CN113248852B - Modified polytetrafluoroethylene composite material, preparation method thereof and sealing element - Google Patents
Modified polytetrafluoroethylene composite material, preparation method thereof and sealing element Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
- C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C08L27/18—Homopolymers or copolymers or tetrafluoroethene
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
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- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
- C08L2205/035—Polymer mixtures characterised by other features containing three or more polymers in a blend containing four or more polymers in a blend
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Abstract
The invention relates to a preparation method of a modified polytetrafluoroethylene composite material, which comprises the steps of pressing and sintering mixed powder; the mixed powder comprises the following components in percentage by weight: 57-85% of polytetrafluoroethylene, 8-18% of polyphenyl ester, 5-20% of polyether-ether-ketone and 2-5% of polyamide-imide. The invention also relates to the modified polytetrafluoroethylene composite material prepared by the preparation method of the modified polytetrafluoroethylene composite material. The invention further relates to a sealing element made of the modified polytetrafluoroethylene composite material for an aeroengine.
Description
Technical Field
The invention relates to the technical field of friction materials, in particular to a modified polytetrafluoroethylene composite material, a preparation method thereof and a sealing element.
Background
Polytetrafluoroethylene (PTFE) is widely applied in various fields as a special engineering plastic, has the characteristics of good acid-base resistance, solvent resistance, high-low temperature resistance and weather resistance, and most importantly, compared with other materials, PTFE has low friction coefficient, excellent self-lubricating property and chemical stability, and is a good sealing material, especially an ideal material for manufacturing sealing elements for aeroengines. The sealing element for the aeroengine is mainly applied to a hydraulic system, and mainly plays roles in protection, lubrication and wear resistance in the hydraulic system. The sealing elements play a crucial role in the relevant mechanical equipment of the aircraft engine, the sealing elements applied to the hydraulic system are often required to bear extreme pressure, load and temperature, but PTFE has poor wear resistance, is easy to wear and has short service life, and if the sealing elements fail in any form, the normal operation of the hydraulic system is affected and even seriously damaged, for example, once an oil leakage occurs, the aircraft engine is greatly damaged. Therefore, modification of PTFE materials is desirable.
At present, the tribology modification modes of PTFE in the scientific and engineering communities are mainly three: filling modification, blending modification and surface modification, wherein the most common mode is filling modification, the modification cost is low, and the technology is relatively mature. Through filling modification of PTFE, the wear resistance of PTFE can be improved to a certain extent, but the mechanical property is often reduced. Aiming at the modification of the PTFE material of the sealing element for the aeroengine, the existing reinforced fillers are of two types: the filler has the general problems of high hardness and modulus, and once the filler is ground out, the filler can be used for reversely biting a hydraulic mechanism, so that the abrasion of a piston/piston rod is caused, and further, the high-modulus filler brings great harm to an aeroengine; the other is colored lubricating filler, such as carbon-based materials like graphite, graphene and carbon nano tubes, which once ground out can pollute the aircraft engine oil, thereby causing pollution to the engine environment.
Disclosure of Invention
Based on the above, there is a need for a modified polytetrafluoroethylene composite material with better wear resistance, especially better wear resistance in high temperature environment, a preparation method thereof and a sealing element.
In one aspect of the invention, a preparation method of a modified polytetrafluoroethylene composite material is provided, which comprises the steps of pressing and sintering mixed powder; the mixed powder comprises the following components in percentage by weight: 57-85% of polytetrafluoroethylene, 8-18% of polyphenyl ester, 5-20% of polyether-ether-ketone and 2-5% of polyamide-imide.
In one embodiment, the mixed powder comprises the following components in percentage by weight: 57-71% of polytetrafluoroethylene, 10-18% of polyphenyl ester, 13-20% of polyether-ether-ketone and 3-5% of polyamide-imide.
In one embodiment, the polyphenyl ester, the polyether-ether-ketone and the polyamide imide powder have the same average particle size of 30-40 μm.
