A method for preparing reinforced polyetheretherketone porous self-lubricating materials

Abstract

This invention discloses a method for preparing a reinforced polyetheretherketone (PEEK) porous self-lubricating material. The main steps are as follows: Step 1: Grind the dried composite powder and mix it with additive powder, ball mill to homogenize, and then dry the homogenized composite powder. The composite powder includes carbon fiber or carbon nanotubes, PEEK powder, and NaCl powder. Step 2: Prepare PEEK / CF / NaCl or PEEK / CNTS / NaCl composite filaments using a twin-screw extruder. Step 3: Prepare samples using FDM printing with the composite filaments. Step 4: Clean the samples obtained in Step 3 using a water washing method. Step 5: Heat-treat the samples to obtain heat-treated composite material samples. Step 6: Immerse the treated composite material samples in lubricating oil and place them in a vacuum chamber to obtain porous self-lubricating samples. This invention provides a controllable and efficient preparation of self-lubricating composite materials. The introduction of carbon fiber or carbon nanotube reinforcing phases and the implementation of the heat treatment process effectively improve the lubrication environment of the friction pair and enhance the self-lubricating performance of the material.

Description

Technical Field

[0001] This invention belongs to the field of bearing cage material technology, specifically a method for preparing a reinforced polyether ether ketone porous self-lubricating material. Background Technology

[0002] Aerospace bearing cages are critical components of aerospace equipment, and their lubrication performance directly affects the service life and accuracy of transmission components. However, the complex service environment makes it difficult to replenish lubricating oil, so conventional lubrication conditions are no longer sufficient to meet their lifespan and performance requirements. To effectively overcome this deficiency, the development of self-lubricating bearing cage materials for use in complex environments is highly anticipated.

[0003] Domestic and international scholars have conducted extensive and systematic research, achieving fruitful results. The main approaches to improving the self-lubricating efficiency of cage materials can be summarized as: improving the wear resistance of friction pair materials and constructing an internal oil-retaining structure for the self-lubricating material. In light of this, research on polyetheretherketone-based porous self-lubricating materials has emerged.

[0004] For polyetheretherketone (PEEK)-based porous self-lubricating materials, existing preparation processes mainly include template filtration and hot-pressing sintering. These processes can effectively reduce production costs, but the porous self-lubricating materials prepared using these processes generally suffer from problems such as disordered internal microstructure, poor connectivity, low oil content, and difficulty in balancing mechanical and self-lubricating properties. Furthermore, the complex coupling effect of the matrix material's microstructure characteristics on self-lubricating performance makes it difficult to improve and balance its macroscopic tribological and mechanical properties, which is a bottleneck hindering the development of this type of material. Moreover, for fiber-reinforced PEEK porous self-lubricating materials, existing methods generally suffer from poor molding effects and difficulty in guaranteeing overall performance. In conclusion, elucidating the mapping mechanism between the microstructure and macroscopic properties of self-lubricating porous materials, exploring an efficient and high-quality molding approach, and achieving integrated design and manufacturing of materials, structures, and properties are key to promoting the development of high-performance porous self-lubricating materials. This is also of great significance for ensuring the operational accuracy and service life of their applications. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a method for preparing reinforced polyether ether ketone porous self-lubricating materials. This method allows for the controllable and efficient preparation of self-lubricating composite materials. Furthermore, the introduction of carbon fiber or carbon nanotube reinforcing phases and the implementation of heat treatment processes can effectively improve the lubrication environment of the friction pair and enhance the self-lubricating performance of the material.

[0006] This invention is achieved through the following technical solution:

[0007] A method for preparing a reinforced polyetheretherketone porous self-lubricating material mainly includes the following steps:

[0008] Step 1: Drying and mixing of powder materials

[0009] The dried composite powder is ground separately and then mixed with additive powder. The mixture is homogenized in a ball mill and then placed in an oven to dry. The composite powder includes carbon fiber or carbon nanotubes, PEEK powder, and NaCl powder.

[0010] Step 2: Preparation of Fiber

[0011] PEEK / CF / NaCl or PEEK / CNTS / NaCl composite filaments were prepared using a twin-screw extruder.

[0012] Step 3: Sample Preparation

[0013] Samples were prepared using FDM printing with PEEK / CF / NaCl or PEEK / CNTS / NaCl composite filaments.

[0014] Step 4: Sample Post-processing

[0015] The sample obtained in step three was cleaned using a water washing method;

[0016] Step 5: Heat treatment of the sample

[0017] The sample is then heat-treated to obtain a heat-treated composite material sample.

[0018] Step Six: Oil Immersion Treatment

[0019] The treated composite material sample was immersed in lubricating oil and placed in a vacuum chamber for 11-13 hours to obtain a porous self-lubricating sample.

[0020] Furthermore, the carbon fiber powder and carbon nanotubes mentioned in step one are pretreated carbon fiber powder and pretreated carbon nanotubes, respectively. The pretreatment method is as follows: place the carbon fiber or carbon nanotubes in a Soxhlet extractor, reflux with acetone for 48 h, then rinse with ethanol and dry in a vacuum oven at 120°C for 2 h, ultrasonically disperse the treated carbon fiber or carbon nanotubes for 5 h, and then dry them in an oven for later use.

[0021] Furthermore, in step one, after grinding the composite powders separately, NaCl is passed through a 325-mesh sieve to ensure a NaCl particle size of less than 48 μm, PEEK particles are 200 mesh, CF particles are 100 mesh, and the carbon nanotubes have the following parameters: absorbance of 30-50 nm, purity > 98%, length < 10 μm, and specific surface area > 100 m². 2 / g, ash content <1.5, COOH content is 0.73.

[0022] Furthermore, the additive powder mentioned in step one includes diisononyl cyclohexane 1,2-dicarboxylate and modified nano-calcium carbonate.

