Low-temperature forming method of metal sealing ring coated with indium layer

Abstract

The invention discloses a low-temperature forming method for a metal sealing ring coated with an indium layer. The low-temperature forming method comprises the following steps that the surface of a metal matrix ring is cleaned; processing a microporous oxidation film on the coating surface of the metal matrix ring; preparing a high-purity indium foil matched with the cladding surface in shape, cleaning the high-purity indium foil, and accurately pre-laminating the high-purity indium foil on the microporous oxidation film of the metal matrix ring; the high-purity indium foil is rolled on the metal matrix ring through a precision rolling mill, the temperature does not exceed 60 DEG C in the rolling process, and the rolling mode is multi-pass and small-pressure; and the metal sealing ring formed after coating is placed in a low-temperature vacuum environment at the temperature of 80-150 DEG C for heat preservation for 1-4 hours. Through a composite combination mechanism of microporous oxidation film anchoring, cold rolling grain refinement and low-temperature diffusion, the core problem of poor binding force of the indium layer and the hard substrate is solved, and the cold and heat cycle resistance is extremely high. The extremely soft indium layer protects the precise flange face, and zero-scratch sealing is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal sealing ring, in particular to a low-temperature forming method of an indium-coated metal sealing ring. BACKGROUND

[0002] In low-temperature engineering, ultra-high vacuum system and spacecraft fuel pipeline, the sealing ring needs to maintain excellent sealing performance at extremely low temperature, while avoiding scratching the flange surface. The traditional metal sealing ring (such as stainless steel C-ring, nickel-based alloy spring ring) relies on the elastic rebound of the material to achieve sealing, which requires a huge initial compression force. At low temperature, the material is prone to failure due to yield, and the hard substrate can easily damage the precise mating surface. Indium is a very soft and ductile metal that does not become brittle at low temperatures, and can fill the micro-unevenness of the flange surface through plastic flow to achieve excellent low-temperature sealing. In the prior art, there are methods of electroplating or embedding indium wires in grooves on the substrate. However, the electroplated indium layer has the following problems: (1) the adhesion between the coating and the substrate is mainly physical adsorption, which is prone to peeling after multiple cold and hot cycles; (2) the coating has defects such as pinholes, which affect the sealing reliability; (3) the process may introduce organic contamination. The indium wire embedding method is complex and difficult to ensure the uniformity and integrity of the structure. SUMMARY

[0003] The present application aims to overcome the shortcomings of the prior art and provide a low-temperature forming method of an indium-coated metal sealing ring.

[0004] The purpose of the present application is achieved by the following technical solutions: A low-temperature forming method of an indium-coated metal sealing ring, the low-temperature forming method comprising the following steps: S1: cleaning the surface of the metal substrate ring; S2: processing a microporous oxide film on the coated surface of the metal substrate ring; S3: preparing a high-purity indium foil matching the shape of the coated surface, then cleaning the high-purity indium foil, and then accurately preattaching the high-purity indium foil to the microporous oxide film of the metal substrate ring; S4: rolling the high-purity indium foil on the metal substrate ring by a precision rolling mill, the temperature during rolling does not exceed 60℃, and the rolling mode is multi-pass and small pressure; S5: placing the metal sealing ring formed after coating in a low-temperature vacuum environment of 80-150℃ for 1-4 hours.

[0005] Further, the cleaning of the surface of the metal substrate ring comprises the following steps: S11: using an organic solvent to preliminarily remove oil from the metal substrate ring; S12: Ventilation drying the machine solvent on the metal matrix ring; S13: Secondary oil removal of the metal matrix ring by using alkaline chemical solution, the temperature of which is controlled at 60-70℃; S14: The metal matrix ring after secondary oil removal is rinsed in a rinsing solution; S15: After rinsing, the metal matrix ring is dried, and the drying temperature is not more than 80℃.

[0006] Further, the metal matrix ring rinsing includes the following steps: S141: The metal matrix is cleaned by flowing cold water; S142: The metal matrix is cleaned by flowing warm water, the temperature of which is 40-50℃; S143: The metal matrix is cleaned by deionized water, the temperature of which is 70-80℃.

[0007] Further, the microporous oxide film processing includes the following steps: S21: The coated surface is subjected to micro-arc oxidation treatment; S22: Then the metal matrix ring is taken out from the electrolytic tank and washed with clean water, and the washed metal matrix ring is immersed in an acidic solution for 10-30 minutes; S23: The metal matrix ring in the acidic solution is taken out and washed thoroughly with deionized water or pure water; S24: The washed metal matrix ring is dried.

[0008] Further, in the rolling process, the thickness of the small amount of the high-purity indium foil is 1%-10% of the total thickness.

