Sealing end face preparation method and sealing ring

Abstract

The invention provides a sealing end face preparation method and a sealing ring. The sealing end face preparation method comprises the steps that S1, a plurality of microgrooves arranged in the circumferential direction are machined in the base body end face of the sealing ring; s2, a plurality of block diamonds are prepared, the multiple diamonds are placed in the multiple microgrooves correspondingly, the diamonds and the base body are fixed through an active brazing technology, and it is guaranteed that the upper end faces of the diamonds protrude out of the end face of the base body; s3, a metal coating is evenly piled on the surface of the diamond block body and the surface of the base body which are fixed through brazing, and the thickness of the metal coating is larger than the protruding height of the diamond block body; and S4, grinding and polishing the end face of the matrix piled-shot metal coating until the top ends of all the diamond blocks are exposed, and enabling the whole end face to reach mirror-level smoothness. According to the sealing end face preparation method and the sealing ring, excellent physical and chemical properties can be achieved, the manufacturing cost is low, reliable batch manufacturing is achieved, and the sealing ring can be matched with a large-specification sealing ring.

Description

Technical Field

[0001] This invention relates to the field of sealing technology, specifically a method for preparing a sealing end face and a sealing ring. Background Technology

[0002] Mechanical seals are key devices widely used in rotating machinery shaft sealing, commonly found in pumps, compressors, and reactors in process industries such as chemical, papermaking, pharmaceutical, and food processing. Their basic sealing mechanism relies on at least one pair of end faces perpendicular to the axis of rotation. Under the combined action of fluid pressure and the elastic force (or magnetic force) of the compensation mechanism, supplemented by auxiliary sealing, the end faces remain in contact and slide relative to each other, thereby achieving the purpose of preventing leakage.

[0003] As industrial technology advances towards high-temperature, high-pressure, and high-speed operating conditions, the friction pair materials used in traditional mechanical seals, such as graphite, cemented carbide, and engineering ceramics, face severe challenges in practical applications. Under high loads or extreme temperature environments, these traditional materials experience significantly accelerated end-face wear, leading to decreased sealing performance and shortened service life, making it difficult to meet the design requirements of modern equipment for sealing reliability and long-term operation.

[0004] In critical friction pair components such as mechanical seals, dry gas seals, and thrust bearings, the wear resistance and surface finish of the end faces directly affect the equipment's service life, sealing stability, and energy consumption. Therefore, the industry has proposed various surface strengthening technologies to improve the performance of friction pairs, mainly including the following two categories: 1. Chemical vapor deposition (CVD) or physical vapor deposition (PVD) ultrahard thin film technology: This process is typically used to deposit diamond or diamond-like carbon films on sealing end faces. Diamond materials are considered ideal surface protection and reinforcement materials due to their excellent self-lubricating properties, high thermal conductivity, and corrosion resistance. Although this method can achieve high surface finish and wear resistance, it still has the following significant drawbacks: 1) Due to the influence of the sealing ring geometry, heat is easily generated in the edge area during the deposition process, resulting in uneven film thickness distribution; 2) The bonding strength between the film and the substrate is significantly affected by the interfacial state, requiring high standards for substrate surface treatment; 3) For workpieces with complex structures, the processing cost is high, the process controllability is poor, and it is currently impossible to achieve excellent deposition for large-sized (such as 300mm outer diameter and above) sealing rings. 4) Diamond films themselves have poor toughness and are prone to brittle cracking or peeling under strong mechanical or thermal shock conditions, which limits their application range.

[0005] 2. Surface spraying hard coating technology: For example, using thermal spraying or cold spraying processes to prepare hard coatings such as tungsten carbide and ceramics. While this method improves surface hardness to some extent, it also has several inherent drawbacks: 1) The bonding strength between the coating and the substrate is generally insufficient, and it is prone to local peeling or overall failure when subjected to alternating stress, mechanical impact or thermal cycling load. 2) The density and uniformity of the sprayed coating are often poor, which affects its overall wear resistance and corrosion resistance; 3) The hardness of the sprayed material is still much lower than that of diamond, resulting in a high wear rate under extreme friction conditions and limited long-term reliability.

[0006] In summary, ideal friction pair materials need to possess high wear resistance, long lifespan, and good thermal conductivity to prevent wear failure. Currently widely used friction pair hard ring materials, such as silicon carbide and cemented carbide, have advantages such as high hardness (Mohs hardness approximately 9), good wear resistance, corrosion resistance, mature processing technology, and relatively controllable cost; however, their wear resistance and heat dissipation performance still face challenges under extremely high speed, high pressure, or highly corrosive conditions. In contrast, diamond, with its highest hardness (Mohs hardness 10), ultra-high thermal conductivity, and non-wetting surface, can achieve near-zero wear and efficient heat dissipation, making it very suitable as a friction pair material. Past methods using CVD diamond thin films have encountered problems such as thin film layers, slow deposition, difficulty in controlling morphology, bonding strength affected by microscopic layering characteristics, and inability to fabricate large-scale sealing ring coatings; existing friction pair surface strengthening technologies all have their limitations, making it difficult to simultaneously meet the multiple requirements of high wear resistance, high bonding strength, and good toughness under complex working conditions.