[0023] Furthermore, the preparation method of the modified nano-calcium carbonate is as follows: nano-calcium carbonate is ultrasonically dispersed in deionized water for 30 min, then heated to 90°C in a water bath. The heated and molten sodium stearate is added to the slurry, and the reaction is maintained at 90°C for 2 h. The mixture is then filtered, the filter cake is washed with hot anhydrous ethanol solution, dried, ground, and sieved to obtain the modified nano-calcium carbonate.

[0024] Furthermore, after the PEEK / CF / NaCl or PEEK / CNTS / NaCl composite filament is prepared in step two, it is stored in an oven at 60°C.

[0025] Furthermore, when using PEEK / CF / NaCl composite filament in step three, the FDM printing process parameters are as follows: nozzle diameter is 1.0 mm, nozzle temperature is 420℃, printing speed is 30 mm / s, and printing layer thickness is 0.2 mm.

[0026] Furthermore, in step three, when using a PEEK / CNTS / NaCl composite filament, the FDM printing process parameters are as follows: nozzle diameter is 0.8 mm, nozzle temperature is 430℃, printing speed is 60 mm / s, and printing layer thickness is 0.2 mm.

[0027] Furthermore, the water washing method in step four is as follows: the printed device model is placed in an ultrasonic cleaner for 48 hours, during which time it is stirred with an electric stirrer. Finally, the sample is taken out and dried in a 120°C oven at a low temperature for 5 hours.

[0028] Furthermore, the heat treatment process parameters in step five are as follows: the oven heating rate is set to 8℃ / min, the temperature is raised to 260℃ and held for 90min, then the temperature is raised to 300℃ at a heating rate of 8℃ / min and held for 2h, and then the oven is taken out and cooled naturally.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. Based on the FDM process, this invention can successfully prepare porous PEEK-based structural parts with different carbon fiber contents. The core processes, such as extrusion and printing parameters, are basically the same, which improves production efficiency and reduces production costs to a certain extent.

[0031] 2. This invention introduces carbon fibers or carbon nanotubes into the preparation of PEEK-based porous materials based on FDM process. Compared with ordinary porous structural parts without carbon fibers or carbon nanotubes, the addition of carbon fibers or carbon nanotubes can significantly improve the dry friction performance of self-lubricating materials. Moreover, the improvement effect is more obvious as the content of carbon fibers or carbon nanotubes increases, and the oil-deficient lubrication performance can also be improved to a certain extent.

[0032] 3. This invention uses diisononyl cyclohexane-1,2-dicarboxylate (also known as Hexamoll DINCH) as a plasticizer and modified nano-calcium carbonate as a dispersant to improve the extrusion and printing performance of the matrix material. The printed parts are also heat-treated. This invention can controllably and efficiently prepare self-lubricating composite materials. At the same time, the introduction of carbon fiber or carbon nanotube reinforcing phase and the implementation of heat treatment process can effectively improve the lubrication environment of the friction pair and improve the self-lubricating performance of the material. Attached Figure Description

[0033] Figure 1 The PEEK / CF / NaCl composite filament with a CF mass fraction of 0.5% was prepared in Example 1 of this invention.

[0034] Figure 2 The microstructure of the porous sample of PEEK / CF / NaCl composite filament with a CF mass fraction of 0.5% prepared in Example 1 of this invention is shown.

[0035] Figure 3 The PEEK / CF / NaCl composite filament with a CF mass fraction of 1% was prepared in Example 2 of this invention;

[0036] Figure 4 The microstructure of the porous sample of PEEK / CF / NaCl composite filament with a CF mass fraction of 1% prepared in Example 2 of this invention is shown.

[0037] Figure 5 The PEEK / CF / NaCl composite filament with a CF mass fraction of 3% was prepared in Example 3 of this invention;

[0038] Figure 6 The microstructure of the porous sample of PEEK / CF / NaCl composite filament with a CF mass fraction of 3% prepared in Example 3 of this invention is shown.

[0039] Figure 7 The PEEK / CNTS / NaCl composite filament with a CNTS mass fraction of 0.5% was prepared in Example 4 of this invention;

[0040] Figure 8 The microstructure of the porous sample of PEEK / CNTS / NaCl composite filament with a CNTS mass fraction of 0.5% prepared in Example 4 of this invention is shown.

[0041] Figure 9 The PEEK / CNTS / NaCl composite filament with a CNTS mass fraction of 1% was prepared in Example 5 of this invention;

[0042] Figure 10The microstructure of the porous sample of PEEK / CNTS / NaCl composite wire with a CNTS mass fraction of 1% prepared in Example 5 of this invention;

[0043] Figure 11 The PEEK / CNTS / NaCl composite filament with a CNTS mass fraction of 3% was prepared in Example 6 of this invention;

[0044] Figure 12 The microstructure of the porous sample of PEEK / CNTS / NaCl composite wire with a CNTS mass fraction of 3% prepared in Example 6 of this invention;

[0045] Figure 13 This is a flowchart illustrating the preparation process of the present invention. Detailed Implementation

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0047] To fully verify the rationality and feasibility of the experimental scheme, in this embodiment, PEEK was used as the matrix material and NaCl was used as the pore-forming agent. Three types of composite materials with CF or CNTS contents of 0.5wt%, 1wt%, and 3wt% were prepared by FDM process. For ease of description and understanding, each sample was numbered as shown in Table 1, and their self-lubricating properties were tested respectively.

[0048]

[0049] The specific implementation steps are as follows.

[0050] Example 1: Preparation of PEEK / CF / NaCl composite material with CF mass fraction of 0.5% and pore-forming agent mass fraction of 50%.

