Silver ornament electrolyte gold plating method

Abstract

The invention relates to the technical field of silver ornament treatment, in particular to a silver ornament electrolyte gold plating method which comprises the steps of (1) silver ornament surface treatment and (2) electroplating. The silver ornament is placed in a container containing purified water, acid liquor is dropwise added to increase the temperature, then a sodium hydroxide solution is dropwise added, and electroplating is conducted. Various impurities such as cortical cells, sweat and dust on the surface of the silver ornament are fully dissolved through alternate acid-base treatment, so that the impurities can be efficiently removed, the silver ornament body can be prevented from being excessively corroded, the crosslinking and mixing of organic particles in the solution can be improved, metal ion deposition can be guided in electroplating, the close arrangement of crystals in the gold plating process can be effectively rented, and the gold plating quality is improved. And under the action of the rare earth cerium, the rare earth cerium can be condensed with various metal ions to form a compact layer, so that the corrosion resistance of a gold-plated layer is improved, and the gold-plated silver ornament is better in color and stable in quality.

Description

Technical Field

[0001] The invention relates to the technical field of silver ornament processing, in particular to a silver ornament electrolyte gold plating method. Background Art

[0002] Gold plating is to plate a thick layer of gold on the surface of an object, making it appear dazzling and golden, and the hand-carved patterns are more vivid under the light. Gold plating is mainly electroplating (electrolysis) and chemical gold plating. Among them, electroplating gold is to use the principle of electrolysis to cover a layer of metal on the conductor, while chemical gold plating mainly attaches gold to the surface of metal or other objects to form a thick layer of gold. There are many studies on the prior art. For example, patent number CN202110671561.4 is a protective film electrolyte, gold-plated silver jewelry and its preparation method, wherein the electrolyte contains thiol, benzimidazole compound, polyoxyethylene ether surfactant and solvent; wherein the thiol is selected from at least one of octadecyl mercaptan, tert-dodecyl mercaptan, hexadecyl mercaptan and 1-dodecyl mercaptan; the benzimidazole compound is selected from at least one of benzimidazole, 2-mercaptobenzimidazole, 2-aminobenzimidazole, and 2-(chloromethyl)benzimidazole; the polyoxyethylene ether surfactant is selected from at least one of octylphenol polyoxyethylene ether, isooctyl alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, and isomeric decanol polyoxyethylene ether. The prepared gold-plated silver jewelry has good stability and can effectively solve the problem of discoloration of gold-plated silver jewelry. Another example is a gold-plated silver jewelry with patent number CN202010410788.9, which includes a silver matrix, a first isolation layer, a second isolation layer, a gold-plated layer and a protective layer; the Vickers hardness of the prepared gold-plated silver jewelry can reach about 110HV, and the purity of gold and silver therein is >99.9%. The product has good wear resistance and corrosion resistance, and will not have problems such as peeling, fading or discoloration, and has good practicality. However, the gold plating process in the prior art directly uses organic matter and a solution containing gold particles for electroplating, and does not modify and optimize the electrolyte for the organic matter in the solution, resulting in poor stability of the gold-plated jewelry. Summary of the invention

[0003] 1. Technical issues to be solved

[0004] In view of the shortcomings of the prior art, the present invention provides a method for gold plating silver jewelry with electrolyte. During the treatment of the silver jewelry, acid-base solution exchange and cleaning are performed to remove impurities on the surface of the silver jewelry. Macromolecular organic matter and multiple metal ions are used in electroplating to make the electroplating layer structure dense and have good anti-corrosion effect.

