Aviation sealing material and preparation method thereof

Abstract

The invention relates to the technical field of sealing material preparation, in particular to an aviation sealing material and preparation thereof. The preparation method comprises the following steps: taking out various raw materials for pretreatment, and drying polytetrafluoroethylene to remove moisture; crushing methyl phenyl vinyl silicone rubber to a proper particle size, and sieving through a screen; cutting the Kevlar fiber into a proper length, and drying the Kevlar fiber; it is ensured that no impurity exists in dicumyl peroxide and tri-octanoyl isopropyl titanate; polyphenylene sulfide fibers, molybdenum disulfide, bronze powder, graphite, fillers and a reinforcing agent need to be subjected to pretreatment such as drying and sieving; various raw materials are fully mixed through a high-speed stirrer to form raw materials; pressing the mixed raw materials into a required shape by using a pressurizing device; the invention aims to provide an aviation sealing material and a preparation method thereof, and solves the problems of poor chemical corrosion resistance, insufficient high temperature resistance, high friction coefficient and limited mechanical property of the material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sealing material preparation, in particular to an aviation sealing material and a preparation method thereof. BACKGROUND

[0002] The aviation sealing material is a key material for ensuring the safe operation of an airplane, an engine and each system, and needs to have excellent sealing property, temperature resistance, corrosion resistance and mechanical strength.

[0003] Ordinary sealing materials, such as rubber and PVC, are prone to swelling, deformation or degradation when contacting chemicals such as acid, alkali and salt, which leads to a significant decrease in sealing performance, and are prone to aging, hardening or loss of elasticity in a high-temperature environment, thereby leading to sealing failure. In addition, ordinary materials are prone to wear and heat generation in a high-speed rotating or reciprocating sealing environment, thereby reducing the sealing performance, and have relatively low tensile strength and wear resistance, which are difficult to adapt to complex mechanical stress. SUMMARY

[0004] The present application aims to provide an aviation sealing material and a preparation method thereof, and solves the problems of poor chemical corrosion resistance and insufficient high-temperature resistance of the material, high friction coefficient and limited mechanical performance.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: an aviation sealing material, the components of which include polytetrafluoroethylene, methylphenyl vinyl silicone rubber, Kevlar fiber, dicumyl peroxide, isopropyl tricaprylyl titanate, polyphenylene sulfide fiber, molybdenum disulfide, bronze powder and graphite; the components are proportioned (in percentage parts) as follows: the polytetrafluoroethylene is proportioned at 54.05%, has an average particle size of 50-70 μm, a purity of ≥99.95% and a water content of ≤0.1%; the methylphenyl vinyl silicone rubber is proportioned at 8.62%, has a molecular weight of 60-80 million Da, a vinyl content of 0.18-0.22 mol% and a phenyl content of 8-10%; the Kevlar fiber is proportioned at 7.18%, has a filament strength of ≥3.6 GPa and a diameter of 10-15 μm; the dicumyl peroxide is proportioned at 2.30%, has a purity of ≥99%, a melting point of 42-44℃ and an activation energy of 160 kJ / mol; the isopropyl tricaprylyl titanate is proportioned at 1.15%, has a purity of ≥95%, a density of 0.92-0.95 g / cm 3, the flash point is greater than or equal to 170 DEG C; the polyphenylene sulfide fiber is 13.22% in proportion, the melting point is 280-285 DEG C, the thermal decomposition temperature is greater than or equal to 400 DEG C, and the diameter is 12-15 microns; the molybdenum disulfide is 3.45% in proportion, the purity is greater than or equal to 99.5%, the particle size D50 is 1-2 microns, and the layered structure content is greater than or equal to 98%; the bronze powder is 5.17% in proportion, is a 90Cu-10Sn alloy, the particle size is 15-25 microns, the hardness is HB80-100, and the thermal conductivity is greater than or equal to 100 W / m K; and the graphite is 1.72% in proportion, is flake graphite, the fixed carbon content is greater than or equal to 99.5%, the particle size is 5-8 microns, and the friction coefficient is 0.08-0.12 (25 DEG C, 1 MPa); A method for preparing an aviation sealing material, comprising the following steps; Step one: a plurality of raw materials are taken out for pretreatment, polytetrafluoroethylene is dried to remove moisture, methylphenyl vinyl silicone rubber is crushed to an appropriate particle size and sieved through a screen, Kevlar fibers are cut to an appropriate length and dried, and the inside of dicumyl peroxide and isopropyl tricaprylyl titanate is ensured to be free of impurities; polyphenylene sulfide fibers, molybdenum disulfide, bronze powder and graphite, which are fillers and reinforcing agents, need to be pretreated by drying, sieving and the like; Step two: the various raw materials are mixed by a high-speed mixer to form raw materials; Step three: a pressurizing device is used to press the mixed raw materials into a desired shape; Step four: a drying device is used to heat the material; Step five: the material is cooled and then subjected to secondary pressurization; Step six: the material is cooled.