[0051] Step 1: Drying and mixing of powder materials

[0052] Appropriate amounts of NaCl and PEEK powder were weighed at a mass ratio of 1:1 and placed in an oven to dry at 120℃ for 12 hours. Carbon fiber was weighed at 0.5 wt% of the PEEK / NaCl matrix in the composite material and dried in an oven at 80℃ for 6 hours. Diisononyl cyclohexane-1,2-dicarboxylate was weighed at 0.5 wt% of the PEEK / NaCl matrix in the composite material. Modified nano-calcium carbonate was weighed at 1 wt% of the PEEK / NaCl matrix in the composite material. The preparation method of the modified nano-calcium carbonate was as follows: Nano-calcium carbonate was ultrasonically dispersed in deionized water for 30 minutes, then heated to 90℃ in a water bath. Molten sodium stearate was added to the slurry, and the reaction was maintained at 90℃ for 2 hours. The mixture was then filtered, the filter cake was washed with hot anhydrous ethanol solution, dried, ground, and sieved.

[0053] PEEK, CF, and NaCl were separately ground and then mixed with additive powders (diisononyl cyclohexane-1,2-dicarboxylate and modified nano-calcium carbonate). The mixture was then homogenized in a ball mill for 8 hours, and the resulting powder was placed in an oven and dried at 120°C for 10 hours. It is important to note that the particle size of the NaCl powder should be smaller than that of the PEEK powder. This not only enhances the uniformity of the powder mixture but also ensures the strength and toughness of the filaments at the same porosity. Furthermore, to ensure the continuity of the carbon fibers in the matrix material and thus better exert their reinforcing effect, larger-sized carbon fibers should be used while ensuring smooth molding of the composite material. In summary, in this example, NaCl was ground and passed through a 325-mesh sieve to obtain a pore-forming agent with a particle size less than 48 μm, PEEK had a particle size of 200 mesh, and CF had a particle size of 100 mesh.

[0054] To enhance the interfacial bonding performance between carbon fiber and matrix material, and to prevent the carbon fiber from agglomerating in large quantities inside the porous component and thus affecting the pore-forming effect, the carbon fiber mentioned above is pretreated carbon fiber. The pretreatment steps for carbon fiber are as follows: the carbon fiber is placed in a Soxhlet extractor and washed with acetone reflux for 48 h, then rinsed with ethanol and dried in a vacuum oven at 120℃ for 2 h to reduce the influence of sizing agent and dust adhering to the surface. After the treated carbon fiber is ultrasonically dispersed for 5 h, it is placed in an oven to dry for later use.

[0055] Step 2: Preparation of Fiber

[0056] The key parameter in preparing PEEK / CF / NaCl composite filaments using a twin-screw extruder lies in the temperature settings of each heating zone. This directly affects the successful forming of the filament and its post-forming flexibility and printability. In this example, the temperature settings for each section of the twin-screw extruder are uniformly set as follows:

[0057] Table 2 Temperature settings for each heating zone of the twin-screw extruder

[0058]

[0059] Based on the above extrusion parameters, the prepared PEEK / CF / NaCl composite filament is as follows: Figure 1 As shown, the filaments were stored in a 60℃ oven after preparation.

[0060] Step 3: Sample Preparation

[0061] Samples were prepared using PEEK / CF / NaCl composite filament and FDM printing. The FDM process parameters were as follows: nozzle diameter 1.0 mm, nozzle temperature 420℃, printing speed 30 mm / s, and printing layer thickness 0.2 mm.

[0062] Step 4: Sample Post-processing

[0063] The sample obtained in step three was cleaned by water washing to remove the pore-forming agent inside the sample. The specific method is as follows: the printed device model was placed in an ultrasonic cleaner for 48 hours, during which time it was stirred with an electric stirrer. Finally, the sample was taken out and dried at low temperature in an oven at 120°C for 5 hours. The obtained sample was then subjected to a laser confocal test. Figure 2 The microstructure of a PEEK-based porous sample with a CF mass fraction of 0.5% is shown in the figure. As can be seen from the figure, NaCl still retains its excellent pore-forming ability after in-situ removal. The PEEK-based porous material has a relatively uniform framework and the pores are clearly visible.

[0064] Step 5: Heat treatment of the sample

[0065] To further improve the mechanical and tribological properties of the material, the prepared samples were heat-treated. For porous components with PEEK as the matrix material, the holding temperature, holding time, and heating rate are the three key factors affecting the overall performance of the molded parts. The heat treatment process parameters are as follows: the oven heating rate was set to 8℃ / min, the temperature was raised to 260℃ and held for 90 min, then the temperature was raised to 300℃ at a rate of 8℃ / min and held for 2 h. After removal, the samples were allowed to cool naturally, thus obtaining the heat-treated composite material samples.

[0066] Step Six: Oil Immersion Treatment

[0067] The treated composite material sample was immersed in lubricating oil and placed in a vacuum chamber for 11-13 hours to obtain a porous self-lubricating sample.

[0068] Self-lubricating performance test

[0069] Frictional properties are a key indicator for evaluating the performance of self-lubricating materials. To ensure that the porous structural component in this example meets the application requirements under harsh and complex conditions such as aerospace service environments, the tribological properties under both dry friction and lean-oil lubrication conditions are studied. The tribological properties of the samples before and after heat treatment were tested using an HT-1000 high-temperature friction and wear testing machine manufactured by Lanzhou Zhongke Kaihua Technology Development Co., Ltd. Test conditions: grinding ball material was 9Cr18, diameter was 5mm; applied load was 5N; friction radius was 5mm; rotational speed was set to 400r / min; test time was 30min. The friction coefficient values ​​output by the equipment were averaged to obtain the friction coefficient of different samples.

