Wear-resistant cavitation-erosion-resistant ultra-high molecular weight polyvinyl composite material for sealing end face of movable guide vane of water turbine as well as preparation method and application of wear-resistant cavitation-erosion-resistant ultra-high molecular weight polyvinyl composite material

Abstract

The invention discloses an anti-wear and cavitation-erosion-resistant ultra-high molecular weight polyethylene composite material for sealing the end face of a movable guide vane of a water turbine and a preparation method and application thereof, and the composite material is prepared from the following raw materials in parts by mass: 100-130 parts of ultra-high molecular weight polyethylene, 0.15-0.45 part of dicumyl peroxide, 1-3 parts of calcium-based montmorillonite and 1-3 parts of SiO2. According to the invention, through comprehensive modification of ultra-high molecular weight polyethylene (UHMWPE), the mechanical properties and wear resistance of the UHMWPE are improved, and the composite material is used for end face sealing, so that the sealing performance of the composite material is more stable and efficient as a whole.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to a wear-resistant and cavitation-resistant ultra-high molecular weight polyethylene composite material for sealing the end face of a moving guide vane of a water turbine, its preparation method, and its application. Background Technology

[0002] The movable guide vane is a core component of the turbine unit, playing a crucial role in ensuring the safe, stable, and efficient operation of the turbine. Failure of the movable guide vane seal may cause a chain of problems.

[0003] First, the guide vane end face seal prevents water from the high-pressure side from leaking to the low-pressure side through the gap between the guide vane end face and the top cover and bottom ring. Leakage in this seal causes energy loss, directly leading to a decrease in turbine efficiency and reduced power generation. Second, if gaps exist in the guide vane end face seal, water jets at high speed from the high-pressure area to the low-pressure area, causing a sharp drop in pressure. When the local pressure falls below the saturated vapor pressure of water, cavitation occurs, forming cavitation bubbles. These cavitation bubbles collapse instantly when they reach the downstream high-pressure area, generating extremely strong micro-jet streams and shock waves. These shock waves act on the sealing surfaces of the guide vane end face, top cover, and bottom ring, causing severe cavitation erosion damage to the flow surface materials, leading to even greater leakage and more intense cavitation, creating a vicious cycle that severely damages the equipment and results in high maintenance costs and long repair cycles. Furthermore, leakage caused by gaps in the turbine guide vanes generates hydraulic excitation forces, causing abnormal vibrations and noise in the moving guide vanes, top cover, seat ring, and even the entire unit. In severe cases, this can affect the unit's service life and safe operation.

[0004] Given the decisive impact of the end face seal of the moving guide vanes of a hydroelectric turbine on the performance and safety of the unit, the development of a reliable and efficient new seal is an urgent need in the field of hydropower equipment. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of the invention, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide an anti-wear and cavitation-resistant ultra-high molecular weight polyethylene composite material for sealing the end face of the moving guide vane of a water turbine.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: The composite material comprises, by mass fraction, 100-130 parts of ultra-high molecular weight polyethylene, 0.15-0.45 parts of dicumyl peroxide, 1-3 parts of calcium-based montmorillonite, and 1-3 parts of SiO2.

[0009] As a preferred embodiment of the composite material described in this invention, the composite material comprises, by mass parts, 100 parts of ultra-high molecular weight polyethylene, 0.15 parts of dicumyl peroxide, 1.5 parts of calcium-based montmorillonite, and 1.5 parts of SiO2.

[0010] As a preferred embodiment of the composite material described in this invention, the ultra-high molecular weight polyethylene has a molecular weight of 450w to 500w.

[0011] In a preferred embodiment of the composite material described in this invention, the SiO2 particle size is 30~100 nm.

[0012] As a preferred embodiment of the composite material described in this invention, the specific surface area of ​​the calcium-based montmorillonite is 100~400 m². 2 / g.

[0013] As a preferred embodiment of the composite material described in this invention, it has the following characteristics. Tensile strength ≥19MPa, elongation at break >300%, cavitation resistance coefficient ≥35MPa, creep <5%.

[0014] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing an anti-wear and cavitation-resistant ultra-high molecular weight polyethylene composite material for sealing the end face of a moving guide vane of a water turbine.