[0006] Preferably, the feeding sequence is: 100 parts of polytetrafluoroethylene → 12 parts of Kevlar fibers → 22 parts of polyphenylene sulfide fibers → dry mixing for 10 min (rotation speed 2000 r / min), 15 parts of methylphenyl vinyl silicone rubber → heating to 80 DEG C (hot water is passed through the jacket) → mixing for 15 min (rotation speed 2500 r / min), 6 parts of molybdenum disulfide → 8 parts of bronze powder → 3 parts of graphite → mixing for 8 min (rotation speed 2200 r / min), 4 parts of dicumyl peroxide → 2 parts of isopropyl tricaprylyl titanate → high-speed dispersion for 7 min (rotation speed 3000 r / min).

[0007] Preferably, the mixing device used is a high-speed mixer, and the high-speed mixer is set to a rotation speed of 2000-3000 r / min and a mixing time of 30-40 min.

[0008] Preferably, the device used for the pressurization is a hydraulic machine, Y32-630 hydraulic machine, the pressurization pressure is set between 10-15Mpa, and the pressure maintaining time is 10-15 minutes.

[0009] Preferably, the device used for the heating is a sintering furnace, SK-5-12 box type sintering furnace, the temperature rising rate is set between 5-10℃ / minute, the sintering temperature is 380-390℃, and the constant temperature time is 2-4 hours.

[0010] Preferably, the device used for the secondary pressurization is a hydraulic machine, Y32-630 hydraulic machine, the material temperature is cooled to 200-250℃ for the secondary pressurization, the pressurization pressure is set between 8-15Mpa, and the pressure maintaining time is 8-10 minutes.

[0011] Preferably, the cooling mode adopts the natural cooling to room temperature mode.

[0012] Compared with the prior art, the application has the beneficial effects of: 1. The application can resist the corrosion of acid, alkali, salt and other chemical substances, is suitable for various corrosive environments, and ordinary sealing materials such as rubber are easy to swell, deform or degrade when contacting chemical substances, can work for a long time in an extremely high temperature environment, has a wide continuous use temperature range, can even bear higher temperature in a short term, has self-lubricating property, low friction coefficient, can be applied to high-speed rotation or reciprocating motion sealing occasions, can obtain higher tensile strength and wear resistance, and can better adapt to complex mechanical stress. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The figure is a flowchart of the application. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Therefore, the following detailed description of the embodiments of the application provided in the drawings is not intended to limit the scope of the claimed application, but only represents selected embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the protection of the application.