In one embodiment, the pressing is cold pressing, the pressing pressure is 27-37 MPa, and the pressing time is 5-15 s.
In one embodiment, the sintering temperature is 380-385 ℃, and the heat preservation time is 1-5 h.
In one embodiment, the preparation method of the mixed powder comprises the following steps:
stirring and mixing polytetrafluoroethylene, polyphenyl ester, polyether-ether-ketone and polyamide-imide to form a uniform mixture, wherein the stirring speed is 650 r/min-850 r/min, and the stirring time is 3 min-5 min.
In another aspect of the present invention, there is provided a modified polytetrafluoroethylene composite obtained according to the method for preparing a modified polytetrafluoroethylene composite.
In still another aspect of the present invention, there is provided a sealing member made of the modified polytetrafluoroethylene composite.
In one embodiment, the sealing element is a seal for an aircraft engine.
Compared with the prior art, the beneficial effect of this application is:
according to the preparation method of the modified polytetrafluoroethylene composite material, the polytetrafluoroethylene is modified through cooperation of three organic fillers, namely the polyphenyl ester, the polyether ether ketone and the polyamide imide, so that the wear resistance of the polytetrafluoroethylene at normal temperature and high temperature can be effectively improved, and compared with the prior art, the wear resistance of the polytetrafluoroethylene at high temperature can be particularly effectively improved (the wear resistance of the polytetrafluoroethylene at high temperature is difficult to improve).
Detailed Description
In order that the invention may be more fully understood, a more particular description of the invention will now be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Other than as shown in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients, physical and chemical properties, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". For example, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can be suitably varied by those skilled in the art in seeking to obtain the desired properties utilizing the teachings disclosed herein. The use of numerical ranges by endpoints includes all numbers within that range and any range within that range, for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4, and 5, and the like.
The embodiment of the invention provides a preparation method of a modified polytetrafluoroethylene composite material, which comprises the following steps of pressing and sintering mixed powder; the mixed powder comprises the following components in percentage by weight: 57-85% of polytetrafluoroethylene, 8-18% of polyphenyl ester, 5-20% of polyether-ether-ketone and 2-5% of polyamide-imide.
The polyphenyl ester can improve the adsorption capacity of the transfer membrane, microfibers are easily formed in a molten state, the wear resistance of the polytetrafluoroethylene can be improved to a certain degree at normal temperature, and the wear resistance of the polytetrafluoroethylene can be obviously improved at high temperature, so that the problem of high-temperature thermal deformation of the composite material in a cross mill can be solved by adding the polyphenyl ester. The "transfer film" refers to that when the modified polytetrafluoroethylene composite material is in a working state, the modified polytetrafluoroethylene composite material and other materials are subjected to counter-grinding, fragments are grinded off and transferred to be adhered to the surface of the counter-grinding material in a transferring way in the friction process to form a layer of thin film, and the thin film is called as the transfer film in tribology. If the transfer film can be stably adsorbed on the surface of the counter-grinding material, the counter-grinding in the later stage is the counter-grinding of the modified polytetrafluoroethylene composite material and the modified polytetrafluoroethylene composite material (namely, the transfer film) on the surface of the counter-grinding material, so that the friction coefficient of a system can be remarkably reduced, and the abrasion of the modified polytetrafluoroethylene composite material can also be remarkably reduced.
The hardness of the polyetheretherketone is higher than that of the polytetrafluoroethylene, the polyetheretherketone can play a role of framework support in the composite material, and most external loads can be borne in the counter-grinding. At normal temperature, the wear modification effect of the polyetheretherketone is the best, but at high temperature, the modification effect is general.
The polyamide-imide has high strength, rigidity, wear resistance and creep resistance at high temperature, and generally shows normal performance at normal temperature, but can obviously play a role in wear resistance after being added in a small amount at high temperature.
