Sulfite cyanide-free electroforming gold liquid and gold electroforming method

Abstract

The invention discloses a sulfite cyanide-free gold electroforming solution and a gold electroforming method, and relates to the technical field of gold electroforming. Wherein each liter of the electroforming gold liquid comprises 50-200 g / L of sulfite, 10-30 g / L of a buffering agent, 0.1-2 g / L of a surface active agent and 0.05-1 g / L of a brightening agent. The sulfite is used as an effective complexing agent and can complex alloy ions under the condition of not generating toxic byproducts, so that metal deposition is realized. Compared with cyanide, the sulfite reduces the risk of environmental pollution while providing the necessary complexing action. And the surface quality and the appearance effect of the plating layer are further improved by adding the surfactant and the brightener, and the purpose is achieved by reducing the interfacial tension and adjusting the crystal growth mode. The application of the buffer agent is to maintain the stability of the pH value of the solution, which is very critical to maintain the constant condition in the electro-deposition process.

Description

Technical Field

[0001] The present invention relates to the technical field of gold electroforming, and more particularly to a sulfite-free cyanide electroforming gold solution and a gold electroforming method. Background Art

[0002] Electroforming is a technique that uses the principle of electrolysis to deposit a layer of metal on the surface of a pre-prepared mold or mandrel. In many application fields, such as electronics, jewelry, ornaments, and precision mold manufacturing, gold has become one of the ideal electroforming materials due to its excellent physical and chemical properties (such as corrosion resistance, good electrical conductivity, and beautiful appearance). However, traditional gold electroforming processes mostly rely on electroforming solutions containing cyanide, which pose significant potential hazards to environmental safety and human health.

[0003] Due to its strong complexing ability, cyanide can effectively keep gold ions stable in the solution, thus ensuring the smooth progress of the electroforming process. However, cyanide is highly toxic, and even a trace amount of leakage can cause serious environmental pollution and harm to human health. In addition, treating cyanide-containing wastewater requires high costs and technical means, increasing the operating costs and management difficulties of enterprises. Therefore, the research and development of a cyanide-free and environmentally friendly electroforming gold solution has become a research hotspot in this field.

[0004] In recent years, researchers have begun to explore the use of low-toxicity complexing agents to replace cyanide in the electroforming process. Among them, sulfite has been widely studied due to its good complexing properties. Sulfite can not only effectively complex gold ions, but also its toxicity is much lower than that of cyanide, causing less harm to the environment and human body. In addition, by adjusting the additive components in the electroforming solution, the coating quality can be further optimized, such as improving the uniformity, brightness, and flatness of the coating.

[0005] Although sulfite shows great potential as a complexing agent, it still faces some technical problems in practical applications. First, the stability of the electroforming solution under the sulfite system is poor and it is prone to decomposition, affecting the electroforming effect. Second, how to ensure the coating quality without using cyanide, especially for high-demand application scenarios, is an important challenge. In response to these problems, researchers have proposed various improvement measures, including adding buffers to adjust the pH value to enhance the solution stability, and introducing specific surfactants and brighteners to improve the coating quality.

[0006] Therefore, how to develop a cyanide-free electroforming gold solution based on the sulfite system and its electroforming method is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a sulfite-free cyanide electroforming gold solution and a gold electroforming method.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] On the one hand, an embodiment of the present invention provides a sulfite-free cyanide electroforming gold solution, and the electroforming gold solution uses sulfite as a complexing agent; wherein, each liter of the electroforming gold solution includes: 50-200 g / L of sulfite, 10-30 g / L of buffer, 0.1-2 g / L of surfactant, and 0.05-1 g / L of brightener.

[0010] Preferably, the sulfite is selected from one or a combination of sodium sulfite and potassium sulfite.

[0011] Preferably, the buffer is selected from one or a combination of boric acid, sodium carbonate, and potassium carbonate.

[0012] Preferably, the surfactant is selected from one or a combination of sodium dodecyl sulfate (SDS) and polyoxyethylene ether compounds.

[0013] Preferably, the brightener is a sulfur-containing organic compound;

[0014] Preferably, the sulfur-containing organic compound is a dithiocarbamate compound.