[0070] For comparison, dense PEEK samples and porous samples without carbon fiber were prepared under the same process conditions. Their average friction coefficients were as follows: Under dry friction conditions, the average friction coefficient of sample #1 was 0.29, and that of sample H1# was 0.263; under lean lubrication conditions, the average friction coefficient of sample #1 was 0.104, and that of sample H1# was 0.072. For the porous samples without carbon fiber (samples #2 and H2#), under dry friction conditions, the average friction coefficient of sample #2 was 0.366, and that of sample H2# was 0.286; under lean lubrication conditions, the average friction coefficient of sample #2 was 0.061, and that of sample H2# was 0.048.

[0071] In this example, the results are as follows: under dry friction conditions, the average friction coefficient of the untreated 3#CF sample is 0.264, and the average friction coefficient of the H3#CF sample is 0.241; under lean lubrication conditions, the average friction coefficient of the 3#CF sample is 0.059, and the average friction coefficient of the H3#CF sample is 0.045.

[0072] The average friction coefficient values ​​mentioned above can be summarized in Table 3 below:

[0073] Table 3. Average friction coefficients of each sample under different lubrication conditions

[0074]

[0075] Comparing the average friction coefficient results of dense PEEK samples and samples without carbon fiber, it is easy to see that the porous structure and the addition of 0.5% carbon fiber by mass endow the material with better dry friction performance and lean oil lubrication performance.

[0076] Example 2: Preparation of PEEK / CF / NaCl composite material with 1% CF mass fraction and 50% pore-forming agent mass fraction.

[0077] Step 1: Drying and mixing of powder materials

[0078] Appropriate amounts of NaCl and PEEK powder were weighed at a mass ratio of 1:1 and placed in an oven to dry at 120℃ for 12 hours. Carbon fiber was weighed at 1 wt% of the PEEK / NaCl matrix in the composite material and dried in an oven at 80℃ for 6 hours. Diisononyl cyclohexane-1,2-dicarboxylate was weighed at 0.5 wt% of the PEEK / NaCl matrix in the composite material. Modified nano-calcium carbonate was weighed at 1 wt% of the PEEK / NaCl matrix in the composite material. The preparation method of the modified nano-calcium carbonate is as follows: Nano-calcium carbonate was ultrasonically dispersed in deionized water for 30 minutes, then heated to 90℃ in a water bath. Molten sodium stearate was added to the slurry, and the reaction was maintained at 90℃ for 2 hours. The mixture was then filtered, the filter cake was washed with hot anhydrous ethanol solution, dried, ground, and sieved.

[0079] PEEK, CF, and NaCl were separately ground and then mixed with additive powders (diisononyl cyclohexane-1,2-dicarboxylate and modified nano-calcium carbonate). The mixture was then homogenized in a ball mill for 8 hours, and the resulting powder was placed in an oven and dried at 120°C for 10 hours. It is important to note that the particle size of the NaCl powder should be smaller than that of the PEEK powder. This not only enhances the uniformity of the powder mixture but also ensures the strength and toughness of the filaments at the same porosity. Furthermore, to ensure the continuity of the carbon fibers in the matrix material and thus better exert their reinforcing effect, larger-sized carbon fibers should be used while ensuring smooth molding of the composite material. In summary, in this example, NaCl was ground and passed through a 325-mesh sieve to obtain a pore-forming agent with a particle size less than 48 μm, PEEK had a particle size of 200 mesh, and CF had a particle size of 100 mesh.

[0080] To enhance the interfacial bonding performance between carbon fiber and matrix material, and to prevent the carbon fiber from agglomerating in large quantities inside the porous component and thus affecting the pore-forming effect, the carbon fiber mentioned above is pretreated carbon fiber. The pretreatment steps for carbon fiber are as follows: the carbon fiber is placed in a Soxhlet extractor and washed with acetone reflux for 48 h, then rinsed with ethanol and dried in a vacuum oven at 120℃ for 2 h to reduce the influence of sizing agent and dust adhering to the surface. After the treated carbon fiber is ultrasonically dispersed for 5 h, it is placed in an oven to dry for later use.

[0081] Step 2: Preparation of Fiber

[0082] The key parameter in preparing PEEK / CF / NaCl composite filaments using a twin-screw extruder lies in the temperature settings of each heating zone. This directly affects whether the filament can be successfully formed, as well as its flexibility and printability after forming. In this example, the temperature settings of each section of the twin-screw extruder are consistent with those in Example 1.

[0083] Based on the above extrusion parameters, the prepared PEEK / CF / NaCl composite filament is as follows: Figure 3 As shown, the filaments were stored in a 60℃ oven after preparation.

[0084] Step 3: Sample Preparation

[0085] Samples were prepared using PEEK / CF / NaCl composite filament and FDM printing. The FDM process parameters were as follows: nozzle diameter 1.0 mm, nozzle temperature 420℃, printing speed 30 mm / s, and printing layer thickness 0.2 mm.

[0086] Step 4: Sample Post-processing

[0087] The sample obtained in step three was cleaned by water washing to remove the pore-forming agent inside the sample. The specific method is as follows: the printed device model was placed in an ultrasonic cleaner for 48 hours, during which time it was stirred with an electric stirrer. Finally, the sample was taken out and dried at low temperature in an oven at 120°C for 5 hours. The obtained sample was then subjected to a laser confocal test. Figure 4 The microstructure morphology of a PEEK-based porous sample with a CF mass fraction of 1% is shown in the figure. As can be seen from the figure, the increased carbon fiber content did not affect the excellent pore-forming ability of NaCl. The PEEK-based porous material has a relatively uniform skeleton and the pores are clearly visible.

[0088] Step 5: Heat treatment of the sample

[0089] To further improve the mechanical and tribological properties of the material, the prepared samples were heat-treated. For porous components with PEEK as the matrix material, the holding temperature, holding time, and heating rate are the three key factors affecting the overall performance of the molded parts. The heat treatment process parameters are as follows: the oven heating rate was set to 8℃ / min, the temperature was raised to 260℃ and held for 90 min, then the temperature was raised to 300℃ at a rate of 8℃ / min and held for 2 h. After removal, the samples were allowed to cool naturally, thus obtaining the heat-treated composite material samples.