[0005] (II) Technical solution

[0006] A method for gold plating of silver ornaments using electrolyte, comprising:

[0007] (1) Surface treatment of silver jewelry

[0008] Place the silver jewelry in a container filled with pure water, drip acid to reduce the pH of the solution to 4-4.5, raise the temperature to 30-45°C and keep it for 20-30 seconds, then drip sodium hydroxide solution until the pH of the solution rises to 9-9.3 and keep it for 15-20 seconds; take out the silver jewelry and rinse it with pure water;

[0009] (2) Electroplating

[0010] Prepare a gold plating solution, according to 1L solution, add 0.1-0.17g polyethyleneimine, 0.1-0.12g amylsulfonic acid, 10-13g gold sodium sulfite, 0.2-0.23g sodium dodecyl sulfate, 50-67g sodium sulfite, 2-4g copper sulfate, 1-3g nickel sulfate, 0.1-0.12g cerium sulfate, 2-4g modified carbon fiber, 30-35g concentrated sulfuric acid, 13-17g polyethylene glycol; use ultrasound to homogenize the gold plating solution;

[0011] Put the silver ornaments into the gold plating solution, keep the silver ornaments completely immersed in the solution system, control the solution temperature to 58-60°C, use a single pulse power supply, adjust the current density to 0.44-0.56A / dm2, and electroplate to obtain gold-plated silver ornaments; take out the silver ornaments, polish them according to the original texture and shape, spray them with transparent polyamide resin on the surface of the ornaments, control the thickness of the spray layer to 40-60μm, put the silver ornaments in a drying oven, first introduce nitrogen to remove the oxygen in the drying oven, wait for 30-40s, put desiccant calcium chloride in the drying oven, continue to fill with nitrogen so that the pressure in the drying oven is 2-2.3 atmospheres, raise the temperature to 40-43°C, continue for 80-90min, reduce the air pressure to standard atmospheric pressure, and continue drying for 30-44min.

[0012] Furthermore, the acid solution is hydrochloric acid with a mass fraction of 1-1.6%.

[0013] Furthermore, the mass fraction of the sodium hydroxide solution is 1.8-2%.

[0014] Furthermore, the preparation method of the modified carbon fiber is as follows: by weight, 1 part of carbon fiber is mixed with 5-8 parts of perchloric acid solution, soaked for 10-15 minutes, centrifuged, the precipitate is collected, and washed with distilled water for 3-4 times; 5-8 parts of precipitate are mixed with 20-30 parts of clean water, 0.1-0.3 parts of ethylenediamine are added, heated to 70-80°C, kept warm for 60-80 minutes, and concentrated to dryness under reduced pressure.

[0015] Furthermore, the mass fraction of the perchloric acid solution is 30-33%.

[0016] Furthermore, the mass fraction of the concentrated sulfuric acid is 80-85%.

[0017] Furthermore, the ultrasonic homogenization time for the gold plating solution is 3-5 minutes.

[0018] Furthermore, the conduction time during electroplating is 10-13ms.

[0019] Furthermore, the shut-off time during electroplating is 10-15 ms, and the electroplating time is 12 min.

[0020] (III) Beneficial effects

[0021] The present invention provides a method for electrolytic gold plating of silver ornaments, wherein the silver ornaments are placed in a container filled with pure water, an acid solution is dripped into the container to increase the temperature, and then a sodium hydroxide solution is dripped into the container, and the alternating acid-base treatment fully dissolves various impurities such as cortical cells, sweat, and dust on the surface of the silver ornaments, which can not only remove them efficiently, but also prevent the silver ornaments from being excessively corroded. Polyethyleneimine, pentylsulfonic acid, sodium gold sulfite, sodium dodecylsulfonate, sodium sulfite, copper sulfate, nickel sulfate, cerium sulfate, modified carbon fiber, concentrated sulfuric acid, and polyethylene glycol are added during electroplating to form a solution system of multiple organic particles interwoven, which fully limits the deposition of gold in the electroplating and prevents the rapid formation of a gold layer that causes uneven material surface. In particular, in the preparation method of modified carbon fiber, carbon fiber and perchloric acid solution are mixed and oxidized, and then heated with ethylenediamine to form a long-chain compound, which can improve the cross-linking and mixing of organic particles in the solution, guide the deposition of metal ions in the electroplating, and effectively rent the close arrangement of crystals in the gold plating process. Moreover, under the action of rare earth cerium, it can condense into a dense layer with a variety of metal ions, improve the stability of the gold-plated layer, improve the corrosion resistance of the gold-plated layer, and make the silver jewelry after gold plating better in color and stable in quality. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0023] Example 1