[0015] On the second aspect, an embodiment of the present invention provides a method for electroforming gold using the sulfite-free cyanide electroforming gold solution, including the following steps:

[0016] 1) Prepare the sulfite-free cyanide electroforming gold solution according to the mass ratio;

[0017] 2) Immerse the workpiece to be electroformed as the cathode and a pure gold plate as the anode in the electroforming gold solution;

[0018] 3) Conduct the electroforming process under a controlled current density, and maintain the solution temperature and pH value within an appropriate range during the process;

[0019] 4) After the electroforming is completed, take out the workpiece and clean and dry it.

[0020] Preferably, the optimal temperature range for the electroforming process is 30°C to 50°C.

[0021] Preferably, the optimal current density is 0.5 A / dm 2 to 2.0 A / dm 2 .

[0022] Preferably, the pH value is maintained between 7.5 and 9.0.

[0023] On the third aspect, an embodiment of the present invention provides a use of the sulfite-free cyanide electroforming gold solution, and the use includes the following aspects:

[0024] 1) For the surface treatment of electronic components, jewelry, and ornaments;

[0025] 2) To improve the gloss and flatness of gold jewelry.

[0026] The technical effects achieved by the present invention are as follows:

[0027] 1) Using sulfite as a complexing agent to replace cyanide in traditional electroforming gold solutions, significantly reducing the risks to the environment and human health. Cyanide is a highly toxic substance, and its use, storage, and disposal require strict control. In contrast, sulfite has lower toxicity and is more suitable for industrial production with strict modern environmental protection requirements.

[0028] 2) By optimizing the formulation, including adding appropriate buffers, surfactants, and brighteners, it is possible to ensure the formation of high-quality gold coatings during the electroforming process. For example, a suitable surfactant can improve the wetting properties of the solution, making the coating more uniform and flat; while the brightener helps to improve the gloss of the coating. In addition, selecting the appropriate additives is crucial for stabilizing the pH value of the solution, which helps to maintain the consistency of the electrochemical reaction and the quality of the coating.

[0029] 3) Defining the optimal operating conditions (such as temperature, current density, and pH value) not only improves production efficiency but also ensures the consistency of the coating. For example, operating within an appropriate temperature range can promote the effective progress of the electrochemical reaction while avoiding the adverse effects caused by too high a temperature. Similarly, precisely controlling the current density helps to obtain the desired coating thickness and structural characteristics.

[0030] In the present invention, sulfite, as an effective complexing agent, can complex metal ions without producing toxic by-products, thereby realizing the deposition of metals. Compared with cyanide, sulfite reduces the risk of environmental pollution while providing the necessary complexing effect. The addition of surfactants and brighteners further enhances the surface quality and appearance of the coating, and they achieve this by reducing the interfacial tension and regulating the crystal growth mode. The application of the buffer is to maintain the stability of the solution pH value, which is crucial for maintaining constant conditions during the electrodeposition process.

[0031] In summary, this cyanide-free electroforming gold solution based on sulfite and its related processes not only solve the safety problems existing in traditional methods but also perform excellently in improving product quality. It represents a more environmentally friendly and efficient development direction for metal surface treatment technologies. Detailed implementation mode

[0032] Next, in combination with the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] Example 1

[0034] Electroforming gold solution formula:

[0035] Sodium sulfite (Na 2 SO 3 ): 150 g / L

[0036] Boric acid (H 3 BO 3 ): 20 g / L

[0037] Sodium dodecyl sulfate (SDS): 1.0 g / L

[0038] Dithiocarbamate compounds: 0.5 g / L

[0039] Electroforming process:

[0040] 1. Prepare the electroforming gold solution according to the above ratio.

[0041] 2. Immerse the workpiece to be plated as the cathode and a pure gold plate as the anode in the electroforming gold solution.

[0042] 3. Control the current density to be 1.0 A / dm 2 , maintain the temperature at 40 °C, and adjust the pH value to 8.0.

[0043] 4. After electroforming is completed, take out the workpiece and clean and dry it.

[0044] Example 2

[0045] Electroforming gold solution formula:

[0046] Potassium sulfite (K2SO3): 180 g / L

[0047] Sodium carbonate (Na2CO3): 25 g / L

[0048] Polyoxyethylene ether compounds: 1.5 g / L

[0049] Dithiocarbamate compounds: 0.7 g / L

[0050] Electroforming process:

[0051] 1. Prepare the corresponding electroforming gold solution.