[0015] The application provides an aviation sealing material, which comprises the following components: polytetrafluoroethylene, methylphenyl vinyl silicone rubber, Kevlar fiber, dicumyl peroxide, trioctanoyl isopropyl titanate, polyphenylene sulfide fiber, molybdenum disulfide, bronze powder and graphite; the components are proportioned as follows (in percentage parts): the polytetrafluoroethylene is 54.05%, the average particle size is 50-70 microns, the purity is greater than or equal to 99.95%, and the water content is less than or equal to 0.1%; the methylphenyl vinyl silicone rubber is 8.62%, the molecular weight is 600-800 thousand Da, the vinyl content is 0.18-0.22 mol%, and the phenyl content is 8-10%; the Kevlar fiber is 7.18%, the original wire strength is greater than or equal to 3.6 GPa, and the diameter is 10-15 microns; the dicumyl peroxide is 2.30%, the purity is greater than or equal to 99%, the melting point is 42-44 DEG C, and the activation energy is 160 kJ / mol; the trioctanoyl isopropyl titanate is 1.15%, the purity is greater than or equal to 95%, the density is 0.92-0.95 g / cm 3 , the flash point is greater than or equal to 170 DEG C; the polyphenylene sulfide fiber is 13.22%, the melting point is 280-285 DEG C, the thermal decomposition temperature is greater than or equal to 400 DEG C, and the diameter is 12-15 microns; the molybdenum disulfide is 3.45%, the purity is greater than or equal to 99.5%, the particle size D50 is 1-2 microns, and the layered structure content is greater than or equal to 98%; the bronze powder is 5.17%, which is a 90Cu-10Sn alloy, the particle size is 15-25 microns, the hardness is HB80-100, and the thermal conductivity is greater than or equal to 100 W / m K; and the graphite is 1.72%, which is flaky graphite, the fixed carbon content is greater than or equal to 99.5%, the particle size is 5-8 microns, and the friction coefficient is 0.08-0.12 (25 DEG C, 1 MPa). A preparation method of the aviation sealing material, comprising the following steps: Step one: a plurality of raw materials are taken out for pretreatment, the polytetrafluoroethylene is dried to remove moisture, the methylphenyl vinyl silicone rubber is crushed to an appropriate particle size and sieved through a screen, the Kevlar fiber is cut to an appropriate length and dried, and the dicumyl peroxide and trioctanoyl isopropyl titanate are ensured to be free of impurities; the polyphenylene sulfide fiber, molybdenum disulfide, bronze powder and graphite, which are fillers and reinforcing agents, need to be pretreated by drying, sieving and the like; Step two: the raw materials are mixed by a high-speed stirrer to form a raw material; Step three: a pressurizing device is used to press the mixed raw material into a required shape; Step four: a drying device is used to heat the material; Step five: the material is cooled and then subjected to secondary pressurizing; Step six: the material is cooled.

[0016] The polytetrafluoroethylene as the main body of the sealing material needs to ensure its high purity to avoid impurities affecting the performance of the material, and it needs to be dried to remove moisture and prevent bubbles or cracks from being generated during preparation; the methyl phenyl vinyl silicone rubber is crushed to an appropriate particle size and sieved through a screen to ensure that it can be uniformly mixed with the polytetrafluoroethylene, and it also needs to be dried to remove moisture and volatile components in the silicone rubber and improve the stability of the mixture; the Kevlar fiber is cut to an appropriate length to enhance the strength and wear resistance of the material, and it is also dried to remove moisture and grease on the surface of the fiber and improve its bonding force with the matrix; the dicumyl peroxide and isopropyl trioctanoyl titanate need to maintain their quality stability and be free of impurities to better mix with other components; the fillers and reinforcing agents such as polyphenylene sulfide fiber, molybdenum disulfide, bronze powder, and graphite need to be pretreated by drying and sieving to ensure that they are uniformly dispersed in the matrix; the polyphenylene sulfide fiber can improve the heat resistance and dimensional stability of the material; molybdenum disulfide and bronze powder as solid lubricants can reduce the friction coefficient of the material; graphite can improve the self-lubricating property and corrosion resistance of the material; the polytetrafluoroethylene accounts for more than 50% of the matrix and serves as the main body of the material to ensure chemical stability and a low friction coefficient; the Kevlar fiber (5.13%-8.82%) and the polyphenylene sulfide fiber (9.23%-15.68%) together improve the mechanical strength and heat resistance; the methyl phenyl vinyl silicone rubber (5.13%-11.76%) provides elasticity; the dicumyl peroxide (1.54%-2.94%) as a vulcanizing agent promotes cross-linking; molybdenum disulfide (2.05%-4.71%) and graphite (1.03%-2.35%) synergistically reduce the friction coefficient; bronze powder (3.08%-7.06%) improves the thermal conductivity and wear resistance; and isopropyl trioctanoyl titanate (0.51%-1.76%) improves the interfacial bonding force.

[0017] The feeding sequence is: 100 parts of polytetrafluoroethylene → 12 parts of Kevlar fiber → 22 parts of polyphenylene sulfide fiber → dry mixing for 10 minutes (at a speed of 2000 r / min), 15 parts of methyl phenyl vinyl silicone rubber → heating to 80°C (hot water is passed through the jacket) → mixing for 15 minutes (at a speed of 2500 r / min), 6 parts of molybdenum disulfide → 8 parts of bronze powder → 3 parts of graphite → mixing for 8 minutes (at a speed of 2200 r / min), 4 parts of dicumyl peroxide → 2 parts of isopropyl trioctanoyl titanate → high-speed dispersion for 7 minutes (at a speed of 3000 r / min); the mixing device used is a high-speed mixer, and the stirring speed of the high-speed mixer is set to between 2000-3000 revolutions / minute, and the stirring time is 30-40 minutes.

