Gradient composite coating metal valve sealing ring and preparation method

Abstract

The invention discloses a gradient composite coating metal valve sealing ring and a preparation method, the gradient composite coating metal valve sealing ring comprises a sealing ring base body, a component gradient transition layer and a soft metal layer, the component gradient transition layer is coated on the sealing ring base body, the soft metal layer is coated on the component gradient transition layer, and the component gradient transition layer is coated on the soft metal layer. Components in the component gradient transition layer are continuously and gradually changed from elements rich in the sealing ring base body to elements rich in the soft metal layer, and the continuous gradual change of the component gradient transition layer points to the soft metal layer from the sealing ring base body. The composition gradient transition layer is arranged between the sealing ring base body and the soft metal layer, and the composition gradient transition layer thoroughly eliminates a physical property mutation interface between the sealing ring base body and the soft metal layer and replaces the physical property mutation interface with a buffer area with continuously changed components and properties. The component gradient transition layer greatly relieves thermal stress and mechanical stress at the interface, the binding force is close to the theoretical limit, and the thermal shock resistance and the fatigue resistance are improved in order of magnitude.

Description

Technical Field

[0001] This invention relates to the field of sealing rings, and particularly to a gradient composite coated metal valve sealing ring and its preparation method. Background Technology

[0002] In the field of high-performance sealing, a common approach to solving the sealing problem of hard metal substrates is to coat their surfaces with soft metal. Existing technologies often employ a two-layer structure: a PVD undercoat followed by electroplating / chemical plating for thickening. However, this structure has an inherent drawback: a clear interface with abrupt changes in physical properties (such as coefficient of thermal expansion and modulus of elasticity) exists between the hard metal substrate and the soft metal coating. Under severe temperature cycling or high mechanical stress, this interface generates significant internal stress, becoming a source of crack initiation and propagation, ultimately leading to peeling or even detachment of the soft metal coating, resulting in seal failure. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a gradient composite coated metal valve sealing ring and its preparation method.

[0004] The objective of this invention is achieved through the following technical solution: A gradient composite coated metal valve sealing ring includes a sealing ring substrate, a composition gradient transition layer, and a soft metal layer. The composition gradient transition layer covers the sealing ring substrate, and the soft metal layer covers the composition gradient transition layer. The composition in the composition gradient transition layer gradually changes from being rich in the elements of the sealing ring substrate to being rich in the elements of the soft metal layer. The continuous gradient of the composition gradient transition layer extends from the sealing ring substrate to the soft metal layer.

[0005] Furthermore, the thickness of the composition gradient transition layer is 1~5μm, and the thickness of the soft metal layer is 5~50μm.

[0006] Furthermore, the material of the sealing ring substrate is any one of stainless steel, nickel-based alloy or tungsten alloy, and the material of the soft metal layer is any one of gold, silver or copper.

[0007] A method for preparing a gradient composite coated metal valve sealing ring, used to manufacture the aforementioned gradient composite coated metal valve sealing ring, the method comprising the following steps: S1: The sealing ring substrate is manufactured through precision machining; S2: Pre-treat the sealing ring substrate; S3: Place the pretreated sealing ring substrate, substrate target material and soft metal target material in a high vacuum PVD equipment, and evacuate the high vacuum PVD equipment. S4: The substrate target and the soft metal target are processed by co-sputtering to deposit the composition gradient transition layer; S5: During the deposition of the composition gradient transition layer, the sputtering power of the substrate target gradually decreases, while the sputtering power of the soft metal target gradually increases; S6: After the composition gradient transition layer is deposited, the high vacuum PVD equipment is cooled. After cooling, the high vacuum PVD equipment is opened and the sealing ring substrate is removed. S7: Place the sealing ring substrate with the composition gradient transition layer in an electroplating tank, and electroplat the soft metal layer on the composition gradient transition layer by pulse electrochemical plating or chemical plating to form a metal valve sealing ring; S8: Perform post-processing on the metal valve sealing ring.

[0008] Furthermore, the pretreatment of the sealing ring substrate includes the following steps: S21: Place the sealing ring substrate into the supercritical cleaning device; S22: Introduce carbon dioxide into the supercritical cleaning device, and control the pressure of the supercritical cleaning device to be above 7.38 MPa and the temperature to be above 31°C, so that the carbon dioxide reaches the supercritical fluid state. S23: Clean the sealing ring substrate with the carbon dioxide; S24: Activate the cleaned sealing ring substrate.

[0009] Furthermore, the activation of the sealing ring matrix includes the following steps: S241: Place the cleaned sealing ring substrate in the PVD vacuum chamber; S242: Evacuate the PVD vacuum chamber to below 5.0 × 10⁻³ Pa; S243: High-purity argon gas is introduced into the PVD vacuum chamber to control the pressure of the PVD vacuum chamber at 0.5~1.0 Pa; S244: Apply a DC pulse bias voltage of -800V to -1000V to the sealing ring substrate to generate high-energy argon plasma to bombard the surface of the sealing ring substrate for 5 to 10 minutes. S245: Stop the supply of high-purity argon gas, and then supply high-purity hydrogen gas to control the pressure of the PVD vacuum chamber at 1.0~2.0 Pa; S246: Then apply radio frequency power or DC pulse bias to the sealing ring substrate to generate hydrogen plasma to bombard the surface of the sealing ring substrate for 3 to 5 minutes, and finally obtain the sealing ring substrate with a clean surface.

