Electroplating solution for metal O-shaped sealing ring and electroplating process

Abstract

The invention relates to the technical field of electroplating, in particular to an electroplating solution for a metal O-shaped sealing ring and an electroplating process, 10 L of the electroplating solution for the metal O-shaped sealing ring comprises the following raw materials of 20-40 g / L of silver salt, 30-50 g / L of conducting salt, 10-20 g / L of complexing agent, 1-5 g / L of brightener, 20-30 g / L of additive and the balance of solvent, and the pH value of the electroplating solution is 6-9. A plating layer obtained by the electroplating solution prepared by the invention is flat, has good adhesive force with a base material, and also has good pressure resistance and heat resistance.

Description

Technical Field

[0001] This invention relates to the field of electroplating technology, specifically to an electroplating solution and electroplating process for metal O-ring seals. Background Technology

[0002] In the field of sealing under extreme operating conditions, metal O-rings achieve reliable sealing due to their "pressure energy conversion" characteristics, with leakage rates as low as 1×10⁻⁶. -10 Helium gas per cc / sec, capable of operating in a temperature range of -270℃ to 750℃ and 1×10 -10 With a pressure range of torr to 30MPa, it is widely used in critical applications such as vacuum chambers, gas turbines, and semiconductor equipment. Surface electroplating, as a core means of improving its performance, solves problems such as corrosion protection and sealing compatibility by depositing functional coatings, and the performance of the electroplating solution directly determines the coating quality and sealing reliability.

[0003] In existing technologies, metal O-ring coatings mainly include silver, gold, and PTFE composite layers: silver plating enhances ductility to adapt to rough sealing surfaces, gold plating meets the chemical inertness requirements of the semiconductor field, and PTFE coatings reduce friction and improve corrosion resistance. While the corresponding electroplating solutions have achieved basic functionality, they face several technical bottlenecks: First, controlling coating uniformity is difficult; traditional electroplating solutions easily lead to uneven current distribution on the inner and outer walls, causing a decrease in the sealing surface's adhesion. Second, there is a conflict between environmental friendliness and performance; traditional gold plating solutions containing cyanide and passivation systems containing chromates, while improving coating adhesion, are gradually being restricted due to heavy metal emissions failing to meet stringent environmental regulations. Therefore, the development of electroplating solutions is crucial.

[0004] Patent CN105648485B discloses a cyanide-free silver plating solution, belonging to the field of cyanide-free silver plating. The cyanide-free silver plating solution is prepared from the following raw materials: silver tetrafluoroborate: 10-60 g / L; methylpentynol: 0.1-1.5 g / L; 1,4-butynediol: 0.1-1.2 g / L; ammonium acetate: 10-20 g / L; anisaldehyde: 7-20 g / L; benzoic acid: 10-25 g / L; wherein the pH value of the cyanide-free silver plating solution is 3-7. The cyanide-free silver plating solution of this invention does not contain cyanide ions, reducing the harm of waste to the environment and operators; the plating solution is simple to prepare and easy to operate. It can obtain a stable plating solution with low plating stress and relatively strong adhesion.

[0005] Patent CN109183096B discloses a surface electroplating solution and electroplating process for alloys. The electroplating solution consists of the following components: soluble palladium salt, soluble platinum salt, complexing agent, conductive salt, buffer, brightener, stabilizer, and anti-pinhole agent, with the balance being solvent, which is deionized water. The electroplating process includes: preparation of the electroplating solution; pretreatment including degreasing, grinding, polishing, and activation; and electroplating. The electroplating solution has good stability and is environmentally friendly. The platinum-palladium coating obtained by electroplating with the electroplating solution of this invention is uniform and dense, with high hardness, good corrosion resistance, good adhesion to the alloy substrate, and a bright coating without peeling or blistering. The electroplating process is simple to operate and the conditions are controllable. By controlling the process parameters during electroplating and uniformly distributing the anode around the cathode, the composition of the coating is controllable, the electroplating efficiency is high, and it is environmentally friendly and suitable for widespread application.

