Mechanical sealing end face structure capable of reducing leakage through surface energy difference

Abstract

The invention discloses a mechanical sealing end face structure capable of reducing leakage through surface energy difference, and relates to the technical field of mechanical sealing. The surface of the static ring is provided with a pit texture, and the surface of the pit texture is coated with a nickel-iron coating. The pit texture and the ferronickel coating are coupled to reduce heat transfer and friction; the surface of the moving ring is uniformly coated with a PTFE (Polytetrafluoroethylene) super-hydrophobic coating; the surface coatings of the static ring and the moving ring are used for improving the attraction force of the sealing surface to water and reducing leakage. By means of the surface energy difference of the dynamic and static ring surface coatings, the attraction force of the sealing surface to water is improved, and therefore leakage in the sealing process is reduced. In addition, through the coupling effect of the surface texture and the coating, the thickness and rigidity of a liquid film between the movable ring and the static ring in the movement process are improved, heat transfer generated by friction in the operation process is reduced, damage to the movable ring and the static ring is reduced, and the service life of the movable ring and the static ring is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical seals, and in particular to a mechanical seal end face structure capable of reducing leakage through surface energy difference. Background Art

[0002] Mechanical seal (end face seal) is a technology that prevents liquid or gas leakage by sealing the end face or gap. It is widely used in rotating equipment such as pumps, compressors, etc. Its sealing principle relies on the preload of the elastic element and the fluid pressure to make the dynamic ring and the static ring fit. The dynamic ring material is usually silicon carbide (SiC) or titanium carbide (TiC), and the static ring material is mostly graphite, ceramic or alloy. The thin liquid film between the sealing surfaces prevents dry friction and lubricates.

[0003] Bionic design is a new direction in the research of end face seals in recent years. By imitating the surface structures with excellent functions in nature (such as the super hydrophobicity of lotus leaves, the low resistance of shark skin, etc.), microstructures are designed on the surface of the sealing ring to improve the sealing performance. For example, introducing micron- or nano-scale grooves and pit structures on the sealing surface can enhance the self-lubricating ability of the sealing surface and reduce friction and wear. Studies have shown that the wedge effect of circular texture is greater than the wedge effect of rectangular texture, so the matrix texture of the present invention selects circular pits.

[0004] In order to improve the sealing performance of mechanical seals, reduce friction loss during operation and extend the service life of mechanical seals, researchers and engineers combined mechanical seals with surface textures and designed a variety of sealing ring structures with different surface textures (surface pits and surface micropore structures), which effectively improved the sealing performance of mechanical seals, reduced friction and wear during operation, and extended the service life of seals.

[0005] Surface coating technology is increasingly used in mechanical seals, especially under harsh working conditions such as high temperature, high pressure, corrosive media and wear. It can significantly improve the performance and life of mechanical seals. Hard coatings such as titanium nitride (TiN), chromium nitride (CrN), tungsten carbide (WC), etc. are deposited on the surface of the seal by physical vapor deposition (PVD) or chemical vapor deposition (CVD). This type of coating has high hardness, high wear resistance and corrosion resistance, can effectively reduce the friction loss of the seal, and is suitable for high-speed rotation and high-wear environments. Different types of coatings have different surface energies and different wettability to lubricants. Studies have found that typical metal materials such as nickel (Ni), chromium (Cr), and titanium (Ti) have high surface energies, about 1,000–2,000mJ / m 2 Polymer materials such as polytetrafluoroethylene (PTFE), fluoropolymer (FEP), and polyvinylidene fluoride (PVDF) have low surface energy, about 10–50 mJ / m 2.