[0018] High-speed stirring helps to break up the agglomerates in the material, improve mixing uniformity, ensure that the components are fully mixed, and achieve uniform consistency. Regular sampling can be taken during the mixing process to detect mixing uniformity. Through high-speed stirring, polytetrafluoroethylene and methylphenyl vinyl silicone rubber, Kevlar fiber and other components form a uniform mixture.

[0019] The device used for pressurization is a hydraulic machine, Y32-630 hydraulic machine, the pressurization pressure is set between 10-15Mpa, and the pressure holding time is 10-15 minutes.

[0020] According to the properties of the mixture and the forming requirements, the pressurization pressure is set between 10-15Mpa, and appropriate pressure helps the mixture to form a dense shape, avoiding the appearance of pores or cracks inside the material; the pressure holding time is usually 10-15 minutes, ensuring that the mixture is fully solidified under pressure and maintains stable shape. Too long or too short pressure holding time will affect the forming quality and performance of the material.

[0021] The device used for heating is a sintering furnace, SK-5-12 box sintering furnace, the heating rate is set between 5-10℃ / min, the sintering temperature is 380-390℃, and the constant temperature time is 2-4 hours.

[0022] According to the properties of the green body and the sintering requirements, the heating rate is set between 5-10℃ / min, and appropriate heating rate helps the green body to be heated uniformly, avoiding the cracking or deformation of the green body due to excessive temperature gradient; the sintering temperature is usually 380-390℃, at this temperature, the inter-particle bonding in the green body occurs, forming a dense structure, the selection of sintering temperature needs to be determined according to the melting point and sintering performance of the material; the constant temperature time is usually 2-4 hours, ensuring that the green body is fully sintered to achieve the required density and strength, and too long or too short constant temperature time will affect the sintering quality and performance of the material.

[0023] The device used for secondary pressurization is a hydraulic machine, the same as Y32-630 hydraulic machine, the material temperature is cooled to about 200-250℃ for secondary pressurization, the pressurization pressure is set between 8-15Mpa, and the pressure holding time is 8-10 minutes.

[0024] The temperature is cooled to about 200-250 DEG C for secondary pressurization to avoid deformation or cracking of the material at high temperature, and the higher temperature helps the material to maintain plasticity during pressurization, which is beneficial to the improvement of the density; the pressurization pressure is set between 8-15 MPa according to the properties of the material and the requirements of secondary pressurization, and the appropriate pressure is helpful to further improve the density and structural stability of the material; the pressure holding time is usually 8-10 minutes to ensure that the material is fully solidified under pressure to achieve the best density and structural stability; the secondary pressurization treatment can further eliminate the pores and cracks in the material, improve the density and structural stability of the material, and at the same time, the secondary pressurization is also helpful to improve the mechanical properties and sealing performance of the material.

[0025] The cooling mode is natural cooling to room temperature.

[0026] The material is gradually cooled to room temperature by natural heat dissipation, and the material needs to be placed steadily during the cooling process to avoid stress or cracking inside the material caused by rapid cooling, and to avoid thermal stress and deformation caused by rapid cooling.

[0027] Working principle: a certain amount of multiple raw materials are mixed by stirring, the mixing device is a high-speed mixer, the stirring speed of the high-speed mixer is set between 2000-3000 revolutions / minute, the stirring time is 30-40 minutes, then the material is pressurized and shaped, the pressurization device is a hydraulic machine, the pressurization pressure is set between 10-15 MPa, the pressure holding time is 10-15 minutes, the material is placed in a sintering furnace for heating treatment, the heating rate is set between 5-10 DEG C / minute, the sintering temperature is 380-390 DEG C, the constant temperature time is 2-4 hours, then the material temperature is cooled to about 200-250 DEG C, and then the hydraulic machine is used for secondary pressurization, and finally the material is naturally cooled to room temperature.

