Metal reinforced composite sealing valve seat as well as preparation method and application thereof

Abstract

The invention relates to the technical field of sealing valve seats, and discloses a metal reinforced composite sealing valve seat and a preparation method and application thereof. The metal reinforced composite sealing valve seat comprises a PTFE ring and a metal ring wrapping the periphery of the PTFE ring. In the metal ring, spiral carbon fibers grow in situ on an interface in contact with the PTFE ring; nano montmorillonite is electrostatically adsorbed on the surface of the spiral carbon fiber; the PTFE ring is prepared from the following components: polytetrafluoroethylene and nano montmorillonite. The metal reinforced composite sealing valve seat has good sealing performance at high temperature, and the sealing performance is slightly influenced by pressure change and mechanical vibration.

Description

Technical Field

[0001] The present invention relates to the technical field of sealing valve seats, and in particular to a metal-reinforced composite sealing valve seat and a preparation method and application thereof. Background Art

[0002] Valves are accessories used in pipeline equipment to adjust and control flow direction and flow rate, and are widely used in industries such as petroleum, chemical industry, shipbuilding, metallurgy, and electric power. The sealing performance of valves determines the stability and safety of the entire pipeline system. If the sealing performance is poor and the medium leaks, it will cause economic losses. The leakage of dangerous media will also cause environmental pollution and even cause explosion accidents.

[0003] The valve seat is a key component of the sealing structure inside the valve, which is directly related to the sealing performance of the valve. Polytetrafluoroethylene (PETF) is one of the most commonly used valve seat materials. The soft sealing valve seat made of it has the advantages of rapid opening and closing, low friction coefficient, good corrosion resistance and electrical insulation, but its high temperature resistance is poor, and the sealing performance is poor when used in high temperature environment. The long-term use temperature is generally below 200℃. Summary of the invention

[0004] In order to solve the technical problem that the existing PETF-based sealing valve seat has poor sealing performance at high temperatures, the present invention provides a metal-reinforced composite sealing valve seat and a preparation method and application thereof. The metal-reinforced composite sealing valve seat has good sealing performance at high temperatures, and the sealing performance is less affected by pressure changes and mechanical vibrations.

[0005] The specific technical scheme of the present invention is: In the first aspect, the present invention provides a metal-reinforced composite sealing valve seat, comprising a PTFE ring and a metal ring wrapped around the outer periphery of the PTFE ring; in the metal ring, spiral carbon fibers are in-situ grown on the interface in contact with the PTFE ring; nano-montmorillonite is electrostatically adsorbed on the surface of the spiral carbon fibers; the components of the PTFE ring include polytetrafluoroethylene and nano-montmorillonite.

[0006] Compared with the soft sealing valve seat, the present invention forms a composite sealing valve seat by wrapping a metal ring around the periphery of the PTFE ring. The limiting effect of the metal ring on the PTFE ring can be utilized to partially eliminate the influence of pressure, temperature changes and mechanical vibrations on the sealing performance. The invention can be used in ball valves with high sealing requirements and meet the low emission requirements.

[0007] However, the bonding force between polytetrafluoroethylene material and metal is weak. Under high temperature environment, due to the different thermal expansion coefficients between the two, interface defects are easily formed, which limits the improvement of the sealing performance of the sealing valve seat at high temperature. In view of this technical problem, the present invention grows spiral carbon fiber in situ on the inner surface of the metal ring (i.e., the interface on the metal ring that contacts the PTFE ring). In the process of preparing the sealing valve seat, polytetrafluoroethylene infiltrates the internal space of the spiral carbon fiber, and the special structure of the spiral carbon fiber can be used to anchor the PTFE ring on the surface of the metal ring. The nano-montmorillonite distributed in the PTFE ring can be used as a reinforcing agent and a wear-resistant agent to improve the wear resistance and mechanical strength of the sealing valve seat. The present invention helps to form a stronger mechanical bond between the spiral carbon fiber and the PTFE ring by electrostatically adsorbing part of the nano-montmorillonite on the surface of the spiral carbon fiber. Through the above method, under the cooperation of spiral carbon fiber and nano-montmorillonite, it helps to avoid the generation of interface defects between the metal ring and the PTFE ring at high temperature, thereby improving the high temperature sealing performance of the sealing valve seat.