[0015] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including, After uniformly mixing ultra-high molecular weight polyethylene, dicumyl peroxide, calcium-based montmorillonite, and SiO2, hot-pressing them at 190~200℃ and 15~20 MPa for 10~15 min yields an wear-resistant and cavitation-resistant ultra-high molecular weight polyethylene-based composite material.

[0016] Another objective of this invention is to overcome the shortcomings of the prior art and provide a sealing device for the end face of a moving guide vane of a water turbine.

[0017] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including, Sealing strip 1; Support component 2 is located below sealing strip 1; The end face 3 of the movable guide vane of the water turbine is located below the support component 2; The sealing strip 1 is made of the composite material described in claim 1. In a preferred embodiment of the turbine movable guide vane end face sealing device of the present invention, the material of the supporting component 2 is polyurethane.

[0018] Beneficial effects of this invention: (1) This invention improves the mechanical properties and wear resistance of ultra-high molecular weight polyethylene (UHMWPE) through comprehensive modification. The composite material is used for end face sealing, making its overall sealing performance more stable and efficient.

[0019] (2) Through the design of the elastic support structure, the end face seal can be effectively contracted when subjected to external force when the end face of the movable guide vane is opened and closed, and is not easily damaged. When the movable guide vane is closed, the elastic support structure can continuously support the sealing strip and play the role of support and compensation, so that the sealing strip achieves a better sealing effect. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the sealing device on the end face of the moving guide vane of the water turbine in Embodiment 4 of the present invention.

[0022] Figure 2 This is a physical image of the sealing strip in Embodiment 4 of the present invention.

[0023] Figure 3 This is a side view of the sealing strip in Embodiment 4 of the present invention.

[0024] Figure 4 This is a physical image of the sealing device on the end face of the moving guide vane of the water turbine in Embodiment 4 of the present invention. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0028] The ultra-high molecular weight polyethylene (UHMWPE) used in this invention was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with a molecular weight of 450w~500w.

[0029] The calcium-based montmorillonite used in this invention was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., and has a specific surface area of ​​240 m². 2 / g.

[0030] The SiO2 used in this invention has a purity of ≥99.5%, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and has a particle size of 30 nm.

[0031] The polyurethane used in this invention was purchased from Lanxess and is an aliphatic polyurethane with an amine equivalent of 920-1100 and an isocyanate content of 3.2%-4.0%.

[0032] In this invention, the tensile strength is tested in accordance with the GB / T 1040.2-2022 standard, wherein the tensile speed is 2 mm / min.

[0033] In this invention, the cavitation resistance coefficient is tested in accordance with the GB / T 6383-2024 standard. That is, the cavitation rate is obtained based on the cavitation depth of the material per unit time, and then the erosion resistance coefficient is calculated based on the cavitation rate.

[0034] In this invention, the creep variable was tested in accordance with the GB / T 11546.1-2008 standard.

[0035] Example 1 This embodiment provides a method for preparing wear-resistant and cavitation-resistant ultra-high molecular weight polyethylene-based composite material for sealing the end face of moving guide vanes in water turbines, specifically as follows: By mass, 100 parts of UHMWPE, 0.15 parts of dicumyl peroxide (DCP), 1.5 parts of calcium-based montmorillonite, and 1.5 parts of SiO2 were taken, mixed evenly, and then hot-pressed at 190°C and 15 MPa pressure for 10 minutes using a vulcanizing machine to obtain the wear-resistant and cavitation-resistant ultra-high molecular weight polyethylene composite material of this embodiment. The molecular weight of UHMWPE is 450w~500w.

[0036] Comparative Example 1 The difference between this comparative example and Example 1 is that montmorillonite and SiO2 are not added, while the rest of the preparation process is the same as in Example 1, resulting in the ultra-high molecular weight polyethylene-based composite material of this comparative example.

[0037] Comparative Example 2 The difference between this comparative example and Example 1 is that montmorillonite is not added and the amount of SiO2 added is adjusted to 1 part. The rest of the preparation process is the same as that of Example 1, and the ultra-high molecular weight polyethylene-based composite material of this comparative example is obtained.