[0006] The present invention proposes a mechanical seal end face structure that reduces leakage through surface energy difference, and achieves a certain friction reduction and leakage reduction effect by adding coatings with different surface energies on the surfaces of dynamic and static rings. Summary of the invention

[0007] The purpose of the present invention is to provide a mechanical seal end face structure that reduces leakage through surface energy difference, and solve the following technical problems: During the movement of the mechanical seal ring, due to the existence of friction, a large amount of friction heat and a large amount of wear will be generated. Since the static ring material is mostly soft material, under high temperature and high friction conditions, the static ring surface will be damaged, thereby reducing the sealing performance of the mechanical seal. Under working conditions with high vibration or impact load, the mechanical seal ring may not be able to maintain a stable sealing effect, resulting in leakage.

[0008] Under the premise that the sealing ring has a surface texture, the present invention processes super hydrophobic and hydrophilic coatings on the surfaces of the dynamic and static sealing rings respectively, and improves the attraction of the hydrophilic sealing surface to water through the surface energy difference between the hydrophobic and hydrophilic surfaces at the sealing surface, thereby reducing leakage during movement. And at the sealing surface, through the coupling of the coating and the surface texture, the stiffness and thickness of the liquid film between the sealing rings during movement are improved, thereby achieving the effect of reducing heat transfer and friction.

[0009] The purpose of the present invention can be achieved through the following technical solutions:

[0010] A mechanical seal end face structure for reducing leakage through surface energy difference, comprising a stationary ring and a dynamic ring;

[0011] The surface of the stationary ring is provided with a pit texture, and a layer of nickel-iron coating is coated on the surface of the pit texture; the pit texture and the nickel-iron coating are coupled to reduce heat transfer and reduce friction;

[0012] A layer of PTFE super-hydrophobic coating is evenly applied on the surface of the moving ring;

[0013] The surface coatings of the stationary ring and the dynamic ring are used to enhance the attraction of the sealing surface to water and reduce leakage.

[0014] As a further solution of the present invention: the coating processing method of the stationary ring surface is chemical solution deposition.

[0015] As a further solution of the present invention: the coating processing method of the surface of the dynamic ring is spraying.

[0016] As a further solution of the present invention: the processing steps of the pit texture and coating on the surface of the stationary ring are:

[0017] Step 1: First, the surface of the silicon wafer is polished with 400#, 800#, and 1200# metallographic sandpaper, and then ultrasonically cleaned in anhydrous ethanol solution and deionized water for 5 minutes to remove surface impurities and oil stains, and finally the surface is blown dry for standby use;

[0018] Step 2: Select a silicon wafer with a 400nm thick thermal oxide film; apply a layer of photoresist film on the wafer by a spin coater, and then develop a photomask pattern on the photoresist film;

[0019] Step 3: Immerse the wafer in a buffered hydrofluoric acid solution to remove the oxide film not covered by the photoresist film;

[0020] Step 4: Perform I CP-DR IE etching, the etching time is 3-4 minutes, and the etching depth is 10-12 μm;

[0021] Step 5: First deposit a Cr layer, and then form a NiFe alloy film on the processed microstructure by electron beam evaporation.

[0022] As a further solution of the present invention: the thicknesses of the NiFe and Cr films are 150 nm and 10 nm respectively.

[0023] As a further solution of the present invention: the composition of the NiFe alloy is Ni 55.5% and Fe 44.5%.

[0024] As a further solution of the present invention: the steps of processing the surface coating of the moving ring are:

[0025] The substrate is ultrasonically cleaned in anhydrous ethanol solution and deionized water for 4-6 minutes to remove oil, dust and oxides on the surface of the substrate;

[0026] Step 2: The moving ring is polished with 400#, 800#, and 1200# metallographic sandpaper to increase the roughness of the substrate surface;

[0027] Step 3: Use a thermosetting resin primer for fluoropolymer coating and spray the primer evenly to fully cover the substrate;

[0028] Step 4: Use a compressed air spray gun to evenly spray PTFE on the substrate; keep the nozzle distance at 15-30cm and keep the nozzle parallel to the substrate plane;

[0029] Step 5: Dry at about 80°C for 35-45 minutes;

[0030] Step 6: Heat the coating to 330°C for high temperature curing for 25-35 minutes to obtain the coating.