[0024] A method for gold plating of silver ornaments using electrolyte, comprising:

[0025] (1) Surface treatment of silver jewelry

[0026] Place the silver jewelry in a container filled with pure water, drip acid to reduce the pH of the solution to 4, raise the temperature to 30°C and hold for 20 seconds, then drip sodium hydroxide solution until the pH of the solution rises to 9 and hold for 15 seconds; take out the silver jewelry and rinse it with pure water;

[0027] The acid solution is hydrochloric acid with a mass fraction of 1%; the mass fraction of the sodium hydroxide solution is 1.8%;

[0028] (2) Electroplating

[0029] Prepare a gold plating solution, according to 1L solution, add 0.1g polyethyleneimine, 0.1g amylsulfonic acid, 10g gold sodium sulfite, 0.2g sodium dodecylsulfonate, 50g sodium sulfite, 2g copper sulfate, 1g nickel sulfate, 0.1g cerium sulfate, 2g modified carbon fiber, 30g concentrated sulfuric acid, and 13g polyethylene glycol; use ultrasound to homogenize the gold plating solution for 3 minutes; put the silver ornaments into the gold plating solution, keep the silver ornaments completely immersed in the solution system, control the solution temperature to 58°C, use a single pulse power supply, and adjust the current density to 0.44A / dm2, electroplating to obtain gold-plated silver ornaments; taking out the silver ornaments, polishing them according to the original pattern and shape, spraying transparent polyamide resin on the surface of the ornaments, controlling the thickness of the spray layer to be 40μm, placing the silver ornaments in a drying oven, first introducing nitrogen to remove the oxygen in the drying oven, waiting for 30s, placing desiccant calcium chloride in the drying oven, continuously filling nitrogen to make the pressure in the drying oven 2 atmospheres, raising the temperature to 40℃, continuing for 80min, reducing the air pressure to standard atmospheric pressure, and continuing to dry for 30min;

[0030] The modified carbon fiber preparation method is as follows: by weight, 1 part of carbon fiber and 5 parts of perchloric acid solution are mixed, soaked for 10 minutes, centrifuged, precipitates are collected, and washed with distilled water for 3 times; 5 parts of precipitates are mixed with 20 parts of clean water, 0.1 parts of ethylenediamine are added, heated to 70°C, kept warm for 60 minutes, and concentrated to dryness under reduced pressure;

[0031] The mass fraction of the perchloric acid solution is 30%; the mass fraction of the concentrated sulfuric acid is 80%.

[0032] Example 2

[0033] A method for gold plating of silver ornaments using electrolyte, comprising:

[0034] (1) Surface treatment of silver jewelry

[0035] Place the silver jewelry in a container filled with pure water, drip acid to reduce the pH of the solution to 4.5, raise the temperature to 45°C and hold for 30 seconds, then drip sodium hydroxide solution until the pH of the solution rises to 9.3 and hold for 20 seconds; take out the silver jewelry and rinse it with pure water;

[0036] The acid solution is hydrochloric acid with a mass fraction of 1.6%; the mass fraction of the sodium hydroxide solution is 2%;

[0037] (2) Electroplating

[0038] Prepare a gold plating solution, according to 1L solution, add 0.17g polyethyleneimine, 0.12g amylsulfonic acid, 13g gold sodium sulfite, 0.23g sodium dodecyl sulfate, 67g sodium sulfite, 4g copper sulfate, 3g nickel sulfate, 0.12g cerium sulfate, 4g modified carbon fiber, 35g concentrated sulfuric acid, 17g polyethylene glycol; use ultrasound to homogenize the gold plating solution for 5min;