[0038] Comparative Example 3 The difference between this comparative example and Example 1 is that montmorillonite is not added and the amount of SiO2 added is adjusted to 3 parts. The rest of the preparation process is the same as that of Example 1, and the ultra-high molecular weight polyethylene-based composite material of this comparative example is obtained.

[0039] Comparative Example 4 The difference between this comparative example and Example 1 is that montmorillonite is not added and the amount of SiO2 added is adjusted to 5 parts. The rest of the preparation process is the same as that of Example 1, and the ultra-high molecular weight polyethylene-based composite material of this comparative example is obtained.

[0040] Comparative Example 5 The difference between this comparative example and Example 1 is that SiO2 is not added and the amount of montmorillonite added is adjusted to 1 part. The rest of the preparation process is the same as that of Example 1, and the ultra-high molecular weight polyethylene-based composite material of this comparative example is obtained.

[0041] Comparative Example 6 The difference between this comparative example and Example 1 is that SiO2 is not added and the amount of montmorillonite added is adjusted to 3 parts. The rest of the preparation process is the same as that of Example 1, and the ultra-high molecular weight polyethylene-based composite material of this comparative example is obtained.

[0042] Comparative Example 7 The difference between this comparative example and Example 1 is that SiO2 is not added and the amount of montmorillonite added is adjusted to 5 parts. The rest of the preparation process is the same as that of Example 1, and the ultra-high molecular weight polyethylene-based composite material of this comparative example is obtained.

[0043] The mechanical properties, wear resistance, and cavitation resistance of the ultra-high molecular weight polyethylene-based composite materials prepared in Example 1 and Comparative Examples 1-7 were tested, and the results are shown in Table 1.

[0044] Table 1. Wear resistance and cavitation resistance of ultra-high molecular weight polyethylene composites with different ratios.

[0045] According to Table 1 and actual experimental test results, by incorporating 3-5 wt% SiO2 particles, the tensile strength of the material increased from 18.9 MPa to 24.8 MPa, while maintaining an elongation at break >300%. Layered silicate (montmorillonite) effectively improved creep resistance, reducing the creep percentage at 80℃ for 24 hours from 8% to less than 3%, and significantly improved water resistance. Only by simultaneously adding 1.5 wt% montmorillonite and 1.5 wt% SiO2 could a composite material with excellent wear resistance and cavitation erosion resistance be prepared.

[0046] Comparative Example 8 The difference between this comparative example and Example 1 is that the UHMWPE was adjusted to have a molecular weight of 1.5 million, while the rest of the preparation process was the same as in Example 1, resulting in the ultra-high molecular weight polyethylene composite material of this comparative example. The results showed that the wear resistance of the composite material was significantly reduced.

[0047] Example 2 This embodiment provides a method for preparing wear-resistant and cavitation-resistant ultra-high molecular weight polyethylene-based composite material for sealing the end face of moving guide vanes in water turbines, specifically as follows: By mass, 130 parts UHMWPE, 0.45 parts dicumyl peroxide (DCP), 3 parts calcium-based montmorillonite, and 3 parts SiO2 were taken, mixed evenly, and then hot-pressed at 200°C and 20 MPa pressure for 15 minutes using a vulcanizing machine to obtain the wear-resistant and cavitation-resistant ultra-high molecular weight polyethylene composite material of this embodiment. The molecular weight of UHMWPE is 450w~500w.

[0048] Example 3 This embodiment provides a method for preparing wear-resistant and cavitation-resistant ultra-high molecular weight polyethylene-based composite material for sealing the end face of moving guide vanes in water turbines, specifically as follows: By mass fraction, 100 parts UHMWPE, 0.15 parts dicumyl peroxide (DCP), 1 part calcium montmorillonite, and 1 part SiO2 were mixed evenly and then hot-pressed at 190°C and 15 MPa pressure using a vulcanizing machine for 10 minutes to obtain the wear-resistant and cavitation-resistant ultra-high molecular weight polyethylene composite material of this embodiment. The molecular weight of UHMWPE is 450w~500w.