According to the preparation method of the modified polytetrafluoroethylene composite material provided by the embodiment of the invention, the wear resistance of polytetrafluoroethylene at normal temperature and high temperature can be effectively improved by synergistically modifying the polytetrafluoroethylene with three organic fillers of polyphenyl ester, polyether ether ketone and polyamide imide, compared with the prior art, the wear resistance of the polytetrafluoroethylene at high temperature can be particularly effectively improved (the wear resistance of the polytetrafluoroethylene at high temperature is difficult to improve), the modified polytetrafluoroethylene composite material prepared by the preparation method is used for manufacturing a sealing element for an aeroengine, the problem of oil leakage of the sealing element for the aeroengine can be effectively reduced, and the sealing property of the sealing element for the aeroengine is greatly improved.
In the mixed powder, the weight percentage content of the polytetrafluoroethylene can be any value between 57% and 85%, for example, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%. In some preferred embodiments, the mixed powder contains 57 to 71 weight percent of polytetrafluoroethylene.
In the mixed powder, the weight percentage content of the polyphenyl ester can be any value between 8% and 18%, for example, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16% and 17%. In some preferred embodiments, the weight percentage of the polyphenyl ester in the mixed powder is 10% to 18%.
In the mixed powder, the weight percentage content of the polyether-ether-ketone can be any value between 5% and 20%, for example, 8%, 10%, 12%, 14%, 16%, 18%. In some preferred embodiments, the mixed powder contains 13% to 20% by weight of polyetheretherketone.
In the mixed powder, the polyamide imide may be present in an amount of 2 to 5% by weight, for example, 2.5%, 3%, 3.5%, 4%, 4.5%. In some preferred embodiments, the polyamide imide is present in the mixed powder in an amount of 3 to 5 wt%.
In some preferred embodiments, the mixed powder comprises the following components in percentage by weight: 57-71% of polytetrafluoroethylene, 10-18% of polyphenyl ester, 13-20% of polyether-ether-ketone and 3-5% of polyamide-imide.
In some preferred embodiments, the mixed powder comprises the following components in percentage by weight: 57-71% of polytetrafluoroethylene, 10-18% of polyphenyl ester, 13-20% of polyether-ether-ketone and 3-5% of polyamide-imide.
The average particle diameter of the polytetrafluoroethylene powder may be any value between 50 μm and 100 μm, and may be 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, or 95 μm, for example.
The average particle diameter of the polyphenyl ester powder can be any value between 30 μm and 40 μm, and can be 32 μm, 34 μm, 36 μm and 38 μm.
The mean particle diameter of the polyether-ether-ketone powder may be any value between 30 μm and 40 μm, and may be, for example, 32 μm, 34 μm, 36 μm, or 38 μm.
The average particle diameter of the polyamide imide powder may be any value between 30 μm and 40 μm, and may be, for example, 32 μm, 34 μm, 36 μm, or 38 μm.
In some preferred embodiments, the polyphenyl ester powder, the polyetheretherketone powder and the polyamideimide powder have the same average particle size.
In some embodiments, the method for preparing the mixed powder comprises:
stirring and mixing polytetrafluoroethylene, polyphenyl ester, polyether-ether-ketone and polyamide-imide to form a uniform mixture, wherein the stirring speed is 650 r/min-1000 r/min, and the stirring time is 3 min-5 min;
the stirring speed can also be independently selected from 700r/min, 750r/min, 800r/min, 850r/min and 900 r/min;
the stirring time can also be independently selected from 3.5min, 4min and 4.5 min.
The mixing method with stirring within the above parameters can make the mixing among the polytetrafluoroethylene, the polyphenyl ester, the polyether ether ketone and the polyamide imide more uniform.
Further, in some embodiments, before the mixed powder is pressed, a step of standing the mixed powder in a room temperature environment is further included, and the step is added to facilitate unwinding of the PTFE macromolecule to complete phase transition.