[0009] Further, the metal matrix ring is a nickel-based alloy ring or a stainless steel ring, and the purity of indium in the high-purity indium foil is not less than 99.99%.

[0010] Further, the thickness of the high-purity indium foil in the metal sealing ring is 10-50μm, and the initial thickness of the high-purity indium foil is 50-200μm.

[0011] Further, the machine solvent is acetone, anhydrous ethanol or isopropyl alcohol, and the alkaline chemical solution is a sodium hydroxide solution.

[0012] Further, the acidic solution is a dilute nitric acid solution or a dilute phosphoric acid solution.

[0013] Further, the metal matrix ring is completely coated with the high-purity indium foil.

[0014] The beneficial effects of the present application are: 1) In the present technology, the core problem of poor bonding force between the indium layer and the hard base is solved through the combined mechanism of micro-porous oxide film anchoring, cold rolling grain refinement and low temperature diffusion, and the cold and hot cycle resistance is extremely strong. The whole processing process is a physical process, without the risk of electroplating liquid pollution; the extremely soft indium layer protects the precise flange surface, realizing zero scratch sealing. The thickness of the indium layer is accurately controlled through the rolling process, with good consistency and high yield.

[0015] 2) In the present technology, the metal base ring is densely coated on the whole surface by high-purity indium foil, rather than being partially filled, which makes the sealing more reliable and the process consistency better, without the risk of falling off. BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 is a structure diagram of the present metal sealing ring; Fig. 2 is a manufacturing flow chart of the present metal sealing ring; In the figure, 1 is a metal base ring, and 2 is a high-purity indium foil. DETAILED DESCRIPTION

[0017] The technical solutions of the present application will be described below in conjunction with the embodiments, obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0018] Referring to Figs. 1-2 , the present application provides a technical solution: A low-temperature forming method of an indium layer coated metal sealing ring, the low-temperature forming method comprising the following steps: (1) clean the surface of the metal base ring 1; the surface of the metal base ring 1 is cleaned, including the following steps: the metal base ring 1 is preliminarily degreased by using an organic solvent; the organic solvent on the metal base ring 1 is ventilated and dried; the metal base ring 1 is secondarily degreased by using an alkaline chemical solution, and the temperature of the alkaline chemical solution is controlled at 60-70 DEG C; the metal base ring 1 after secondary degreasing is placed in a rinsing liquid for rinsing; after rinsing, the metal base ring 1 is dried, and the drying temperature is not more than 80 DEG C. The rinsing of the metal base ring 1 includes the following steps: the metal base is cleaned by using flowing cold water; the metal base is cleaned by using flowing warm water, and the temperature of the warm water is 40-50 DEG C; the metal base is cleaned by using deionized water, and the temperature of the deionized water is 70-80 DEG C. The organic solvent is acetone, anhydrous ethanol or isopropyl alcohol, and the alkaline chemical solution is sodium hydroxide solution. In the first stage, the thick heavy mineral oil, lubricant and rust preventive oil remaining in the machining process are removed by using the raw materials: acetone: the solubility to the organic oil stain is extremely strong, and the volatilization is fast. Anhydrous ethanol or isopropyl alcohol: the toxicity is lower, and it is a good alternative solvent, and it is suitable for removing general oil stains. The detailed steps are as follows: immersion and wiping: the seal ring base is immersed in the solvent, or the solvent is dipped on a dust-free cloth to manually wipe, to ensure comprehensive coverage. Ultrasonic assistance: the container containing the solvent is placed in an ultrasonic cleaner, and the oil stains in the gap and blind hole are shaken out by using the cavitation effect, and the time is about 3-10 minutes. Volatilization and drying: after taking out, the residual solvent is completely volatilized at a ventilated place. In the second stage, the animal and plant oil and polishing paste are removed by saponification and emulsification, and the polar oil stains, fingerprints, polishing paste and the like which are difficult to be dissolved by the solvent are completely removed. The raw materials used are as follows: main body: sodium hydroxide, providing strong alkalinity. Auxiliary agent: sodium carbonate (maintaining alkalinity), trisodium phosphate (softening water, enhancing rinsing effect), sodium silicate (having corrosion inhibition effect on metal). Surfactant: such as sodium dodecyl benzene sulfonate, having emulsification and dispersion effect. Solvent: deionized water. Typical formula example (content per liter of water): sodium hydroxide 20-40 g; sodium carbonate 20-30 g; trisodium phosphate 10-20 g; sodium silicate 3-8 g; surfactant 1-3 mL. The detailed steps are as follows: heating immersion: the degreasing liquid is heated to 60-70 DEG C, and the base is put in and immersed for 5-15 minutes. The temperature and time need to be accurately controlled, to prevent over-corrosion to the nickel-based alloy or stainless steel base. Mechanical stirring: assisted by slight air stirring or mechanical shaking, the contact of the new solution and the surface of the workpiece is improved, and the degreasing efficiency is improved. In the third stage, the workpiece surface is thoroughly cleaned and the residual chemical reagent and particles are removed. The raw materials used are as follows: deionized water or ultrapure water. The detailed steps are as follows: three-stage countercurrent rinsing: first stage: flowing cold water rinsing, removing most of the residual liquid. Second stage: flowing warm water (40-50 DEG C) rinsing, further cleaning. Third stage: hot deionized water (70-80 DEG C) rinsing, using the characteristic that the surface tension of hot water is small, so that the water is more easily separated from the surface of the workpiece, and the heat can promote the workpiece to be quickly dried, reducing water stains.In the second or third stage of rinsing, ultrasonic waves are used again to ensure that the particles of impurities embedded in the surface microstructure are completely removed. Finally, drying: first choice is to put into a clean oven at ≤80°C to dry. Second choice is to dry with filtered, oil-free compressed air or nitrogen.