[0008] Preferably, the spiral carbon fiber is electrostatically adsorbed with nano-montmorillonite via polydiallyldimethylammonium ions attached to the surface thereof.

[0009] Polydiallyldimethylammonium ions can make the surface of the helical carbon fiber carry cations, thereby adsorbing negatively charged nano-montmorillonite through electrostatic forces.

[0010] Preferably, in the raw material of the PTFE ring, the mass ratio of polytetrafluoroethylene to nano-montmorillonite is 100:5-10.

[0011] Furthermore, the raw materials of the PTFE ring include, by weight: 100 parts of polytetrafluoroethylene, 7 to 12 parts of nano-montmorillonite, 2 to 4 parts of graphite, 5 to 9 parts of glass fiber, and 1 to 5 parts of calcium silicate.

[0012] Preferably, a groove is provided on the lower surface of the PTFE ring, and an O-ring is embedded in the groove.

[0013] The valve seat sealing performance can be further improved by embedding an O-ring on the lower surface of the PTFE ring.

[0014] Preferably, the metal ring is made of stainless steel.

[0015] In a second aspect, the present invention provides a method for preparing the metal reinforced composite sealing valve seat, comprising the following steps: S1: in situ growth of helical carbon fibers on the inner surface of a metal ring; S2: attaching polydiallyldimethylammonium ions to the inner surface of the metal ring treated in step S1; S3: placing the metal ring processed in step S2 in a mold, adding PTFE ring raw materials including polytetrafluoroethylene and nano-montmorillonite, compression molding, sintering, and demolding.

[0016] Preferably, the metal ring contains iron; the specific process of step S1 includes: placing the metal ring in a reaction device, replacing the air with an inert gas, introducing acetylene, hydrogen and a growth promoter to contact the inner surface of the metal ring to carry out a cracking reaction.

[0017] Furthermore, the temperature of the cracking reaction is 650-700° C., and the time is 1-2 hours; the flow rate of acetylene is 0.8-1.3 L / min, and the flow rate ratio of acetylene to hydrogen is 1:1.5-2.0; the growth promoter is thiophene, and the growth promoter is passed through a 2-3% v / v thiophene solution and then introduced into the reaction device.

[0018] Preferably, before step S1, the metal ring is first cleaned with ethanol and water and then dried.

[0019] Preferably, the specific process of step S2 includes: coating the inner surface of the metal ring treated in step S1 with a polydiallyldimethylammonium chloride (PDDA) solution, washing with water after sufficient adhesion, and drying.

[0020] Furthermore, the concentration of the polydiallyldimethylammonium chloride solution is 1 to 5 mg / mL; and the sufficient adhesion time is 10 to 15 minutes.

[0021] In a third aspect, the present invention provides application of the metal reinforced composite sealing valve seat in a ball valve.

[0022] Compared with the prior art, the present invention has the following advantages: (1) The present invention forms a composite sealing valve seat by wrapping a metal ring around a PTFE ring, thereby improving the sealing performance of the sealing valve seat and reducing the influence of pressure, temperature changes and mechanical vibration on the sealing performance; (2) The present invention helps to avoid interface defects between the metal ring and the PTFE ring at high temperatures by in-situ growing spiral carbon fibers at the interface between the metal ring and the PTFE ring and electrostatically adsorbing nano-montmorillonite on the surface of the spiral carbon fibers, thereby improving the high-temperature sealing performance of the sealing valve seat. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The figure is a schematic diagram of a cross-sectional structure of the metal reinforced composite sealing valve seat of the present invention.

[0024] The reference numerals are: 1-PTFE ring, 2-metal ring, 3-O-ring. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the embodiments.

[0026] Overall embodiment A metal-reinforced composite sealing valve seat comprises a PTFE ring and a metal ring wrapped around the outer periphery of the PTFE ring; in the metal ring, spiral carbon fibers are in-situ grown on the interface in contact with the PTFE ring; nano-montmorillonite is electrostatically adsorbed on the surface of the spiral carbon fibers; and components of the PTFE ring include polytetrafluoroethylene and nano-montmorillonite.

[0027] In some specific embodiments, the helical carbon fiber is electrostatically adsorbed with nano-montmorillonite via polydiallyldimethylammonium ions attached to the surface thereof.