In some embodiments, the pressing is cold pressing, the pressing pressure is 27-37 Mpa, and the pressing time is 5-15 s;
the pressing pressure can also be independently selected from 28 Mpa, 30 Mpa, 32 Mpa, 34 Mpa and 36 Mpa;
the pressing time may also be independently selected from 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14 s.
In some embodiments, the sintering temperature is 380-385 ℃, and the holding time is 1-5 h;
the sintering temperature can also be 381 ℃, 382 ℃, 383 ℃ and 384 ℃;
the heat preservation time can also be 1.5h, 2h, 2.5h, 3h, 3.5h, 4h and 4.5 h.
In another aspect of the present invention, there is provided a modified polytetrafluoroethylene composite prepared according to the method for preparing a modified polytetrafluoroethylene composite.
In still another aspect of the present invention, there is provided a sealing member made of the modified polytetrafluoroethylene composite.
The sealing member may be used as a sealing ring such as a rectangular ring, a U-shaped seal, etc., a dust seal, etc., and is particularly preferable as a sealing ring for use in a high-temperature environment.
In some preferred embodiments, the sealing element is a sealing element for an aircraft engine.
The following are specific examples. The present invention is intended to be further described in detail to assist those skilled in the art and researchers to further understand the present invention, and the technical conditions and the like do not limit the present invention. Any modification made within the scope of the claims of the present invention is within the scope of the claims of the present invention. The following is an English reference description of the invention:
PTFE: polytetrafluoroethylene, POB: polyphenyl esters, PEEK: polyether ether ketone, PAI: polyamideimide, PDA: poly-dopamine.
The polytetrafluoroethylene powder used in the following examples and comparative examples had a particle size of about 80 μm, and the polyphenylene ether, polyether ether ketone and polyamide imide powder had a particle size of about 35 μm, which was approximately the same.
Example 1
1. Mixing 8g of polyphenyl ester powder, 5g of polyether ether ketone powder and 2g of polyamide imide powder in a high-speed mixer, intermittently mixing for 3min, adding 85g of polytetrafluoroethylene powder, mixing, and intermittently mixing for 2 min.
2. Placing the mixed powder in a room temperature (23-25 ℃) environment for 24 hours, then placing the composite powder in a steel mould for powder cold pressing and pressing, wherein the pressing pressure is 27Mpa, obtaining a prefabricated part, then placing the prefabricated part in a sintering furnace for high-temperature sintering, and the sintering temperature is 380 ℃, and finally obtaining the modified polytetrafluoroethylene sealing element blank for the aircraft engine.
Example 2
1. 13g of polyphenyl ester powder, 13g of polyether ether ketone powder and 3g of polyamide imide powder are mixed in a high-speed mixer, and are mixed intermittently for 3min, and then 71g of polytetrafluoroethylene powder is added and mixed intermittently for 2 min.
2. Placing the mixed powder in a room temperature (23-25 ℃) environment for 24 hours, then placing the composite powder in a steel mould for powder cold pressing and pressing, wherein the pressing pressure is 27Mpa, obtaining a prefabricated part, then placing the prefabricated part in a sintering furnace for high-temperature sintering, and the sintering temperature is 380 ℃, and finally obtaining the modified polytetrafluoroethylene sealing element blank for the aircraft engine.
Example 3
1. Mixing 18g of polyphenyl ester powder, 20g of polyether ether ketone powder and 5g of polyamide imide powder in a high-speed mixer, intermittently mixing for 3min, adding 57g of polytetrafluoroethylene powder, mixing, and intermittently mixing for 2 min.
2. Placing the mixed powder in a room temperature (23-25 ℃) environment for 24 hours, then placing the composite powder in a steel mould for powder cold pressing and pressing, wherein the pressing pressure is 35Mpa, obtaining a prefabricated part, then placing the prefabricated part in a sintering furnace for high-temperature sintering, and the sintering temperature is 385 ℃, and finally obtaining the modified polytetrafluoroethylene sealing element blank for the aircraft engine.