[0010] Furthermore, the pulsed electrochemical plating includes the following steps: S71: Preparation of pulse electrochemical plating solution; S72: Place the sealing ring substrate into the electroplating solution; S73: Apply a direct current to the sealing ring substrate, wherein the current density of the direct current is 3.0 A / dm², the pulse on-time is 0.1~10 ms, and the pulse off-time is 1~50 ms; S74: After electroplating is completed, remove the metal valve sealing ring.

[0011] Furthermore, the post-processing of the metal valve sealing ring includes the following steps: S81: Place the electroplated metal valve sealing ring in the secondary reverse osmosis water tank and let it stand for a period of time; S82: Remove the metal valve sealing ring from the secondary reverse osmosis water tank and place it in a flowing room temperature deionized water tank for rough washing, and clean it by mechanical agitation or air stirring for 1-2 minutes; S83: After the rough cleaning is completed, the metal valve sealing ring is placed in a flowing deionized water tank at 40~50℃ for fine cleaning, and ultrasonic cleaning is performed for 3~5 minutes. S84: After the fine washing is completed, the metal valve sealing ring is placed in a still hot water bath at 70-80℃ and soaked for 1-2 minutes to achieve the final washing; S85: After the final wash is completed, dry the metal valve sealing ring; S86: Perform hydrogen removal treatment on the dried metal valve sealing ring.

[0012] Furthermore, the drying of the metal valve sealing ring includes the following steps: S851: Insert the metal valve sealing ring into a corrosion-resistant drum or basket, and then place the drum or basket in a centrifuge; S852: Start the centrifuge and operate it for 1 to 3 minutes, with the centrifuge speed being 200 to 500 rpm; S853: Then transfer the metal valve sealing ring to a vacuum-sealed drying oven; S854: Vacuum the drying oven so that the pressure drop of the drying oven is between -0.05 and -0.08 MPa, and maintain it for 2-3 minutes; S855: Introduce clean hot air at 80~110℃ into the drying oven and dry for 15~30 minutes.

[0013] Furthermore, the hydrogen removal treatment of the metal valve sealing ring includes the following steps: S861: Place the dried metal valve sealing ring into a vacuum furnace; S862: Inert gas is introduced into the vacuum furnace, and the vacuum furnace is evacuated to below 1.0×10⁻²Pa; S863: Heat the vacuum furnace to 190°~230°C at a heating rate of 3~5°C / min; S864: The vacuum furnace is kept at 190°C to 230°C for 3 to 8 hours; S865: Control the vacuum furnace to cool to room temperature, with a cooling rate not exceeding 2℃ / min.

[0014] The beneficial effects of this invention are: 1) In this technology, a composition gradient transition layer is set between the sealing ring substrate and the soft metal layer. The composition gradient transition layer completely eliminates the interface of abrupt physical property changes between the sealing ring substrate and the soft metal layer, replacing it with a buffer zone where composition and properties change continuously. The composition gradient transition layer greatly alleviates the thermal and mechanical stresses at the interface, the bonding force approaches the theoretical limit, and the thermal shock resistance and fatigue resistance are improved by orders of magnitude.

[0015] 2) In this technology, the bottom layer of the composition gradient transition layer achieves a perfect metallurgical bond with the sealing ring substrate, and the top layer is perfectly compatible with the soft metal layer. At the same time, it serves as an excellent diffusion barrier layer to prevent the matrix elements and coating elements from diffusing into each other at high temperatures to form a brittle phase.

[0016] 3) In this technology, the target power of the high-vacuum PVD equipment can be used to achieve precise control of the gradient layer composition curve and thickness, resulting in good process repeatability and easy industrialization.

[0017] 4) In this technology, the PVD coating has the advantages of high adhesion and density, and overcomes its inherent interface mismatch problem through gradient design. At the same time, it combines the advantages of economical thickening by electroplating / chemical plating, and achieves the peak of the comprehensive performance of the sealing ring. Attached Figure Description