[0006] Although the above patents have all studied the stability, adhesion, and corrosion resistance of electroplating solutions, they have not studied the pressure resistance of the coating and the cyclic stability of the coating under high temperature and high pressure. If the coating falls off, it will affect the reactor reaction. Therefore, there is an urgent need in the market to develop an electroplating solution suitable for metal O-ring seals of reactor pressure vessels. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of this invention is to obtain an electroplating solution with excellent adhesion and temperature and pressure resistance of the coating.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides an electroplating solution for metal O-rings, comprising, in 10L, the following raw materials: 20-40g / L silver salt, 30-50g / L conductive salt, 10-20g / L complexing agent, 1-5g / L brightener, 20-30g / L additive, with the balance being solvent, wherein the pH value of the electroplating solution is 6-9.

[0009] In some embodiments, the silver salt is any one of silver tetrafluoroborate, potassium silver cyanide, silver methanesulfonate, silver ethanesulfonate, silver p-toluenesulfonate, silver trifluoromethanesulfonate, silver sulfite, and silver ammonium sulfite.

[0010] Preferably, the silver salt is silver tetrafluoroborate.

[0011] In some embodiments, the conductive salt is any one of pyrophosphate, sulfate, thiosulfate, and sulfonate.

[0012] Preferably, the conductive salt is a pyrophosphate.

[0013] More preferably, the conductive salt is potassium pyrophosphate.

[0014] In some embodiments, the complexing agent is any one of dithioethylene glycol, guanidinoacetic acid, triethanolamine, and acetyl thiocyanate.

[0015] Preferably, the complexing agent is guanidinoacetic acid.

[0016] In some embodiments, the brightener is 2-mercaptobenzothiazole.

[0017] In some embodiments, the pH value of the electroplating solution is adjusted using potassium hydroxide or sodium hydroxide.

[0018] In some embodiments, the method for preparing the additive includes the following steps: (1) Add polyethylene glycol dimethacrylate to an ethanol solution and stir for 1-2 hours. Then add 1-vinylimidazole and an initiator. Purge the air in the system with an inert gas and heat to 65-75°C for 2-3 hours to obtain a copolymer solution. (2) 1-(2-hydroxyethyl)-3-imidazolium tetrafluoroborate, allyl alcohol glycidyl ether, and potassium hydroxide were added to ethanol and reacted at 70-80℃ for 4-6 h. The mixture was then dried to obtain the product. (3) Add the product obtained in step (2) to the copolymer solution obtained in step (1), stir at 70-80℃ for 4-5 hours, and dry to obtain the additive.

[0019] Electroplating solutions often require the addition of additives to maintain the smoothness of the coating and good adhesion between the coating and the substrate. However, conventional electroplating additives may not meet the requirements of the metal O-ring seals for reactor pressure vessels. Therefore, the applicant has prepared a new electroplating additive. First, a copolymer is formed by copolymerizing polyethylene glycol methacrylate with 1-vinylimidazolium. Then, 1-(2-hydroxyethyl)-3-imidazolium tetrafluoroborate and allyl alcohol glycidyl ether are reacted, followed by further copolymerization with the copolymer. The resulting additive, when used in the electroplating solution, enables… The coating exhibits excellent pressure and temperature resistance, as well as good cycle performance, making it suitable for metal O-ring seals in reactor pressure vessels. This is likely because the long-chain polyethylene glycol can adsorb onto the cathode surface, enhancing polarization and contributing to a fine, bright coating. Meanwhile, the imidazole ring possesses strong coordination ability, interacting with silver ions to regulate the discharge process of silver ions on the cathode surface and improve coating crystallinity. Furthermore, the introduced ionic liquid side chains have strong conductivity, resulting in a more uniform distribution of electrical energy and more effectively suppressing dendrite growth, leading to a denser and smoother coating.

[0020] In some embodiments, the initiator is any one of azobisisobutyronitrile, benzoyl peroxide, ammonium persulfate, and potassium persulfate.

[0021] Preferably, the initiator is ammonium persulfate.

[0022] In some embodiments, the mass ratio of the initiator to polyethylene glycol dimethacrylate is (0.003-0.01):1. In some embodiments, the mass ratio of polyethylene glycol dimethacrylate to 1-vinylimidazole in step (1) is 1:(0.3-0.8).