[0052] 2. Similarly, the workpiece to be plated is used as the cathode, and a pure gold plate is used as the anode, which are immersed in the solution.

[0053] 3. Control the current density to be 1.5 A / dm 2 , keep the temperature at 45 °C, and the pH value at 8.5.

[0054] 4. After completion, perform cleaning and drying treatments.

[0055] Example 3

[0056] Electroforming gold solution formula:

[0057] Sodium sulfite (Na 2 SO 3 ) and potassium sulfite (K 2 SO 3 ) mixture (each accounting for half): 160 g / L potassium carbonate (K 2 CO 3 ): 22 g / L

[0058] Sodium dodecyl sulfate (SDS): 0.8 g / L

[0059] Dithiocarbamate compounds: 0.6 g / L

[0060] Electroforming process:

[0061] 1. Prepare the electroforming gold solution.

[0062] 2. Use the same electroforming steps.

[0063] 3. Control the conditions as current density 1.2 A / dm 2 , temperature 42 °C, and pH value 8.2.

[0064] Comparative example

[0065] Comparative example 1

[0066] Use the traditional cyanide electroforming gold solution without adding any surfactants or brighteners.

[0067] Comparative example 2

[0068] Adopt the formula of Example 1 but omit the surfactant.

[0069] Comparative example 3

[0070] Adopt the formula of Example 1 but do not add the buffer boric acid.

[0071] Statistically analyze the gloss score and flatness score of the coating, as shown in Table 1.

[0072] Table 1

[0073]

[0074]

[0075] Conclusion

[0076] Through comparative experiments, it can be found that the sulfite-free cyanide electroforming gold solution and its method provided by the present invention can significantly improve the glossiness and flatness of the coating, while reducing the harm to the environment. Especially after adding appropriate surfactants, brighteners and buffers, the coating quality has been significantly improved. In contrast, the comparative examples without adding these components or using traditional cyanide electroforming gold solution perform poorly in terms of coating quality and environmental protection. Therefore, the present invention not only has innovation and practicality, but also meets the requirements of modern industry for green manufacturing.

[0077] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0078] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sulfite cyanide-free electroplating gold liquid, characterized in that: The electroforming gold liquid uses sulfite as a complexing agent; wherein each liter of the electroforming gold liquid includes: 50-200 g / L of sulfite, 10-30 g / L of a buffer, 0.1-2 g / L of a surfactant, and 0.05-1 g / L of a brightener.

2. The sulfite cyanide-free electroforming gold liquid according to claim 1, characterized in that: The sulfite is selected from one or more combinations of sodium sulfite and potassium sulfite.

3. The sulfite cyanide-free electroplating gold liquid according to claim 1, characterized in that: The buffer is selected from one or more combinations of boric acid, sodium carbonate and potassium carbonate.

4. The sulfite cyanide-free electroforming gold liquid according to claim 1, characterized in that: The surfactant is selected from one or more combinations of sodium dodecyl sulfate (SDS) and polyoxyethylene ether compounds.

5. The sulfite cyanide-free electroforming gold liquid according to claim 1, characterized in that: The brightener is a sulfur-containing organic compound; Preferably, the sulfur-containing organic compound is a dithiocarbamate compound.

6. A method for electroforming gold using the sulfite cyanide-free electroforming gold solution according to any one of claims 1 to 5, characterized in that: The following steps are involved: 1) preparing the sulfite cyanide-free electroforming gold solution according to the mass ratio; 2) The workpiece to be electroformed is used as the cathode and the pure gold plate is used as the anode, and they are immersed in the electroforming gold liquid; 3) performing the electroforming process under controlled current density, during which the solution temperature and pH value are maintained within a suitable range; 4) After electroforming is completed, remove the workpiece and clean and dry it.

7. The method according to claim 6, characterized in that The optimal temperature range of the electroforming process is 30°C to 50°C.

8. The method according to claim 6, characterized in that The optimal current density is 0.5A / dm 2 Up to 2.0A / dm 2 .

9. The method according to claim 6, characterized in that The pH is maintained between 7.5 and 9.

0.

10. A use of the sulfite cyanide-free electroforming gold liquid according to claim 1, characterized in that: The uses include the following aspects: 1) Used for surface treatment of electronic components, jewelry and decorations; 2) Improve the gloss and smoothness of gold jewelry.

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