[0049] The mechanical properties, wear resistance, and cavitation resistance of the composite materials prepared in Examples 2 and 3 were tested. It was found that the composite materials prepared in Examples 2 and 3 also had good mechanical properties and wear resistance, but Example 1 showed the best results.

[0050] Example 4 This embodiment provides a sealing device for the end face of a movable guide vane of a water turbine, the structural schematic diagram of which is shown below. Figure 1 As shown, including, Sealing strip 1 is used to seal the end face of the moving guide vanes of the water turbine; Support component 2 is located below sealing strip 1 to provide support for the sealing structure; The end face 3 of the movable guide vane of the water turbine is located below the support component 2; The sealing strip is made of the material prepared in Example 1 and has excellent wear resistance and corrosion resistance. The material of the supporting component 2 is polyurethane.

[0051] Figure 2 This is a photograph of the actual sealing strip 1 in Example 4. Figure 3 This is a side view of sealing strip 1 in Example 4. Figure 4 This is a physical image of the sealing device at the end face of the moving guide vane of the water turbine in Example 4.

[0052] Comparative Example 9 The difference between this comparative example and Example 4 is that no supporting components are provided, but the rest of the structure is the same as that of Example 4.

[0053] During operation, it was found that the end face sealing device of the turbine movable guide vane with elastic support structure is less prone to damage, has a longer service life, and has a better sealing effect.

[0054] In summary, this invention provides a wear-resistant and cavitation-resistant ultra-high molecular weight polyethylene (UHMWPE) composite material for sealing the end face of moving guide vanes in water turbines, its preparation method, and its application. By modifying ultra-high molecular weight polyethylene (UHMWPE) to improve its mechanical properties and wear resistance, this composite material, when used for end face sealing, provides a more stable and efficient overall sealing performance.

[0055] The elastic support structure design allows the end face seal to effectively contract and not be easily damaged when subjected to external force during the opening and closing of the movable guide vane. When the movable guide vane is closed, the elastic support structure can continuously support the sealing strip, playing a supporting and compensating role, so that the sealing strip can achieve a better sealing effect.

[0056] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A wear-resistant and cavitation-resistant ultra-high molecular weight polyethylene composite material for sealing the end face of a moving guide vane of a water turbine, characterized in that: The composite material comprises, by mass fraction, 100-130 parts of ultra-high molecular weight polyethylene, 0.15-0.45 parts of dicumyl peroxide, 1-3 parts of calcium-based montmorillonite, and 1-3 parts of SiO2.

2. The composite material as described in claim 1, characterized in that: The composite material comprises, by mass parts, 100 parts ultra-high molecular weight polyethylene, 0.15 parts dicumyl peroxide, 1.5 parts calcium-based montmorillonite, and 1.5 parts SiO2.

3. The composite material as described in claim 1, characterized in that: The molecular weight of the ultra-high molecular weight polyethylene is 450w to 500w.

4. The composite material as described in claim 1, characterized in that: The SiO2 particle size is 30~100 nm.

5. The composite material as described in claim 1, characterized in that: The specific surface area of ​​the calcium-based montmorillonite is 100~400 m². 2 / g.

6. The composite material as described in claim 1, characterized in that: It has the following characteristics, Tensile strength ≥19MPa, elongation at break >300%, cavitation resistance coefficient ≥35MPa, creep <5%.

7. The method for preparing the composite material according to any one of claims 1 to 6, characterized in that: include, After uniformly mixing ultra-high molecular weight polyethylene, dicumyl peroxide, calcium-based montmorillonite, and SiO2, hot-pressing them at 190~200℃ and 15~20 MPa for 10~15 min yields an wear-resistant and cavitation-resistant ultra-high molecular weight polyethylene-based composite material.

8. A sealing device for the end face of a movable guide vane of a water turbine, characterized in that: include, Sealing strip (1); Support component (2) is located below sealing strip (1); The end face (3) of the movable guide vane of the water turbine is located below the support component (2); The sealing strip (1) is made of the composite material described in claim 1.

9. The sealing device for the end face of the movable guide vane of a water turbine as described in claim 8, characterized in that: The material of the support component (2) is polyurethane.

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