[0018] Figure 1 This diagram illustrates the connection relationship between the sealing ring matrix, the composition gradient transition layer, and the soft metal layer. Figure 2 This diagram illustrates the relationship between the power of the substrate target and the power of the soft metal target during the fabrication of the composition gradient transition layer. Figure 3 This diagram illustrates the relationship between the proportions of the matrix target and the soft metal target during the fabrication of the composition gradient transition layer. Figure 4 A flowchart illustrating the manufacturing process of metal valve sealing rings; In the figure, 1-sealing ring substrate, 2-composition gradient transition layer, 3-soft metal layer. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] See Figures 1-4 The present invention provides a technical solution: A gradient composite coated metal valve sealing ring includes a sealing ring substrate 1, a composition gradient transition layer 2, and a soft metal layer 3. The composition gradient transition layer 2 coats the sealing ring substrate 1, and the soft metal layer 3 coats the composition gradient transition layer 2. The composition in the composition gradient transition layer 2 gradually changes from being rich in elements of the sealing ring substrate 1 to being rich in elements of the soft metal layer 3, with the gradual change in composition gradient transition layer 2 pointing from the sealing ring substrate 1 to the soft metal layer 3. The thickness of the composition gradient transition layer 2 is 1~5μm, and the thickness of the soft metal layer 3 is 5~50μm. The material of the sealing ring substrate 1 is any one of stainless steel, nickel-based alloy, or tungsten alloy, and the material of the soft metal layer 3 is any one of gold, silver, or copper. The composition gradient transition layer is provided between the sealing ring substrate and the soft metal layer, which completely eliminates the abrupt physical property interface between the sealing ring substrate and the soft metal layer, replacing it with a buffer zone where composition and properties change continuously. The compositional gradient transition layer greatly alleviates the thermal and mechanical stresses at the interface, bringing the bonding strength close to the theoretical limit, and resulting in an order-of-magnitude improvement in thermal shock resistance and fatigue resistance. A method for preparing a gradient composite coated metal valve sealing ring, used to manufacture a gradient composite coated metal valve sealing ring, the preparation method includes the following steps: (1) The sealing ring substrate 1 is manufactured by precision machining. Before obtaining the sealing ring substrate 1, precision machining is required. The purpose of precision machining is to obtain a precise geometric shape and form a specific surface state that is conducive to the bonding of the coating. First, the sealing working surface of the sealing ring substrate is machined using the existing "hard dry turning" process. Using CBN (cubic boron nitride) tools, the substrate tempered to HRC45 or higher is precision machined without the use of cutting fluid. Then, by controlling the cutting parameters (such as extremely high cutting speed and extremely small depth of cut), a layer of extremely fine bainite or ultrafine grain structure is generated within a depth of 0.5~2μm on the surface of the sealing surface by utilizing the intense plastic deformation and high temperature effect. This structure has high hardness, compressive stress, and high grain boundary density, providing a high-density nucleation site for subsequent PVD deposition that is far superior to that of conventional surfaces.

[0021] (2) Pretreatment of sealing ring substrate 1; the pretreatment of sealing ring substrate 1 includes the following steps: placing sealing ring substrate 1 into a supercritical cleaning device; introducing carbon dioxide into the supercritical cleaning device, controlling the pressure of the supercritical cleaning device above 7.38 MPa and the temperature above 31°C, so that the carbon dioxide reaches the supercritical fluid state; cleaning the sealing ring substrate 1 with carbon dioxide; activating the cleaned sealing ring substrate 1. The activation of the sealing ring substrate 1 includes the following steps: placing the cleaned sealing ring substrate 1 in a PVD vacuum chamber; evacuating the PVD vacuum chamber to below 5.0 × 10⁻³ Pa; introducing high-purity argon gas into the PVD vacuum chamber to control the pressure of the PVD vacuum chamber at 0.5~1.0 Pa; applying a DC pulse bias voltage of -800V to -1000V to the sealing ring substrate 1 to generate high-energy argon plasma to bombard the surface of the sealing ring substrate 1 for 5~10 minutes; stopping the introduction of high-purity argon gas and then introducing high-purity hydrogen gas to control the pressure of the PVD vacuum chamber at 1.0~2.0 Pa; then applying radio frequency power or a DC pulse bias voltage to the sealing ring substrate 1 to generate hydrogen plasma to bombard the surface of the sealing ring substrate 1 for 3~5 minutes, finally obtaining a sealing ring substrate 1 with a clean surface. The purpose of degreasing is to remove contaminants from the surface of the sealing ring substrate 1, creating the necessary conditions for subsequent plasma activation. The first step is supercritical CO2 cleaning, where the workpiece is placed in a supercritical cleaning device. Carbon dioxide is introduced, and the process is carried out at a temperature above 31°C and a pressure above 7.38 MPa to achieve a supercritical fluid state. Supercritical CO2 has extremely strong penetrating and dissolving capabilities, capable of dissolving and removing all organic oil stains and fingerprints without leaving any liquid residue, completely avoiding the environmental pollution and potential chemical corrosion of the workpiece caused by traditional alkaline degreasing solutions. The purpose of activating the surface of the sealing ring substrate 1 is to obtain an atomically clean, non-recontaminated, highly active surface in situ through physical bombardment and chemical reaction in a vacuum environment. The detailed activation steps are as follows: the supercritically cleaned and dried workpiece is directly placed into the vacuum chamber of the PVD equipment. Then, high-energy argon ion sputtering cleaning is employed. The vacuum is evacuated to ≤5.0×10⁻³Pa, and high-purity argon gas is introduced to a pressure of 0.5-1.0Pa. A DC pulse bias of -800V to -1000V is applied to the workpiece to generate high-energy argon plasma, which powerfully bombards the workpiece surface for 5-10 minutes. Through the physical sputtering effect, the last few atomic layers of contaminants and the natural oxide film on the surface are thoroughly stripped away. Next, hydrogen plasma reduction activation is used: the argon gas is stopped, and high-purity hydrogen gas is introduced to a pressure of 1.0-2.0Pa. Radio frequency power (e.g., 13.56MHz, 300-500W) or a DC pulse bias is applied to generate hydrogen plasma. This process lasts for 3-5 minutes. The hydrogen free radicals react chemically with the trace oxides (e.g., Cr₂O₃) remaining after sputtering, reducing them to elemental metals and water vapor, thus obtaining a stoichiometrically pure metal surface.After the hydrogen plasma treatment is completed, the deposition of the PVD composition gradient transition layer begins immediately without disrupting the vacuum.