Example 4
1. 10g of polyphenyl ester powder, 15g of polyether ether ketone powder and 4g of polyamide imide powder are mixed in a high-speed mixer, and are mixed intermittently for 3min, and then 71g of polytetrafluoroethylene powder is added and mixed intermittently for 2 min.
2. Placing the mixed powder in a room temperature (23-25 ℃) environment for 24 hours, then placing the composite powder in a steel mould for powder cold pressing at 37Mpa to obtain a prefabricated part, then placing the prefabricated part in a sintering furnace for high-temperature sintering at 385 ℃, and finally obtaining the modified polytetrafluoroethylene sealing element blank for the aircraft engine.
Example 5
1. Mixing 15g of polyphenyl ester powder, 8g of polyether ether ketone powder and 2g of polyamide imide powder in a high-speed mixer, intermittently mixing for 3min, adding 75g of polytetrafluoroethylene powder, mixing, and intermittently mixing for 2 min.
2. Placing the mixed powder in a room temperature (23-25 ℃) environment for 28 hours, then placing the composite powder in a steel mould for powder cold pressing at 37Mpa to obtain a prefabricated part, then placing the prefabricated part in a sintering furnace for high-temperature sintering at 385 ℃, and finally obtaining the modified polytetrafluoroethylene sealing element blank for the aircraft engine.
Comparative example 1
Placing 100g of polytetrafluoroethylene powder in a room temperature (23-25 ℃) environment for 24 hours, then placing the powder in a steel mould for powder cold pressing and pressing, wherein the pressing pressure is 27Mpa, obtaining a prefabricated part, then placing the prefabricated part in a sintering furnace for high-temperature sintering, and the sintering temperature is 380 ℃, and finally obtaining a polytetrafluoroethylene sealing element blank for an aeroengine.
Comparative example 2
1. 15g of polyphenyl ester powder and 85g of polytetrafluoroethylene powder are mixed in a high-speed mixer and mixed intermittently for 3 min.
2. Placing the mixed powder in a room temperature (23-25 ℃) environment for 24 hours, then placing the composite powder in a steel mould for powder cold pressing and pressing, wherein the pressing pressure is 27Mpa, obtaining a prefabricated part, then placing the prefabricated part in a sintering furnace for high-temperature sintering, and the sintering temperature is 380 ℃, and finally obtaining the modified polytetrafluoroethylene sealing element blank for the aircraft engine.
Comparative example 3
1. 20g of polyetheretherketone powder and 80g of polytetrafluoroethylene powder were mixed in a high-speed mixer and mixed intermittently for 3 min.
2. Placing the mixed powder in a room temperature (23-25 ℃) environment for 24 hours, then placing the composite powder in a steel mould for powder cold pressing and pressing, wherein the pressing pressure is 27Mpa, obtaining a prefabricated part, then placing the prefabricated part in a sintering furnace for high-temperature sintering, and the sintering temperature is 380 ℃, and finally obtaining the modified polytetrafluoroethylene sealing element blank for the aircraft engine.
Comparative example 4
1.5 g of polyamideimide powder and 95g of polytetrafluoroethylene powder were mixed in a high-speed mixer, and intermittently mixed for 3 min.
2. Placing the mixed powder in a room temperature (23-25 ℃) environment for 24 hours, then placing the composite powder in a steel mould for powder cold pressing and pressing, wherein the pressing pressure is 27Mpa, obtaining a prefabricated part, then placing the prefabricated part in a sintering furnace for high-temperature sintering, and the sintering temperature is 380 ℃, and finally obtaining the modified polytetrafluoroethylene sealing element blank for the aircraft engine.
Comparative example 5
1. 15g of polyphenyl ester powder, 20g of polyether ether ketone powder and 65g of polytetrafluoroethylene powder are mixed in a high-speed mixer and mixed intermittently for 5 min.