[0028] In some specific embodiments, in the raw materials of the PTFE ring, the mass ratio of polytetrafluoroethylene to nano-montmorillonite is 100:5-10.

[0029] In some specific embodiments, the raw materials of the PTFE ring include, by weight: 100 parts of polytetrafluoroethylene, 7 to 12 parts of nano-montmorillonite, 2 to 4 parts of graphite, 5 to 9 parts of glass fiber, and 1 to 5 parts of calcium silicate.

[0030] In some specific embodiments, a groove is provided on the lower surface of the PTFE ring, and an O-ring is embedded in the groove.

[0031] In some specific embodiments, the metal ring is made of stainless steel.

[0032] A method for preparing the metal reinforced composite sealing valve seat comprises the following steps: S1: in situ growth of helical carbon fibers on the inner surface of a metal ring; S2: attaching polydiallyldimethylammonium ions to the inner surface of the metal ring treated in step S1; S3: placing the metal ring processed in step S2 in a mold, adding PTFE ring raw materials including polytetrafluoroethylene and nano-montmorillonite, compression molding, sintering, and demolding.

[0033] In some specific embodiments, the metal ring contains iron; the specific process of step S1 includes: placing the metal ring in a reaction device, replacing the air with an inert gas, introducing acetylene, hydrogen and a growth promoter to contact the inner surface of the metal ring to perform a cracking reaction. Optionally or preferably, the temperature of the cracking reaction is 650-700°C, and the time is 1-2h; the flow rate of acetylene is 0.8-1.3L / min, and the flow rate ratio of acetylene to hydrogen is 1:1.5-2.0; the growth promoter is thiophene, and the growth promoter is passed through the hydrogen through a 2-3% v / v thiophene solution and then introduced into the reaction device.

[0034] In some specific embodiments, before step S1, the metal ring is first cleaned with ethanol and water and then dried.

[0035] In some specific embodiments, the specific process of step S2 includes: coating the inner surface of the metal ring treated in step S1 with a polydiallyl dimethyl ammonium chloride (PDDA) solution, washing with water after sufficient adhesion, and drying. Optionally or preferably, the concentration of the polydiallyl dimethyl ammonium chloride solution is 1 to 5 mg / mL; the sufficient adhesion time is 10 to 15 minutes. Specific embodiments The present invention is described below by specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, changes and advantages that can be thought of by those skilled in the art are included in the present invention, and the attached claims and any equivalents thereof are the protection scope of the present invention.

[0037] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meanings as those commonly understood by ordinary technicians in the field to which the present disclosure belongs. Unless otherwise specified, the raw materials and equipment used in the present invention are conventional raw materials and equipment in the field and can be obtained from conventional commercial channels; unless otherwise specified, the methods used in the present invention are conventional methods in the field.

[0038] Example 1: Structure and preparation method of sealing valve seat A metal reinforced composite sealing valve seat, the structure is as follows Figure 1 As shown, it is composed of a PTFE ring 1, a metal ring 2 and an O-ring 3. The metal ring 2 is wrapped around the outer periphery of the PTFE ring 1, and the side of the metal ring 2 in contact with the PTFE ring 1 is defined as the inner surface of the metal ring 1. A groove is provided on the lower surface of the PTFE ring 1, and the O-ring 3 is embedded in the groove (the O-ring is assembled when in use).

[0039] The metal reinforced composite sealing valve seat of this embodiment is prepared by the following steps: S1: Preparation of metal ring 316L stainless steel is machined into L-shape by CNC machining and then spun into Figure 1 The shape of the metal ring is obtained.

[0040] S2: In situ growth of helical carbon fibers The metal ring was cleaned with ethanol and water, dried, and then placed in a CVD tube furnace. After nitrogen was introduced to replace the air in the furnace, the temperature was raised to 650°C, hydrogen was passed through a thiophene acetone solution (concentration of 2.5% v / v), and acetylene was introduced into the furnace at the same time, and the flow rates of hydrogen and acetylene were controlled to be 1.5L / min and 1.0L / min respectively. After 1 hour, the introduction of acetylene and hydrogen was stopped, and the metal ring with spiral carbon fibers grown in situ on the inner surface was obtained.