[0022] (3) Place the pretreated sealing ring substrate 1, substrate target, and soft metal target in a high-vacuum PVD equipment, and evacuate the high-vacuum PVD equipment. The composition of the substrate target is the same as that of the sealing ring substrate 1, and the composition of the soft metal target is the same as that of the soft metal layer 3. The high-vacuum PVD equipment is the existing technology, and the high-vacuum PVD equipment is evacuated to a vacuum level below 5.0 × 10⁻³ Pa. The sealing ring substrate 1 is either transferred or quickly transferred and installed into the vacuum chamber of the high-vacuum PVD equipment without disrupting the vacuum. Ensure that the sealing ring substrate 1 is located in a uniform region that can simultaneously receive sputtering streams from the substrate target and the soft metal target. After the vacuum chamber is evacuated to a high vacuum (≤5.0 × 10⁻³ Pa), argon gas is introduced, and the sealing ring substrate 1 is cleaned in situ for the last time by argon ion bombardment to ensure interface purity.

[0023] (4) Co-sputtering is used to process the substrate target and soft metal target for depositing the composition gradient transition layer 2. In a high-vacuum PVD equipment, the substrate target and soft metal target can be deposited using the existing co-sputtering method or the existing multi-source evaporation method. This technology does not change the target material, but only dynamically adjusts the power, thereby achieving continuous composition and no interface gradient. This is fundamentally different from the traditional multilayer film technology of depositing one layer first and then another.

[0024] (5) During the deposition of the composition gradient transition layer 2, the sputtering power of the substrate target gradually decreases, while the sputtering power of the soft metal target gradually increases. At the beginning of deposition, the water-cooled sputtering substrate target, as used in the prior art, is mainly used. Subsequently, during the deposition process, the following operations are performed continuously and synchronously: the sputtering power of the substrate target is gradually reduced, and the sputtering power of the soft metal target is gradually increased. Deposition of the composition gradient transition layer 2: Start dual targets and simultaneously turn on the sputtering power (such as DC or RF power) of the substrate target and the soft metal target. In the initial stage, the power settings of the two are extremely unequal. In the initial stage, the power of the substrate target is set to high power (e.g., 80% of the rated power), and the power of the soft metal target is set to low power or zero power (e.g., 5% of the rated power or directly turned off). This is mainly because the metal atoms of the substrate target form an initial layer on the substrate with a very strong metallurgical bond and similar composition to the sealing ring substrate 1. Gradient Transition Stage (Achieving Continuous Gradual Composition Change): The core operation involves the equipment continuously and linearly performing the following actions within a predetermined time period (e.g., 20 minutes): gradually decreasing the sputtering power of the substrate target while simultaneously gradually increasing the sputtering power of the soft metal target. The atomic stream flowing from the chamber to the sealing ring substrate 1 has a dynamically and continuously changing composition. Initially, it is dominated by the "substrate target," and as the power is adjusted, more and more "soft metal stream" is gradually mixed in, eventually becoming dominated by the "soft metal stream." These atoms deposit, migrate, and form an alloy film on the surface of the sealing ring substrate 1, achieving a continuous gradual change in composition from "substrate-rich metal" to "soft metal-rich metal" from the bottom layer to the surface. Final Stage (Forming a "Soft Metal-Rich" Surface Layer): The substrate target power is reduced to a low power (e.g., 5% of the rated power). The soft metal target power is increased to a high power (e.g., 80% of the rated power). The soft metal atoms are predominantly present, providing a perfect, firmly bonded, and pure substrate for subsequent electroplating of functional layers.

[0025] (6) After the composition gradient transition layer 2 is deposited, the high vacuum PVD equipment is cooled. After cooling, the high vacuum PVD equipment is opened and the sealing ring substrate 1 is removed. Generally, when the high vacuum PVD equipment is cooled to below 100°C, the high vacuum PVD equipment can be opened and the sealing ring substrate 1 in the high vacuum PVD equipment can be removed to prevent the composition gradient transition layer 2 from reacting with other gases in the air at high temperature, which would cause the composition gradient transition layer 2 to be contaminated.

