Metallic gasket with special wetting regulation and method for producing same

Abstract

The present application relates to the technical field of metal static sealing, and discloses a metal sealing gasket with special wettability regulation and a preparation method thereof, the preparation method comprising the following steps: firstly, cleaning the metal sealing gasket; secondly, electroplating copper on the surface of the metal sealing gasket through an electrochemical method; thirdly, performing ammonia-alkali etching and fluorination treatment; and finally, obtaining the metal sealing gasket with special wettability regulation after high-temperature treatment. Compared with the prior art, the metal sealing gasket with special wettability regulation is obtained through a simple and rapid processing mode, and the metal sealing gasket has more excellent sealing performance in a flange. Compared with the cyanide silver plating method currently adopted, the present application is simpler, more environmentally friendly, and suitable for large-scale preparation and popularization.

Description

Technical Field

[0001] This invention relates to the field of metal static sealing technology, and in particular to a metal sealing gasket with special wettability control and its preparation method. Background Technology

[0002] In the piping system of launch vehicle engines, sealing rings can form a sealing surface with flanges under preload to prevent leakage of high-pressure media. With the significant increase in rocket carrying capacity and engine thrust, graphite sealing rings are prone to disintegration and collapse, leading to a sharp decline in sealing performance. Compared to graphite sealing rings, metal sealing rings have advantages such as high strength, wear resistance, and high load-bearing capacity, making them more suitable for harsh operating conditions, especially strong vibration, wide temperature thresholds, and high pressure. Currently, the commonly used metal sealing rings are silver-plated alloys, but this still cannot meet the requirements. Therefore, further development of metal sealing rings is imperative. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a metal sealing gasket with specially regulated wettability and its preparation method. First, copper is electroplated onto the surface of the metal sealing gasket using an electrochemical method, followed by ammonia-alkali etching and fluorination treatment to improve the performance of the metal sealing gasket. This patent provides a simple and rapid process to obtain a metal sealing gasket with special surface wettability, resulting in superior sealing performance in flanges, and enabling large-scale production and widespread application.

[0004] To achieve this technical objective, the present invention adopts the following solution: In a first aspect, the present invention provides a method for preparing a metal sealing gasket with special wettability control, comprising the following steps: S1. Clean the metal sealing gasket to remove oil and impurities from its surface; S2. Prepare the electroplating solution and use a three-electrode system to electrodeposit the metal sealing gasket; S3. Immerse the electrodeposited metal sealing gasket in the prepared ammonia-alkali etching solution for treatment. S4. Immerse the etched metal sealing gasket in the prepared fluorination solution for fluorination treatment. S5. The fluorinated metal gasket is placed in a high-temperature oven for reaction, and after cooling, a metal gasket with special wettability control is obtained.

[0005] Furthermore, a preferred embodiment of the present invention is as follows: The dimensions of the metal sealing gasket are: inner diameter 48 mm, outer diameter 60 mm, and thickness 1 mm.

[0006] In step S1, the metal sealing gasket is ultrasonically cleaned for 30 minutes using 1 M sodium hydroxide solution, water, 5 vol% hydrochloric acid aqueous solution, and water respectively to remove grease and oxide layer from the gasket surface.

[0007] In step S2, an electroplating solution is prepared, and copper is electroplated onto the surface of the metal sealing gasket using a three-electrode system. The electroplating solution consists of copper nitrate, potassium chloride, concentrated sulfuric acid, and water, with a mass ratio of 20:0.02:13:187. The working electrode of the three-electrode system is the metal sealing gasket obtained in step S1, the reference electrode is a silver-silver chloride electrode, and the counter electrode is a platinum electrode with dimensions of 3 cm × 3 cm. Electrodeposition is performed using the constant current mode of an electrochemical workstation, with a current of 0.2 amperes and a time of 6000 seconds.

[0008] In step S3, an ammonia-alkali etching solution is prepared to react some of the copper into copper hydroxide. The ammonia-alkali etching solution consists of sodium hydroxide, ammonium persulfate, and water, with a mass ratio of sodium hydroxide, ammonium persulfate, and water of 2:0.55:50. The metal sealing gasket is immersed in the ammonia-alkali etching solution for 8-20 minutes, preferably 14-18 minutes, and more preferably 16 minutes.