2. Placing the mixed powder in a room temperature (23-25 ℃) environment for 24 hours, then placing the composite powder in a steel mould for powder cold pressing and pressing, wherein the pressing pressure is 27Mpa, obtaining a prefabricated part, then placing the prefabricated part in a sintering furnace for high-temperature sintering, and the sintering temperature is 380 ℃, and finally obtaining the modified polytetrafluoroethylene sealing element blank for the aircraft engine.
Comparative example 6
1. 15g of polyphenylene ether powder, 5g of polyamideimide powder and 80g of polytetrafluoroethylene powder were mixed in a high-speed mixer and intermittently mixed for 5 minutes.
2. Placing the mixed powder in a room temperature (23-25 ℃) environment for 24 hours, then placing the composite powder in a steel mould for powder cold pressing and pressing, wherein the pressing pressure is 27Mpa, obtaining a prefabricated part, then placing the prefabricated part in a sintering furnace for high-temperature sintering, and the sintering temperature is 380 ℃, and finally obtaining the modified polytetrafluoroethylene sealing element blank for the aircraft engine.
Comparative example 7
1. 20g of polyether ether ketone powder, 5g of polyamide imide powder and 75g of polytetrafluoroethylene powder were mixed in a high-speed mixer, and intermittently mixed for 5 minutes.
2. Placing the mixed powder in a room temperature (23-25 ℃) environment for 24 hours, then placing the composite powder in a steel mould for powder cold pressing and pressing, wherein the pressing pressure is 27Mpa, obtaining a prefabricated part, then placing the prefabricated part in a sintering furnace for high-temperature sintering, and the sintering temperature is 380 ℃, and finally obtaining the modified polytetrafluoroethylene sealing element blank for the aircraft engine.
The raw material compositions of the modified polytetrafluoroethylene or polytetrafluoroethylene parts prepared in examples 1-5 and comparative examples 1-7 are listed in table 1, the blank parts prepared in examples 1-5 and comparative examples 1-7 are subjected to tribological property tests at room temperature and high temperature, the blank parts prepared in examples 1-5 and comparative examples 1-7 are used as aeroengine sealing elements, equivalent simulation experiments are respectively carried out on the working environments of the aeroengine at room temperature and high temperature, the sealing performance is examined by testing the oil leakage amount, and the results are shown in table 1 below, wherein the raw material proportions are calculated by weight percent of the whole composite material:
the test conditions or test standards of each performance test item are as follows:
1. and (3) testing tribological properties: a GCr15 bearing steel ball (phi =4mm, Ra =0.04 μm) and the samples of the workpieces prepared in the examples 1-5 and the comparative examples 1-7 are selected to carry out a counter-grinding experiment, the steel ball is fixed on the sensor and is in close contact with the surface of the sample, the sample is fixed on the test bench and rotates along with the test bench, and the steel ball rotates on the surface of the sample under the principle of relative motion and leaves grinding marks. The test was carried out at a rotational linear speed of 200r/min, a rotational radius of 3mm and a positive pressure (Fz) of 2N applied. And (3) testing the volume wear rate by adopting a NexView three-dimensional white light interferometer, and testing the friction coefficient by adopting a controllable environment friction wear tester UMT.
2. Oil leakage of equivalent simulation experiment:
according to the working mechanism of the sealing position of the aircraft engine and the analysis of the actual working condition of the trial run of the engine pedestal, the main factors influencing the sealing oil leakage, such as load, vibration, working temperature and working spectrum, are obtained. For these factors, test conditions were set up for simulation. And (3) simulating the load borne by the sealing mechanism during the engine bench test, and designing a load simulation device. Axial load is applied through the hydraulic device, radial load is applied through the pneumatic device, and the axial load and the radial load act together to simulate the load borne by a mechanism at the sealing position. The closed circulation temperature control device of the tester controls the temperature of the fuel oil at the inlet of the test piece, so that the temperature of the sealing mechanism is basically consistent with the test-run temperature of the rack.