[0007] Therefore, there is an urgent need to develop a new surface preparation method and structure to improve the comprehensive performance and service life of key friction pairs such as mechanical seals under extreme working conditions such as high speed, high pressure, high temperature, strong corrosion, dry friction, and insufficient lubrication. Summary of the Invention

[0008] The problem solved by this invention is to overcome at least one defect in the prior art and provide a sealing end face preparation method and sealing ring that can combine excellent physicochemical properties with low cost and reliable mass production, and can also be adapted to large-size sealing rings.

[0009] To address the above problems, the present invention provides a method for preparing a sealing end face, which includes the following steps: S1: Multiple pre-positioned microgrooves arranged in a circumferential array are machined on the substrate end face of the sealing component; S2: Prepare multiple block diamonds, place the multiple diamonds into the multiple microgrooves respectively, and use active brazing process to fix each diamond to the substrate, ensuring that the upper end face of each diamond protrudes from the end face of the substrate; S3: A metal coating is provided on the surface of the brazed diamond block and the substrate, and the thickness of the metal coating is higher than the protrusion height of the diamond block; S4: Grind and polish the end face of the metal cladding on the substrate until the top of all diamond blocks is exposed and the entire end face achieves a mirror finish.

[0010] Furthermore, in step S1, the method of fixing the diamond to the substrate includes, but is not limited to, active brazing, high-temperature adhesive bonding, or in-situ ultrasonic pressing.

[0011] Preferably, the diamond and the substrate are fixed by active brazing, and the active brazing is carried out in a vacuum, the brazing temperature is 800°C to 900°C, and the solder used for brazing is a high-temperature brazing solder containing active titanium.

[0012] Furthermore, the microgrooves are prepared by machining, laser processing, or precision electrical discharge machining.

[0013] Furthermore, in step S2, the diamond is a single-crystal or polycrystalline diamond block that has undergone pre-bevel treatment.

[0014] Furthermore, in step S3, the metal coating is formed by spraying, overlay welding or laser cladding welding; and the metal coating is a stainless steel powder, nickel-based cemented carbide powder or cobalt-based cemented carbide powder coating.

[0015] Furthermore, in step S4, the mirror-level finish refers to a surface roughness Ra ≤ 0.1 μm.

[0016] On the other hand, the present invention also provides a sealing ring, the sealing end face of which is prepared by any of the preceding methods.

[0017] Furthermore, the sealing ring includes an annular base, on which a plurality of block diamonds are arranged in a circumferential array on the sealing end face of the base. The end face of the base is provided with a metal coating, and the metal coating is flush with the outer end face of the plurality of diamonds to form an integral smooth plane.

[0018] Preferably, the surface roughness Ra of the overall smooth plane is ≤ 0.1 μm.

[0019] The sealing end face preparation method and sealing ring of the present invention have the following advantages compared with the prior art: This invention provides an innovative fabrication scheme for a highly wear-resistant, high-heat-dissipation, and ultra-smooth sealing end face. Through a combination of processes including "microgroove positioning - active brazing - metal filling - precision finishing," it achieves a high-strength metallurgical bond between the diamond block and the substrate, a mirror-like surface finish with an overall roughness Ra ≤ 0.1 μm, and high consistency in block distribution and performance. It also possesses the potential for efficient mass production, ultimately enabling the sealing end face to exhibit excellent wear resistance, low friction, and long service life under extreme operating conditions. Furthermore, after each diamond block is embedded in the substrate surface, gaps exist between them. These gaps are filled by a metal coating scheme, ensuring sealing performance and resolving residual stress at the junction of the superhard layer (thermal expansion coefficient 1×10^-6 m / m*K) and the stainless steel substrate (thermal expansion coefficient 11~17×10^-6 m / m*K). Simultaneously, the small diamond blocks facilitate industrial production and cutting, demonstrating high technological maturity.

[0020] Other improvements and advantages of this application will be set forth in the following detailed description and will be apparent in part from the specification or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained through the structures particularly pointed out in the specification and drawings. Attached Figure Description

[0021] Figure 1 This is a top view of the sealing ring of the present invention; Figure 2 for Figure 1 Enlarged structural diagram at point X in the diagram; Figure 3 This is a cross-sectional view of the diamond-matrix connection structure in this invention.