[0039] Place the silver ornaments into the gold plating solution, keep the silver ornaments completely immersed in the solution system, control the solution temperature to 60°C, use a single pulse power supply, adjust the current density to 0.56A / dm2, and electroplate to obtain gold-plated silver ornaments; take out the silver ornaments, polish them according to the original texture and shape, spray them with transparent polyamide resin on the surface of the ornaments, control the thickness of the spray layer to 60μm, place the silver ornaments in a drying oven, first introduce nitrogen to remove the oxygen in the drying oven, wait for 40s, put desiccant calcium chloride in the drying oven, continue to fill with nitrogen so that the pressure in the drying oven is 2.3 atmospheres, raise the temperature to 43°C, continue for 90min, reduce the air pressure to standard atmospheric pressure, and continue drying for 44min.

[0040] The modified carbon fiber preparation method is as follows: by weight, 1 part of carbon fiber and 8 parts of perchloric acid solution are mixed, soaked for 15 minutes, centrifuged, precipitates are collected, and washed with distilled water for 4 times; 8 parts of precipitates are mixed with 30 parts of clean water, 0.3 parts of ethylenediamine are added, heated to 80°C, kept warm for 80 minutes, and concentrated under reduced pressure to dryness;

[0041] The mass fraction of the perchloric acid solution is 33%; the mass fraction of the concentrated sulfuric acid is 85%.

[0042] Example 3

[0043] A method for gold plating of silver ornaments using electrolyte, comprising:

[0044] (1) Surface treatment of silver jewelry

[0045] Place the silver jewelry in a container filled with pure water, drip acid to reduce the pH of the solution to 4, raise the temperature to 38°C and hold for 27 seconds, then drip sodium hydroxide solution until the pH of the solution rises to 9.3 and hold for 15 seconds; take out the silver jewelry and rinse it with pure water;

[0046] The acid solution is hydrochloric acid with a mass fraction of 1.6%; the mass fraction of the sodium hydroxide solution is 1.8%;

[0047] (2) Electroplating

[0048] Prepare a gold plating solution, according to 1L solution, add 0.17g polyethyleneimine, 0.1g pentylsulfonic acid, 13g sodium gold sulfite, 0.2g sodium dodecylsulfonate, 67g sodium sulfite, 2g copper sulfate, 3g nickel sulfate, 0.12g cerium sulfate, 2g modified carbon fiber, 35g concentrated sulfuric acid, and 17g polyethylene glycol; use ultrasound to homogenize the gold plating solution for 3 minutes; put the silver ornaments into the gold plating solution, keep the silver ornaments completely immersed in the solution system, control the solution temperature to 60°C, use a single pulse power supply, and adjust the current density to 0.49A / dm2, electroplating to obtain gold-plated silver jewelry; take out the silver jewelry, polish it according to the original texture and shape, spray transparent polyamide resin on the surface of the jewelry, control the thickness of the spray layer to be 55μm, place the silver jewelry in a drying oven, first introduce nitrogen to remove the oxygen in the drying oven, wait for 30s, put desiccant calcium chloride in the drying oven, continue to fill with nitrogen so that the pressure in the drying oven is 2.3 atmospheres, raise the temperature to 40℃, continue for 90min, reduce the air pressure to standard atmospheric pressure, and continue drying for 30min.

[0049] The modified carbon fiber preparation method is as follows: by weight, 1 part of carbon fiber and 8 parts of perchloric acid solution are mixed, soaked for 10 minutes, centrifuged, precipitates are collected, and washed with distilled water for 4 times; 5 parts of precipitates are mixed with 30 parts of clean water, 0.1 parts of ethylenediamine are added, heated to 80° C., kept warm for 60 minutes, and concentrated under reduced pressure to dryness;

[0050] The mass fraction of the perchloric acid solution is 33%; the mass fraction of the concentrated sulfuric acid is 80%.