The actual test load and temperature are obtained through the equivalent simulation conversion, the experiment cycle number is 200 ten thousand, and the equivalent stroke reciprocating experiment is 1 ten thousand hours. The specific experimental operation is carried out according to national standard GB/T32217-. Wherein the diameter of the piston rod is phi 36mm, the surface of the piston rod is plated with hard chromium, the surface roughness Ra = 0.10-0.15, the hardness of the nitrile rubber dust ring is 72-75 IRHD; the amount of oil leakage was measured using a measuring cup.
TABLE 1
As can be seen from Table 1:
(1) through comparative analysis of examples 1-5 and comparative examples 1-7, it can be seen that compared with pairwise modification and independent modification of polyphenyl ester, polyether ether ketone and polyamide imide, the wear rate of the polytetrafluoroethylene composite material synergistically modified by polyphenyl ester, polyether ether ketone and polyamide imide provided by the invention at normal temperature and high temperature is remarkably reduced, and the oil leakage is low, so that the sealing element for the aircraft engine prepared from the polytetrafluoroethylene composite material has better sealing performance.
(2) Through comparative analysis of the embodiments 1 and 5 and the embodiments 2, 3 and 4, in the modified polytetrafluoroethylene composite material, the weight percentage of polytetrafluoroethylene is preferably 57-71%, the weight percentage of polyphenyl ester is preferably 10-18%, the weight percentage of polyether-ether-ketone is preferably 13-20%, and the weight percentage of polyamide-imide is preferably 3-5%. Particularly, for the sealing element prepared from the modified polytetrafluoroethylene composite material in example 3, the sealing effect is close to the normal temperature sealing effect in a high temperature environment of 180 ℃, and the wear resistance is not obviously reduced due to high temperature.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. The preparation method of the modified polytetrafluoroethylene composite material is characterized by comprising the steps of pressing and sintering mixed powder;
the mixed powder comprises the following components in percentage by weight:
57-85% of polytetrafluoroethylene
8-18% of polyphenyl ester
5-20% of polyether-ether-ketone
2% -5% of polyamide-imide.
2. The preparation method of the modified polytetrafluoroethylene composite material as claimed in claim 1, wherein the mixed powder comprises the following components in percentage by weight:
57-71 percent of polytetrafluoroethylene
10-18% of polyphenyl ester
13-20% of polyether-ether-ketone
3% -5% of polyamide-imide.
3. The method for producing a modified polytetrafluoroethylene composite according to claim 1 or 2, wherein said polytetrafluoroethylene has an average particle diameter of 50 to 100 μm.
4. The method for preparing a modified polytetrafluoroethylene composite according to claim 1 or 2, wherein said polyphenylene ether, said polyether ether ketone and said polyamide imide powder have the same average particle size of 30 μm to 40 μm.
5. The preparation method of the modified polytetrafluoroethylene composite material according to claim 1 or 2, wherein the pressing is cold pressing, the pressing pressure is 27-37 Mpa, and the pressing time is 5-15 s.
6. The preparation method of the modified polytetrafluoroethylene composite material according to claim 1 or 2, wherein the sintering temperature is 380-385 ℃, and the heat preservation time is 1-5 h.
7. The method for preparing a modified polytetrafluoroethylene composite according to claim 1 or 2, wherein said method for preparing a mixed powder comprises:
stirring and mixing polytetrafluoroethylene, polyphenyl ester, polyether-ether-ketone and polyamide-imide to form a uniform mixture, wherein the stirring speed is 650 r/min-1000 r/min, and the stirring time is 3 min-5 min.
8. The modified polytetrafluoroethylene composite obtained by the method for producing a modified polytetrafluoroethylene composite according to any one of claims 1 to 7.
9. A sealing member made of the modified polytetrafluoroethylene composite as set forth in claim 8.
10. The sealing element of claim 9, wherein the sealing element is an aircraft engine sealing element.
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