[0026] (7) Place the sealing ring substrate 1 with the composition gradient transition layer 2 in the electroplating tank, and electroplat a soft metal layer 3 on the composition gradient transition layer 2 using pulse electrochemical plating or chemical plating to form a metal valve sealing ring; the pulse electrochemical plating includes the following steps: preparing the pulse electrochemical plating solution; placing the sealing ring substrate 1 into the electroplating solution; passing a direct current through the sealing ring substrate 1, the current density of the direct current is 3.0A / dm², the pulse conduction time is 0.1~10ms, and the pulse off time is 1~50ms; after the electroplating is completed, the metal valve sealing ring is removed. 1) Chemical plating operation steps, chemical plating is a technology that does not require an external power source, and achieves metal deposition by reducing metal ions on the catalytic surface through a reducing agent in the solution. Steps: First, prepare the plating solution by dissolving the following components sequentially in deionized water in the plating tank: main salt (providing the metal ions to be deposited, such as nickel sulfate or palladium chloride); reducing agent (providing electrons, such as sodium hypophosphite or dimethylamine borane); complexing agent (stabilizing the metal ions and preventing spontaneous decomposition of the solution, such as citrate or EDTA); buffer, stabilizer, accelerator, etc. Mount the catalytically active (or activated) workpiece in an insulated rack. Plating process: Heat the plating solution and stabilize it at a specific working temperature (e.g., 80-90℃ for nickel-based, 40-60℃ for copper-based), with a temperature control accuracy of ±2℃; immerse the workpiece in the plating solution while maintaining gentle, continuous mechanical or air agitation; continue deposition, allowing the metal deposition reaction to occur uniformly across the entire surface of the workpiece. The target thickness is obtained by controlling the immersion time and plating solution load (the ratio of workpiece surface area to plating solution volume). Finally, post-plating treatment: After the predetermined time is reached, the workpiece is removed; it is initially rinsed in a static deionized water tank to recover the carry-over liquid; and then thoroughly rinsed with flowing deionized water. 2) Pulse electrochemical plating operation steps: Pulse electrochemical plating is a technology that greatly improves the deposition quality at the microscopic level by precisely controlling the on and off of the current, based on traditional DC electroplating. Steps: Prepare the plating solution: Similar to chemical plating, but without reducing agents, mainly containing main salt, conductive salt, and additives (brightener, leveling agent); use the workpiece as the cathode and connect it to the negative terminal of the pulse power supply. Install a suitable anode. Plating process: Similar to chemical plating, the workpiece is immersed in the plating solution. Set pulse parameters (core step): Set three key parameters on the pulse power supply: peak current density (Jp): usually 2 to 5 times the DC current density (e.g., 3.0 A / dm²); pulse on-time (Ton): usually 0.1 to 10 ms; pulse off-time (Toff): usually 1 to 50 ms. Turn on the power supply, and the current is output in the form of square wave pulses. During the Ton period, a high Jp is applied instantaneously, resulting in extremely high cathodic polarization, forming a large number of crystal nuclei, and deposition proceeds rapidly; during the Toff period, the current is zero, the metal ions consumed at the cathode interface are replenished by diffusion, the adsorbed hydrogen bubbles are desorbed, and the adsorbed impurities are desorbed.There are three types of pulse electroplating solutions: pulse silver plating solution (cyanide-free system), pulse gold plating solution (acidic citrate system), and pulse copper plating solution (acidic sulfate system). The pulse silver plating solution (cyanide-free system) includes: silver aminosulfonate as the main salt (15~40g / L), potassium aminosulfonate as the conductive salt (80~150g / L), ammonium iminodisulfonate as the complexing agent (50~120g / L), thiomalic acid as the brightener (0.5~2.0g / L), fatty alcohol polyoxyethylene ether as the auxiliary brightener (0.1~0.5mL / L), and deionized water as the solvent. The pulsed gold plating solution (acidic citrate system) includes: potassium gold cyanide as the main salt (8-20 g / L, calculated as gold), tripotassium citrate as the conductive salt and complexing agent (80-180 g / L), citric acid as the buffer (10-25 g / L), cobalt sulfate as the brightener (0.05-0.20 g / L), and deionized water as the solvent (pH 3.5-4.5). The pulsed copper plating solution (acidic sulfate system) includes: copper sulfate pentahydrate as the main salt (180-250 g / L), sulfuric acid as the conductive acid (50-80 g / L), hydrochloric acid providing 50-100 mg / L of chloride ions, commercial additives including carrier, brightener, and leveling agent added according to the supplier's recommended proportions, and deionized water as the solvent.

