cathode movement 5m / min, anode current density less than 0.4 A / dm 2 , use oxygen-free electrolytic copper corner as anode.
[0056] 3. Acid copper plating:
[0057] After the steel parts are pre-plated with cyanide-free copper, an acid copper coating 3 is prepared by using the current acid copper plating process, and the coating thickness is 12 μm.
[0058] 4. Bright nickel plating:
[0059] After the steel parts are plated with acid copper, a bright nickel plating layer 4 is prepared by using the current bright nickel plating process, and the plating thickness is 10 μm.
[0060] 5. Gold plating
[0061] After the steel part is plated with bright nickel, a gold-plated layer 5 is prepared by the following sulfite gold-plating process, and the thickness of the plating layer is 0.3 μm.
[0062] Gold 12.5g / L, sodium sulfite 160g / L, potassium citrate 90g / L, EDTA disodium salt 40g / L, cobalt sulfate heptahydrate 0.75g / L, potassium chloride 95g / L, plating solution pH 9, plating tank temperature 55℃, cathode current density 0.6A / dm 2 , cathode moves 4m / min, anode is Figure 1 Anode assembly shown.
[0063] 6. Drying:
[0064] The steel parts were gold plated, washed with water and then dried at 75°C for 20 minutes. Example
[0065] The gold-plated layer is prepared by a sulfite gold-plating process, and an anode device is used to replace a traditional gold-plating anode to improve the stability of the sulfite gold-plating solution.
[0066] like Figure 1 As shown, the anode device includes an anode basket 1, an anode basket upper cover 2, and an anode 3, forming an anode chamber to separate the plating solution from the anode. The side of the anode basket facing the cathode is a porous plate surface, and a cation exchange membrane is fixed on the porous plate surface to form a cation channel. The anode basket and the anode basket upper cover are made of polyvinyl chloride plates, and the anode adopts a titanium coated anode used for sulfate trivalent chromium plating. The anode is vertically passed through the anode basket upper cover, and the anode and the anode basket upper cover are welded together by plastic welding. The anode basket upper cover and the anode basket are bolted together to form an anode device. The anode basket upper cover is provided with an exhaust hole for discharging the oxygen generated on the anode during electroplating. The anolyte is a sodium sulfate solution with a mass concentration of 120g / L, which is added to the anode chamber. The anode device is hung on the anode bar of the plating tank, and the plating tank is divided into two parts: the anode chamber and the plating solution area.
[0067] like Figure 2 As shown, a cyanide-free pre-plated copper layer 2, an acid copper plating layer 3, a bright nickel plating layer 4, and a gold plating layer 5 are sequentially prepared on a steel substrate 1.
[0068] 1. Pre-treatment:
[0069] According to the current pre-treatment process, the steel substrate 1 is subjected to "alkaline chemical degreasing → water washing → acid washing → water washing → alkaline cathode electrolytic degreasing → water washing → alkaline anode electrolytic degreasing → water washing → activation → water washing".
[0070] 2. Cyanide-free copper plating:
[0071] After pretreatment, the steel parts were subjected to Zunyi Huitong's HT-810 polymerized thiocyanate copper plating process to prepare a cyanide-free pre-plated copper layer 2, with a coating thickness of 4 μm.
[0072] Polythiocyanate cuprous 21g / L, polythiocyanate sodium 140g / L, potassium sodium tartrate 12g / L, HT-810 brightener 1.5mL / L, HT-810 moving agent 3mL / L, plating tank temperature 53℃, plating solution pH 12.8, cathode current density 0.8A / dm 2 , cathode movement 5m / min, anode current density less than 0.4 A / dm 2 , using oxygen-free electrolytic copper particles as anode.
[0073] 3. Acid copper plating:
[0074] After the steel parts are pre-plated with cyanide-free copper, an acid copper coating 3 is prepared by using the current acid copper plating process, and the coating thickness is 10 μm.