[0019] (2) Processing a microporous oxide film on the cladding surface of the metal matrix ring 1; the microporous oxide film processing includes the following steps: micro-arc oxidation treatment is performed on the cladding surface; then the metal matrix ring 1 is taken out of the electrolytic tank and washed with clean water, and the washed metal matrix ring 1 is immersed in an acidic solution for 10-30 minutes; the metal matrix ring 1 in the acidic solution is taken out and washed thoroughly with deionized water or pure water; the washed metal matrix ring 1 is dried. The acidic solution is a dilute nitric acid solution or a dilute phosphoric acid solution. The micro-arc oxidation treatment is a prior art. Among them, a microporous oxide film is formed on the cladding surface by micro-arc oxidation or anodic oxidation treatment. This microporous oxide film is mainly used to greatly increase the surface area and mechanical embedding capacity of the matrix, and prevent the formation of brittle intermetallic compounds between the metal matrix ring 1 and the high-purity indium foil 2. The specific steps are as follows: prepare the solution: use an acidic aqueous solution, usually dilute nitric acid (such as 5-10% by volume) or dilute phosphoric acid, or a buffered acetic acid solution. Soak: after micro-arc oxidation treatment, the workpiece is taken out of the electrolytic tank and washed with water, and then immediately immersed in the prepared acidic solution. Control the time: soak for 10-30 minutes at room temperature, the time should not be too short (otherwise the neutralization is not complete), nor too long (may slightly corrode the surface of the ceramic layer). Thoroughly wash with water: after taking out the workpiece, it must be immediately washed thoroughly and completely with flowing deionized water or pure water to remove all acidic substances and reaction products. Dry: finally dry to complete the entire treatment.

[0020] (3) Prepare a high-purity indium foil 2 matching the shape of the cladding surface, clean the high-purity indium foil 2, and then accurately pre-laminate the high-purity indium foil 2 on the microporous oxide film of the metal matrix ring 1; the metal matrix ring 1 is a nickel-based alloy ring or a stainless steel ring, and the purity of indium in the high-purity indium foil 2 is not less than 99.99%. The metal matrix ring 1 is completely cladded with the high-purity indium foil 2. The nickel-based alloy in the nickel-based alloy ring can be Inconel 718 or Inconel 625, and the stainless steel in the stainless steel ring can be 304 or 316L.

[0021] (4) The high-purity indium foil 2 is rolled on the metal base ring 1 by a precision rolling mill, and the temperature during rolling does not exceed 60°C. The rolling mode is multi-pass and small reduction. During rolling, the thickness of the small reduction of the high-purity indium foil 2 is 1% to 10% of the total thickness. The thickness of the high-purity indium foil 2 in the metal seal ring is 10 to 50 μm, and the initial thickness of the high-purity indium foil 2 is 50 to 200 μm. First, the pretreated seal ring base and the high-purity indium foil with matching size are accurately aligned and pre-assembled. Then, it is sent to the precision rolling mill to perform the multi-pass and small reduction cold rolling procedure. The reduction of each pass is strictly controlled, usually between 1% and 10%, to ensure that the indium material can flow plastically and uniformly, so as to tightly embed the porous structure of the micro-arc oxidation layer on the surface of the base, and form a strong mechanical interlocking effect. Cold isostatic pressing technology is used to realize uniform pressure on the complex profile; a multi-pass, small reduction gradient rolling process is used, and low-temperature intermediate annealing can be introduced when the cumulative deformation reaches 50%-60% to promote the plastic flow and densification of the indium layer; an online thickness monitoring and closed-loop feedback system is integrated to realize precise control of the thickness of the cladding layer; the whole process from pretreatment to cladding is completed in a clean environment under the protection of inert atmosphere, ensuring the purity of the interface.