[0031] Beneficial effects of the present invention:

[0032] The present invention improves the attraction of the sealing surface to water through the surface energy difference of the coating on the surface of the dynamic and static rings, thereby reducing leakage during the sealing process. In addition, through the coupling effect of the surface texture and the coating, the thickness and stiffness of the liquid film between the dynamic and static rings during the movement are increased, the heat transfer caused by friction during the operation is reduced, the damage to the dynamic and static rings is reduced, and the service life of the dynamic and static rings is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below in conjunction with the accompanying drawings.

[0034] Figure 1 It is a schematic diagram of the overall structure of the static ring of the present invention;

[0035] Figure 2 1 is a schematic diagram of the top view of the static ring of the present invention;

[0036] Figure 3 yes Figure 2 Schematic diagram of the local structure of DD;

[0037] Figure 4 It is a schematic diagram of the overall structure of the dynamic ring of the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] See also Figure 1-4 As shown, the present invention is a mechanical seal end face structure that reduces leakage through surface energy difference, including a stationary ring 1 and a dynamic ring 3; mainly, a layer of nickel-iron coating 2 is evenly applied on the surface of the stationary ring (Si) under the premise of texture, and a layer of PTFE super-hydrophobic coating 4 is evenly applied on the surface of the dynamic and static rings. Through the surface energy difference of the coating on the surface of the sealing dynamic and static rings, the attraction of the sealing surface to water is improved, so as to achieve the effect of reducing leakage. And the coupling effect of the texture and the coating is realized to achieve the effect of reducing heat transfer and friction.

[0040] Since the surface of the stationary ring is textured, it is difficult to ensure the uniformity and flatness of the coating by simple spraying / brushing, so the coating processing method of the stationary ring is chemical solution deposition. The surface of the dynamic ring is flat, and the coating processing method is spraying.

[0041] The surface of the stationary ring is provided with a pit texture, and a layer of nickel-iron coating is coated on the surface of the pit texture; the pit texture and the nickel-iron coating are coupled to reduce heat transfer and reduce friction;

[0042] A layer of PTFE super-hydrophobic coating is evenly applied on the surface of the moving ring;

[0043] The surface coatings of the stationary ring and the dynamic ring are used to enhance the attraction of the sealing surface to water and reduce leakage.

[0044] The coating processing method of the stationary ring surface is chemical solution deposition.

[0045] The coating processing method of the moving ring surface is spraying.

[0046] The processing steps of the pit texture and coating on the surface of the stationary ring are as follows:

[0047] Step 1: First, the surface of the silicon wafer is polished with 400#, 800#, and 1200# metallographic sandpaper, and then ultrasonically cleaned in anhydrous ethanol solution and deionized water for 5 minutes to remove surface impurities and oil stains, and finally the surface is blown dry for standby use;

[0048] Step 2: Select a silicon wafer with a 400nm thick thermal oxide film; apply a layer of photoresist film on the wafer by a spin coater, and then develop a photomask pattern on the photoresist film;

[0049] Step 3: Immerse the wafer in a buffered hydrofluoric acid solution to remove the oxide film not covered by the photoresist film;

[0050] Step 4: Perform I CP-DR IE etching, the etching time is 3-4 minutes, and the etching depth is 10-12 μm;

[0051] Step 5: First deposit a Cr layer, and then form a NiFe alloy film on the processed microstructure by electron beam evaporation.

[0052] The thicknesses of the NiFe and Cr films are 150 nm and 10 nm, respectively.

[0053] The composition of the NiFe alloy is Ni 55.5% and Fe 44.5%.