[0028] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An aviation sealing material, comprising: Polytetrafluoroethylene, methylphenyl vinyl silicone rubber, Kevlar fiber, dicumyl peroxide, trioctanoyl isopropyl titanate, polyphenylene sulfide fiber, molybdenum disulfide, bronze powder, graphite; The composition ratios (in percentages) are as follows: the polytetrafluoroethylene ratio is 54.05%, the average particle size is 50-70 μm, the purity is ≥99.95%, and the moisture content is ≤0.1%; the methylphenyl vinyl silicone rubber ratio is 8.62%, the molecular weight is 600,000-800,000 Da, the vinyl content is 0.18-0.22 mol%, and the phenyl content is 8-10%; the Kevlar fiber ratio is 7.18%, the raw fiber strength is ≥3.6 GPa, and the diameter is 10-15 μm; the dicumyl peroxide ratio is 2.30%, the purity is ≥99%, the melting point is 42-44° C., and the activation energy is 160 kJ / mol; the trioctanoyl isopropyl titanate ratio is 1.15%, the purity is ≥95%, and the density is 0.92-0.95 g / cm 3 , flash point ≥170℃; the polyphenylene sulfide fiber ratio is 13.22%, melting point 280-285℃, thermal decomposition temperature ≥400℃, diameter 12-15μm; the molybdenum disulfide ratio is 3.45%, purity ≥99.5%, particle size D50 = 1-2μm, layered structure content ≥98%; the bronze powder ratio is 5.17%, 90Cu-10Sn alloy, particle size 15-25μm, hardness HB80-100, thermal conductivity ≥100W / m·K; the graphite ratio is 1.72%, flake graphite, fixed carbon content ≥99.5%, particle size 5-8μm, friction coefficient 0.08-0.12 (25℃, 1MPa); A method for preparing an aviation sealing material comprises the following steps: Step 1: Take out various raw materials for pretreatment, dry the polytetrafluoroethylene and remove moisture; crush the methylphenyl vinyl silicone rubber to an appropriate particle size and sieve it through a mesh; cut the Kevlar fiber into appropriate lengths and dry it; ensure that there are no impurities in dicumyl peroxide and trioctanoyl isopropyl titanate; polyphenylene sulfide fiber, molybdenum disulfide, bronze powder, graphite, and other fillers and reinforcing agents need to be dried and sieved before pretreatment; Step 2: The various raw materials are mixed thoroughly by a high-speed blender to form a raw material; Step 3: Using a pressurizing device to press the mixed raw materials into a desired shape; Step 4: Use a drying device to heat the material; Step 5: After the material cools down, pressurize it again; Step 6: Cool the material.

2. The aviation sealing material and preparation method thereof according to claim 1, characterized in that: The feeding order is: 100 parts of polytetrafluoroethylene → 12 parts of Kevlar fiber → 22 parts of polyphenylene sulfide fiber → dry mixing for 10 minutes (speed 2000 r / min), 15 parts of methylphenyl vinyl silicone rubber → heating to 80°C (hot water is passed through the jacket) → mixing for 15 minutes (speed 2500 r / min), 6 parts of molybdenum disulfide → 8 parts of bronze powder → 3 parts of graphite → mixing for 8 minutes (speed 2200 r / min), 4 parts of diisopropyl peroxide → 2 parts of trioctanoyl titanate → high-speed dispersion for 7 minutes (speed 3000 r / min).

3. The aviation sealing material and preparation method thereof according to claim 1, characterized in that: The mixing device used is a high-speed mixer, SHR-300A high-speed mixer, the stirring speed of the high-speed mixer is set between 2000-3000 rpm, and the stirring time is 30-40 minutes.

4. The aviation sealing material and preparation method thereof according to claim 1, characterized in that: The device used for pressurization is a hydraulic press, Y32-630 hydraulic press, the pressurization pressure is set between 10-15 MPa, and the pressure holding time is 10-15 minutes.

5. The aviation sealing material and preparation method thereof according to claim 1, characterized in that: The heating device used is a sintering furnace, SK-5-12 box-type sintering furnace, the heating rate is set between 5-10°C / minute, the sintering temperature is 380-390°C, and the constant temperature time is 2-4 hours.

6. The aviation sealing material and preparation method thereof according to claim 1, characterized in that: The device used for the secondary pressurization is a hydraulic press, such as the Y32-630 hydraulic press. The secondary pressurization is performed after the material temperature cools to about 200-250°C. The pressurization pressure is set between 8-15Mpa and the pressure holding time is 8-10 minutes.

7. The aviation sealing material and preparation method thereof according to claim 1, characterized in that: The cooling method is to cool naturally to room temperature.

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