[0041] S3: Cationic modification PDDA was dissolved in deionized water to prepare a PDDA solution with a concentration of 1 mg / mL. The PDDA solution was applied to the inner surface of the metal layer treated in step S2 by spraying, and then allowed to stand for 15 minutes, washed with water, and dried.

[0042] S4: PTFE ring ingredients The following raw materials were weighed according to weight: 100 parts of PTEF powder, 12 parts of nano-montmorillonite, 3 parts of graphite, 7 parts of glass fiber, and 1 part of calcium silicate. All the raw materials were put into a high-speed mixer and mixed at a speed of 2000 r / min for 5 minutes to obtain a mixed powder.

[0043] S5: Molding and sintering The metal ring treated in step S3 is placed in a mold, and the mixed powder obtained in step S4 is added into the mold, and then placed in a hydraulic press, pre-pressed at 2MPa for 5min, and then the pressure is increased to 60MPa and continued to be pressed for 10min. Then it is transferred to a sintering furnace, and under nitrogen protection, the temperature is increased to 300℃ at a rate of 1℃ / min, kept warm for 0.5h, and then continued to be increased to 380℃ at a rate of 0.5℃ / min, kept warm for 4h, and then cooled to room temperature at a rate of 0.6℃ / min, demolded, and a metal reinforced composite sealing valve seat is obtained.

[0044] Example 2: Structure and preparation method of sealing valve seat The metal reinforced composite sealing valve seat structure of this embodiment is the same as that of embodiment 1, and is prepared by the following steps: S1: Preparation of metal ring 316L stainless steel is machined into L-shape by CNC machining and then spun into Figure 1 The shape of the metal ring is obtained.

[0045] S2: In situ growth of helical carbon fibers The metal ring was washed with ethanol and water, dried, and then placed in a CVD tube furnace. After nitrogen was introduced to replace the air in the furnace, the temperature was raised to 600°C, hydrogen was passed through a thiophene acetone solution (concentration of 3% v / v), and acetylene was introduced into the furnace at the same time, and the flow rates of hydrogen and acetylene were controlled to be 2.0L / min and 1.3L / min respectively. After 2 hours, the introduction of acetylene and hydrogen was stopped, and the metal ring with spiral carbon fibers grown in situ on the inner surface was obtained.

[0046] S3: Cationic modification PDDA was dissolved in deionized water to prepare a PDDA solution with a concentration of 5 mg / mL. The PDDA solution was applied to the inner surface of the metal layer treated in step S2 by spraying, and after standing for 10 minutes, the PDDA solution was washed with water and dried.

[0047] S4: PTFE ring ingredients The following raw materials were weighed according to weight: 100 parts of PTEF powder, 10 parts of nano-montmorillonite, 2 parts of graphite, 5 parts of glass fiber, and 3 parts of calcium silicate. All the raw materials were put into a high-speed mixer and mixed at a speed of 2000 r / min for 5 minutes to obtain a mixed powder.

[0048] S5: Molding and sintering The metal ring treated in step S3 is placed in a mold, and the mixed powder obtained in step S4 is added into the mold, and then placed in a hydraulic press, pre-pressed at 2MPa for 5min, and then the pressure is increased to 60MPa and continued to be pressed for 10min. Then it is transferred to a sintering furnace, and under nitrogen protection, the temperature is increased to 300℃ at a rate of 1℃ / min, kept warm for 0.5h, and then continued to be increased to 380℃ at a rate of 0.5℃ / min, kept warm for 4h, and then cooled to room temperature at a rate of 0.6℃ / min, demolded, and a metal reinforced composite sealing valve seat is obtained.

[0049] Example 3: Structure and preparation method of sealing valve seat The metal reinforced composite sealing valve seat structure of this embodiment is the same as that of embodiment 1, and is prepared by the following steps: S1: Preparation of metal ring 316L stainless steel is machined into L-shape by CNC machining and then spun into Figure 1 The shape of the metal ring is obtained.

[0050] S2: In situ growth of helical carbon fibers The metal ring was washed with ethanol and water, dried, and then placed in a CVD tube furnace. After nitrogen was introduced to replace the air in the furnace, the temperature was raised to 650°C, hydrogen was passed through a thiophene acetone solution (concentration of 2% v / v), and acetylene was introduced into the furnace at the same time, and the flow rates of hydrogen and acetylene were controlled to be 1.6L / min and 0.8L / min respectively. After 1.5h, the introduction of acetylene and hydrogen was stopped, and the metal ring with spiral carbon fibers grown in situ on the inner surface was obtained.