[0090] Step Six: Oil Immersion Treatment

[0091] The treated composite material sample was immersed in lubricating oil and placed in a vacuum chamber for 11-13 hours to obtain a porous self-lubricating sample.

[0092] Self-lubricating performance test

[0093] In this example, the test conditions are the same as in Example 1. The results are as follows: Under dry friction conditions, the average friction coefficient corresponding to sample 4#CF is 0.197, and the average friction coefficient corresponding to sample H4#CF is 0.195; Under lean lubrication conditions, the average friction coefficient corresponding to sample 4#CF is 0.057, and the average friction coefficient corresponding to sample H4#CF is 0.041.

[0094] The average friction coefficient values ​​mentioned above can be summarized in Table 4 below:

[0095] Table 4. Average friction coefficients of each sample under different lubrication conditions

[0096]

[0097] Comparing the average friction coefficient results of dense PEEK samples and samples without carbon fiber, it can be seen that the porous structure and the addition of 1% carbon fiber by mass also endow the material with better dry friction performance and lean oil lubrication performance.

[0098] Example 3: Preparation of PEEK / CF / NaCl composite material with 3% CF mass fraction and 50% pore-forming agent mass fraction.

[0099] Step 1: Drying and mixing of powder materials

[0100] Appropriate amounts of NaCl and PEEK powder were weighed at a mass ratio of 1:1 and placed in an oven to dry at 120℃ for 12 hours. Carbon fiber was weighed at 3 wt% of the PEEK / NaCl matrix in the composite material and dried in an oven at 80℃ for 6 hours. Diisononyl cyclohexane-1,2-dicarboxylate was weighed at 0.5 wt% of the PEEK / NaCl matrix in the composite material. Modified nano-calcium carbonate was weighed at 1 wt% of the PEEK / NaCl matrix in the composite material. The preparation method of the modified nano-calcium carbonate is as follows: Nano-calcium carbonate was ultrasonically dispersed in deionized water for 30 minutes, then heated to 90℃ in a water bath. Molten sodium stearate was added to the slurry, and the reaction was maintained at 90℃ for 2 hours. The mixture was then filtered, the filter cake was washed with hot anhydrous ethanol solution, dried, ground, and sieved.

[0101] PEEK, CF, and NaCl were separately ground and then mixed with additive powders (diisononyl cyclohexane-1,2-dicarboxylate and modified nano-calcium carbonate). The mixture was then homogenized in a ball mill for 8 hours, and the resulting powder was placed in an oven and dried at 120°C for 10 hours. It is important to note that the particle size of the NaCl powder should be smaller than that of the PEEK powder. This not only enhances the uniformity of the powder mixture but also ensures the strength and toughness of the filaments at the same porosity. Furthermore, to ensure the continuity of the carbon fibers in the matrix material and thus better exert their reinforcing effect, larger-sized carbon fibers should be used while ensuring smooth molding of the composite material. In summary, in this example, NaCl was ground and passed through a 325-mesh sieve to obtain a pore-forming agent with a particle size less than 48 μm, PEEK had a particle size of 200 mesh, and CF had a particle size of 100 mesh.

[0102] The carbon fibers mentioned above are pretreated carbon fibers. The pretreatment steps for carbon fibers are as follows: the carbon fibers are placed in a Soxhlet extractor and washed with acetone reflux for 48 h. Then, they are rinsed with ethanol and dried in a vacuum oven at 120℃ for 2 h to reduce the influence of sizing agents and dust adhering to the surface. After the treated carbon fibers are ultrasonically dispersed for 5 h, they are dried in an oven for later use.

[0103] Step 2: Preparation of Fiber

[0104] The key parameter in preparing PEEK / CF / NaCl composite filaments using a twin-screw extruder lies in the temperature settings of each heating zone, which directly affects the successful forming of the filament and its flexibility and printability after forming. In this example, the temperature settings of each section of the twin-screw extruder are consistent with those in Example 1.

[0105] Based on the above extrusion parameters, the prepared PEEK / CF / NaCl composite filament is as follows: Figure 2 As shown, the filaments were stored in a 60℃ oven after preparation.

[0106] Step 3: Sample Preparation

[0107] Samples were prepared using PEEK / CF / NaCl composite filament and FDM printing. The FDM process parameters were as follows: nozzle diameter 1.0 mm, nozzle temperature 420℃, printing speed 30 mm / s, and printing layer thickness 0.2 mm.

[0108] Step 4: Sample Post-processing

[0109] The sample obtained in step three was cleaned by water washing to remove the pore-forming agent inside the sample. The specific method is as follows: the printed device model was placed in an ultrasonic cleaner for 48 hours, during which time it was stirred with an electric stirrer. Finally, the sample was taken out and dried at low temperature in an oven at 120°C for 5 hours. The obtained sample was then subjected to a laser confocal test. Figure 6 The microstructure morphology of a PEEK-based porous sample with a carbon fiber content of 3% is shown. As can be seen from the figure, the skeleton of the PEEK-based porous material with a carbon fiber content of 3% is relatively uniform and the pores are clearly visible.

[0110] Step 5: Heat treatment of the sample

[0111] The prepared samples were subjected to heat treatment. The heat treatment process parameters were as follows: the oven heating rate was set to 8℃ / min, the temperature was raised to 260℃ and held for 90min, then the temperature was raised to 300℃ at a rate of 8℃ / min and held for 2h. After being removed and allowed to cool naturally, the heat-treated composite material samples were obtained.

[0112] Step Six: Oil Immersion Treatment

[0113] The treated composite material sample was immersed in lubricating oil and placed in a vacuum chamber for 11-13 hours to obtain a porous self-lubricating sample.