[0051] Comparative Example 1

[0052] No cerium sulfate was used in the electroplating process. The specific operation is as follows: place the silver ornaments in a container filled with pure water, drip acid solution to reduce the solution pH to 4, raise the temperature to 30°C and keep it for 20 seconds, then drip sodium hydroxide solution until the solution pH rises to 9, and keep it for 15 seconds; take out the silver ornaments and rinse them with pure water; the acid solution is hydrochloric acid with a mass fraction of 1%; the mass fraction of the sodium hydroxide solution is 1.8%;

[0053] Prepare a gold plating solution, according to 1L solution, add 0.1g polyethyleneimine, 0.1g amylsulfonic acid, 10g sodium gold sulfite, 0.2g sodium dodecylsulfonate, 50g sodium sulfite, 2g copper sulfate, 1g nickel sulfate, 2g modified carbon fiber, 30g concentrated sulfuric acid, 13g polyethylene glycol; use ultrasound to homogenize the gold plating solution for 3min; put the silver ornaments into the gold plating solution, use a single pulse power supply, adjust the current density to 0.44A / dm2, the conduction time to 10ms, the off time to 10ms, the electroplating time to 12min, and electroplate the gold-plated silver ornaments;

[0054] The preparation method of modified carbon fiber is as follows: by mass, 1 part of carbon fiber and 5 parts of perchloric acid solution are mixed, soaked for 10 minutes, centrifuged, precipitates are collected, and washed with distilled water for 3 times; 5 parts of precipitates are mixed with 20 parts of clean water, 0.1 parts of ethylenediamine are added, heated to 70°C, kept warm for 60 minutes, and concentrated to dryness under reduced pressure; the mass fraction of the perchloric acid solution is 30%; the mass fraction of the concentrated sulfuric acid is 80%.

[0055] Comparative Example 2, no modified carbon fiber was used. The specific operation is as follows: place the silver ornaments in a container filled with pure water, drip acid solution to reduce the solution pH to 4, raise the temperature to 30°C and keep it for 20 seconds, then drip sodium hydroxide solution until the solution pH rises to 9, and keep it for 15 seconds; take out the silver ornaments and rinse them with pure water; the acid solution is hydrochloric acid with a mass fraction of 1%; the mass fraction of sodium hydroxide solution is 1.8%;

[0056] Prepare a gold plating solution, according to 1L solution, add 0.1g polyethyleneimine, 0.1g pentylsulfonic acid, 10g gold sodium sulfite, 0.2g sodium dodecylsulfonate, 50g sodium sulfite, 2g copper sulfate, 1g nickel sulfate, 0.1g cerium sulfate, 30g concentrated sulfuric acid, 13g polyethylene glycol; use ultrasound to homogenize the gold plating solution for 3 minutes; put the silver ornaments into the gold plating solution, use a single pulse power supply, adjust the current density to 0.44A / dm2, the conduction time to 10ms, the off time to 10ms, the electroplating time to 12min, and electroplate the gold-plated silver ornaments; the mass fraction of the concentrated sulfuric acid is 80%.

[0057] Experimental example

[0058] Experimental equipment: Silver bracelets were provided by Yiwu Shixuan E-commerce Company; constant temperature and humidity test chamber was provided by Guangdong Aisili Testing Instrument Co., Ltd.

[0059] Silver bracelets were used as experimental objects, with an inner ring diameter of 58 mm and a weight of 27 g. Five bracelets were taken respectively and gold plated according to Examples 1-3 and Comparative Examples 1-2. The jewelry was placed in a constant temperature and humidity test box, stored at 75°C and 66% air humidity for 6 hours, the bracelets were taken out, placed in clean water 3 times its mass, 15% starch and 8% apple pomace of the total mass were added to the water, lactic acid bacteria were inoculated and cultured for 20 hours, and then soaked at 25°C for 3 days to simulate sweat corrosion; the bracelets were taken out from the fermentation liquid and the aforementioned constant temperature in the incubator was repeated, and then placed in the fermentation liquid, and this was repeated 4 times. The bracelets were taken out and the surface of the bracelets was observed. The results are as follows:

[0060]

[0061]

[0062] As can be seen from the table, the surface corrosion degree of Examples 1-3 using the method of the present invention is low, and after high-temperature treatment, they also perform well in biological corrosion simulated by fermentation products rich in microorganisms. Obviously, the material is stable after gold plating using the method of the present invention and has good use value.