[0023] In some embodiments, the molar ratio of 1-(2-hydroxyethyl)-3-imidazolium tetrafluoroborate, allyl alcohol glycidyl ether, and potassium hydroxide is (1-1.5):1:(0.05-0.15).

[0024] In some embodiments, the mass ratio of the product in step (3) to the polyethylene glycol dimethacrylate in step (1) is (0.05-0.1):1.

[0025] In some embodiments, the solvent is deionized water.

[0026] A second aspect of the present invention provides an electroplating process for an electroplating solution used in metal O-ring seals, comprising the following steps: S1. Pre-plating treatment: Degreasing: After immersing the metal O-ring in a mixed solution of sodium hydroxide and sodium carbonate, remove it, wash it with deionized water, and dry it to obtain a degreased metal O-ring. Grinding: Grind the degreased metal O-ring with sandpaper; Chemical polishing: The polished metal O-ring is immersed in hydrogen peroxide, oxalic acid and sodium hydroxide at 30°C for 40 seconds, washed with deionized water and dried to obtain a pretreated metal O-ring. S2, Electroplating: The pretreated metal O-ring and silver plate are placed in an electrolytic tank containing electroplating solution. The cleaned metal O-ring is used as the cathode and the silver plate as the anode. The distance between the cathode and anode is 6-15 cm. Electroplating is carried out at 20-30℃ and a current density of 0.5-1.5 A / dm² for 1-2 hours. Afterward, the surface is cleaned with distilled water and dried to complete the electroplating.

[0027] Compared with the prior art, the present invention has the following beneficial effects: (1) The electroplating solution prepared by the present invention using silver salt, conductive salt, complexing agent, brightener, additive and solvent has a smooth coating with good adhesion to the substrate, and also has good pressure resistance and heat resistance.

[0028] (2) This invention solves the problem that traditional small molecule additives are easily encapsulated in the coating and have a short service life by designing polymer additives. At the same time, through the synergistic effect of various chemical bonds, it avoids the competitive adsorption and compatibility problems when multiple additives are used together, making the electroplating process more stable and controllable.

[0029] (3) The additives prepared in this invention can be adsorbed on the cathode surface to improve polarization, which helps to obtain a fine and bright coating and improve the flatness of the coating. In addition, they can coordinate with silver ions to improve the crystallinity of the coating, reduce its internal stress, and improve its adhesion and pressure and heat resistance. Furthermore, the introduced ionic liquid side chains have strong conductivity, which makes the electrical energy distribution more uniform and can more effectively inhibit dendrite growth, obtain a denser and flatter coating, and facilitate the formation of uniform sealing contact. Detailed Implementation

[0030] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0031] In the following examples and comparative examples, the compounds and related reagents used were all commercially available. Polyethylene glycol dimethacrylate (PEG600DMA) was purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd. The metal O-ring was made of Inconel 718 tubing, with a structure as shown in the journal "Development of Metal O-rings for Reactor Pressure Vessels" doi: 10.3969 / j.issn.1001-4837.2016.05.001.

[0032] Unless otherwise specified, the post-processing steps such as "washing", "extraction", "concentration", "drying" and "soaking" used below are routine operations for those skilled in the art, and can be selected according to actual operation.

[0033] Preparation Example 1 The preparation method of additive-1 includes the following steps: (1) Add 10g of polyethylene glycol dimethacrylate to 100ml of 5wt% ethanol solution and stir for 1.5h. Then add 5g of 1-vinylimidazole and 0.05g of ammonium persulfate. Purge the air in the system with nitrogen and heat to 70℃ for 2.5h to obtain copolymer solution. (2) 1.2 mol of 1-(2-hydroxyethyl)-3-imidazolium tetrafluoroborate, 1 mol of allyl alcohol glycidyl ether, and 0.1 mol of potassium hydroxide were added to 200 ml of anhydrous ethanol and reacted at 75 °C for 5 h. The mixture was neutralized to neutral with 10 wt% dilute hydrochloric acid, filtered to remove sodium chloride, and extracted with deionized water and ethyl acetate by rotary evaporation. The aqueous phase was collected, concentrated, and dried to obtain the product. (3) Add 8g of the product obtained in step (2) to the copolymer solution obtained in step (1), stir at 75°C for 4.5h, and dry to obtain additive-1.