[0114] Self-lubricating performance test

[0115] In this example, the test conditions are the same as in Example 1. The results are as follows: Under dry friction conditions, the average friction coefficient corresponding to sample 5#CF is 0.127, and the average friction coefficient corresponding to sample H5#CF is 0.119; Under lean lubrication conditions, the average friction coefficient corresponding to sample 5#CF is 0.053, and the average friction coefficient corresponding to sample H5#CF is 0.033.

[0116] The average friction coefficient values ​​mentioned above can be summarized in Table 5 below:

[0117] Table 5. Average friction coefficients of each sample under different lubrication conditions.

[0118]

[0119] Comparing the average friction coefficient results of dense PEEK samples and samples without carbon fiber, it can be seen that the porous structure and the addition of 3% carbon fiber by mass endow the material with better dry friction and lean oil lubrication performance.

[0120] Example 4: Preparation of a PEEK / CNTS / NaCl composite material with a CNTS mass fraction of 0.5% and a pore-forming agent mass fraction of 50%.

[0121] Step 1: Drying and mixing of powder materials

[0122] Weigh appropriate amounts of NaCl and PEEK powder in a 1:1 mass ratio and dry them in an oven at 120℃ for 12 hours. Weigh 0.5 wt% of carbon nanotubes as part of the PEEK / NaCl matrix in the composite material and dry them in an oven at 80℃ for 6 hours. Weigh 0.5 wt% of diisononyl cyclohexane-1,2-dicarboxylate as part of the PEEK / NaCl matrix in the composite material. Weigh 1 wt% of modified nano-calcium carbonate as part of the PEEK / NaCl matrix in the composite material. The preparation method of modified nano-calcium carbonate is as follows: Disperse nano-calcium carbonate with deionized water using ultrasound for 30 minutes, then heat to 90℃ in a water bath. Add the molten sodium stearate to the slurry, maintain the reaction at 90℃ for 2 hours, filter, wash the filter cake with hot anhydrous ethanol solution, and then dry, grind, and sieve.

[0123] PEEK, carbon nanotubes, and NaCl were separately ground and then mixed with additive powders (diisononyl cyclohexane-1,2-dicarboxylate and modified nano-calcium carbonate). The mixture was then homogenized in a ball mill for 8 hours, and the resulting powder was dried in an oven at 120°C for 10 hours. It is important to note that the particle size of the NaCl powder should be smaller than that of the PEEK powder. This not only enhances the uniformity of the powder mixture but also ensures the strength and toughness of the filaments at the same porosity. To ensure the continuity of the carbon nanotubes in the matrix material and thus better exert their reinforcing effect, larger-sized carbon nanotubes should be used, provided that the composite material can be successfully molded. In summary, in this example, NaCl was ground and passed through a 325-mesh sieve to obtain a pore-forming agent with a particle size less than 48 μm, PEEK had a particle size of 200 mesh, and the main parameters of the carbon nanotubes used are shown in Table 6.

[0124] Table 6 Main parameters of carbon nanotubes

[0125]

[0126] To enhance the interfacial bonding performance between carbon fiber and matrix material, and to prevent the carbon fiber from agglomerating in large quantities inside the porous component and thus affecting the pore-forming effect, the carbon fiber mentioned above is pretreated carbon fiber. The pretreatment steps for carbon fiber are as follows: the carbon fiber is placed in a Soxhlet extractor and washed with acetone reflux for 48 h, then rinsed with ethanol and dried in a vacuum oven at 120℃ for 2 h to reduce the influence of sizing agent and dust adhering to the surface. After the treated carbon fiber is ultrasonically dispersed for 5 h, it is placed in an oven to dry for later use.

[0127] Step 2: Preparation of Fiber

[0128] The key parameter in preparing PEEK / CNTS / NaCl composite filaments using a twin-screw extruder lies in the temperature settings of each heating zone. This directly affects the successful forming of the filament and its post-forming flexibility and printability. In this example, the temperature settings for each section of the twin-screw extruder are uniformly set as follows:

[0129] Table 7 Temperature settings for each heating zone of the twin-screw extruder

[0130]

[0131] Based on the above extrusion parameters, the prepared PEEK / CF / NaCl composite filament is as follows: Figure 7 As shown, the filaments were stored in a 60℃ oven after preparation.

[0132] Step 3: Sample Preparation

[0133] The sample was prepared by FDM printing using PEEK / CNTS / NaCl composite filament. The FDM process parameters were as follows: nozzle diameter 0.8 mm, nozzle temperature 430℃, printing speed 60 mm / s, and printing layer thickness 0.2 mm.

[0134] Step 4: Sample Post-processing

[0135] The sample obtained in step three was cleaned by water washing to remove the pore-forming agent inside the sample. The specific method is as follows: the printed device model was placed in an ultrasonic cleaner for 48 hours, during which time it was stirred with an electric stirrer. Finally, the sample was taken out and dried at low temperature in an oven at 120°C for 5 hours. The obtained sample was then subjected to a laser confocal test. Figure 8 The microstructure morphology of a PEEK-based porous sample with a CNTS mass fraction of 0.5% is shown in the figure. As can be seen from the figure, NaCl still retains its excellent pore-forming ability after in-situ removal. The PEEK-based porous material has a relatively uniform framework and the pores are clearly visible.

[0136] Step 5: Heat treatment of the sample

[0137] To further improve the mechanical and tribological properties of the material, the prepared samples were heat-treated. For porous components with PEEK as the matrix material, the holding temperature, holding time, and heating rate are the three key factors affecting the overall performance of the molded parts. The heat treatment process parameters are as follows: the oven heating rate was set to 8℃ / min, the temperature was raised to 260℃ and held for 90 min, then the temperature was raised to 300℃ at a rate of 8℃ / min and held for 2 h. After removal, the samples were allowed to cool naturally, thus obtaining the heat-treated composite material samples.