[0022] Explanation of reference numerals in the attached figures: 1. Matrix; 2. Microgroove; 3. Diamond; 4. Metal coating. Detailed Implementation

[0023] First, those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0024] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0025] See appendix Figures 1-3This invention provides a method for preparing a sealing end face, comprising the following steps: S1: On the end face of the substrate 1 of the sealing component to be processed, microgrooves 2 are prepared by precision machining, laser processing or precision electrical discharge machining and other micro-machining techniques. These microgrooves 2 are matched with the size of the pre-made diamonds 3 and are used to pre-position each diamond 3. Here, the microgrooves 2 are arranged in a circumferential array, and the shape, depth and distribution density of the microgrooves 2 can be precisely controlled according to the design requirements to ensure that the diamonds 3 can be accurately embedded and positioned. More specifically, the microgrooves 2 are located in the radial center of the substrate 1, which not only improves the stability of the diamonds 3 after they are assembled with the substrate 1, but also further ensures the sealing performance of the sealing ring. S2: Pre-beveled (the size of the bevel can be determined according to design requirements) and selected bulk diamonds 3 are quantitatively placed into the microgrooves 2 prepared in step 1, ensuring that the upper surface of each diamond 3 protrudes from the end face of the substrate 1. The beveling of the diamonds 3 helps to improve the filling and encapsulation effect of metal powder in subsequent processes, and improves the smooth transition of the interface after final polishing, preventing bonding problems caused by different coefficients of thermal expansion. Subsequently, special active brazing filler is filled around the diamonds 3, and they are batch clamped by tooling and placed in a vacuum device for vacuum brazing to achieve a high-strength metallurgical bond between the diamonds 3 and the substrate 1. In this step, the diamonds 3 are pre-beveled single-crystal or polycrystalline diamond 3 bulks, the active brazing is carried out in a vacuum, the brazing temperature is 800°C to 900°C, and the solder used for brazing is high-temperature solder paste containing active titanium or titanium-copper alloy brazing paste. In some other embodiments, the diamonds 3 and the substrate 1 can also be fixed by high-temperature adhesive bonding or in-situ ultrasonic pressing. S3: After brazing, the diamond 3 protrudes from the end face of the substrate 1. To obtain a smooth final surface, at least one of supersonic flame spraying, plasma spraying, or arc spraying is used to uniformly deposit a metal cladding layer 4 on the entire end face of the substrate 1 (including the end face of the diamond 3) after brazing. The metal powder is preferably a material with good compatibility with the substrate material, including but not limited to stainless steel powder, nickel-based cemented carbide powder, or cobalt-based cemented carbide powder. The thickness of the metal cladding layer 4 should be slightly higher than the protrusion height of the diamond 3 to ensure the flat grinding in the next step. In some other embodiments, the metal cladding layer 4 can also be formed by overlay welding or laser cladding welding in this step. S4: The end face with the deposited metal coating 4 is subjected to precision surface grinding and polishing. First, excess metal deposits are ground away until the highest point of the diamond 3 is just exposed; then, multi-stage fine polishing is performed to finally achieve a mirror-like finish with a surface roughness Ra ≤ 0.1 μm for the entire end face (including the diamond 3 and the surrounding metal coating 4); this step ensures an extremely low coefficient of friction and excellent sealing performance when the friction pair is in contact.

[0026] In the above method, the gaps between each diamond 3 are filled with metal powder, which not only ensures sealing but also solves the residual stress at the junction of the superhard layer (thermal expansion coefficient 1×10^-6 m / m*K) and the stainless steel matrix (thermal expansion coefficient 11~17×10^-6 m / m*K). Furthermore, the small-sized diamond 3 facilitates industrial production and cutting, and the technology is highly mature.

[0027] In this embodiment, the preparation of a sealing end face of a 440 stainless steel friction pair is taken as an example for further explanation: First, a regular circular array of microgrooves 2, 4x4mm in length and width and approximately 0.1mm in depth, is machined on the end face of the sealing ring with an inner diameter of 110mm and an outer diameter of 122mm using an ultrashort pulse laser. Precision-cut 4×4×0.8mm single-crystal diamond blocks 3 are then placed into the microgrooves 2. High-temperature brazing paste containing active titanium or titanium-copper alloy brazing paste is then filled in. The sealing ring is then mounted in a fixture and placed in a vacuum brazing furnace, where a vacuum of 100°C is applied. -2 Below Pa, the temperature was initially raised to 850°C and held for 10 minutes, then cooled with the furnace. When the furnace temperature dropped below 200°C, the furnace was opened and the sealing ring removed. Next, a 316L stainless steel powder coating was applied to the brazed end face using plasma spraying, arc spraying, or high-velocity oxygen fuel (HVOF). The thickness of the stainless steel powder coating was controlled to be slightly greater than the thickness of the portion of the brazed diamond 3 protruding from the substrate 1. Finally, the end face was planar ground on a precision surface lathe using a diamond 3 mirror core turning tool until a uniformly distributed diamond 3 block end face was observed to be exposed. Subsequently, multi-stage polishing was performed using diamond 3 polishing paste of different grit sizes. The final end face surface roughness Ra value was below 0.1 μm.