[0022] (5) The metal seal ring formed after cladding is placed in a low-temperature vacuum environment of 80-150°C for 1-4 hours.

[0023] Examples An Inconel 718 seal ring for a space probe liquid helium pipeline is prepared. A C-shaped ring of finished Inconel 718 is subjected to micro-arc oxidation treatment, and a porous oxide film with a thickness of about 5 μm is generated on the surface. A high-purity indium foil (99.995%) is cut and pre-assembled on the sealing ridge of the ring. At room temperature, the indium layer is rolled from the initial 150 μm to 25±3 μm in multiple passes. The metal seal ring is obtained by treating in a 120°C vacuum furnace for 2 hours. Tests show that the indium layer on the metal seal ring has no peeling, and the leakage rate is still lower than 5×10⁻¹¹ mbar•L / s after 50 cycles in liquid helium at about 269°C.

[0024] The above only describes the preferred embodiments of the present application, and it should be understood that the present application is not limited to the forms disclosed herein, and should not be considered as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concepts described herein by the above teachings or related art or knowledge. Any modification and change made by those skilled in the art without departing from the spirit and scope of the present application shall be within the protection scope of the appended claims of the present application.

Claims

1. A low-temperature forming method for an indium-coated metal sealing ring, characterized in that, The low-temperature forming method includes the following steps: S1: Clean the surface of the metal substrate ring; S2: A microporous oxide film is processed on the coating surface of the metal substrate ring; S3: Prepare a high-purity indium foil that matches the shape of the coating surface, clean the high-purity indium foil, and then precisely pre-attach the high-purity indium foil to the microporous oxide film of the metal substrate ring. S4: The high-purity indium foil is rolled onto the metal matrix ring using a precision rolling mill. The temperature during the rolling process does not exceed 60°C, and the rolling method is multi-pass rolling with small pressure. S5: Place the metal sealing ring formed after coating in a low-temperature vacuum environment of 80~150℃ for 1~4 hours.

2. The low-temperature forming method for an indium-coated metal sealing ring according to claim 1, characterized in that, Cleaning the surface of the metal substrate ring includes the following steps: S11: The metal matrix ring is initially degreased using an organic solvent; S12: Dry the organic solvent on the metal matrix ring by ventilation; S13: The metal matrix ring is degreased a second time using an alkaline chemical solution, wherein the temperature of the alkaline chemical solution is controlled at 60~70℃; S14: The metal matrix ring after secondary degreasing is placed in the rinsing solution for rinsing; S15: After rinsing, the metal matrix ring is dried at a temperature not exceeding 80°C.

3. The low-temperature forming method for an indium-coated metal sealing ring according to claim 2, characterized in that, The ring rinsing of the metal substrate includes the following steps: S141: The metal substrate is cleaned with flowing cold water; S142: The metal substrate is cleaned with flowing warm water at a temperature of 40~50℃; S143: The metal substrate is cleaned with deionized water at a temperature of 70~80℃.

4. A low-temperature forming method for an indium-coated metal sealing ring according to any one of claims 1-3, characterized in that, The microporous oxide film processing includes the following steps: S21: Perform micro-arc oxidation treatment on the coated surface; S22: Next, the metal matrix ring is removed from the electrolytic cell and rinsed with clean water. The rinsed metal matrix ring is then soaked in an acidic solution for 10-30 minutes. S23: Remove the metal matrix ring from the acidic solution and rinse thoroughly with deionized water or purified water; S24: Dry the rinsed metal matrix ring.

5. A low-temperature forming method for an indium-coated metal sealing ring according to any one of claims 1-3, characterized in that: During the rolling process, the thickness of the high-purity indium foil under small pressure is 1% to 10% of the total thickness.

6. A low-temperature forming method for an indium-coated metal sealing ring according to any one of claims 1-3, characterized in that: The metal matrix ring is a nickel-based alloy ring or a stainless steel ring, and the indium purity in the high-purity indium foil is not less than 99.99%.

7. A low-temperature forming method for an indium-coated metal sealing ring according to any one of claims 1-3, characterized in that: The high-purity indium foil in the metal sealing ring has a thickness of 10~50μm, and the initial thickness of the high-purity indium foil is 50~200μm.

8. A low-temperature forming method for an indium-coated metal sealing ring according to claim 2 or 3, characterized in that: The organic solvent is acetone, anhydrous ethanol, or isopropanol, and the alkaline chemical solution is sodium hydroxide solution.

9. A low-temperature forming method for an indium-coated metal sealing ring according to any one of claims 1-3, characterized in that: The acidic solution is a dilute nitric acid solution or a dilute phosphoric acid solution.

10. A low-temperature forming method for an indium-coated metal sealing ring according to any one of claims 1-3, characterized in that: The metal matrix ring is completely covered by the high-purity indium foil.

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