[0063] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0064] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for gold plating of silver ornaments using electrolyte, characterized in that: include: 1) Surface treatment of silver jewelry Place the silver jewelry in a container filled with pure water, drip acid to reduce the pH of the solution to 4-4.5, raise the temperature to 30-45°C and keep it for 20-30 seconds, then drip sodium hydroxide solution until the pH of the solution rises to 9-9.3 and keep it for 15-20 seconds; Take out the silver jewelry and rinse it with pure water; 2) Electroplating Prepare a gold plating solution, according to 1L solution, add 0.1-0.17g polyethyleneimine, 0.1-0.12g amylsulfonic acid, 10-13g gold sodium sulfite, 0.2-0.23g sodium dodecyl sulfate, 50-67g sodium sulfite, 2-4g copper sulfate, 1-3g nickel sulfate, 0.1-0.12g cerium sulfate, 2-4g modified carbon fiber, 30-35g concentrated sulfuric acid, 13-17g polyethylene glycol; use ultrasound to homogenize the gold plating solution; Place the silver ornaments into the gold plating solution, keep the silver ornaments completely immersed in the solution system, control the solution temperature to 58-60℃, use a single pulse power supply, and adjust the current density to 0.44-0.56A / dm 2 , electroplating to obtain gold-plated silver ornaments; taking out the silver ornaments, polishing them according to the original patterns and shapes, spraying transparent polyamide resin on the surface of the ornaments, controlling the thickness of the spray layer to be 40-60 μm, placing the silver ornaments in a drying oven, first introducing nitrogen to remove the oxygen in the drying oven, waiting for 30-40 seconds, placing desiccant calcium chloride in the drying oven, continuously filling nitrogen to make the pressure in the drying oven 2-2.3 atmospheres, raising the temperature to 40-43°C, continuing for 80-90 minutes, reducing the air pressure to standard atmospheric pressure, and continuing to dry for 30-44 minutes.

2. The method for gold plating of silver jewelry using electrolyte according to claim 1, characterized in that: The acid solution is hydrochloric acid with a mass fraction of 1-1.6%.

3. The method for gold plating of silver jewelry with electrolyte according to claim 1, characterized in that: The mass fraction of the sodium hydroxide solution is 1.8-2%.

4. The method for gold plating of silver jewelry with electrolyte according to claim 1, characterized in that: The preparation method of the modified carbon fiber is as follows: by weight, 1 part of carbon fiber is mixed with 5-8 parts of perchloric acid solution, soaked for 10-15 minutes, centrifuged, precipitates are collected, and washed with distilled water for 3-4 times; 5-8 parts of precipitates are mixed with 20-30 parts of clean water, 0.1-0.3 parts of ethylenediamine are added, heated to 70-80°C, kept warm for 60-80 minutes, and concentrated under reduced pressure to dryness.

5. The method for gold plating of silver jewelry with electrolyte according to claim 4, characterized in that: The mass fraction of the perchloric acid solution is 30-33%.

6. The method for gold plating of silver jewelry using electrolyte according to claim 1, characterized in that: The mass fraction of the concentrated sulfuric acid is 80-85%.

7. The method for gold plating of silver jewelry with electrolyte according to claim 1, characterized in that: The ultrasonic homogenization time of the gold plating solution is 3-5 minutes.

8. The method for gold plating of silver jewelry with electrolyte according to claim 1, characterized in that: The conduction time during the electroplating is 10-13ms.

9. The method for gold plating of silver jewelry with electrolyte according to claim 1, characterized in that: The shut-off time during electroplating is 10-15 ms, and the electroplating time is 12 minutes.

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