[0054] The steps of processing the surface coating of the moving ring are as follows:

[0055] Step 1: Place the substrate in anhydrous ethanol solution and deionized water for ultrasonic cleaning for 4-6 minutes to remove oil, dust and oxides on the surface of the substrate;

[0056] Step 2: The moving ring is polished with 400#, 800#, and 1200# metallographic sandpaper to increase the roughness of the substrate surface;

[0057] Step 3: Use a thermosetting resin primer for fluoropolymer coating and spray the primer evenly to fully cover the substrate;

[0058] Step 4: Use a compressed air spray gun to evenly spray PTFE on the substrate; keep the nozzle distance at 15-30cm and keep the nozzle parallel to the substrate plane;

[0059] Step 5: Dry at about 80°C for 35-45 minutes;

[0060] Step 6: Heat the coating to 330°C for high temperature curing for 25-35 minutes to obtain the coating.

[0061] The present invention uniformly applies a hydrophilic coating on the surface of the static ring with a micro-pit texture, and uniformly applies a super-hydrophobic coating on the surface of the dynamic ring. The desired effect is achieved through the different affinity of the two coatings to water and the coupling effect of the surface texture and the coating.

[0062] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A mechanical seal end face structure for reducing leakage through surface energy difference, characterized in that: Including static ring and dynamic ring; The surface of the stationary ring is provided with a pit texture, and a layer of nickel-iron coating is coated on the surface of the pit texture; the pit texture and the nickel-iron coating are coupled to reduce heat transfer and reduce friction; A layer of PTFE super-hydrophobic coating is evenly applied on the surface of the moving ring; The surface coatings of the stationary ring and the dynamic ring are used to enhance the attraction of the sealing surface to water and reduce leakage.

2. A mechanical seal end face structure for reducing leakage through surface energy difference according to claim 1, characterized in that: The coating processing method of the stationary ring surface is chemical solution deposition.

3. A mechanical seal end face structure for reducing leakage through surface energy difference according to claim 1, characterized in that: The coating processing method of the moving ring surface is spraying.

4. A mechanical seal end face structure for reducing leakage through surface energy difference according to claim 1, characterized in that: The processing steps of the pit texture and coating on the surface of the stationary ring are as follows: Step 1: First, the surface of the silicon wafer is polished with 400#, 800#, and 1200# metallographic sandpaper, and then ultrasonically cleaned in anhydrous ethanol solution and deionized water for 5 minutes to remove surface impurities and oil stains, and finally the surface is blown dry for standby use; Step 2: Select a silicon wafer with a 400nm thick thermal oxide film; apply a layer of photoresist film on the wafer by a spin coater, and then develop a photomask pattern on the photoresist film; Step 3: Immerse the wafer in a buffered hydrofluoric acid solution to remove the oxide film not covered by the photoresist film; Step 4: Perform ICP-DRIE etching, the etching time is 3-4 minutes, and the etching depth is 10-12μm; Step 5: First, a Cr layer is deposited, and then a NiFe alloy film is formed on the processed microstructure by electron beam evaporation.

5. A mechanical seal end face structure for reducing leakage through surface energy difference according to claim 4, characterized in that: The thicknesses of the NiFe and Cr films are 150 nm and 10 nm, respectively.

6. A mechanical seal end face structure for reducing leakage through surface energy difference according to claim 4, characterized in that: The composition of NiFe alloy is Ni 55.5% and Fe 44.5%.

7. The mechanical seal end face structure for reducing leakage by surface energy difference according to claim 1, characterized in that: The steps of processing the surface coating of the moving ring are as follows: Step 1: Place the substrate in anhydrous ethanol solution and deionized water for ultrasonic cleaning for 4-6 minutes to remove oil, dust and oxides on the surface of the substrate; Step 2: The moving ring is polished with 400#, 800#, and 1200# metallographic sandpaper to increase the roughness of the substrate surface; Step 3: Use a thermosetting resin primer for fluoropolymer coating and spray the primer evenly to fully cover the substrate; Step 4: Use a compressed air spray gun to evenly spray PTFE on the substrate; keep the nozzle distance at 15-30cm and keep the nozzle parallel to the substrate plane; Step 5: Dry at about 80°C for 35-45 minutes; Step 6: Heat the coating to 330°C for high temperature curing for 25-35 minutes to obtain the coating.

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