[0051] S3: Cationic modification PDDA was dissolved in deionized water to prepare a PDDA solution with a concentration of 3 mg / mL. The PDDA solution was applied to the inner surface of the metal layer treated in step S2 by spraying, and then allowed to stand for 15 minutes, washed with water, and dried.

[0052] S4: PTFE ring ingredients The following raw materials were weighed according to weight: 100 parts of PTEF powder, 7 parts of nano-montmorillonite, 4 parts of graphite, 9 parts of glass fiber, and 5 parts of calcium silicate. All the raw materials were put into a high-speed mixer and mixed at a speed of 2000 r / min for 5 minutes to obtain a mixed powder.

[0053] S5: Molding and sintering The metal ring treated in step S3 is placed in a mold, and the mixed powder obtained in step S4 is added into the mold, and then placed in a hydraulic press, pre-pressed at 2MPa for 5min, and then the pressure is increased to 60MPa and continued to be pressed for 10min. Then it is transferred to a sintering furnace, and under nitrogen protection, the temperature is increased to 300℃ at a rate of 1℃ / min, kept warm for 0.5h, and then continued to be increased to 380℃ at a rate of 0.5℃ / min, kept warm for 4h, and then cooled to room temperature at a rate of 0.6℃ / min, demolded, and a metal reinforced composite sealing valve seat is obtained.

[0054] Comparative Example 1: Structure and Preparation Method of Sealing Valve Seat The sealing valve seat structure of this comparative example is different from that of Example 1 only in that the sealing valve seat of this comparative example is only composed of a PTFE ring 1 and an O-ring 3 , and is not provided with a metal ring 2 .

[0055] The sealing valve seat of this comparative example is prepared by the following steps: S1: PTFE ring ingredients The following raw materials were weighed according to weight: 100 parts of PTEF powder, 12 parts of nano-montmorillonite, 3 parts of graphite, 7 parts of glass fiber, and 1 part of calcium silicate. All the raw materials were put into a high-speed mixer and mixed at a speed of 2000 r / min for 5 minutes to obtain a mixed powder.

[0056] S2: Molding and sintering The mixed powder obtained in step S2 is put into a mold, placed in a hydraulic press, pre-pressed at 2MPa for 5min, then pressurized to 60MPa for 10min. Then transferred to a sintering furnace, heated to 300°C at a rate of 1°C / min under nitrogen protection, kept warm for 0.5h, continued to heat to 380°C at a rate of 0.5°C / min, kept warm for 4h, then cooled to room temperature at a rate of 0.6°C / min, demolded, and a sealing valve seat was obtained.

[0057] Comparative Example 2: Structure and Preparation Method of Sealing Valve Seat The structure of the metal reinforced composite sealing valve seat of this comparative example is the same as that of Example 1, and the difference between the preparation process and that of Example 1 is that ordinary straight carbon fibers are in-situ grown on the inner surface of the metal ring in this comparative example, rather than spiral carbon fibers. Specifically, the metal reinforced composite sealing valve seat of this comparative example is prepared by the following steps: S1: Preparation of metal ring 316L stainless steel is machined into L-shape by CNC machining and then spun into Figure 1 The shape of the metal ring is obtained.

[0058] S2: In-situ growth of straight carbon fibers The metal ring was cleaned with ethanol and water, dried, and then placed in a CVD tube furnace. After nitrogen was introduced to replace the air in the furnace, the temperature was raised to 650°C, hydrogen was passed through a thiophene acetone solution (concentration of 2.5% v / v), and propylene was introduced into the furnace at the same time, and the flow rates of hydrogen and propylene were controlled to be 1.5L / min and 1.0L / min respectively. After 1 hour, the introduction of propylene and hydrogen was stopped, and the metal ring was cooled to room temperature to obtain a metal ring with linear carbon fibers in situ grown on the inner surface.