[0075] 4. Bright nickel plating:
[0076] After the steel parts are plated with acid copper, a bright nickel plating layer 4 is prepared by using the current bright nickel plating process, and the plating thickness is 10 μm.
[0077] 5. Gold plating
[0078] After the steel part is plated with bright nickel, a gold-plated layer 5 is prepared by the following sulfite gold-plating process, and the thickness of the plating layer is 0.3 μm.
[0079] Gold 15g / L, sodium sulfite 180g / L, potassium citrate 100g / L, EDTA disodium salt 45g / L, cobalt sulfate heptahydrate 1.0g / L, potassium chloride 100g / L, plating solution pH 9, plating tank temperature 50℃, cathode current density 0.7A / dm 2 , cathode moves 4m / min, anode is Figure 1 Anode assembly shown.
[0080] 6. Drying:
[0081] The steel parts were gold plated, washed with water and then dried at 80°C for 15 minutes.
[0082] Test Example 1:
[0083] Prepare 1000mL of test solution, which contains 160g / L sodium sulfite, 90g / L potassium citrate, 40g / L disodium EDTA, and 75g / L potassium chloride, and adjust the pH of the test solution to 9 with sodium hydroxide solution. Determine the mass concentration of sodium sulfite in the test solution by potassium permanganate titration, and the result is 156.2g / L.
[0084] Use titanium coated plate as anode, wrap the anode with cation exchange membrane to form an anode chamber, put the anode into the test solution, inject 100g / L sodium sulfate solution into the anode chamber. Heat the test solution to 50℃ and keep it warm. Use stainless steel plate as cathode and 2 The electrolysis was carried out for 12 h at a cathode current density of .
[0085] The volume of the test solution was supplemented to 1000 mL, and then the mass concentration of sodium sulfite in the test solution was determined by potassium permanganate titration, and the result was 155.5 g / L, and the recovery rate was 99.55%. The test showed that the technical solution of the utility model can effectively prevent sodium sulfite from being anodic oxidized.
[0086] Test Example 2:
[0087] The gold-plated parts prepared in Example 1 and Example 2 were tested for coating adhesion by a 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 placed in a heating furnace and heated to 300°C for 30 minutes. After being taken out, they were placed in water at room temperature and suddenly cooled. No bubbling or shedding occurred in the coating. The gold-plated layer structure prepared by the present technical solution had good adhesion.
[0088] Test Example 3:
[0089] The gold-plated parts prepared in Example 1 and Example 2 were subjected to a neutral salt spray test for 144 hours in accordance with GB / T 10125-2021 "Artificial atmosphere corrosion test salt spray test". No corrosive products were generated on the surface of the plated parts. The corrosion resistance of the gold-plated layer structure prepared by this technical solution meets the technical requirements of the industry.
[0090] 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 ordinary technicians in this field, 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 sulfite gold-plated anode device, characterized in that: The invention comprises an anode basket, an anode basket cover, and an anode, which form an anode chamber in a sulfite gold plating tank to separate the plating solution from the anode; The side of the anode basket facing the cathode is a porous plate surface, and the cation exchange membrane is fixed on the porous plate surface; The anode chamber is filled with an anolyte.
2. A sulfite gold-plated anode device as claimed in claim 1, characterized in that: The anode basket and the anode basket upper cover are made of polyvinyl chloride plates.
3. A sulfite gold-plated anode device as claimed in claim 1, characterized in that: The anode is a titanium coated anode.
4. A sulfite gold-plated anode device as claimed in claim 1, characterized in that: The anode vertically passes through the upper cover of the anode basket, and the anode and the upper cover of the anode basket are welded together by a plastic welding method.
5. A sulfite gold-plated anode device as claimed in claim 1, characterized in that: The anode basket upper cover is provided with exhaust holes.
6. A sulfite gold-plated anode device as claimed in claim 1, characterized in that: The anode basket upper cover is fixed to the anode basket by bolts.