[0009] In step S4, a fluorination solution is prepared to modify the wettability of copper hydroxide (i.e., fluorination treatment). The fluorination solution is an ethanol solution of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, with a volume ratio of 2:98 between 1H,1H,2H,2H-perfluorodecyltriethoxysilane and ethanol. The metal sealing gasket is immersed in the fluorination solution for 0 or 30 minutes. After fluorination treatment, the sealing performance of the metal sealing gasket is significantly improved. When the immersion time is 0 minutes, the resulting metal sealing gasket has super-oleophilic properties, which facilitates rapid oil film spreading and eliminates dry friction during startup. When the immersion time is 30 minutes, the resulting metal sealing gasket has oleophobic properties, effectively reducing media adhesion and penetration. It is suitable for different working conditions.

[0010] In step S5, the fluorinated metal gasket is reacted in an oven at 80°C for 60 minutes.

[0011] Secondly, the present invention also provides a metal sealing gasket with special wettability control prepared according to the aforementioned preparation method.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention introduces a special wettable surface into metal sealing gaskets for the first time, which greatly improves the sealing performance of the gaskets.

[0013] (2) Compared with the cyanide silver plating method currently used for silver plating of metal sealing gaskets, the technical solution of the present invention is simpler and more environmentally friendly.

[0014] (3) The present invention provides a suitable range of process parameters, which can achieve effective sealing under different normal pressures and internal fluid pressures.

[0015] (4) By controlling the fluorination treatment time, the wettability of the metal sealing gasket surface can be adjusted from superoleophilic to oleophobic, making it suitable for different working scenarios. Attached Figure Description

[0016] Figure 1 The image shows a scanning electron microscope image of the metal sealing gasket obtained in Example 2 of the present invention, where the scale bars of a1 and a2 are 1 micrometer and 20 micrometers, respectively.

[0017] Figure 2 These are scanning electron microscope images of the metal sealing gaskets obtained in Comparative Examples 4-6 of the present invention, wherein the scale bars of b1, c1, and d1 are 1 micrometers, and the scale bars of a2, c2, and d2 are 20 micrometers; b is Comparative Example 4, c is Comparative Example 5, and d is Comparative Example 6.

[0018] Figure 3 This is a scanning electron microscope image of the cross-section of the metal sealing gasket obtained in Embodiment 1 of the present invention.

[0019] Figure 4 These are optical photographs of the oil contact angles of the metal sealing gaskets obtained in Examples 1-2, Comparative Examples 1, and Comparative Examples 4-6 of the present invention.

[0020] Figure 5 This is a bar chart showing the static sealing test results of the metal sealing gasket obtained in Embodiment 1 of the present invention.

[0021] Figure 6 This is a bar chart showing the static sealing test results of the metal sealing gasket obtained in Embodiment 2 of the present invention.

[0022] Figure 7 This is a bar chart showing the static sealing test results of the metal sealing gasket obtained in Comparative Example 1 of the present invention.

[0023] Figure 8 This is a bar chart showing the static sealing test results of the metal sealing gasket obtained in Comparative Example 2 of the present invention.

[0024] Figure 9 This is a bar chart showing the static sealing test results of the metal sealing gasket obtained in Comparative Example 3 of the present invention.

[0025] Figure 10 This is a bar chart showing the static sealing test results of the metal sealing gasket obtained in Comparative Example 4 of this invention.

[0026] Figure 11 This is a bar chart showing the static sealing test results of the metal sealing gasket obtained in Comparative Example 5 of the present invention.

[0027] Figure 12 This is a bar chart showing the static sealing test results of the metal sealing gasket obtained in Comparative Example 6 of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0029] Unless otherwise specified, the experimental methods used in the embodiments and comparative examples of this invention are conventional methods. Unless otherwise specified, the materials and reagents used are commercially available.