[0034] Preparation Example 2 The preparation method of additive-2 is the same as that of preparation example 1, except that the amount of 1-vinylimidazole added in step (1) is 9g.

[0035] Preparation Example 3 The preparation method of additive-3 is the same as that of preparation example 1, except that the amount of product added in step (3) is 11g.

[0036] Preparation Example 4 The preparation method of additive-4 includes the following steps: 10g of polyethylene glycol dimethacrylate was added to 100ml of 5wt% ethanol solution and stirred for 1.5h. Then, 5g of 1-vinylimidazole and 0.05g of ammonium persulfate were added. Nitrogen gas was introduced to replace the air in the system, and the temperature was raised to 70℃ and reacted for 2.5h. After drying, additive-4 was obtained.

[0037] Example 1 An electroplating solution for metal O-rings, per 10L, comprises the following raw materials: 30g / L silver tetrafluoroborate, 40g / L potassium pyrophosphate, 15g / L guanidinoacetic acid, 3g / L 2-mercaptobenzothiazole, 25g / L additive-1, with the balance being solvent, and the pH of the electroplating solution is adjusted to 7.5 with potassium hydroxide.

[0038] The electroplating process of the electroplating solution for the metal O-ring in this embodiment includes the following steps: S1. Pre-plating treatment: Degreasing: The metal O-ring is immersed in a mixed solution of 20 g / L sodium hydroxide and 10 g / L sodium carbonate at 35°C for 5 min, then removed, rinsed with deionized water, and dried to obtain a degreased metal O-ring. Grinding: Grind the degreased metal O-ring with sandpaper to a roughness Ra=0.8μm; Chemical polishing: The polished metal O-ring is immersed in a mixed solution of 30wt% hydrogen peroxide, 20g / L oxalic acid and 10g / L sodium hydroxide at 30℃ for 40s, washed with deionized water and dried to obtain a pretreated metal O-ring. S2, Electroplating: The pretreated metal O-ring and silver plate were placed in an electrolytic cell containing electroplating solution. The pretreated metal O-ring was used as the cathode and the silver plate as the anode. The distance between the cathode and anode was 10 cm. Electroplating was carried out at 25°C and a current density of 1 A / dm² for 1.5 h. Afterward, the surface was cleaned with distilled water and dried to complete the electroplating.

[0039] Example 2 An electroplating solution for metal O-rings, per 10L, comprises the following raw materials: 20g / L silver tetrafluoroborate, 30g / L potassium pyrophosphate, 10g / L guanidinoacetic acid, 1g / L 2-mercaptobenzothiazole, 20g / L additive-1, with the balance being solvent, and the pH of the electroplating solution is adjusted to 6 with potassium hydroxide.

[0040] The electroplating process of the electroplating solution for the metal O-ring in this embodiment includes the following steps: S1. Pre-plating treatment: Degreasing: The metal O-ring is immersed in a mixed solution of 20 g / L sodium hydroxide and 10 g / L sodium carbonate at 35°C for 5 min, then removed, rinsed with deionized water, and dried to obtain a degreased metal O-ring. Grinding: Grind the degreased metal O-ring with sandpaper to a roughness Ra=0.8μm; Chemical polishing: The polished metal O-ring is immersed in a mixed solution of 30wt% hydrogen peroxide, 20g / L oxalic acid and 10g / L sodium hydroxide at 30℃ for 40s, washed with deionized water and dried to obtain a pretreated metal O-ring. S2, Electroplating: The pretreated metal O-ring and silver plate were placed in an electrolytic cell containing electroplating solution. The pretreated metal O-ring was used as the cathode and the silver plate as the anode. The distance between the cathode and anode was 6 cm. Electroplating was carried out at 20℃ and a current density of 0.5 A / dm² for 1 hour. After that, the surface was cleaned with distilled water and dried to complete the electroplating.