[0027] (8) Post-treatment of metal valve sealing rings. The post-treatment of metal valve sealing rings includes the following steps: placing the electroplated metal valve sealing rings in a secondary reverse osmosis water tank for a period of time; removing the metal valve sealing rings from the secondary reverse osmosis water tank and placing them in a flowing room temperature deionized water tank for rough washing, and cleaning them by mechanical agitation or air stirring for 1-2 minutes; after rough washing, placing the metal valve sealing rings in a flowing deionized water tank at 40-50℃ for fine washing, and cleaning them by ultrasonic cleaning for 3-5 minutes; after fine washing, placing the metal valve sealing rings in a static hot water tank at 70-80℃ for immersion for 1-2 minutes to achieve final washing; After washing, the metal valve sealing rings are dried. The drying process includes the following steps: Place the metal valve sealing rings in a corrosion-resistant drum or basket, then place the drum or basket in a centrifuge; start the centrifuge and run it for 1-3 minutes at a speed of 200-500 rpm; then transfer the metal valve sealing rings to a vacuum-sealed drying chamber; evacuate the drying chamber to a pressure drop of -0.05 to -0.08 MPa, maintaining this pressure for 2-3 minutes; introduce clean hot air at 80-110°C into the drying chamber and dry for 15-30 minutes. The dried metal valve sealing rings are then subjected to hydrogen removal treatment. The hydrogen removal treatment of metal valve sealing rings includes the following steps: The dried metal valve sealing rings are placed in a vacuum furnace; inert gas is introduced into the vacuum furnace, and the furnace is evacuated to below 1.0 × 10⁻² Pa; the vacuum furnace is heated to 190°~230°C at a rate of 3~5°C / min; the vacuum furnace is held at 190°~230°C for 3~8 hours; the vacuum furnace is then cooled to room temperature at a rate not exceeding 2°C / min. The purpose of cleaning the metal valve sealing rings is to thoroughly and efficiently remove residual plating solution from the workpiece surface, preventing residues from corroding the plating layer, causing spots, or contaminating subsequent processes. The first step is recovery rinsing. The electroplated workpiece is first immersed in a static two-stage reverse osmosis (RO) water tank. Concentration diffusion is used to initially dilute the high-concentration plating solution carried out by the workpiece. This water can be periodically reused as a replenishing solution in the plating tank, achieving metal salt recovery and wastewater reduction. The second step involves a three-stage countercurrent rinsing process: The first stage (rough rinse – room temperature flow) involves rinsing for 1-2 minutes in a flowing, room temperature deionized water bath using mechanical agitation or air stirring to remove most of the residual liquid. The second stage (fine rinse – heating + ultrasonic) involves treating the plating in a flowing deionized water bath heated to 40-50°C with ultrasonic waves (40-80kHz frequency) for 3-5 minutes. The combined effect of heat and ultrasonic cavitation thoroughly removes impurities and additives adhering to the micropores. The third stage (final rinse – hot water rinsing) involves immersing the plating in a still hot water bath at 70-80°C for 1-2 minutes. This step utilizes the low surface tension of hot water to allow water to roll off quickly and evenly, greatly reducing water stains after drying and providing a certain degree of "heat sealing" for the plating.The purpose of drying is to quickly and thoroughly remove moisture from the workpiece surface, prevent flash rust and water stains, and prepare for subsequent heat treatment. Specific steps: First, centrifugal drying is used. The cleaned workpiece is placed in a corrosion-resistant drum or basket and centrifuged at 200-500 rpm for 1-3 minutes, using centrifugal force to force out most of the visible water from crevices and blind holes. Next, negative pressure suction and hot air drying are performed. The workpiece is transferred to a vacuum-sealed drying chamber, the vacuum pump is turned on, and the pressure inside the chamber is reduced to ~0.05 to ~0.08 MPa and maintained for 2-3 minutes. The negative pressure "draws out" and evaporates deep-seated moisture. Then, clean hot air (filtered for oil and water removal) at 80-110℃ is blown in under negative or normal pressure for 15-30 minutes to ensure complete drying. The purpose of hydrogen removal treatment is to eliminate the "hydrogen embrittlement" phenomenon caused by cathode hydrogen evolution during electroplating, restoring and improving the toughness of the base material, which is crucial for high-strength steel and nickel-based alloys. Specific steps: Arrange the dried workpieces neatly on a heat treatment tray, ensuring smooth air circulation; place the workpieces in an air-circulating oven or vacuum furnace; strictly control the temperature between 190℃ and 230℃, with the optimal temperature precisely selected based on the tensile strength of the base material (higher strength requires lower temperature); control the heating rate at 3~5℃ / min to avoid thermal shock; hold for 3~8 hours, the time depending on the workpiece cross-sectional thickness and coating density, ensuring sufficient time for hydrogen atoms to diffuse and escape; the best method is to perform the process under low vacuum (≤1.0×10⁻²Pa) or inert gas (such as nitrogen or argon) protection, which can prevent the workpiece surface from being oxidized during prolonged heating and maintain the coating's brightness; after holding, turn off the heat source and allow the workpiece to cool to room temperature with the furnace (cooling rate ≤2℃ / min); in a vacuum or protective atmosphere, wait until it cools to <60℃ before removing it from the vacuum to avoid oxidation of the hot workpiece.

[0028] Example 1: Nickel-based alloy ring for sealing high-temperature gas pipelines 1) The Inconel 718 sealing ring is precision machined, cleaned and activated, and then installed in a high-vacuum PVD equipment.