[0138] Step Six: Oil Immersion Treatment

[0139] The treated composite material sample was immersed in lubricating oil and placed in a vacuum chamber for 11-13 hours to obtain a porous self-lubricating sample.

[0140] Self-lubricating performance test

[0141] Frictional properties are a key indicator for evaluating the performance of self-lubricating materials. To ensure that the porous structural component in this example meets the application requirements under harsh and complex conditions such as aerospace service environments, the tribological properties under both dry friction and lean-oil lubrication conditions are studied. The tribological properties of the samples before and after heat treatment were tested using an HT-1000 high-temperature friction and wear testing machine manufactured by Lanzhou Zhongke Kaihua Technology Development Co., Ltd. Test conditions: grinding ball material was 9Cr18, diameter was 5mm; applied load was 5N; friction radius was 5mm; rotation speed was set to 400r / min; test time was 30min. The friction coefficient values ​​output by the equipment were averaged to obtain the friction coefficient of different samples.

[0142] For comparison, dense PEEK samples and porous samples without carbon nanotubes were prepared under the same process conditions. Their average friction coefficients were as follows: Under dry friction conditions, the average friction coefficient of sample #1 was 0.29, and that of sample H1# was 0.263; under lean lubrication conditions, the average friction coefficient of sample #1 was 0.104, and that of sample H1# was 0.072. For porous samples without carbon nanotubes (samples #2 and H2#), under dry friction conditions, the average friction coefficient of sample #2 was 0.366, and that of sample H2# was 0.286; under lean lubrication conditions, the average friction coefficient of sample #2 was 0.061, and that of sample H2# was 0.048.

[0143] In this example, the results are as follows: under dry friction conditions, the average friction coefficient of the untreated 3#CNTS sample is 0.245, and the average friction coefficient of the H3#CNTS sample is 0.225; under lean lubrication conditions, the average friction coefficient of the 3#CNTS sample is 0.057, and the average friction coefficient of the H3#CNTS sample is 0.043.

[0144] The average friction coefficient values ​​mentioned above can be summarized in Table 8 below:

[0145] Table 8. Average friction coefficients of various samples under different lubrication conditions

[0146]

[0147] Comparing the average friction coefficient results of dense PEEK samples and samples without carbon nanotubes, it is easy to see that the porous structure and the addition of carbon nanotubes with a mass fraction of 0.5% endow the material with better dry friction performance and lean oil lubrication performance.

[0148] Example 5: Preparation of a PEEK / CNTS / NaCl composite material with a CNTS mass fraction of 1% and a pore-forming agent mass fraction of 50%.

[0149] The difference from Example 4 is that the amount of carbon nanotubes weighed is 1 wt%.

[0150] Self-lubricating performance test

[0151] Tribological properties are a key indicator for evaluating the performance of self-lubricating materials. To ensure that the porous structure in this example meets the application requirements under harsh and complex conditions such as aerospace service environments, the tribological properties under both dry friction and lean-oil lubrication conditions are studied. The tribological properties of the samples before and after heat treatment were tested using an HT-1000 high-temperature friction and wear testing machine manufactured by Lanzhou Zhongke Kaihua Technology Development Co., Ltd. Test conditions: grinding ball material was 9Cr18, diameter was 5mm; applied load was 5N; friction radius was 5mm; rotation speed was set to 400r / min; test time was 30min. The friction coefficient values ​​output by the equipment were averaged to obtain the friction coefficient of different samples.

[0152] For comparison, dense PEEK samples and porous samples without carbon nanotubes were prepared under the same process conditions. Their average friction coefficients were as follows: Under dry friction conditions, the average friction coefficient of sample #1 was 0.29, and that of sample H1# was 0.263; under lean lubrication conditions, the average friction coefficient of sample #1 was 0.104, and that of sample H1# was 0.072. For porous samples without carbon nanotubes (samples #2 and H2#), under dry friction conditions, the average friction coefficient of sample #2 was 0.366, and that of sample H2# was 0.286; under lean lubrication conditions, the average friction coefficient of sample #2 was 0.061, and that of sample H2# was 0.048.

[0153] In this example, the results are as follows: under dry friction conditions, the average friction coefficient of the untreated 4#CNTS sample is 0.245, and the average friction coefficient of the H4#CNTS sample is 0.225; under lean lubrication conditions, the average friction coefficient of the 4#CNTS sample is 0.059, and the average friction coefficient of the H4#CNTS sample is 0.045.

[0154] The average friction coefficient values ​​mentioned above can be summarized in Table 9 below:

[0155] Table 9. Average friction coefficients of each sample under different lubrication conditions.

[0156]

[0157] Comparing the average friction coefficient results of dense PEEK samples and samples without carbon nanotubes, it is easy to see that the porous structure and the addition of 1% carbon nanotubes by mass endow the material with better dry friction performance and lean oil lubrication performance.

[0158] Example 6: Preparation of a PEEK / CNTS / NaCl composite material with a CNTS mass fraction of 3% and a pore-forming agent mass fraction of 50%.

[0159] The difference from Example 4 is that the amount of carbon nanotubes weighed is 3 wt%;

[0160] Self-lubricating performance test

[0161] Frictional properties are a key indicator for evaluating the performance of self-lubricating materials. To ensure that the porous structural component in this example meets the application requirements under harsh and complex conditions such as aerospace service environments, the tribological properties under both dry friction and lean-oil lubrication conditions are studied. The tribological properties of the samples before and after heat treatment were tested using an HT-1000 high-temperature friction and wear testing machine manufactured by Lanzhou Zhongke Kaihua Technology Development Co., Ltd. Test conditions: grinding ball material was 9Cr18, diameter was 5mm; applied load was 5N; friction radius was 5mm; rotation speed was set to 400r / min; test time was 30min. The friction coefficient values ​​output by the equipment were averaged to obtain the friction coefficient of different samples.