[0030] The dimensions of the metal sealing gaskets used in the embodiments and comparative examples of this invention are: inner diameter of 48 mm, outer diameter of 60 mm, and thickness of 1 mm. Example 1

[0031] This embodiment provides a method for preparing a metal sealing gasket with special wettability control, including the following steps: S1. Treat the metal sealing gasket with sodium hydroxide solution (1 M), water, dilute hydrochloric acid (5 vol%) and water for 30 minutes respectively to remove the grease and oxide layer on the surface of the metal sealing gasket. S2. Prepare the electroplating solution and electroplat copper on the surface of the metal sealing gasket using a three-electrode system. The mass ratio of copper nitrate, potassium chloride, concentrated sulfuric acid, and water in the electroplating solution is 20:0.02:13:187. The working electrode of the three-electrode system is the metal sealing gasket obtained in step S1, the reference electrode is a silver-silver chloride electrode, and the counter electrode is a platinum electrode (3 cm × 3 cm). Electrodeposition is performed using the constant current mode of an electrochemical workstation with a current of 0.2 amperes and a time of 6000 seconds. S3. Prepare an ammonia-alkali etching solution to react some of the copper into copper hydroxide. The mass ratio of sodium hydroxide, ammonium persulfate, and water in the ammonia-alkali etching solution is 2:0.55:50. The reaction time of the metal sealing gasket in the ammonia-alkali etching solution is 16 minutes. S4. Prepare a fluorination solution to modify the wettability of copper hydroxide. The volume ratio of 1H,1H,2H,2H-perfluorodecyltriethoxysilane to ethanol in the fluorination solution is 2:98. The modification time of the metal sealing gasket in the fluorination solution is 0 minutes.

[0032] S5. Place the fluorinated metal sealing gasket in an 80℃ oven for a high-temperature reaction for 60 minutes. Example 2

[0033] The difference between Example 2 and Example 1 is that the fluorination treatment time is different. The fluorination modification time in Example 2 is 30 minutes. Comparative Example 1

[0034] Comparative Example 1 is an untreated metal gasket. Comparative Examples 2 and 3

[0035] The difference between Comparative Examples 2 and 3 and Example 1 lies in the reaction time of the ammonia-alkali etching. The reaction time of Comparative Example 2 is 12 minutes, and the reaction time of Comparative Example 3 is 20 minutes. Comparative Examples 4-6

[0036] The difference between Comparative Examples 4-6 and Example 2 lies in the reaction time of the ammonia-alkali etching. The reaction time of Comparative Example 4 is 8 minutes, the reaction time of Comparative Example 5 is 12 minutes, and the reaction time of Comparative Example 6 is 20 minutes.

[0037] The metal gasket samples from the examples and comparative examples were tested: (1) Surface morphology test The metal sealing gaskets in Example 2 and Comparative Examples 4-6 were tested using scanning electron microscopy, such as... Figure 1 , Figure 2 As shown, the scale bars are 1 micrometer and 20 micrometers, respectively. The comparison reveals that the copper hydroxide nanoneedles on the surface of Example 2 are the most fully developed, with a denser structure over a large area. The needle-like structures on the surfaces of Comparative Examples 4 and 5 are in the process of development, while the needle-like structures on the surface of Comparative Example 6 are partially destroyed.

[0038] (2) Coating thickness test The cross-section of the metal sealing gasket in Example 1 was tested using a scanning electron microscope, such as... Figure 3 As shown in the figure, the thickness of the copper plating layer is between 350 and 400 micrometers, and the thickness of the copper hydroxide obtained by ammonia-alkali etching is about 500 nanometers.

[0039] (3) Wettability test The oil contact angles of Examples 1, 2, Comparative Example 1, and Comparative Examples 4-6 were tested, such as... Figure 4 As shown in the figure, the surface oil contact angle of Example 1 is 7°, which indicates superoleophilicity, while the surface oil contact angles of Example 2 and Comparative Examples 4-6 are between 110° and 115°, indicating oleophobicity.

[0040] When the fluorination treatment time is 0 minutes (Example 1), the resulting metal sealing gasket exhibits superoleophilicity; when the fluorination treatment time is 30 minutes (Examples 2, Comparative Examples 4-6), the resulting metal sealing gasket exhibits oleophobicity, thus meeting different requirements. This invention, by adjusting the fluorination time (0 or 30 minutes), allows for a controllable transition of the wettability of the metal sealing gasket from superoleophilic to oleophobic, making it suitable for diverse operating conditions.