[0029] 2) Deposition of PVD gradient layer: The high vacuum PVD equipment is equipped with nickel and silver targets.

[0030] Initial stage: Nickel target turned on, power 6kW; silver target power 0kW.

[0031] Gradient deposition (within 20 minutes): Nickel target power linearly decreases from 6 kW to 0.5 kW; simultaneously, silver target power linearly increases from 0 kW to 5 kW.

[0032] A gradient transition layer with a composition of approximately 3 μm thick, transitioning from nickel-rich to silver-rich, was obtained.

[0033] 3) Pulse electroplating was used to deposit silver for 60 minutes at an average current density of 2.0 A / dm² to obtain a dense silver functional layer with a thickness of about 30 μm.

[0034] 4) Effect verification: After testing, the coating showed no signs of peeling after 50 cycles of thermal shock test (water quenching) at 800℃, while the traditional PVD base sample showed edge peeling after 20 cycles.

[0035] Example 2: Hastelloy rings for sealing highly corrosive chemical pumps 1) The Hastelloy C~276 sealing ring is precision machined, activated by plasma-assisted ultra-cleaning, and then installed in a high-vacuum PVD equipment.

[0036] 2) Deposition of PVD gradient layer: The high vacuum PVD equipment is equipped with molybdenum target and silver target.

[0037] Initial stage: Turn on the molybdenum target with a power of 5kW; turn on the silver target with a power of 0.5kW.

[0038] Gradient deposition (within 25 minutes): Molybdenum target power linearly decreases from 5kW to 0.3kW; simultaneously, silver target power linearly increases from 0.5kW to 4.5kW.

[0039] A gradient transition layer with a composition of approximately 3.5 μm thick, transitioning from molybdenum-rich to silver-rich, was obtained.

[0040] 3) Pulse electroplating was used to deposit silver for 70 minutes at an average current density of 1.8 A / dm² to obtain a dense silver functional layer with a thickness of about 35 μm.

[0041] 4) Performance Verification: After immersion in 30% hydrochloric acid solution at 80℃ for 1200 hours, the sealing ring showed no signs of substrate corrosion, and the coating adhesion remained intact. Its corrosion resistance life is more than 5 times that of traditional nickel-plated silver sealing rings.

[0042] Example 3: 316 stainless steel ring for sealing ultra-high vacuum chambers 1) The 316 stainless steel sealing ring is precision machined, cleaned by supercritical CO2 and activated by argon-hydrogen plasma, and then installed in a high-vacuum PVD equipment.

[0043] 2) Deposition of PVD gradient layer: The high vacuum PVD equipment is equipped with chromium target and gold target.

[0044] Initial stage: Chromium target turned on, power 4kW; gold target power 0kW.

[0045] Gradient deposition (within 15 minutes): Chromium target power linearly decreases from 4kW to 0.2kW; simultaneously, gold target power linearly increases from 0kW to 3.5kW.

[0046] A gradient transition layer with a thickness of approximately 2 μm and a composition that gradually changes from chromium-rich to gold-rich was obtained.

[0047] 3) Pulse electroplating was used to deposit a dense gold functional layer of about 15 μm thickness for 100 minutes at an average current density of 0.5 A / dm².

[0048] 4) Performance Verification: Testing showed that the outgassing rate of the sealing ring after baking at 250℃ was less than 5.0 × 10⁻¹² mbar•L / (s•cm²). This is also observed in ultra-high vacuum systems (ultimate vacuum < 5 × 10⁻¹² mbar•L / (s•cm²)). 9 After undergoing 1000 cycles of opening and closing in the Pa), the leakage rate remained consistently below 1×10⁻¹. 0 mbar•L / s, meeting the extreme requirements of clean vacuum in semiconductor processes.

[0049] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A gradient composite coated metal valve sealing ring, characterized in that: It includes a sealing ring matrix, a composition gradient transition layer, and a soft metal layer. The composition gradient transition layer covers the sealing ring matrix, and the soft metal layer covers the composition gradient transition layer. The composition in the composition gradient transition layer gradually changes from being rich in the elements of the sealing ring matrix to being rich in the elements of the soft metal layer. The continuous gradient of the composition gradient transition layer points from the sealing ring matrix to the soft metal layer.

2. The gradient composite coated metal valve sealing ring according to claim 1, characterized in that: The thickness of the composition gradient transition layer is 1~5μm, and the thickness of the soft metal layer is 5~50μm.

3. A gradient composite coated metal valve sealing ring according to claim 1 or 2, characterized in that: The material of the sealing ring substrate is any one of stainless steel, nickel-based alloy or tungsten alloy, and the material of the soft metal layer is any one of gold, silver or copper.