[0162] For comparison, dense PEEK samples and porous samples without carbon nanotubes were prepared under the same process conditions. Their average friction coefficients were as follows: Under dry friction conditions, the average friction coefficient of sample #1 was 0.29, and that of sample H1# was 0.263; under lean lubrication conditions, the average friction coefficient of sample #1 was 0.104, and that of sample H1# was 0.072. For porous samples without carbon nanotubes (samples #2 and H2#), under dry friction conditions, the average friction coefficient of sample #2 was 0.366, and that of sample H2# was 0.286; under lean lubrication conditions, the average friction coefficient of sample #2 was 0.061, and that of sample H2# was 0.048.

[0163] In this example, the results are as follows: under dry friction conditions, the average friction coefficient of the untreated 5#CNTS sample is 0.125, and the average friction coefficient of the H5#CNTS sample is 0.041; under lean lubrication conditions, the average friction coefficient of the 5#CNTS sample is 0.044, and the average friction coefficient of the H5#CNTS sample is 0.037.

[0164] The average friction coefficient values ​​mentioned above can be summarized in Table 10 below:

[0165] Table 10 Average friction coefficients of each sample under different lubrication conditions

[0166]

[0167] Comparing the average friction coefficient results of dense PEEK samples and samples without carbon nanotubes, it is easy to see that the porous structure and the addition of 3% carbon nanotubes by mass endow the material with better dry friction performance and lean oil lubrication performance.

[0168] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a reinforced polyetheretherketone porous self-lubricating material, characterized in that: The main steps include: Step 1: Drying and mixing of powder materials The dried composite powder was ground separately and then mixed with the additive powder. The mixture was stirred evenly in a ball mill and then placed in an oven to dry. The composite powder included carbon fiber or carbon nanotubes, PEEK powder, and NaCl powder. The additive powder included diisononyl cyclohexane 1,2-dicarboxylate and modified nano-calcium carbonate. The preparation method of the modified nano-calcium carbonate was as follows: nano-calcium carbonate was ultrasonically dispersed in deionized water for 30 minutes and then heated to 90°C in a water bath. The heated and molten sodium stearate was added to the slurry, and the reaction was maintained at 90°C for 2 hours. The mixture was then filtered, the filter cake was washed with hot anhydrous ethanol solution, dried, ground, and sieved to obtain modified nano-calcium carbonate. Step 2: Preparation of Fiber PEEK / CF / NaCl or PEEK / CNTS / NaCl composite filaments were prepared using a twin-screw extruder. Step 3: Sample Preparation Samples were prepared using FDM printing with PEEK / CF / NaCl or PEEK / CNTS / NaCl composite filaments. Step 4: Sample Post-processing The sample obtained in step three was cleaned using a water washing method; Step 5: Heat treatment of the sample The sample is then heat-treated to obtain a heat-treated composite material sample. Step Six: Oil Immersion Treatment The treated composite material sample was immersed in lubricating oil and placed in a vacuum chamber for 11-13 hours to obtain a porous self-lubricating sample.

2. The method for preparing a reinforced polyetheretherketone porous self-lubricating material according to claim 1, characterized in that: The carbon fiber powder and carbon nanotubes mentioned in step one are pretreated carbon fiber powder and pretreated carbon nanotubes, respectively. The pretreatment method is as follows: place the carbon fiber or carbon nanotubes in a Soxhlet extractor, reflux with acetone for 48 h, then rinse with ethanol and dry in a vacuum oven at 120℃ for 2 h. After ultrasonic dispersion of the treated carbon fiber or carbon nanotubes for 5 h, dry them in an oven for later use.

3. The method for preparing a reinforced polyetheretherketone porous self-lubricating material according to claim 1, characterized in that: In step one, after grinding the composite powders separately, NaCl is passed through a 325-mesh sieve to ensure a NaCl particle size of less than 48 μm, PEEK particles are 200 mesh, CF particles are 100 mesh, and the carbon nanotubes have the following parameters: absorbance of 30-50 nm, purity > 98%, length < 10 μm, and specific surface area > 100 m². 2 / g, ash content <1.5, COOH content is 0.

73.

4. The method for preparing a reinforced polyetheretherketone porous self-lubricating material according to claim 1, characterized in that: After the PEEK / CF / NaCl or PEEK / CNTS / NaCl composite filament is prepared in step two, it is stored in an oven at 60℃.

5. The method for preparing a reinforced polyetheretherketone porous self-lubricating material according to claim 1, characterized in that: When using PEEK / CF / NaCl composite filament in step three, the FDM printing process parameters are as follows: nozzle diameter is 1.0 mm, nozzle temperature is 420℃, printing speed is 30 mm / s, and printing layer thickness is 0.2 mm.

6. The method for preparing a reinforced polyetheretherketone porous self-lubricating material according to claim 1, characterized in that: When using a PEEK / CNTS / NaCl composite filament in step three, the FDM printing process parameters are as follows: nozzle diameter is 0.8 mm, nozzle temperature is 430℃, printing speed is 60 mm / s, and printing layer thickness is 0.2 mm.

7. The method for preparing a reinforced polyetheretherketone porous self-lubricating material according to claim 1, characterized in that: The water washing method in step four is as follows: the printed device model is placed in an ultrasonic cleaner for 48 hours, during which time it is stirred with an electric stirrer. Finally, the sample is taken out and dried in a 120°C oven for 5 hours.

8. The method for preparing a reinforced polyetheretherketone porous self-lubricating material according to claim 1, characterized in that: The heat treatment process parameters in step five are as follows: the oven heating rate is set to 8℃ / min, the temperature is raised to 260℃ and held for 90min, then the temperature is raised to 300℃ at a heating rate of 8℃ / min and held for 2h, and then the oven is taken out and cooled naturally.

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