[0059] S3: Cationic modification PDDA was dissolved in deionized water to prepare a PDDA solution with a concentration of 1 mg / mL. The PDDA solution was applied to the inner surface of the metal layer treated in step S2 by spraying, and then allowed to stand for 15 minutes, washed with water, and dried.

[0060] S4: PTFE ring ingredients The following raw materials were weighed according to weight: 100 parts of PTEF powder, 12 parts of nano-montmorillonite, 3 parts of graphite, 7 parts of glass fiber, and 1 part of calcium silicate. All the raw materials were put into a high-speed mixer and mixed at a speed of 2000 r / min for 5 minutes to obtain a mixed powder.

[0061] S5: Molding and sintering The metal ring treated in step S3 is placed in a mold, and the mixed powder obtained in step S4 is added into the mold, and then placed in a hydraulic press, pre-pressed at 2MPa for 5min, and then the pressure is increased to 60MPa and continued to be pressed for 10min. Then it is transferred to a sintering furnace, and under nitrogen protection, the temperature is increased to 300℃ at a rate of 1℃ / min, kept warm for 0.5h, and then continued to be increased to 380℃ at a rate of 0.5℃ / min, kept warm for 4h, and then cooled to room temperature at a rate of 0.6℃ / min, demolded, and a metal reinforced composite sealing valve seat is obtained.

[0062] Comparative Example 3: Structure and Preparation Method of Sealing Valve Seat The structure of the metal reinforced composite sealing valve seat of this comparative example is the same as that of Example 1, and the difference between the preparation process and that of Example 1 is that after the spiral carbon fiber is grown in situ, no cationic modification is performed in this comparative example. Specifically, the metal reinforced composite sealing valve seat of this comparative example is prepared by the following steps: S1: Preparation of metal ring 316L stainless steel is machined into L-shape by CNC machining and then spun into Figure 1 The shape of the metal ring is obtained.

[0063] S2: In situ growth of helical carbon fibers The metal ring was cleaned with ethanol and water, dried, and then placed in a CVD tube furnace. After nitrogen was introduced to replace the air in the furnace, the temperature was raised to 650°C, hydrogen was passed through a thiophene acetone solution (concentration of 2.5% v / v), and acetylene was introduced into the furnace at the same time, and the flow rates of hydrogen and acetylene were controlled to be 1.5L / min and 1.0L / min respectively. After 1 hour, the introduction of acetylene and hydrogen was stopped, and the metal ring with spiral carbon fibers grown in situ on the inner surface was obtained.

[0064] S3: PTFE ring ingredients The following raw materials were weighed according to weight: 100 parts of PTEF powder, 12 parts of nano-montmorillonite, 3 parts of graphite, 7 parts of glass fiber, and 1 part of calcium silicate. All the raw materials were put into a high-speed mixer and mixed at a speed of 2000 r / min for 5 minutes to obtain a mixed powder.

[0065] S4: Molding and sintering The metal ring treated in step S3 is placed in a mold, and the mixed powder obtained in step S3 is added into the mold, and then placed in a hydraulic press, pre-pressed at 2MPa for 5min, and then the pressure is increased to 60MPa and continued to be pressed for 10min. Then it is transferred to a sintering furnace, and under nitrogen protection, the temperature is increased to 300℃ at a rate of 1℃ / min, and kept warm for 0.5h, and then the temperature is continued to be increased to 380℃ at a rate of 0.5℃ / min, and kept warm for 4h, and then cooled to room temperature at a rate of 0.6℃ / min, demolded, and a metal reinforced composite sealing valve seat is obtained.

[0066] Test example: Sealing performance test of sealing valve seat The sealing valve seats in each embodiment and comparative example were assembled in a ball valve, and the sealing performance was tested at room temperature (23°C) and at 280°C after 24 hours of use. The testing conditions were as follows: the external leakage rate at the valve seat was used to characterize the sealing performance, the testing gas was helium, and the air pressure was 2MPa.

[0067] Table 1 Sealing performance test results of sealing valve seat Analyzing the data in Table 1, we can see that: (1) Examples 1 to 3 have low leakage rates at both room temperature and high temperature, and can meet the external leakage rate requirements (≤10 -5 Pa·m 3 / s).