[0028] In the technical solution provided in this embodiment, the depth of the microgroove 2 is approximately 100 μm; the length and width of the microgroove 2 are 4 × 4 mm. This design is a further optimization based on the aforementioned structural dimensions of the microgroove 2, providing an optimal range of depth and length-width ratios. Within this range, sufficient mechanical fitting and brazing filler space can be provided for the diamond 3 block to ensure bonding strength, while precise dimensional constraints can effectively control the protrusion height and consistency of the block, thereby reducing the difficulty of subsequent metal filling and overall finishing processes, and ensuring the uniformity and repeatability of the final surface quality.

[0029] In other embodiments, the shape of the diamond 3 is not limited to a cuboid structure, but can also be other shapes such as rings or trapezoids.

[0030] On the other hand, this application embodiment also provides a sealing ring, the sealing end face of which is prepared by the above-described end face preparation method. Specifically, the sealing ring includes an annular substrate 1, with a plurality of block diamonds 3 arranged in a circumferential array on the sealing end face of the substrate 1. A metal cladding 4 is provided on the end face of the substrate 1, and the metal cladding 4 is flush with the outer end faces of the plurality of diamonds 3 to form an integral smooth plane. Preferably, the surface roughness Ra of the integral smooth plane is ≤ 0.1 μm. In addition, the substrate 1 in this structure includes, but is not limited to, a metal material.

[0031] In the description of this invention, references to terms such as "this embodiment," "some embodiments," etc., indicate that a specific feature, mechanism, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, mechanisms, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0032] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a sealing end face, characterized in that, Includes the following steps: S1: Multiple pre-positioned microgrooves (2) arranged in a circumferential array are machined on the end face of the substrate (1) of the sealing component; S2: Prepare multiple block diamonds (3), place multiple diamonds (3) into multiple microgrooves (2) respectively, and fix each diamond (3) to the substrate (1) to ensure that the upper end face of each diamond (3) protrudes from the end face of the substrate (1); S3: A metal cladding (4) is provided on the surface of the brazed diamond (3) and the substrate (1), and the thickness of the metal cladding (4) is higher than the protrusion height of the diamond (3) block; S4: Grind and polish the end face of the metal cladding (4) on the substrate (1) until the top of all diamond (3) blocks are exposed and the entire end face achieves a mirror finish.

2. The method for preparing the sealing end face according to claim 1, characterized in that: In step S1, the fixing methods of the diamond (3) and the substrate (1) include, but are not limited to, active brazing, high-temperature adhesive bonding or in-situ ultrasonic pressing.

3. The method for preparing the sealing end face according to claim 2, characterized in that: The diamond (3) and the substrate (1) are fixed by active brazing, and the active brazing is carried out in a vacuum. The brazing temperature is 800°C to 900°C, and the brazing material used is a high-temperature brazing material containing active titanium.

4. The method for preparing the sealing end face according to claim 1, characterized in that: In step S1, the microgroove (2) is prepared by machining, laser processing or precision electrical discharge machining.

5. The method for preparing the sealing end face according to claim 1, characterized in that: In step S2, the diamond (3) is a single crystal or polycrystalline diamond (3) block that has been pre-beveled.

6. The method for preparing the sealing end face according to claim 1, characterized in that: In step S3, the metal coating (4) is formed by spraying, overlay welding or laser cladding welding process; and the metal coating (4) is a stainless steel powder, nickel-based hard alloy powder or cobalt-based hard alloy powder coating.

7. The method for preparing a sealing end face according to claim 1, characterized in that: In step S4, the mirror-level finish refers to a surface roughness Ra ≤ 0.1 μm.

8. A sealing ring, characterized in that: Its sealing end face is prepared by the preparation method described in any one of claims 1 to 7.

9. The sealing ring according to claim 8, characterized in that: The substrate (1) includes an annular base. Multiple diamond blocks (3) are arranged in a circumferential array on the sealed end face of the base (1). A metal cladding (4) is provided on the end face of the base (1), and the metal cladding (4) is flush with the outer end face of the multiple diamond blocks (3) to form an integral smooth plane.

10. The sealing ring according to claim 9, characterized in that: The surface roughness Ra of the overall smooth plane is ≤0.1 μm.

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