[0041] Example 3 An electroplating solution for metal O-rings, per 10L, comprises the following raw materials: 40g / L silver tetrafluoroborate, 50g / L potassium pyrophosphate, 20g / L guanidinoacetic acid, 5g / L 2-mercaptobenzothiazole, 30g / L additive-1, with the balance being solvent, and the pH of the electroplating solution is adjusted to 9 with potassium hydroxide.

[0042] The electroplating process of the electroplating solution for the metal O-ring in this embodiment includes the following steps: S1. Pre-plating treatment: Degreasing: The metal O-ring is immersed in a mixed solution of 20 g / L sodium hydroxide and 10 g / L sodium carbonate at 35°C for 5 min, then removed, rinsed with deionized water, and dried to obtain a degreased metal O-ring. Grinding: Grind the degreased metal O-ring with sandpaper to a roughness Ra=0.8μm; Chemical polishing: The polished metal O-ring is immersed in a mixed solution of 30wt% hydrogen peroxide, 20g / L oxalic acid and 10g / L sodium hydroxide at 30℃ for 40s, washed with deionized water and dried to obtain a pretreated metal O-ring. S2, Electroplating: The pretreated metal O-ring and silver plate were placed in an electrolytic cell containing electroplating solution. The pretreated metal O-ring was used as the cathode and the silver plate as the anode. The distance between the cathode and anode was 15 cm. Electroplating was carried out at 30°C and a current density of 1.5 A / dm² for 2 hours. After that, the surface was cleaned with distilled water and dried to complete the electroplating.

[0043] Example 4 An electroplating solution and electroplating process for a metal O-ring is disclosed. The specific implementation method is the same as in Example 1, except that additive-1 is replaced with an equal amount of additive-2.

[0044] Example 5 An electroplating solution and electroplating process for a metal O-ring is disclosed. The specific implementation method is the same as in Example 1, except that additive-1 is replaced with an equal amount of additive-3.

[0045] Example 6 An electroplating solution and electroplating process for a metal O-ring is disclosed. The specific implementation method is the same as in Example 1, except that additive-1 is replaced with an equal amount of additive-4.

[0046] Example 7 An electroplating solution and electroplating process for a metal O-ring seal are disclosed. The specific implementation method is the same as in Example 1, except that additive-1 is replaced with polyethylene glycol-600 in equal amounts.

[0047] Performance testing For the metal O-rings obtained after electroplating in each embodiment, with ring dimensions of Φ535.5mm × Φ13.1mm, the following tests were performed: 1. Adhesion: Place the electroplated metal O-ring on a table and cut 100 1mm × 1mm grids into the surface with a sharp knife, scratching to the bottom layer. Then, apply 3M 600 test tape to the grid and vertically pull the tape along a direction perpendicular to the grid surface. Measure the percentage (w / %) of the area where the silver plating has peeled off. 2. Hydrostatic test: The electroplated metal O-ring seal was used in the reactor pressure vessel of a pressurized water reactor nuclear power plant. The test was conducted at a water pressure of 22.8 MPa, a compression load of 7300 kN, and a pressure holding time of 40 min. The seal surface was observed for leakage or abnormalities, as well as changes in the silver plating layer. 3. Hot and cold cycle test: The electroplated metal O-rings were used in a pressurized water reactor nuclear power plant reactor pressure vessel for a cyclic process of pressurization and heating, holding at 350°C, and cooling down. Specifically, the pressure was increased to 15.5 MPa (absolute), the temperature was increased to 350°C, the holding time was 30 minutes, and the temperature was cooled to 85°C. The average heating rate was 78°C / h, the average cooling rate was 86°C / h, and the cycle was repeated 20 times. The test system operated stably throughout the test, and visual inspection was conducted to check for leaks or abnormalities on the sealing surface and to observe changes in the silver plating layer.