[0068] (2) Compared with Comparative Example 1, the leakage rates of Examples 1 to 3 and Comparative Examples 2 to 3 after long-term use at high temperature are significantly lower. This is because, based on Comparative Example 1, Examples 1 to 3 and Comparative Examples 2 to 3 wrap a metal ring around the periphery of the PTFE ring, which can partially eliminate the influence of temperature on the sealing performance by utilizing the restrictive effect of the metal ring on the PTFE ring, thereby improving the high-temperature sealing performance of the valve seat.

[0069] (3) Compared with Comparative Example 2, the leakage rate of Example 1 after long-term use at high temperature is significantly lower. This is because in Example 1, spiral carbon fibers are grown in situ on the inner surface of the metal ring (i.e., the interface on the metal ring where the PTFE ring contacts the metal ring). In the process of preparing the sealing valve seat, polytetrafluoroethylene infiltrates into the inner space of the spiral carbon fibers, and the special structure of the spiral carbon fibers can be used to anchor the PTFE ring on the surface of the metal ring, thereby reducing the interface defects caused by the different thermal expansion coefficients of the PTFE ring and the metal ring at high temperature, thereby improving the high-temperature sealing performance of the valve seat; while in Comparative Example 2, ordinary linear carbon fibers are used, and the internal space cannot be used to anchor the PTFE ring on the surface of the metal ring.

[0070] (4) Compared with Comparative Example 3, the leakage rate of Example 1 after long-term use at high temperature is significantly lower. This is because Example 1 attaches polydiallyldimethylammonium ions to the surface of the spiral carbon fiber, so that the surface of the spiral carbon fiber has a positive charge, and the nano-montmorillonite can be electrostatically adsorbed during the preparation of the sealing valve seat, which helps to form a stronger mechanical bond between the spiral carbon fiber and the PTFE ring, thereby further improving the high-temperature sealing performance of the valve seat.

[0071] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A metal reinforced composite sealing valve seat, characterized in that: It comprises a PTFE ring and a metal ring wrapped around the outer periphery of the PTFE ring; in the metal ring, spiral carbon fibers are in-situ grown on the interface in contact with the PTFE ring; nano-montmorillonite is electrostatically adsorbed on the surface of the spiral carbon fibers; and the components of the PTFE ring include polytetrafluoroethylene and nano-montmorillonite.

2. The metal reinforced composite sealing valve seat according to claim 1, characterized in that: In the raw materials of the PTFE ring, the mass ratio of polytetrafluoroethylene to nano-montmorillonite is 100:5-10.

3. The metal reinforced composite sealing valve seat according to claim 2, characterized in that: The raw materials of the PTFE ring include, by weight: 100 parts of polytetrafluoroethylene, 7 to 12 parts of nano-montmorillonite, 2 to 4 parts of graphite, 5 to 9 parts of glass fiber, and 1 to 5 parts of calcium silicate.

4. The metal reinforced composite sealing valve seat according to claim 1, characterized in that: A groove is arranged on the lower surface of the PTFE ring, and an O-ring is embedded in the groove.

5. The metal reinforced composite sealing valve seat according to claim 1, characterized in that: The material of the metal ring is stainless steel.

6. A method for preparing the metal reinforced composite sealing valve seat according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: in situ growth of helical carbon fibers on the inner surface of a metal ring; S2: attaching polydiallyldimethylammonium ions to the inner surface of the metal ring treated in step S1; S3: placing the metal ring processed in step S2 in a mold, adding PTFE ring raw materials including polytetrafluoroethylene and nano-montmorillonite, compression molding, sintering, and demolding.

7. The preparation method according to claim 6, characterized in that: The metal ring contains iron; the specific process of step S1 includes: placing the metal ring in a reaction device, replacing the air with an inert gas, introducing acetylene, hydrogen and a growth promoter to contact the inner surface of the metal ring to perform a cracking reaction.

8. The preparation method according to claim 6, characterized in that: The specific process of step S2 includes: coating the polydiallyldimethylammonium chloride solution on the inner surface of the metal ring treated in step S1, washing with water after sufficient adhesion, and drying.

9. The preparation method according to claim 8, characterized in that: The concentration of the polydiallyldimethylammonium chloride solution is 1-5 mg / mL; and the sufficient adhesion time is 10-15 min.

10. Use of the metal reinforced composite sealing valve seat according to any one of claims 1 to 5 in a ball valve.

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