4. A method for preparing a gradient composite coated metal valve sealing ring, used to manufacture a gradient composite coated metal valve sealing ring as described in any one of claims 1-3, characterized in that, The preparation method includes the following steps: S1: The sealing ring substrate is manufactured through precision machining; S2: Pre-treat the sealing ring substrate; S3: Place the pretreated sealing ring substrate, substrate target material and soft metal target material in a high vacuum PVD equipment, and evacuate the high vacuum PVD equipment. S4: The substrate target and the soft metal target are processed by co-sputtering to deposit the composition gradient transition layer; S5: During the deposition of the composition gradient transition layer, the sputtering power of the substrate target gradually decreases, while the sputtering power of the soft metal target gradually increases; S6: After the composition gradient transition layer is deposited, the high vacuum PVD equipment is cooled. After cooling, the high vacuum PVD equipment is opened and the sealing ring substrate is removed. S7: Place the sealing ring substrate with the composition gradient transition layer in an electroplating tank, and electroplat the soft metal layer on the composition gradient transition layer by pulse electrochemical plating or chemical plating to form a metal valve sealing ring; S8: Perform post-processing on the metal valve sealing ring.

5. The preparation method according to claim 4, characterized in that: The pretreatment of the sealing ring substrate includes the following steps: S21: Place the sealing ring substrate into the supercritical cleaning device; S22: Introduce carbon dioxide into the supercritical cleaning device, and control the pressure of the supercritical cleaning device to be above 7.38 MPa and the temperature to be above 31°C, so that the carbon dioxide reaches the supercritical fluid state. S23: Clean the sealing ring substrate with the carbon dioxide; S24: Activate the cleaned sealing ring substrate.

6. The preparation method according to claim 5, characterized in that: The activation of the sealing ring matrix includes the following steps: S241: Place the cleaned sealing ring substrate in the PVD vacuum chamber; S242: Evacuate the PVD vacuum chamber to below 5.0 × 10⁻³ Pa; S243: High-purity argon gas is introduced into the PVD vacuum chamber to control the pressure of the PVD vacuum chamber at 0.5~1.0 Pa; S244: Apply a DC pulse bias voltage of -800V to -1000V to the sealing ring substrate to generate high-energy argon plasma to bombard the surface of the sealing ring substrate for 5 to 10 minutes. S245: Stop the supply of high-purity argon gas, and then supply high-purity hydrogen gas to control the pressure of the PVD vacuum chamber at 1.0~2.0 Pa; S246: Then apply radio frequency power or DC pulse bias to the sealing ring substrate to generate hydrogen plasma to bombard the surface of the sealing ring substrate for 3 to 5 minutes, and finally obtain the sealing ring substrate with a clean surface.

7. The preparation method according to claim 4, characterized in that: The pulsed electrochemical plating includes the following steps: S71: Preparation of pulse electrochemical plating solution; S72: Place the sealing ring substrate into the electroplating solution; S73: Apply a direct current to the sealing ring substrate, wherein the current density of the direct current is 3.0 A / dm², the pulse on-time is 0.1~10 ms, and the pulse off-time is 1~50 ms; S74: After electroplating is completed, remove the metal valve sealing ring.

8. The preparation method according to claim 4, characterized in that: The post-processing of the metal valve sealing ring includes the following steps: S81: Place the electroplated metal valve sealing ring in the secondary reverse osmosis water tank and let it stand for a period of time; S82: Remove the metal valve sealing ring from the secondary reverse osmosis water tank and place it in a flowing room temperature deionized water tank for rough washing, and clean it by mechanical agitation or air stirring for 1-2 minutes; S83: After the rough cleaning is completed, the metal valve sealing ring is placed in a flowing deionized water tank at 40~50℃ for fine cleaning, and ultrasonic cleaning is performed for 3~5 minutes. S84: After the fine washing is completed, the metal valve sealing ring is placed in a still hot water bath at 70-80℃ and soaked for 1-2 minutes to achieve the final washing; S85: After the final wash is completed, dry the metal valve sealing ring; S86: Perform hydrogen removal treatment on the dried metal valve sealing ring.

9. The preparation method according to claim 8, characterized in that: The drying of the metal valve sealing ring includes the following steps: S851: Insert the metal valve sealing ring into a corrosion-resistant drum or basket, and then place the drum or basket in a centrifuge; S852: Start the centrifuge and operate it for 1 to 3 minutes. The speed of the centrifuge is 200 to 500 rpm. S853: Then transfer the metal valve sealing ring to a vacuum-sealed drying oven; S854: Vacuum the drying oven so that the pressure drop of the drying oven is between -0.05 and -0.08 MPa, and maintain it for 2-3 minutes; S855: Introduce clean hot air at 80~110℃ into the drying oven and dry for 15~30 minutes.

10. The preparation method according to claim 8, characterized in that: The hydrogen removal treatment of the metal valve sealing ring includes the following steps: S861: Place the dried metal valve sealing ring into a vacuum furnace; S862: Inert gas is introduced into the vacuum furnace, and the vacuum furnace is evacuated to below 1.0×10⁻²Pa; S863: Heat the vacuum furnace to 190°~230°C at a heating rate of 3~5°C / min; S864: The vacuum furnace is kept at 190°C to 230°C for 3 to 8 hours; S865: Control the vacuum furnace to cool to room temperature, with a cooling rate not exceeding 2℃ / min.

Images