[0048] The test results are shown in Table 1: Table 1 As shown in Table 1, the electroplating solutions of Examples 1-3 can improve the adhesion, pressure resistance, and temperature resistance of the coating, making them suitable for metal O-ring seals in reactor pressure vessels. A comparison of the data from Example 4 and Example 1 shows that changing the ratio of polyethylene glycol dimethacrylate to 1-vinylimidazole may lead to excessive complexation with silver ions, causing over-polarization and a decrease in coating adhesion. A comparison of the data from Example 5 and Example 1 shows that changing the ratio of the product to polyethylene glycol dimethacrylate may exacerbate side reactions, resulting in pinholes and blistering in the coating; further testing is not required in this case. A comparison of Example 6 and Example 1 shows that using only the copolymer of polyethylene glycol dimethacrylate and 1-vinylimidazole as an additive may result in insufficient coating density, leading to a decrease in the coating's adhesion, pressure resistance, and temperature resistance. A comparison of Example 7 and Example 1 shows that directly using polyethylene glycol as an additive reduces all properties of the coating.

[0049] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An electroplating solution for metal O-ring seals, characterized by comprising: Based on 10L, it includes the following raw materials: silver salt 20-40g / L, conductive salt 30-50g / L, complexing agent 10-20 g / L, brightener 1-5g / L, additives 20-30g / L, and the balance is solvent. The pH value of the electroplating solution is 6-9.

2. The electroplating solution for a metal O-ring according to claim 1, characterized by The silver salt is any one of silver tetrafluoroborate, potassium silver cyanide, silver methanesulfonate, silver ethanesulfonate, silver p-toluenesulfonate, silver trifluoromethanesulfonate, silver sulfite, and silver ammonium sulfite.

3. The electroplating solution for a metal O-ring according to claim 1, wherein The conductive salt is any one of pyrophosphate, sulfate, thiosulfate, and sulfonate.

4. The electroplating solution for a metal O-ring according to claim 1, characterized by The complexing agent is any one of dithioethylene glycol, guanidinoacetic acid, triethanolamine, and acetyl thiocyanate.

5. The electroplating solution for a metal O-ring according to claim 1, wherein The brightener is 2-mercaptobenzothiazole.

6. The electroplating solution for metal O-ring according to claim 1, wherein The pH value of the electroplating solution is adjusted using potassium hydroxide or sodium hydroxide.

7. The electroplating solution for metal O-ring according to claim 1, wherein The method for preparing the additive includes the following steps: (1) Add polyethylene glycol dimethacrylate to an ethanol solution and stir for 1-2 hours. Then add 1-vinylimidazole and an initiator. Purge the air in the system with an inert gas and heat to 65-75°C for 2-3 hours to obtain a copolymer solution. (2) 1-(2-hydroxyethyl)-3-imidazolium tetrafluoroborate, allyl alcohol glycidyl ether, and potassium hydroxide were added to ethanol and reacted at 70-80℃ for 4-6 h. The mixture was then dried to obtain the product. (3) Add the product obtained in step (2) to the copolymer solution obtained in step (1), stir at 70-80℃ for 4-5 hours, and dry to obtain the additive.

8. The electroplating solution for metal O-ring according to claim 7, wherein The mass ratio of polyethylene glycol dimethacrylate to 1-vinylimidazole in step (1) is 1:(0.3-0.8).

9. The electroplating solution for metal O-ring according to claim 7, wherein The mass ratio of the product described in step (3) to the polyethylene glycol dimethacrylate in step (1) is (0.5-0.9):

1.

10. An electroplating process for an electroplating solution for a metal O-ring according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Pre-plating treatment: Degreasing: After immersing the metal O-ring in a mixed solution of sodium hydroxide and sodium carbonate, remove it, wash it with deionized water, and dry it to obtain a degreased metal O-ring. Grinding: Grind the degreased metal O-ring with sandpaper; Chemical polishing: The polished metal O-ring is immersed in hydrogen peroxide, oxalic acid and sodium hydroxide at 30°C for 40 seconds, washed with deionized water and dried to obtain a pretreated metal O-ring. S2, Electroplating: The pretreated metal O-ring and silver plate are placed in an electrolytic cell containing electroplating solution. The pretreated metal O-ring is used as the cathode and the silver plate is used as the anode. The distance between the cathode and anode is 6-15 cm. Electroplating is carried out at 20-30℃ and a current density of 0.5-1.5 A / dm² for 1-2 hours. Afterward, the surface is cleaned with distilled water and dried to complete the electroplating.

Images