[0041] (4) Metal static seal test Metal static seal tests were performed on each embodiment and comparative example, using a flange to clamp the sealing ring and a pressure sensor. A hydraulic press was used to provide a normal load to simulate the preload of a normal flange structure. An oil pump supplied oil to the inside of the flange. Oil leaking through the sealing ring collected at the oil sump of the lower flange and flowed out of the flange. The leaked oil was collected and weighed in real time. The leakage rate of the sealing ring was calculated, and the results are as follows. Figure 5-12 As shown. Under an internal fluid pressure of 5.7 MPa and a normal pressure of 2 tons, the average leakage rates of Example 2 and Comparative Example 1 were 1.47 and 62.22 g / min, respectively, while the average leakage rates of Comparative Examples 4-6 were 11.4, 8.66, and 6.94 g / min, respectively. This indicates that, compared to the untreated metal gasket (Comparative Example 1), Examples 2 and Comparative Examples 4-6, which have oleophobic properties, all exhibit good metal static sealing performance. Furthermore, when the internal fluid pressure was increased to 6.7 MPa and the normal pressure of 2 tons, the average leakage rate of Example 1 was 9.29 g / min, while the average leakage rate of Comparative Example 1 was extremely high. The average leakage rates of Comparative Examples 2 and 3 were 40.97 and 21.35 g / min, respectively. This indicates that, compared to the untreated metal gasket (Comparative Example 1) and the oleophobic metal gasket, Examples 1 and Comparative Examples 2 and 3, which have superoleophilic properties, all exhibit better metal static sealing performance.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should all be considered to be within the protection scope of the present invention.

Claims

1. A method for preparing a metal sealing gasket with special wettability control, characterized in that, Includes the following steps: S1. Clean the metal sealing gasket; S2. Prepare the electroplating solution and use a three-electrode system to electrodeposit the metal sealing gasket; S3. Immerse the electrodeposited metal sealing gasket in the prepared ammonia-alkali etching solution for treatment. S4. Immerse the etched metal sealing gasket in the prepared fluorination solution for fluorination treatment. S5. The fluorinated metal gasket is placed in a high-temperature oven for reaction, and after cooling, a metal gasket with special wettability control is obtained.

2. The method for preparing a metal sealing gasket with special wettability control according to claim 1, characterized in that, The dimensions of the metal sealing gasket are: inner diameter 48 mm, outer diameter 60 mm, and thickness 1 mm.

3. The method for preparing a metal sealing gasket with special wettability control according to claim 1, characterized in that, In step S1, the metal sealing gasket is ultrasonically cleaned for 30 minutes using 1 M sodium hydroxide solution, water, 5 vol% hydrochloric acid aqueous solution, and water, respectively.

4. The method for preparing a metal sealing gasket with special wettability control according to claim 1, characterized in that, In step S2, the electroplating solution is composed of copper nitrate, potassium chloride, concentrated sulfuric acid and water, and the mass ratio of copper nitrate, potassium chloride, concentrated sulfuric acid and water is 20:0.02:13:

187.

5. The method for preparing a metal sealing gasket with special wettability control according to claim 1, characterized in that, In step S2, the working electrode of the three-electrode system is the metal sealing gasket obtained in step S1, the reference electrode is a silver-silver chloride electrode, and the counter electrode is a platinum electrode with a size of 3 cm × 3 cm. Electrodeposition is performed in constant current mode on an electrochemical workstation with a current of 0.2 amperes and a time of 6000 seconds.

6. The method for preparing a metal sealing gasket with special wettability control according to claim 1, characterized in that, In step S3, the ammonia-alkali etching solution is composed of sodium hydroxide, ammonium persulfate and water, with a mass ratio of sodium hydroxide, ammonium persulfate and water of 2:0.55:

50.

7. The method for preparing a metal sealing gasket with special wettability control according to claim 1, characterized in that, In step S3, the metal sealing gasket is immersed in the ammonia-alkali etching solution for 8 to 20 minutes.

8. The method for preparing a metal sealing gasket with special wettability control according to claim 1, characterized in that, In step S4, the fluorination solution is an ethanol solution of 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and the volume ratio of 1H,1H,2H,2H-perfluorodecyltriethoxysilane to ethanol is 2:98; the metal sealing gasket is immersed in the fluorination solution for 0 or 30 minutes.

9. The method for preparing a metal sealing gasket with special wettability control according to claim 1, characterized in that, In step S5, the fluorinated metal gasket is reacted in an oven at 80°C for 60 minutes.

10. A metal sealing gasket with special wettability control, prepared by the method of preparing a metal sealing gasket with special wettability control according to any one of claims 1-9.

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